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1994 results match your search term:
- 38999
- The 38999 is a cylindrical fiber optic connector for military applications. The 38999 is often used as an abbreviation for MIL-DTL-38999 Series I, II, III and IV Hermetic Connectors.
Learn more about 38999...
- A B Switch
- A device that accepts inputs (optical or electrical) from a primary path and a secondary path to provide automatic or manual switching in the event that the primary path signal is broken or otherwise disrupted. In optical A/B switches, optical signal power thresholds dictate whether the primary path is functioning and signals a switch to the secondary path until optical power is restored to the primary path.
Learn more about A B Switch...
- AB Switch
Learn more about AB Switch...
- ABCD Matrix
- A 2-by-2 matrix describing the effect of an optical element on a laser beam.
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- Aberration
- Deviation from what is normal, correct, or natural. In optics, aberrations may be defects in a lens system that cause its image to deviate from the rules of paraxial imagery.
Learn more about Aberration...
- Aberration Sensor
- An optical instrument with knife-edge scanning technology that can detect and measure abberations in an optical system.
Learn more about Aberration Sensor...
- Ablation Threshold
- The point at which absorbed laser energy is sufficient to break the bonds between molecules of a material.
Learn more about Ablation Threshold...
- Ablative Photodecomposition
- The phenomenon whereby pulsed ultraviolet radiation is absorbed by a material, causing excitation within and between molecules sufficient to break the molecular bonds and fragment the material without generating enough heat to cause melting or carbonization.
Learn more about Ablative Photodecomposition...
- Abrasion Mark
- Any scratch, dig, or mark on an optical surface caused by friction in polishing, mishandling, or environmental factors.
Learn more about Abrasion Mark...
- Abrasive
- A material such as silicon carbide, aluminum oxide, silica, cerium oxide, emery or rouge that is used to figure, shape, or finish optical elements. Abrasives differ from polishing materials mainly in particle size.
Learn more about Abrasive...
- Abridged Spectrophotometer
- An instrument used to measure transmission or reflection as a function of wavelength, using narrow bandpass filters rather than the more conventional dispersive element
Learn more about Abridged Spectrophotometer...
- Absorb
- To transform radiant energy into a different form, usually with a resultant rise in
temperature.
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- Absorbance
- The ability of a medium to absorb radiation depending on temperature and
wavelength. Expressed as the negative common logarithm of the transmittance.
Learn more about Absorbance...
- Absorptance
- Ratio of the absorbed radiant or luminous flux to the incident flux.
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- Absorption
- That portion of fiber optic attenuation resulting from the conversion of optical power to heat.
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- Absorption Coefficient
- The absorption coefficient ? is a property of a material. It defines the extent to which a material absorbs energy, for example that of sound waves or electromagnetic radiation. Wallace Sabine was a pioneer of this concept in acoustics and defined the unit of the Sabine. A Sabine is defined as a fraction of acoustic power absorbed by a 1m square of open window. In SI units, absorption coefficient is measured in inverse metres, and is represented by the Greek letter ?.
In chemistry and biological sciences, the absorption coefficient is a measure of the solubility of a gas in a liquid measured as the volume of the gas (taken under standard conditions) that saturates a unit volume of the liquid.
Learn more about Absorption Coefficient...
- Accelerated Aging
- The operation of a sample population of the lasers for an extended period of time under harsher conditions then those specified. These conditions are believed to accelerate degradation processes. Care must be taken not to introduce degradation processes that would not be relevant under operation within specified conditions.
Learn more about Accelerated Aging...
- Acceptance Angle
- The maximum angle within which light will be accepted by an element, such as a detector or waveguide. In the latter, it is quantified as half the vertex angle of the cone within which optical power may be coupled into bound modes of a fiber. Also called acceptance cone.
Learn more about Acceptance Angle...
- Acceptance Cone
- In fiber optics, the cone within which optical power may be coupled into the bound modes of an optical fiber. Note: The acceptance cone is derived by rotating the acceptance angle about the fiber axis.
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- Acceptance Pattern
- A curve expressing an optical fiber's total transmitted power as a function of its launch angle at the input.
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- Access Network
- Part of the telecommunication network that connects to individual and corporate users.
Learn more about Access Network...
- Acousto Optic Modulators
- Optical modulators based on the acousto-optic effect.
Learn more about Acousto Optic Modulators...
- Acousto Optic Tunable Filter
- An optical filter that can be tuned by altering the refractive index using acoustic waves in the 40- to 68-MHz frequency range.
Learn more about Acousto Optic Tunable Filter...
- Acousto Optics
- The study of the interactions between sound waves and light in a solid medium. Sound waves can be made to modulate, deflect and focus light waves, important factors in laser and holographic applications.
Learn more about Acousto Optics...
- Acoustophotorefractive Effect
- A semipermanent change in the index of refraction resulting from the interaction between high-intensity, short-duration laser pulses and propagating signal acoustic waves.
Learn more about Acoustophotorefractive Effect...
- Acrylate
- A polymer material used in optical fibers as a buffer coating or cladding or in capillary as a coating.
Learn more about Acrylate...
- Active Area
- The area of a detector with greatest response.
Learn more about Active Area...
- Active Branching Device
- A device which converts an optical input into two or more optical outputs with gain or generation.
Learn more about Active Branching Device...
- Active Device
- A device that requires a source of energy for its operation and has an output that is a function of present and past input signals. Examples include controlled power supplies, transistors, LEDs, amplifiers, and transmitters.
Learn more about Active Device...
- Active Medium
- A medium in which lasing will take place, rather than absorption, at a given
wavelength.
Learn more about Active Medium...
- Active Mode Locking
- A technique of mode locking based on active modulation of the intracavity losses or the round trip phase change.
Learn more about Active Mode Locking...
- Active Port Diameter
- On a light source or detector, the diameter of the area in which light can be coupled to or from an
optical fiber.
Learn more about Active Port Diameter...
- Active Region
- The layer of material in a laser diode from which the optical radiation is emitted.
Learn more about Active Region...
- Active Star
- An active device that connects two or more fiber optic link segments. Optical signals received on the
input fiber of any input/output port pairs are converted to electrical signals. These are relayed to the
outputs of all other input/output port pairs, and converted to optical signals which are transmitted on
the output fibers. Collisions are detected and enforced by the Active Star. An Active Star may have two
types of ports: (1) Asynchronous Ports capable of receiving FOIRL compatible signals, and (2)
Synchronous Ports that transmit and receive only those optical signals synchronized to the 10BASE-F
synchronous Active Idle signal. Synchronous ports must be used to connect Active Stars.
Learn more about Active Star...
- Acute Bisectrix
- In biaxial crystals, the principal angle that bisects the smaller angle between the optic axes.
Learn more about Acute Bisectrix...
- Adapter
- A device for coupling two connectors.
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- Adapter Sleeve
- A mechanical fixture within an adapter body that aligns and holds two terminated fiber connectors. Adapter sleeve material is typically phosphor bronze, ceramic or polymer.
Learn more about Adapter Sleeve...
- Adapters
- An adapter is a mechanical device designed to align fiber-optic connectors. It contains the split sleeve, also known as the interconnect sleeve, that holds the two ferrules together. Adapters can help mate or connect a variety of fiber optic cables together.
Learn more about Adapters...
- ADC
Learn more about ADC...
- Add Drop Multiplexing
- A multiplexing function offered in connection with SONET that allows lower level signals to be added or dropped from a high-speed optical carrier in a wire center. The connection to the add/drop multiplexer is via a channel to a central office port at a specific digital speed (DS3, DS1, etc.)
Learn more about Add Drop Multiplexing...
- Additive Pulse Mode Locking
- A technique for mode locking a laser using a nonlinear interaction in an external resonator.
Learn more about Additive Pulse Mode Locking...
- Adiabatic Soliton Compression
- A pulse compression technique based on the adaptation of solitons to slowly varying propagation parameters.
Learn more about Adiabatic Soliton Compression...
- Adjustable Attenuator
- An attenuator in which the level of attenuation is varied with an internal adjustment. Also known as
Variable Attenuator.
Learn more about Adjustable Attenuator...
- ADM
- Abbreviation for add-drop multiplexer.A device which adds or drops signals from a communications network.
Learn more about ADM...
- ADSL
- Asymmetric Digital Subscriber Line. Most common form of DSL where the data rate being transmitted to the subscriber is high than the data rate transmitted from the subscriber.
Learn more about ADSL ...
- Adsorption
- In chemistry, the taking up by the surface of a solid or liquid (adsorbent) of the atoms, ions, or molecules of a gas or other liquid (adsorbate). Porous or finely divided solids can hold more adsorbate because of the relatively large surface area exposed.
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- AEA
- American Electronics Association
Learn more about AEA...
- Aerial Plant
- Cable that is suspended in the air on telephone or electric utility poles.
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- AFCEA
- An acronym for Armed Forces Communications and Electronics Association.
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- AGC
- Abbreviation for automatic gain control. A process or means by which gain is automatically adjusted in a specified manner as a function of input level or another specified parameter.
Learn more about AGC...
- Aging
- The operation of a sample population of the lasers for an extended period of time under specified conditions.
Learn more about Aging...
- Algorithm
- A procedure for solving a mathematical problem, as of finding the greatest common divisor, in a finite
number of steps that frequently involves repetition of an operation.
Learn more about Algorithm...
- Aligned Bundle
- An assembly of fibers in which the coordinates of each fiber are the same at the two ends of the bundle. Also called coherent bundle.
Learn more about Aligned Bundle...
- Alignment Laser
- A laser, usually employing helium-neon or other gases as the active medium, used for alignment in industrial applications.
Learn more about Alignment Laser...
- Alignment Sensitivity
- The sensitivity of a laser, an optical resonator or some other device with respect to misalignment.
Learn more about Alignment Sensitivity...
- All Dieletric Cable
- Cable made entirely of dielectric (insulating) materials without any metal conductors, armor, or strength members.
Learn more about All Dieletric Cable...
- All Silica Fiber
- Also known as all-glass fiber. A fiber with both a silica core and a silica cladding, regardless of the presence of a polymer overcoat or buffer.
Learn more about All Silica Fiber...
- All Solid State Lasers
- Laser systems containing solid-state devices only.
Learn more about All Solid State Lasers...
- Alpha
- A positive number that indicates the core refractive index shape and ranges from one to infinity.
Learn more about Alpha...
- Alternate Buffer
- In a data communications device, the section of memory set aside for the transmission or receipt of data after the primary buffer is full. This helps the device control the flow of data so transmission is not interrupted because there's no place to put the incoming or outgoing data.
Learn more about Alternate Buffer...
- AM
- Abbreviation for amplitude modulation. A transmission technique in which the amplitude of the carrier varies in accordance with the signal.
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- Ambient Temperature
- The average or mean temperature of the surrounding air, which comes in contact with the equipment and instruments under test.
Learn more about Ambient Temperature...
- Amp
- An abbreviation for ampere.
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- Amplification
- The growth of the radiation field in the laser resonator cavity. As the light wave bounces back and forth between the cavity mirrors, it is amp stimulated emission on each pass through the active medium.
Learn more about Amplification...
- Amplification Factor
- The factor by which the power of a signal is amplified.
Learn more about Amplification Factor...
- Amplified Spontaneous Emission
- A background noise mechanism common to all types of erbium-doped fiber amplifiers (EDFAs). It contributes to the noise figure of the EDFA which causes loss of signal-to-noise ratio (SNR).
Learn more about Amplified Spontaneous Emission...
- Amplifier
- A device that enlarges and strengthens a signal's output without significantly distorting its original waveshape. There are amplifiers for acoustical, optical and electronic signals.
Learn more about Amplifier...
- Amplifier Chains
- Amplifiers consisting of several stages.
Learn more about Amplifier Chains...
- Amplifier Noise
- Noise introduced to a signal in an amplifier device.
Learn more about Amplifier Noise...
- Amplitude
- The maximum value of the electromagnetic wave, measured from the mean to the extreme; in other words, the height of the wave.
Learn more about Amplitude...
- Amplitude Modulated Sensor
- A type of fiber optic sensor that detects alteration in position, distance, pressure, liquid level or temperature by transmitting light across a gap to a reflector; a change in the light returned to the sensor indicates a change in the position of the reflector, hence a change in the parameter being measured.
Learn more about Amplitude Modulated Sensor...
- Amplitude Modulation
- A transmission technique in which the amplitude of the carrier varies in accordance with the signal.
Learn more about Amplitude Modulation...
- Amplitude Squeezed Light
- Light with an intensity noise below the shot noise level.
Learn more about Amplitude Squeezed Light...
- Analog
- Signals that are continually changing, as opposed to being digitally encoded.
Learn more about Analog...
- Analog Signal
- An electrical signal that varies continuously over an infinite range of voltage or current values, as
opposed to a digital signal, which varies discretely between two values, usually one and zero. It is easiest to think of analog signals as sine waves or various sizes. Compare with Digital Signal.
Learn more about Analog Signal...
- Analog to Digital Converter
- A device that converts an analog signal, that is, a signal in the form of a continuously variable voltage or current, to a digital signal, in the form of bits.
Learn more about Analog to Digital Converter...
- Angle of Deviation
- In optics, the net angular deflection experienced by a light ray after one or more refractions or reflections.
Learn more about Angle of Deviation...
- Angle of Incidence
- The angle between an incident ray and the normal to a reflecting or refracting surface.
Learn more about Angle of Incidence...
- Angle of Refraction
- The angle formed between a refracted ray and the normal to the surface. This angle lies in a common
plane with the angle of incidence.
Learn more about Angle of Refraction...
- Angled Physical Contact
- A style of fiber optic connector with a 5°-15° angle on the connector tip for the minimum possible backreflection.
Learn more about Angled Physical Contact...
- Angstrom
- A unit of length in optical measurements where
1Å = 10-10 meters, or 10-4 micrometers, or = 10-1 nanometers.
The angstrom has been used historically in the field of optics, but it is not as SI (Système Internationale or International System) unit. Rarely used in fiber optics; nanometers is preferred.
Learn more about Angstrom...
- Angular Misalignment
- Loss at a connector due to fiber end face angles being misaligned.
Learn more about Angular Misalignment...
- Angular Misalignment Loss
- The optical power loss caused by angular deviation from the optimum alignment of source to optical
fiber, fiber-to-fiber, or fiber-to-detector. See also: Extrinsic Joint Loss; Intrinsic Joint Loss; Lateral Offset Loss.
Learn more about Angular Misalignment Loss...
- Angular Tilt
- The angle formed by the axes of two fibers to be joined. Angular tilt causes an extrinsic loss that
depends upon the joining hardware and method.
Learn more about Angular Tilt...
- Annealing
- The process of heating and slowly cooling a solid material, like glass or metal, to stabilize its thermal, electrical or optical properties or, as in semiconductor materials, to reverse lattice damage resulting from ion implantation of dopants.
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- Annealing Furnace
- An oven or furnace that possesses the design requirements and heat control necessary to anneal glass for the optical industry.
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- Anode
- An electrical element in laser excitation, which attracts electrons from a cathode.
Learn more about Anode...
- ANSI
- An acronym for American National Standards Institute.
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- Anti Reflection Coatings
- Used on the backs of laser output mirrors to suppress unwanted multiple reflections, which reduce power.
Learn more about Anti Reflection Coatings...
- Anti Reflection Coatings
- Optical thin-film coatings for reducing reflections from surfaces.
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- Antiguide
- A waveguide that has a core with a lower refractive index than the refractive index of the cladding. This structure can limit the power of the transmitted beam by removing unwanted radiation, for example, by allowing higher-order modes of laser light to escape while lower-order modes continue propagating through the core.
Learn more about Antiguide...
- APC
- Abbreviation for angled physical contact. A style of fiber optic connector with a 5°-15° angle on the connector tip for the minimum possible backreflection.
Learn more about APC...
- APC Angled Physical Contact
- An abbreviation for angled physical contact.
Learn more about APC Angled Physical Contact...
- APD
- Abbreviation for Avalanche Photodiode. A photodiode that exhibits internal amplification of photocurrent through avalanche multiplication of carriers in the junction region.
Learn more about APD...
- Aperature
- Area of a fiber core which will accept light entry, also known as light acceptance.
Learn more about Aperature...
- Apertometer
- An instrument designed to measure the numerical aperture of an objective.
Learn more about Apertometer...
- APF
- An abbreviation for All Plastic Fiber.
Learn more about APF...
- APOMA
- An acronym for American Precision Optics Manufacturers Association.
Learn more about APOMA...
- AR Coating
- Antireflection coating. A thin, dielectric or metallic film applied to an optical surface to reduce its reflectance and thereby increase its transmittance.
Learn more about AR Coating...
- Aramid Yarn
- An ingredient in optical fiber cable that provides support, protection and tensile strength. Also referred to as Kevlar- a brand of aramid yarn.
Learn more about Aramid Yarn...
- Architecture
- The manner in which hardware or software is structured. Architecture typically describes how the system or program is constructed, how its components fit together; also refers to the protocols and interfaces modules or components of the system. Network architecture defines the functions and
description of data formats and procedures used for communication between nodes or workstations.
Learn more about Architecture...
- Argon Ion Lasers
- Gas lasers based on light amplification in ionized argon in a gas discharge.
Learn more about Argon Ion Lasers...
- Armadillo Cable Assembly
- A ruggedized duplex fiber optic cable assembly featuring rigid plastic connector shell and integrated strain relief boot.
Learn more about Armadillo Cable Assembly...
- Armadillo Loopback
- A ruggedized fiber optic test adapter designed to loop a signal from the Tx side of a port to the Rx side, simulating a complete connection.
Learn more about Armadillo Loopback...
- Armor
- Of a communications cable, a component intended to protect the critical internal components, e.g., buffer tubes or fibers, or electrical conductors, from damage from external mechanical attack, e.g., rodent attack or abrasion.
Learn more about Armor...
- Arrayed Waveguide Grating
- An array of curved planar waveguides that separates many optical channels at once. Also called Waveguide Array. A device, built with silicon planar lightwave circuits (PLC), that allows multiple wavelengths to be combined and separated in a dense wavelength-division multiplexing (DWDM) system.
Learn more about Arrayed Waveguide Grating...
- ASCII
- Abbreviation for American standard code for information interchange. An encoding scheme used to interface between data processing systems, data communication systems, and associated equipment.
Learn more about ASCII...
- ASE
- A background noise mechanism common to all types of erbium-doped fiber amplifiers (EDFAs). It contributes to the noise figure of the EDFA which causes loss of signal-to-noise ratio (SNR).
Learn more about ASE...
- ASI
- An acronym for American Standards Institute.
Learn more about ASI...
- ASIC
- Abbreviation for application-specific integrated circuit. A custom-designed integrated circuit.
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- ASTM
- Abbreviation for American Society for Testing and Materials. An organization that provides a forum for the development and publication of voluntary consensus standards for materials, products, systems, and services that serve as a basis for manufacturing, procurement, and regulatory activities.
Learn more about ASTM...
- Async
- A mode of data transmission wherein the occurrence of each character is not related to a fixed time
frame of reference. Compare with synchronous transmission.
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- Asynchronous
- Data that is transmitted without an associated clock signal. The time spacing between data characters or blocks may be of arbitrary duration. Opposite of synchronous.
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- Asynchronous Transfer Mode ATM
- A method of data multiplexing that can provide large, instantaneous bandwidths for busy traffic while permitting slow traffic to use that bandwidth between bursts. Very short, fixed-length packets or cells are used to transmit information. Its basic cell is 53 bytes long.
Learn more about Asynchronous Transfer Mode ATM...
- Asynchronous Transmission
- A mode of data transmission whereby each bit of information is generated separately with some stop/start code to indicate the interval between bits.
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- ATC
- An abbreviation for Automatic Temperature
Compensation. Temperature compensation using APC circuit.
Learn more about ATC...
- ATDM
- An abbreviation for asynchronous time division multiplexing.
Learn more about ATDM...
- ATE
- Abbreviation for automatic test equipment. Test equipment computer programmed to perform a number of test measurements on a device without the need for changing the test setup.
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- ATM
- An abbreviation for asynchronous transfer mode.
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- Atomic Absorption Spectrophotometer
- An instrument used to analyze the sharp resonance line of a sample that, in a flame, emits an atomic
vapor. It consists essentially of a light source, a combustion system, a monochromator, a
photomultiplier and an electronic readout system.
Learn more about Atomic Absorption Spectrophotometer...
- Attenuation
- The reduction in optical power as it passes along a fiber, usually expressed in decibels (dB). See optical loss.
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- Attenuation Coefficient
- Characteristic of the attenuation of an optical fiber per unit length, in dB/km.
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- Attenuation Constant
- The real part of the axial propagation constant for a particular mode. The attenuation coefficient for the mode power is twice the attenuation constant.
Learn more about Attenuation Constant...
- Attenuation Limited Operation
- The condition in a fiber optic link when operation is limited by the power of the received signal (rather than by bandwidth or distortion).
Learn more about Attenuation Limited Operation...
- Attenuation Limited Power
- In fiber optics, the limitation on performance imposed by the amplitude of a received signal rather than distortion.
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- Attenuation Meter
- A device used to measure power loss in fiber optic connectors, cables, or systems.
Learn more about Attenuation Meter...
- Attenuation-Limited Operation
- The condition in a fiber optic link when operation is limited by the power of the received signal (rather than by bandwidth or distortion).
Learn more about Attenuation-Limited Operation...
- Attenuator
- A device that reduces signal power in a fiber optic link by inducing loss.
Learn more about Attenuator...
- Autocorrelators
- Devices for measuring the intensity or field autocorrelation function of light, mostly used for determining the duration of ultrashort pulses.
Learn more about Autocorrelators...
- Automatic Gain Control
- A method of producing an essentially constant output signal from an electronic circuit despite variations in the strength of the input signal.
Learn more about Automatic Gain Control...
- Automatic Optical Inspection
- A system for automatic industrial process control or measurement, consisting of an optical module for image acquisition, a segmentation processor to isolate the image from its background, and an image analysis processor.
Learn more about Automatic Optical Inspection...
- Automatic Power Control Circuit
- A circuit that controls the operation of a laser diode to ensure constant power. The output power of a laser diode decreases as ambient temperature rises and
vice versa.
Learn more about Automatic Power Control Circuit...
- Automatic Temperature Compensation
- Temperature compensation using APC circuit.
Learn more about Automatic Temperature Compensation...
- Avalanche Multiplication
- A current-multiplying phenomenon that occurs in a semiconductor photodiode that is reverse-biased just below its breakdown voltage.
Learn more about Avalanche Multiplication...
- Avalanche Photodiode
- A photodiode that exhibits internal amplification of photocurrent through avalanche multiplication of carriers in the junction region.
Learn more about Avalanche Photodiode...
- Average Power
- The average over time of a modulated signal. The average power (often simply called "power" when the context makes it clear) is the average amount of work done or energy transferred per unit time. Fiber optic power meters are instruments that measure the average power of a continuous light beam. They are used to test signal power in fiber optic networks.
Learn more about Average Power...
- Average Wavelength
- The average of the two wavelengths for which the peak optical power has dropped to half.
Learn more about Average Wavelength...
- AWG
- Abbreviation for American Wire Gauge. Based on a circular mil system. 1 mil equals .001 inch. Used to determine the size of conductors.
Learn more about AWG...
- AWG
- Abbreviation for Arrayed Waveguide Grating. An array of curved planar waveguides that separates many optical channels at once. Also called Waveguide Array. A device, built with silicon planar lightwave circuits (PLC), that allows multiple wavelengths to be combined and separated in a dense wavelength-division multiplexing (DWDM) system.
Learn more about AWG...
- Axial Misalignment Loss
- The optical power loss caused by two fiber axes that are parallel but not on the same central axis.
Learn more about Axial Misalignment Loss...
- Axial Propagation Constant
- In an optical fiber, the propagation constant evaluated along the optical axis of the fiber in the direction of transmission. Note: The real part of the axial propagation constant is the attenuation constant. The imaginary part is the phase constant.
Learn more about Axial Propagation Constant...
- Axial Ray
- A light ray that travels along the optical fiber's axis.
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- AXIS
- A straight line, real or imaginary, passing through a body and indicating its center; a line so positioned that various portions of an object are located symmetrically in relation to the line. See also optical axis.
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- B Constant
- Thermistor constant used in temperature sensor when ATC is operating.
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- B Integral
- Calculates the exponential growth of the least stable spatial frequency in a laser beam, and is the numerical equivalent of the nonlinear phase shift along the laser system's optical axis.
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- Back Channel
- A channel for communication with the source in an otherwise unidirectional network, such as a channel that provides interactive features in a cable television network.
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- Back Reflection Optical Return Loss
- Light reflected from the cleaved or polished end of a fiber caused by the difference of refractive indices of air and glass. Typically 4% of the incident light. Expressed in dB relative to incident power. See also narcissus.
Learn more about Back Reflection Optical Return Loss...
- Backbone
- A transmission network that carries high speed telecommunications between locations. This is normally the main portion of a telecommunication network, with branches going to individual buildings. In a local area network, this is usually the link between routers, switches, and bridges.
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- Backbone Cabling
- The inter-building and intra-building cable connections between entrance facilities, equipment rooms and telecommunications closets. Backbone cabling consists of the transmission media, main and intermediate cross-connects and terminations at these locations.
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- Backbone System
- A transmission network that carries high-speed telecommunications between regions (e.g., a nationwide long-distance telephone system). Sometimes used to describe the part of a local area network that carries signals between branching points.
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- Backreflection (BR)
- In cases where light is launched into an optical fiber, backreflection refers to the light that is returned to the launch point.
Learn more about Backreflection (BR)...
- Backscattering
- The scattering of light in a fiber back toward the source, used to make OTDR measurements.
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- Balanced
- Signaling code with an equal number of high and low states.
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- Bandgap
- In a semiconductor material, the minimum energy necessary for an electron to transfer from the valence band into the conduction band, where it moves more freely.
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- Bandpass
- The range of frequencies that will pass through a filter or other device. Synonymous with passband.
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- Bandpass Filter
- A filter with a transmission that is high for a particular band of frequencies, but that falls to low values above and below this band.
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- Bandwidth
- The information carrying capacity of the system. In analog systems, this is also the highest frequency that can be carried.
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- Bandwidth BW
- The range of signal frequencies or bit rate within which a fiber optic component, link or network will operate.
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- Bandwidth Distance Product
- Of an optical fiber, under specified launching and cabling conditions, at a specified wavelength, a figure of merit equal to the product of the fiber's length and the 3-dB bandwidth of the optical signal.
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- Bandwidth Limited Operation
- In fiber optics, the limitation on performance imposed by the system bandwidth rather than the amplitude of the signal.
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- Bandwidth Limited Pulses
- Pulses with a duration as short as possible with their optical spectrum.
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- Barrier Layer
- In the fabrication of an optical fiber, a layer that can be used to create a boundary against OH-ion diffusion into the core.
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- Baseband
- The simplest method of transmission on a local area network. The entire bandwidth of the cable is used to transmit a single unmodulated digital signal. Baseband transmission is capable of accommodating multiple signals through time division multiplexing. The alternative to baseband transmission is broadband.
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- Baud
- The number of signal level transitions per second in digital data. The term is often confused with bits per second. Telecommunications specialists prefer to use "bits-per-second" to provide an accurate description.
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- Baud Rate
- Measurement of data transmission speed, expressed in bits per second or bps.
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- Bayonet Coupling
- A quick coupling device for plug and receptacle connection, designed to lock a connector into an
adapter or receptacle. An example is an ST® connector.
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- BB I
- Abbreviation for broadband interactive services. The delivery of all types of interactive video, data and voice services over a broadband communications network.
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- Beacon Token Process
- A process defined by SMT used to locate ring failures. When a station notes such a failure, it enters the beacon process and begins to continuously transmit "beacon frames". The location will continue to transmit unless it receives a beacon from a station "upstream", in which case it will stop sending its own beacon and repeat the beacon from the upstream station. Soon, only one station, the station immediately "downstream" from the failure, will be beaconing. When a beaconing station receives its own beacon, it indicates that the ring has been restored and that station will stop beaconing and issue a claim.
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- Beam Attenuator
- A device designed to decrease flux density or power per unit area of a light beam through absorption and scattering of the beam.
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- Beam Bender
- A mirror used to manipulate the beam in a laser system.
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- Beam Combining
- A class of techniques for power scaling of laser sources by combining the outputs of multiple devices.
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- Beam Diameter
- The distance between two diametrically opposed points at which the irradiance is a specified fraction of the beam's peak irradiance; most commonly applied to beams that are circular or nearly circular in cross section. Synonym: Beamwidth.
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- Beam Divergence
- The increase in beam diameter with increase of distance from the source.
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- Beam Expander
- A system of optical components designed to increase the diameter of a radiation beam.
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- Beam Optics
- A discipline within the broad study of optics that is specifically oriented toward the investigation of waves with small angular divergence.
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- Beam Parameter Product
- Product of the beam radius in a focus and the far-field beam divergence.
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- Beam Pointing Fluctuations
- Fluctuations of the propagation direction of a laser beam.
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- Beam Positioner
- A device (e.g., prisms, lenses, tubes) used to align a beam in a system.
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- Beam Profilers
- Devices for measuring the intensity profile of a laser beam.
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- Beam Quality
- A measure for how well a laser beam can be focused.
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- Beam Radius
- A measure of the transverse extension of a light beam.
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- Beam Shapers
- Optical devices for modifying the shapes of laser beams.
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- Beam Waist
- Location with minimum beam radius.
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- Beamsplitter
- An optical device for dividing for dividing a beam into two or more separate beams. A simple beamsplitter may be a very thin sheet of glass inserted in the beam at an angle to divert a portion of the beam in a different direction. A more sophisticated type consists of two right-angle prisms cemented together at their hypotenuse faces. The cemented face of one prism is coated, before cementing, with a metallic or dielectric layer having the desired reflecting properties, both in percentage of reflection and desired color.
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- Beamsplitting Block
- A glass block that produces stationary fringes in the region crossed by incident light beams.
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- Beat
- The signal formed when two signals, such as light waves, of different frequencies are present simultaneously in a nonlinear device. The frequency of the beat is equal to the difference in frequency of the two primary signals. Beats also are produced in superheterodyne receivers, where the beat is between the incoming signal and the local oscillator in the receiver.
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- Beat Length
- A characteristic of optical fiber used to calculate the fiber's ability to maintain polarization. The beat length describes the length required for the polarization to rotate 360 degrees. For a given wavelength, it is inversely proportional to the fiber's birefringence.
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- Beat Note
- An oscillation of the optical intensity arising from the superposition of light with different optical frequencies.
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- Beauty Defect
- A defect on or in an optical element that does not appreciably impair the function of the surface.
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- Bel (B)
- The logarithm to the base 10 of a power ratio, expressed as B = log10(P1/P2), where P1 and P2 are distinct powers.The decibel, equal to one-tenth bel, is a more commonly used unit.
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- Bend Loss
- 1. A form of increased attenuation in a fiber that results from bending a fiber around a restrictive
curvature (a macrobend) or from minute distortions in the fiber (microbends). 2. A form of increased
attenuation caused by allowing high order modes to radiate from the walls of a fiber optic cable. There are 2 common types of bend losses. The first type results when the fiber optic cable is curved through a restrictive radius or curvature. The second type is generally referred to as microbends. It is caused by small distortions of the fiber optic cable imposed by externally induced perturbations as, for example, slip shod cabling techniques.
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- Bend Radius
- The radius of curvature that an optical fiber can bend without sustaining damage.
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- Bending of Light
- The action occurring when light passes through an optical interface at other than normal incidence, i.e., refraction.
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- BER Bit Error Rate
- Bit Error Rate. The number of bit errors that occur within the space of one second. This measurement is one of the prime considerations in determining signal quality. The higher the data transmission rate the greater the standard. A DS-1 signal is considered acceptable with a BER of 10-6, but an OC-3 signal requires a BER of no more than 10-12.
In telecommunication transmission, the bit error rate (BER) is the percentage of bits that have errors relative to the total number of bits received in a transmission, usually expressed as ten to a negative power. For example, a transmission might have a BER of 10 to the minus 6, meaning that, out of 1,000,000 bits transmitted, one bit was in error. The BER is an indication of how often data has to be retransmitted because of an error. Too high a BER may indicate that a slower data rate would actually improve overall transmission time for a given amount of transmitted data since the BER might be reduced, lowering the number of packets that had to be resent.
A BERT (bit error rate test or tester) is a procedure or device that measures the BER for a given transmission.
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- BER Floor
- A limiting of the bit-error ratio (BER) in a digital fiber optic system as a function of received power due to the presence of signal degradation mechanisms or noise.
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- Bias
- (1) To influence to a single direction; (2) Voltage that is applied to a solid-state
device.
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- Biconic
- A connector type which has a taper sleeve which would be fixed to the fiber optic cable. When this plug was inserted into its receptacle the tapered end was a means for locating the fiber optic cable in the proper position. With this connector cap, fit over the ferrules, rest against guided rings and screw onto the threaded sleeve to secure the connection. This was one of the earliest connectors used in fiber optic systems but is in little use at present.
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- Biconic Connector
- A type of fiber optic connector consisting of two cone-shaped ferrules aligned by a mating sleeve.
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- BIDI
- Abbreviation for bidirectional transceiver, a device that sends information in one direction and receives information from the opposite direction.
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- Bidirectional
- The ability for light to transmit in both directions through a fiber.
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- Bifurcated Fiber
- A branched fiber optic lightguide that performs both receiving and transmitting functions.
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- Binary
- A numbering system that allows only two values, zero and one, '0' and '1'. Binary is the way most
computers store information, in combination of ones and zeros. Voltage on. Voltage off. See also: Bit.
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- Birefringence
- The separation of a light beam, as it penetrates a doubly refracting object, into two diverging beams, commonly known as ordinary and extraordinary beams.
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- Birefringent
- Having a refractive index that differs for light of different polarizations.
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- Birefringent Phase Matching
- A technique of phase matching based on the birefringence of a crystal material.
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- Birefringent Tuners
- Device for wavelength tuning of lasers based on birefringence and polarization rotation.
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- BISDN
- An abbreviation for broadband integrated services digital network.
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- Bit
- An electrical or optical pulse that carries information.
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- Bit Depth
- The number of levels that a pixel might have, such as 256 with an 8-bit depth or 1,024 with a 10-bit depth.
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- Bit Error Rate (BER)
- In digital applications it is the ratio of bits received in error to bits sent. BERs of 10-9 (one error bit to a billion sent) are common.
Learn more about Bit Error Rate (BER)...
- Bit Period (T)
- The amount of time required to transmit a logical one or a logical zero.
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- Bit Rate
- 1. The number of bits of data transmitted over a phone line per second. You can usually figure how
many characters per second you will be transmitting, in synchronous communications, if you divide the bit rate by ten. The total bits transmitted will depend on re-transmissions, which depends on the noise of the line, etc. 2. The number of bits of data transmitted per second over a communications link. This usually represented as BPS (bps) with KBPS (Kbps) standing for kilo bits per second (1000 BPS) and MBPS standing for mega bits per second (million BPS) and GBPS standing for giga bits per second
(billion BPS) etc.
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- BITE
- Abbreviation for built-in test equipment.Features designed into a piece of equipment that allow on-line diagnosis of failures and operating status.
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- Block
- A collection of transmitted information which is seen as a discrete entity. Usually has its own address, control, routing and error checking information. See also packet and packet switching.
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- Blocking
- A connection can't be made. A call can't be completed. These are many reasons for blocking.
Sometimes not enough equipment. Sometimes not sufficient lines, or sufficient room on the lines.
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- Blue Lasers
- Lasers emitting blue light.
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- BNC
- Popular coax bayonet style connector, often used for baseband video.
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- Bound Mode
- In an optical fiber, a mode that (a) has a field intensity that decays monotonically in the transverse direction everywhere external to the core and (b) does not lose power to radiation.
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- BPON
- An abbreviation for broadband on passive optical network.
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- Bps
- Bits per second. Term used by telecommunication engineers to describe bandwidth. Bytes per second is the term used by software engineers to describe bandwidth.
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- Bragg Grating
- A filter that separates light into many colors via Bragg's law. Generally refers to a fiber Bragg grating used in optical communications to separate wavelengths.
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- Bragg Method of Crystal Analysis
- A technique in which a beam of x-rays is directed against a crystal, the atoms of which, because of their lattice arrangement, reflect the ray in the same way as a series of plane surfaces. If the wavelength of the x-rays is known, the measurements of the diffraction patterns formed by the reflected radiations provide a means of calculating the distances between the atomic planes.
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- Bragg Mirrors
- Mirror structures based on Bragg reflection at a period structure.
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- Bragg Scattering
- Scattering of light caused by a change in refractive index, as used in Fiber Bragg Gratings and Distributed Bragg Reflectors.
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- Bragg's Law
- The law expressing the condition under which a crystal will reflect a beam of x-rays with the greatest amount of distinction or resolution and, at the same time, denoting the angle at which the reflection occurs.
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- Braid
- An essential part of many fiber-optic cable designs, consisting of a layer of woven yarn. Note: In the case of single-fiber loose-buffered or two-fiber "zip-cord" loose-buffered fiber-optic cables, the braid is situated between the buffer tube and jacket. In the case of cables having multiple buffer tubes, the braid is usually situated between the inner jacket and outer jacket.
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- Break Out
- To separate the individual fibers or buffer tubes of a fiber-optic cable for the purpose of splicing or installing optical connectors.
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- Break Out Cable
- Same as a Fan Out cable. This is a multiple fiber optic cables constructed in the tight buffered design. It is designed for ease of connectorization and rugged applications for intra-building and inter-building requirements.
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- Break Out Kit
- Used to build up the outer diameter of fiber cable for connecting.
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- Breakdown Voltage
- In avalanche photodiodes, the point at which an increase in the reverse bias voltage causes the current gain to approach infinity.
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- Breakout Cable
- A type of fiber optic cable containing several fibers, each with its own jacket and all of them surrounded by one common jacket. Breakout cables are designed for convenient installation of fiber optic connectors but tend to have high transmission losses due to bends in the fibers.
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- Brewster Plates
- Coplanar plates inserted into beams at Brewster's angle.
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- Brewster Windows
- Transparent plates which are oriented at Brewster's angle.
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- Bridge
- A MAC-level store-and-forward network node. Bridges are used to interconnect LAN segments, thus
creating extended LANs. They filter (drop) or forward frames to other LAN segments based on the
frame destination and source address.
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- Brightness
- The visual sensation of the luminous power of a light beam, as opposed to scientifically measured power of the beam.
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- Brightness Converters
- Optically pumped devices where the generated optical output has a higher brightness than the optical pump source.
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- Brillouin Scattering
- A nonlinear scattering effect involving acoustic phonons.
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- Broad Area Laser Diodes
- Laser diodes with a strongly asymmetric shape of the emitting region.
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- Broadband
- Indicating a capability to deal with a relatively wide spectral bandwidth; high-speed data transmission in which a single cable can carry a large amount of data at once.
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- Broadband LAN
- LAN which uses FDM (frequency division multiplexing) to divide a single physical channel into a number of smaller independent frequency channels. The different channels created by FDM can be used to transfer different forms of information - voice, data, and video.
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- Broadcast Transmission
- Sending the same signal to many different places, like a television broadcasting station. Broadcast transmission can be over optical fibers if the same signal is delivered to many subscribers.
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- Buffer
- A protective coating applied directly on the fiber.
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- Buffer Coating
- A protective layer, such as an acrylic polymer, applied over the fiber cladding for protective purposes.
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- Buffer Tube
- A hard plastic tube, having an inside diameter several times that of a fiber, that holds one or more fibers.
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- Buffered Fiber
- Fiber optic cable protected with an additional material, usually hytrel or nylon, to provide ease in handling, connectorization and increased tensile strength.
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- Buffering
- It is used in two contexts: First, it refers to a protective material extruded directly on the fiber optic cable coating to protect it from the environment. Secondly, it refers to extruding a tube around the coated fiber optic cable to allow isolation of the fiber from stresses.
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- Building Entrance
- Terminal cable entrance point where typically a trunk cable between buildings is terminated and fiber is then distributed through the building.
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- Bulk Lasers
- Lasers based on bulk crystals as gain media.
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- Bundle
- A group of optical fibers or electrical conductors, such as wires and coaxial cables, usually in a single jacket. Note: Multiple bundles of optical fibers or electrical conductors may be placed in the same cable.
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- Bundle of Fibers
- A rigid or flexible group of fibers assembled in a unit. Coherent fiber bundles have fibers arranged in the same way on each end and can transmit images.
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- Burn
- A surface imperfection caused by a polisher running dry too long. It occurs with felt or plastic polishers, and may appear as a reddish brown.
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- Burn In
- The operation of a laser diode or other component prior to its use in its intended application, as a means of testing and stabilizing it.
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- Burn Through
- A detector's ability to sense an object on the opposite side of a thin but opaque barrier such as cardboard.
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- Burst Mode Laser
- A high-frequency pulse-rate laser with an output limited by the heat capacity of the laser medium. Instead of having continuous cooling, the laser operates until the medium reaches a maximum acceptable temperature, then shuts off and is aggressively cooled before repeating the cycle.
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- Bus
- Wiring or cables that carry signals around inside a computer, or between computers and other devices.
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- Bus Network
- A network topology in which all terminals are attached to a transmission medium serving as a bus. All other terminals receive all signals transmitted from a terminal connected to the bus.
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- Butt Splice
- A joining of two fibers without optical connectors arranged end-to-end by means of a coupling. Fusion splicing is an example.
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- Bypass
- The ability of a station to isolate itself optically from a network while maintaining the continuity of the cable plant.
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- Bypass
- The ability of a saturation to isolate itself optically from a network while maintaining the continuity of the cable plant.
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- Bypass Switch
- An FDDI station option that ensures ring integrity. The bypass switch has a default state when power is lost. When a power failure occurs, optical connections are made within the DAS that reconnect the incoming primary ring fiber with the primary ring fiber. Similar connections are made on the secondary ring. This allows network operation to continue without the need for reconfiguration, which can still be employed for emergency situations.
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- Byte
- A unit of 8 bits.
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- C Band
- A range of wavelengths from 1530 to 1565 nm. In this region, erbium-doped amplifiers (EDFAs) have highest gain. See EDFA and optical bands.
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- Cable
- One or more fibers enclosed in protective coverings and strength members.
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- Cable Assembly
- An optical fiber cable that has connectors installed on one or both ends.
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- Cable Bend Radius
- Cable bend radius during installation infers that the cable is experiencing a tensile load. Free bend
infers a lower allowable bend radius since it is at a condition of no load.
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- Cable Jacket
- The outermost protective covering applied over the internal cable elements (i.e., core, cladding, buffer,
and strength member).
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- Cable Plant
- The cable plant consists of all the optical elements. For example, fiber, connectors, splices, etc.
between a transmitter and a receiver.
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- Cable Television
- Communications system that distributes broadcast and non-broadcast signals as well as a multiplicity of satellite signals, original programming and other signals by means of a coaxial cable and/or optical fiber.
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- Caching
- An access-driven form of replication. Data is replicated and stored locally as it is referenced; only an initial reference to a piece of data requires access to the master copy. Updates merely invalidate the cached items.
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- Campus Bridge
- Brings a new dimension to internetworking, the ability to link LAN segments to 30 kilometers or more
via single mode fiber optic cable.
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- Carbon Dioxide Laser
- A gas laser in which the energy-state transitions between vibrational and rotational states of CO2 molecules give emission at long IR, about 10 µm, wavelengths. The laser can maintain continuous and very high levels of power.
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- Carrier Envelope Offset
- The offset between the optical phase and the maximum of the wave envelope of an optical pulse.
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- Carrier Frequency
- The electromagnetic wave frequency selected to transmit information. Optical carrier frequency is from
the infrared, visible or ultraviolet spectrum areas (1012 Hz and above).
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- Carrier Injection
- The process whereby light is emitted at the junction of N- and P-type semiconductors when an external electric source is applied to drive the electrons and the holes into the junction.
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- Carrier Sense Multiple Access With Collision Detection
- 1. A technique used to control the transmission channel of a local area network to ensure that there is
no conflict between terminals that wish to transmit. 2. A technique employed in Ethernet based LANs
to control the transmission channel. It assures that there is no conflict between terminals that wish to
transmit.
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- Carrier Signal
- A continuous waveform (usually electrical) whose properties are capable of being modualted or
impressed with a second information carrying signal. The carrier itself conveys no information until
altered in some fashion, such as having its amplitude changed (amplitude modulation), its frequency
changed (frequency modulation), or its phase changed (phased modulation). These changes convey
the information.
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- Carrier to Noise Ratio
- The ratio, in decibels, of the level of the carrier to that of the noise in a receiver's IF bandwidth before any nonlinear process such as amplitude limiting and detection takes places.
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- Cascade Amplification
- In a series of amplifiers, amplification by each of the preceding output.
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- Cascade Tube
- An instrument consisting of a high-voltage vacuum tube used to form hard x-rays or high-speed ion beams. By partitioning the tube into separate sections, the total voltage is divided.
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- Catastrophic Failure
- A failure in which the device characteristics change suddenly, generally in less
than a second.
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- Catastrophic Optical Damage
- Catastrophic optical damage occurs when the semiconductor in the emission region is melted and recrystallized.
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- Category 5e
- Category 5 (CAT5) cable is a popular twisted pair copper cable. It is used for Ethernet cable applications. Category 5e (CAT5e) can support short-run Gigabit Ethernet (1000 Mbps) networking, unlike CAT5 which supports Fast Ethernet (100 Mbps).
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- Cathode
- A negatively charged electrical element providing electrons for an electrical
discharge.
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- CATV
- An abbreviation for Community Antenna Television or cable TV.
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- Causality
- The concept of relating effects to causes, or the compatibility of phenomena with this concept.
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- Cavity
- In a laser, the optical resonator formed by two coaxial mirrors, one totally and one partially reflective, positioned so that laser oscillations occur.
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- Cavity Dumping
- A Q-switch method that can result in extreme pulse shortening.
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- CCIR
- Abbreviation for Consultative Committee on Radio.
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- CCITT
- Abbreviation for Comite Consulatif International de Telegraphic et Telephonic. An international
communications standards. Based in Geneva, Switzerland. Concerned with devising and proposing
recommendations for international telecommunications.
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- CCTV
- Abbreviation for closed-circuit television.An arrangement in which programs are directly transmitted to specific users and not broadcast to the public.
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- CDMA
- Abbreviation for code-division multiple access. A coding scheme in which multiple channels are independently coded for transmission over a single wideband channel using an individual modulation scheme for each channel.
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- Cell
- A fixed-length data packet transmitted in certain digital systems such as ATM.
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- Center Wavelength (Laser)
- 1. The nominal value central operating wavelength defined by a peak mode measurement where the
effective optical power resides. 2. The wavelength of an optical source that might be considered its
middle. One measure of this is the average of the two wavelengths corresponding to the Full Width
Half Maximum-FWHM.
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- Center Wavelength (LED)
- 1. The average of the two wavelengths measured at the half amplitude points of the power spectrum.
2. The wavelength of an optical source that might be considered its middle. One measure of this is the
average of the two wavelengths corresponding to the Full Width Half Maximum-FWHM.
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- Central Member
- The center component of a cable. It serves as an antibuckling element to resist temperature-induced
stresses. Sometimes serves as a strength element. The central member is composed of steel,
fiberglass, or glass-reinforced plastic.
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- Central Office
- 1. The place where communications common carriers terminate customer lines and locate switching
equipment that interconnects those lines. 2. The places where communications common carriers
terminate customer lines and locate switching equipment that interconnects those lines. It is the lowest
hierarchical level of a TELCO backbone network. It is from the Central office level that local loops go
out to end-user customer premises equipment.
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- Centro Symmetrical Reflective Optics
- An optical technique in which a concave mirror is used to control coupling of light from one fiber optic cable to another.
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- Ceramic Gain Media
- Laser gain media which have a ceramic microscopic structure.
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- Chalcogenide Glass
- An infrared-transmitting material used in optical fibers for applications in the wavelength region from 2 to 11 µm.
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- Channel
- 1. A communications path or the signal sent over a channel. Through multiplexing several channels,
voice channels can be transmitted over an optical channel. 2. A communications path derived from a
specific transmission medium, as for example fiber optic cables. The channel supports the end-to-end
communications of an information source and destination. Besides the transmission medium a
channel needs to have a transmitter/receiver (transceiver) and a modulator/demodulator (modem). By
multiplexing, several channels can share the same specific transmission medium. Channel is
synonymous with link. The term channel is usually employed within the context of multiplexing but not
always.
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- Channel Capacity
- Maximum number of channels that a cable system can carry simultaneously.
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- Channel Coding
- Data encoding and error correction techniques used to protect the integrity of data. Typically used in channels with high bit error rates such as terrestrial and satellite broadcast and videotape recording.
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- Channel Density
- The number of channels per unit bandwidth handled by a single optical fiber.
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- Channel Electron Multiplier
- A photoelectric detector consisting of a glass tube internally coated with a low conductance material. Voltage applied along the tube causes photoemission from the photocathode at the end of the tube exposed to the radiation, accelerating emission to the anode, which is located near the readout area. Secondary electrons are generated by collisions of the cascading electrons striking the channel walls. The device can multiply both electrons and high-energy protons.
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- Channel Impedance
- The parallel resistance and capacitance appearing between the active guard ring junctions in a silicon photodiode.
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- Channel Markers
- A/B Markers easily identify the TX and RX connector on each end of a fiber optic cable assembly. These channel markers assure that the proper connections are made between the transmitting and receiving ports of a transceiver.
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- Channel Spacing
- The amount of bandwidth allocated per channel.
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- Channel Substrate Planar Growth
- The creation of a diode laser structure by liquid-phase epitaxy over a grooved substrate.
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- Characteristic Angle
- The angle at which a given mode propagates down an optical fiber.
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- Chelate Laser
- A laser having a rare-earth chelate within a plastic host as the lasing material. The chelate laser is easily pumped and has a high quantum efficiency and narrow emission lines.
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- Chemical Laser
- A laser that relies on chemical activity instead of electrical energy to produce the pumping action necessary to form pulses of light.
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- Chemiluminescence
- Luminescence arising from chemical reactions.
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- Chirp
- In laser diodes, the shift of the laser's center wavelength during single pulse durations due to laser instability.
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- Chirped Pulse
- A pulse in which the wavelength changes during the duration of the pulse.
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- Chirped Pulse Amplification Laser
- A laser whose pulses are expanded, using gratings and optical fibers, before amplification and compressed to increase beam intensity without damage to the optical train.
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- Chromatic Bandwidth
- The inverse of the Chromatic Dispersion.
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- Chromatic Dispersion
- The temporal spreading of a pulse in an optical waveguide caused by the wavelength dependence of the velocities of light.
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- Chromium Doped Gain Media
- Laser gain media doped with chromium ions.
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- Circuit
- Originally a physical connection that transmits electricity or signals. Now also a communication channel that guarantees a fixed transmission capacity.
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- Circuit Switching
- Making temporary physical or virtual connections between two points, which guarantees a fixed transmission capacity.
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- Circular Birefringence
- The optical phenomenon in which right circularly polarized light transmitted by an active medium travels at a different velocity than that of left circularly polarized light.
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- Circular Dichroism
- The optical phenomenon in which planar polarization is converted to elliptical polarization when plane-polarized light traverses an active medium.
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- Circulator
- Passive three-port devices that couple light from Port 1 to 2 and Port 2 to 3 and have high isolation in other directions.
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- Cladding
- The low-refractive-index material that surrounds the core of an optical fiber to contain core light while protecting against surface contaminant scattering. In all glass fibers, the cladding is glass. In plastic-clad silica fibers, the plastic cladding may also serve as the coating.
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- Cladding Diameter
- In the cross section of a realizable optical fiber, ideally circular, but in practice assumed to a first approximation to be elliptical, the average of the diameters of the smallest circle that can be circumscribed about the cladding, and the largest circle that can be inscribed within the cladding.
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- Cladding Glass
- The glass that is found around the glass core of a fiber, and that has a lower refractive index that the fiber.
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- Cladding Mode
- An undesired mode that is confined to the cladding of an optical fiber by virtue of the fact that the cladding has a higher refractive index than the surrounding medium, i.e., air or primary polymer overcoat.
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- Cladding Mode Stripper
- A mechanism or device, especially a coating with a refractive index equal to or slightly greater that that of an optical fiber's cladding, that removes modes propagating through the cladding by allowing them to radiate out of the fiber.
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- Cladding Ray
- A ray that is reflected into the core of an optical fiber from the outer surface of the cladding.
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- Classification Duration
- For a laser, the maximum exposure time that the laser design allows.
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- Cleave
- The process of scoring and breaking the optical fiber end in order to terminate a connector. Also known as cleaving.
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- Cleaving
- The process of separating an optical fiber by a controlled fracture of the glass, for the purpose of
obtaining a fiber end, which is flat, smooth, and perpendicular to the fiber axis.
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- CLEO
- An acronym for Conference on Lasers and Electro-Optics.
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- Clock
- 1. An electronic component that emits consistent signals, like a metronome, that paces a computer's
operations. 2. An oscillator-generated signal that provides a timing reference for a transmission link. A
clock provides signals used in a transmission system to control the timing of certain functions, such as
the duration of signal elements or the sampling rate. It also generates periodic, accurately spaced
signals used for such purposes as timing, regulation of the operations of a processor, or generation of
interrupts. A clock has two functions: to generate periodic signals for synchronization on a
transmission facility, and to provide a time base for the sampling of signal elements. In computers, a
clock synchronizes certain procedures, such as communication with other devices.
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- Clustering
- The tendency of laser-active ions in laser gain media to form clusters in their host medium.
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- CMOS
- Abbreviation for complementary metal oxide semiconductor. A family of IC's.Particularly useful for low-speed or low-power applications.
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- CMTS
- Abbreviation for cable modem termination system.
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- CNR
- Abbreviation for Carrier-to-Noise Ratio. The ratio, in decibels, of the level of the carrier to that of the noise in a receiver's IF bandwidth before any nonlinear process such as amplitude limiting and detection takes places.
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- Coadding
- A method of improving the signal-to-noise ratio of an interferogram by adding another interferogram to it.
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- Coated Optics
- Optical elements having refracting or reflecting surfaces that have been coated with one or more layers of dielectric or metallic material. These layers serve to reduce or increase reflection and to protect the surfaces from fumes or abrasion. Magnesium fluoride, silicon oxide, and zinc sulphide are a few of the most commonly used coatings.
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- Coating
- A material put on a fiber during the drawing process to protect it from the environment.
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- Coax
- An abbreviation for coaxial cable.
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- Code
- A specific way of using symbols and rules to represent information.
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- Coder
- Digital information transformed into pulses of electricity, digitized as ones and zeros with no errors.
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- Coherence
- A term describing light as waves which are in phase in both time and space.
Monochromaticity and low divergence are two properties of coherent light.
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- Coherence Length
- That length over which energy in two separate waves remains constant. With respect to a laser, the greatest distance between two arms of an interferometric system for which suficient interferometric effects can be obtained.
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- Coherence Time
- A measure of temporal coherence, expressed as the time over which the field correlation decays.
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- Coherent Bundle
- See aligned bundle.
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- Coherent Bundle of Fibers
- Fibers packaged together in a bundle so they retain a fixed arrangement at the two ends and can transmit an image.
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- Coherent Communications
- In fiber optics, a communication system where the output of a local laser oscillator is mixed optically with a received signal, and the difference frequency is detected and amplified.
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- Coherent Light
- This is light of which all parameters are predictable and correlated at any point into time or space,
particularly over an area perpendicular to the direction of propagation or over time at a particular point
in space. Simply, coherent light usually refers to the phenomenon relating to the existence of a
correlation between the phases of the corresponding components of two light waves or to the values of
the phase of a given component at two instants in time or two points in space. Coherent light does not
occur naturally in the Universe. It can only be generated in a laser.
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- Coherent Radiation
- Radiation composed of wave trains vibrating in phase with each other. Simply expressed: parallel rays of light.
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- Coherent States
- A special kind of pure quantum-mechanical states.
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- Colliding Pulse Modelocked Ring Laser
- A ring dye laser that uses prisms and a saturable absorber within the laser cavity to shape and shorten the pulses generated. Counterpropagating modes oscillating simultaneously in the ring configuration collide coherently within the saturable absorber jet, providing stable operation.
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- Collimated Beams
- Laser beams with weak divergence.
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- Collimation
- 1. The process of aligning the optical axes of optical systems to the reference mechanical axes or surfaces of an instrument. 2. The adjustment of two or more optical axes with respect to each other.
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- Collimator
- An optical instrument consisting of a well-corrected objective lens with an illuminated slit or reticle at its focal plane. Collimators are used in lens testing to determine focal lengths, and in other metrological applications where a distant object at a known location is required.
Highly reflective and yet extremely low in secondary reflection, these devices are critical for interferometric applications. Fiber collimators are fundamental sub-components and building blocks for optical communications and broadband networks, and are widely used to covert a divergent output laser beam from a fiber or waveguide into an expanding beam of parallel light. With collimators, fiber optical components for signal transmission, switching and management can be furnished.
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- Collinear Pumping
- A method of exciting a laser by coupling it directly to another laser.
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- Collision
- The result of two work stations trying to use a shared transmission medium (cable) simultaneously
(overlapping). The electrical signals, which carry the information they are sending, bump into each
other (a collision). This ruins both signals (interference) meaning they both have to retransmit their
information. In most systems, a built in delay will make sure the collision does not occur again. The
whole process takes fractions of a second. Collisions in LANs make no sound.
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- Collision Detection
- The process of detecting that simultaneous (and therefor damaging) transmission has taken place on
a shared medium. Typically, each transmitting workstation that detects the collision will wait some
period of time and try again. Collision detection is an essential part of the CSMA/CD access method.
Workstations can tell that a collision has taken place if, having sent data, they do not receive an
acknowledgment from the receiving station.
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- Collision Detector
- An optoelectronic circuit that monitors the signals received via the fiber optic cable from the passive
Codestar and sends a "collision presence" signal to the host when more than one data signal is
detected coming for the Codestar.
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- Color Center Laser
- Certain color centers in the alkali halides have been optically pumped to produce efficient tunable pulsed and continuous-wave lasers emitting in the range of 0.8 to 3.3 µm.
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- Color Subcarrier
- The 3.58 MHz signal which carriers color information in a TV signal.
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- Combiner
- A passive device in which optical power from several input fibers is collected at a common point.
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- Common Carrier
- An organization licensed by some public regulatory authority, e.g. the FCC, to provide a specific set of
services for a specific set of rates. Common means the carrier is obligated to carry for everyone.
Carrier means they convey something - freight, data, etc. - for their customers. Examples are GTE
Sprint, Yellow Freight, AT&T Communications, MCI, American Airlines.
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- Communications Application Compiler
- A piece of software that translates instructions written in a high-level language into a lower-level
language so that the processor can understand them.
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- Communicator Bandwidth
- The maximum rate at which temporally disjunct optical signals can be produced or detected.
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- Compatibility
- The ability of a computer system to accept and process data prepared by another similar system
without having to adapt it.
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- Compatibility Interfaces
- The MDI coaxial cable interface and the AUI branch cable interface, the two points at which hardware
compatibility is defined to allow connection of independently designed and manufactured components
to the baseband transmission system.
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- Compensator
- An optical element that measures the phase difference between two components of elliptically polarized light to correct for mechanical or optical displacement.
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- Compilation
- The translation of programs written in a language understandable to programmers into instructions
understandable to the computer.
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- Composite Cable
- A cable containing both fiber and copper conductors. Also known as hybrid cable.
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- Composite Laser Crystals
- Laser crystals consisting of several parts of different materials or with different chemical compositions.
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- Composite Second Order
- An important distortion measure of analog CATV systems.It is mainly caused by second order distortion in the transmission system.
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- Composite Sync
- A signal consisting of horizontal sync pulses, vertical sync pulses, and equalizing pulses only, with a no-signal reference level.
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- Composite Triple Beat
- An important distortion measure of analog CATV systems.It is mainly caused by second order distortion in the transmission system.
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- Composite Video
- A signal which consists of the luminance (black and white), chrominance (color), blanking pulses, sync pulses, and color burst.
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- Compound Semiconductor
- A semiconductor made up of two or more elements, in contrast to those composed of a single element such as germanium or silicon.
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- Compression
- The use of any of several techniques to reduce the number of bits needed to represent information in
data transmission or storage. This saves storage space on magnetic storage devices such as hard
disk, tape drives and floppy disks. It also saves transmission time.
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- Compression Utilities
- Applications that squeeze data into smaller files by coding them into special formats or algorithms that
take less space.
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- COMSAT
- An abbreviation for communications satellite.
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- Concatenation
- The process of connecting pieces of fiber together.
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- Concentrator
- A multi-port repeater.
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- Concentricity
- In a wire or cable, the measurement of the location of the center of the conductor with respect to the
geometric center of the circular insulation.
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- Concentricity Error
- In an optical fiber, the distance between the center of the two concentric circles that specify the cladding diameter and the center of the two concentric circles that specify the core diameter.
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- Conduit
- Pipe or tubing through which cables can be pulled or housed.
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- Connect Time
- The time a circuit is in use. Connect time typically refers to circuit-switched systems, such as telephone
lines.
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- Connecting Hardware
- A device, used to terminate an optical fiber cable with connectors and adapters, that provides an administration point for cross-connecting between cabling
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