A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
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n: Abbreviation for nano. One billionth or 10-9.
N: Abbreviation for Newtons. Measure of force generally used to specify fiber optic cable strength.
nA: Abbreviation for nanoamp. One billionth of an Amp or 10-9 Amps.
NA: See numerical aperture.
NAB: Abbreviation for National Association of Broadcasters.
NA Mismatch Loss: The loss of power at a joint that occurs when the transmitting half has a numerical aperture greater than the NA of the receiving half. The loss occurs when coupling light from a source to fiber, from fiber to fiber, or from fiber to detector.
National Electric Code® (NEC): A standard governing the use of electrical wire, cable and fixtures installed in buildings; developed by the NEC Committee of the American National Standards Institute (ANSI), sponsored by the National Fire Protection Association (NFPA), identified by the description ANSI/NFPA 70-1990.
NCTA: Abbreviation for National Cable Television Association. The major trade association for the cable television industry.
NDSF: See non dispersion-shifted fiber.
Near-End Crosstalk (NEXT, RN): The optical power reflected from one or more input ports, back to another input port. Also known as isolation directivity.
Near Infrared: The part of the infrared near the visible spectrum, typically 700 nm to 1500 nm or 2000 nm; it is not rigidly defined.
NEMA: Abbreviation for National Electrical Manufacturers Association.
NEP: See noise equivalent power.
Network: 1) An interconnection of three or more communicating entities and (usually) one or more nodes. 2) A combination of passive or active electronic components that serves a given purpose.
NF: See noise figure.
NFPA: Abbreviation for National Fire Protection Association.
nm: Abbreviation for nanometer. One billionth of a meter or 10-9 meters.
Noise Equivalent Power (NEP): The noise of optical receivers, or of an entire transmission system, is often expressed in terms of noise equivalent optical power.
Noise Figure (NF): The ratio of the output signal-to-noise ratio to the input signal-to-noise ratio for a given element in a transmission system. Used for optical and electrical components.
Non Dispersion-shifted Fiber (NDSF): The most popular type of single-mode fiber deployed. It is designed to have zero dispersion near 1310 nm.
Nonlinearity: The deviation from linearity in an electronic circuit, an electro-optic device or a fiber that generates undesired components in a signal.
Non Zero-dispersion-shifted Fiber (NZ-DSF): A dispersion shifted SM fiber that has the zero dispersion point near the 1550 nm window, but outside the window actually used to transmit signals. This is a strategy to maximize bandwidth while minimizing fiber nonlinearities.
NRZ: Abbreviation for nonreturn to zero. A common means of encoding data that has two states termed "zero" and "one" and no neutral or rest position.
ns: Abbreviation for nanosecond. One billionth of a second or 10-9 seconds.
NTSC: Abbreviation for National Television Systems Committee. The organization which formulated the NTSC system. 2) Standard used in the U.S. that delivers 525 lines at 60 frames per second.
Numerical Aperture (NA): The light-gathering ability of a fiber; the maximum angle to the fiber axis at which light will be accepted and propagated through the fiber. The measure of the light-acceptance angle of an optical fiber. NA = sin a, where a is the acceptance angle. NA is also used to describe the angular spread of light from a central axis, as in exiting a fiber, emitting from a source, or entering a detector.
nW: Abbreviation for nanowatt. One billionth of a Watt or 10-9 Watts.
NZ-DSF: See non zero-dispersion-shifted fiber.
OC-x: Abbreviation for optical carrier. A carrier rate specified in the SONET standard.
O/E: Abbreviation for optical-to-electrical converter.
OEIC: Abbreviation for opto-electronic integrated circuit.
OEM: Abbreviation for original equipment manufacturer.
OLTS: Abbreviation for optical loss test set.
1U: One "U". "U" = 1.75 inches.
Open Standard Interconnect: A seven-layer model defined by ISO for defining a communication network.
Optical Amplifier: A device that amplifies an input optical signal without converting it into electrical form. The best developed are optical fibers doped with the rare earth element, erbium.
Optical Bandpass: The range of optical wavelengths which can be transmitted through a component.
Optical Channel: An optical wavelength band for WDM optical communications.
Optical Channel Spacing: The wavelength separation between adjacent WDM channels.
Optical Channel Width: The optical wavelength range of a channel.
Optical Continuous Wave Reflectometer (OCWR): An instrument used to characterize a fiber optic link wherein an unmodulated signal is transmitted through the link, and the resulting light scattered and reflected back to the input is measured. Useful in estimating component reflectance and link optical return loss.
Optical Directional Coupler (ODC): A component used to combine and separate optical power.
Optical Fall Time: The time interval for the falling edge of an optical pulse to transition from 90% to 10% of the pulse amplitude. Alternatively, values of 80% and 20% may be used.
Optical Fiber: A glass or plastic fiber that has the ability to guide light along its axis.
Optical Isolator: A component used to block out reflected and unwanted light. Used in laser modules, for example. Also called an isolator.
Optical Link Loss Budget: The range of optical loss over which a fiber optic link will operate and meet all specifications. The loss is relative to the transmitter output power.
Optical Loss Test Set (OLTS): A source and power meter combined to measure attenuation.
Optical Path Power Penalty: The additional loss budget required to account for degradations due to reflections, and the combined effects of dispersion resulting from intersymbol interference, mode-partition noise, and laser chirp.
Optical Power Meter: An instrument that measures the amount of optical power present at the end of a fiber or cable.
Optical Pump Laser: A shorter wavelength laser that is used to pump a length of fiber with energy to provide amplification at one or more longer wavelengths. See also EDFA.
Optical Return Loss (ORL): The ratio (expressed in units of dB) of optical power reflected by a component or an assembly to the optical power incident on a component port when that component or assembly is introduced into a link or system.
Optical Rise Time: The time interval for the rising edge of an optical pulse to transition from 10% to 90% of the pulse amplitude. Alternatively, values of 20% and 80% may be used.
Optical Signal-to-Noise-Ratio (OSNR): The optical equivalent of SNR.
Optical Spectrum Analyzer (OSA): A device that allows the details of a region of an optical spectrum to be resolved. Commonly used to diagnose DWDM systems.
Optical Time Domain Reflectometer (OTDR): An instrument that locates faults in optical fibers or infers attenuation by backscattered light measurements.
Optical Waveguide: Another name for optical fiber.
OSA: See optical spectrum analyzer.
OSI: Abbreviation for open standards interconnect.
OSNR: See optical signal-to-noise ratio.
OTDR: Abbreviation for optical time domain reflectometer.
p: Abbreviation for pico. One trillionth or 10-12.
pA: Abbreviation for picoamp. One trillionth of an Amp or 10-12 Amps.
PABX: Abbreviation for private automatic branch exchange.
PAL: Abbreviation for phase alternation line. A composite color standard used in many parts of the world for TV broadcast. The phase alternation makes the signal relatively immune to certain distortions (compared to NTSC). Delivers 625 lines at 50 frames per second. PAL-plus is an enhanced-definition version.
Passband: The region of frequency in electronics or wavelength in optics which is useful.
Passive Branching Device: A device which divides an optical input into two or more optical outputs.
PC: Abbreviation for Physical contact. Refers to an optical connector that allows the fiber ends to physically touch. Used to minimize backreflection and insertion loss.
PCB: Abbreviation for Printed circuit board.
PCM: See pulse-code modulation.
PCS Fiber: See plastic clad silica.
Peak Power Output: The output power averaged over that cycle of an electromagnetic wave having the maximum peak value that can occur under any combination of signals transmitted.
PFM: Abbreviation for pulse-frequency modulation. Also referred to as square wave FM.
Phase Constant: The imaginary part of the axial propagation constant for a particular mode, usually expressed in radians per unit length. See also attenuation.
Phase Noise: Rapid, short-term, random fluctuations in the phase of a wave caused by time-domain instabilities in an oscillator.
Photoconductive: Losing an electrical charge on exposure to light.
Photodetector: An optoelectronic transducer such as a PIN photodiode or avalanche photodiode.
Photodiode: A semiconductor device that converts light to electrical current.
Photon: A quantum of electromagnetic energy. A particle of light.
Photonic: A term coined for devices that work using photons, analogous to "electronic" for devices working with electrons.
Photovoltaic: Providing an electric current under the influence of light or similar radiation.
Pigtail: A short optical fiber permanently attached to a source, detector, or other fiber optic device.
PINFET: PIN detector plus a FET amplifier. Offers superior performance over a PIN alone.
PIN Photodiode: See photodiode.
Planer Waveguide: A waveguide fabricated in a flat material such as thin film.
Plastic Clad Silica (PCS): Also called hard clad silica (HCS). A step-index fiber with a glass core and plastic or polymer cladding instead of glass.
Plastic Fiber: An optical fiber having a plastic core and plastic cladding.
Plenum: The air handling space between walls, under structural floors, and above drop ceilings, which can be used to route intrabuilding cabling.
Plenum Cable: A cable whose flammability and smoke characteristics allow it to be routed in a plenum area without being enclosed in a conduit.
PMD: See polarization mode dispersion.
Point-to-Point Transmission: Transmission between two designated stations.
Polarization: The direction of the electric field in the lightwave.
Polarization Maintaining Fiber: Fiber that maintains the polarization of light that enters it.
Polarization Mode Dispersion (PMD): Polarization mode dispersion is an inherent property of all optical media. It is caused by the difference in the propagation velocities of light in the orthogonal principal polarization states of the transmission medium. The net effect is that if an optical pulse contains both polarization components, then the different polarization components will travel at different speeds and arrive at different times, smearing the received optical signal.
Port: Hardware entity at each end of the link.
POS: Abbreviation for point of sale.
POTS: Abbreviation for plain old telephone system.
p-p: Abbreviation for peak-to-peak. A peak-to-peak value is the algebraic difference between extreme values of a varying quantity.
PPM: Abbreviation for pulse-position modulation. A method of encoding data.
Preform: The glass rod from which optical fiber is drawn.
Profile Dispersion: Dispersion attributed to the variation of refractive index contrast with wavelength.
ps: Abbreviation for picosecond. One trillionth of a second or 10-12 seconds.
Pulse: A current or voltage which changes abruptly from one value to another and back to the original value in a finite length of time. Used to describe one particular variation in a series of wave motions.
Pulse-Code Modulation (PCM): A technique in which an analog signal, such as a voice, is converted into a digital signal by sampling the signal's amplitude and expressing the different amplitudes as a binary number. The sampling rate must be at least twice the highest frequency in the signal.
Pulse Dispersion: The spreading out of pulses as they travel along an optical fiber.
Pulse Spreading: The dispersion of an optical signal as it propagates through an optical fiber.
pW: Abbreviation for picowatt. One trillionth of a Watt or 10-12 Watts.
QAM: See quadrature amplitude modulation.
Quadrature Amplitude Modulation: A coding technique that uses many discrete digital levels to transmit data with minimum bandwidth. QAM256 used 256 discrete levels to transmit digitized video.
Quantum Efficiency: In a photodiode, the ratio of primary carriers (electron-hole pairs) created to incident photons. A quantum efficiency of 70% means seven out of ten incident photons create a carrier.
Quaternary Signal: A digital signal having four significant conditions.
Radiation-Hardened Fiber: An optical fiber made with core and cladding materials that are designed to recover their intrinsic value of attenuation coefficient, within an acceptable time period, after exposure to a radiation pulse.
Radiometer: An instrument, distinct from a photometer, to measure power (Watts) of electromagnetic radiation.
Radiometry: The science of radiation measurement.
Rayleigh Scattering: The scattering of light that results from small inhomogeneities of material density or composition.
Rays: Lines that represent the path taken by light.
Receiver: A terminal device that includes a detector and signal processing electronics. It functions as an optical-to-electrical converter.
Receiver Overload: The maximum acceptable value of average received power for an acceptable BER or performance.
Receiver Sensitivity: The minimum acceptable value of received power needed to achieve an acceptable BER or performance. It takes into account power penalties caused by use of a transmitter with worst-case values of extinction ratio, jitter, pulse rise and fall times, optical return loss, receiver connector degradations, and measurement tolerances. The receiver sensitivity does not include power penalties associated with dispersion, jitter, or reflections from the optical path; these effects are specified separately in the allocation of maximum optical path penalty. Sensitivity usually takes into account worst-case operating and end-of-life (EOL) conditions.
Recombination: Combination of an electron and a hole in a semiconductor that releases energy, sometimes leading to light emission.
Refraction: The changing of direction of a wavefront in passing through a boundary between two dissimilar media, or in a graded-index medium where refractive index is a continuous function of position.
Refractive Index: A property of optical materials that relates to the speed of light in the material.
Refractive Index Gradient: The change in refractive index with distance from the axis of an optical fiber.
Refractive Index Profile: The description of the value of the refractive index as a function of distance from the optical axis along an optical fiber diameter.
Regenerative Repeater: A repeater, designed for digital transmission, in which digital signals are amplified, reshaped, retimed, and retransmitted.
Regenerator: Synonym for regenerative repeater.
Repeater: A receiver and transmitter set designed to regenerate attenuated signals. Used to extend operating range.
Residual Loss: The loss of the attenuator at the minimum setting of the attenuator.
Responsivity: The ratio of a photodetector's electrical output to its optical input in Amperes/Watt (A/W).
Return Loss: See optical return loss.
RFI: Abbreviation for radio frequency interference. Synonym of electromagnetic interference.
RGB: Abbreviation for red, green, and blue. The basic parallel component set in which a signal is used for each primary color; or the related equipment or interconnect formats or standards.
Ribbon Cables: Cables in which many fibers are embedded in a plastic material in parallel, forming a flat ribbon-like structure.
RIN: Abbreviation for relative intensity noise. Often used to quantify the noise characteristics of a laser.
Ring: A set of stations wherein information is passed sequentially between stations, each station in turn examining or copying the information, and finally returning it to the originating station.
Ring Network: A network topology in which terminals are connected in a point-to-point serial fashion in an unbroken circular configuration.
Rise Time: The time taken to make a transition from one state to another, usually measured between the 10% and 90% completion points of the transition. Alternatively the rise time may be specified at the 20% and 80% amplitudes. Shorter or faster rise times require more bandwidth in a transmission channel.
RMS: Abbreviation for root mean square. Technique used to measure AC voltages.
RTS: Abbreviation for request to send.
RZ: Abbreviation for return to zero. A common means of encoding data that has two information states called "zero" and "one" in which the signal returns to a rest state during a portion of the bit period.
s: Abbreviation for second.
SAE: Abbreviation for Society of Automotive Engineers.
SBS: See stimulated Brillouin scattering.
SC: Abbreviation for Subscription channel connector. A push-pull type of optical connector that originated in Japan. Features high packing density, low loss, low backreflection, and low cost.
Scattering: The change of direction of light rays or photons after striking small particles. It may also be regarded as the diffusion of a light beam caused by the inhomogeneity of the transmitting material.
SDH: Abbreviation for synchronous digital hierarchy.
SECAM: Abbreviation for Système Èlectronique Couleur avec Mèmoire. A TV standard used in various parts of the world. Delivers 625 lines at 50 frames per second.
Selfoc Lens: A trade name used by the Nippon Sheet Glass Company for a graded-index fiber lens; a segment of graded-index fiber made to serve as a lens.
Self-phase modulation (SPM): A fiber nonlinearity caused by the nonlinear index of refraction of glass. The index of refraction varies with optical power level which causes distortion in the waveform.
Semiconductor Optical Amplifier (SOA): A laser diode without end mirror coupled to fibers on both ends. Light coming in either fiber is amplified by a single pass through the laser diode. An alternative to EDFA's.
Sensitivity: See receiver sensitivity.
SH: Abbreviation for short-haul. A classification of video performance under RS-250B/C. Higher performance than long-haul or medium-haul.
Sheath: An outer protective layer of a fiber optic cable.
Shot Noise: Noise caused by current fluctuations arising from the discrete nature of electrons.
Si: Abbreviation for silicon. Generally used in detectors. Good for short wavelengths only (e.g., < 1000 nm).
Sideband: Frequencies distributed above and below the carrier that contain energy resulting from amplitude modulation. The frequencies above the carrier are called upper sidebands, and the frequencies below the carrier are called lower sidebands.
Silica Glass: Glass made mostly of silicon dioxide, SiO2, used in conventional optical fibers.
Signal-to-Noise Ratio (SNR): The ratio of the total signal to the total noise which shows how much higher the signal level is than the level of the noise. A measure of signal quality.
Simplex: Single element (e.g., a simplex connector is a single-fiber connector).
Simplex Cable: A term sometimes used for a single-fiber cable.
Simplex Transmission: Transmission in one direction only.
Single Attachment Concentrator: A concentrator that offers one attachment to the FDDI network.
Single-Line Laser: Synonym for single-longitudinal mode laser.
Single-Longitudinal Mode Laser (SLM): An injection laser diode which has a single dominant longitudinal mode. A single-mode laser with a side mode suppression ratio (SMSR)< 25 dB.
Single-mode (SM) Fiber: A small-core optical fiber through which only one mode will propagate. The typical diameter is 8-9 microns.
Single-mode Laser Diode (SMLD): Synonym for single-longitudinal mode laser.
Single-mode Optical Loss Test Set (SMOLTS): An optical loss test set for use with single-mode fiber.
SI Units: Abbreviation for International System of Units, commonly known as the metric system.
SLED: See surface-emitting diode.
SLM: See single-longitudinal mode laser.
SMF: Abbreviation for single-mode fiber.
SMA: A threaded type of optical connector. One of the earliest optical connectors to be widely used. Offers poor repeatability and performance.
Smart Structures: Also smart skins. Materials containing sensors (fiber optic or other types) to measure their properties during fabrication and use.
SMD: Abbreviation for surface-mount device.
SMPTE: Abbreviation for Society of Motion Picture and Television Engineers.
SMT: Abbreviation for Surface-mount technology.
S/N: See signal-to-noise ratio.
SNR: See signal-to-noise ratio.
SOA: See semiconductor optical amplifier.
Soliton Pulse: An optical pulse having a shape, spectral content, and power level designed to take advantage of nonlinear effects in an optical fiber waveguide, for the purpose of essentially negating dispersion over long distances.
SONET: Abbreviation for synchronous optical network transport system. An interface standard for synchronous 2.488 Gb/s optical fiber transmission, developed by the Exchange Carriers Standards Association.
Source: In fiber optics, a transmitting LED or laser diode, or an instrument that injects test signals into fibers.
Spectral Width: A measure of the extent of a spectrum. For a source, the width of wavelengths contained in the output at one half of the wavelength of peak power. Typical spectral widths are 50 to 160 nm for an LED and 0.1-5 nm for a laser diode.
Spectral Width, Full Width, Half Maximum (FWHM): The absolute difference between the wavelengths at which the spectral radiant intensity is 50 percent of the maximum power.
Splice: A permanent connection of two optical fibers through fusion or mechanical means.
Splitting Ratio: The ratio of power emerging from two output ports of a coupler.
SPM: See self-phase modulation.
SRS: See stimulated Raman scattering.
ST: Abbreviation for straight tip connector. Popular fiber optic connector originally developed by AT&T.
Stabilized Light Source: An LED or laser diode that emits light with a controlled and constant spectral width, central wavelength, and peak power with respect to time and temperature.
Star Coupler: A coupler in which power at any input port is distributed to all output ports.
Star Network: A network in which all terminals are connected through a single point, such as a star coupler or concentrator.
Step-Index Fiber: Fiber that has a uniform index of refraction throughout the core.
Stimulated Brillouin Scattering (SBS): The easiest fiber nonlinearity to trigger. When a powerful light wave travels through a fiber it interacts with acoustical vibration modes in the glass. This causes a scattering mechanism to be formed that reflects much of the light back to the source.
Stimulated Raman Scattering (SRS): A fiber nonlinearity similar to SBS but having a much higher threshold. This mechanism can also cause power to be robbed from shorter wavelength signals and provide gain to longer wavelength signals.
Strength Member: The part of a fiber optic cable composed of aramid yarn, steel strands, or fiberglass filaments that increase the tensile strength of the cable.
Submarine Cable: A cable designed to be laid underwater.
Subscriber Loop: Also called local loop. The link from the telephone company central office (CO) to the home or business (customer premises).
Supertrunk: A cable that carries several video channels between facilities of a cable television company.
Surface-Emitting Diode: An LED that emits light from its flat surface rather than its side. Simple and inexpensive, with emission spread over a wide angle.
Sync: This signal is derived from the composite or combination of the horizontal and vertical drives. See also composite sync.
Synchronous: A data signal that is sent along with a clock signal.
T: Abbreviation for tera. One trillion or 1012.
Tap Loss: In a fiber optic coupler, the ratio of power at the tap port to the power at the input port.
Tap Port: In a coupler where the splitting ratio between output ports is not equal, the output port containing the lesser power.
TAXI: Abbreviation for transparent asynchronous transmitter-receiver interface. A chip used to transmit parallel data over a serial interface.
TBC: Abbreviation for timebase corrector.
T-Carrier: Generic designator for any of several digitally multiplexed telecommunications carrier systems.
TDM: See time-division multiplexing.
TEC: Abbreviation for thermoelectric cooler.
Tee Coupler: A three-port optical coupler.
10BASE-F: A fiber optic version of an IEEE 802.3 network.
10BASE-FB: That portion of 10BASE-F that defines the requirements for a fiber backbone.
10BASE-FL: That portion of 10BASE-F that defines a fiber optic link between a concentrator and a station.
10BASE-FP: That portion of 10BASE-F that defines a passive star coupler.
10BASE-T: A twisted-pair cable version of an IEEE 802.3 network.
10BASE-2: A thin-coaxial-cable version of an IEEE 802.3 network.
10BASE-5: A thick-coaxial-cable version of an IEEE 802.3 network; very similar to the original Ethernet specification.
Ternary: A semiconductor compound made of three elements (e.g., GaAlAs).
TFOCA: Abbreviation for tactical fiber optic cable assembly.
Thermal Noise: Noise resulting from thermally induced random fluctuation in current in the receiver's load resistance.
Throughput Loss: In a fiber optic coupler, the ratio of power at the throughput port to the power at the input port.
Throughput Port: In a coupler where the splitting ratio between output ports is not equal, the output port containing the greater power.
TICL: Abbreviation for temperature induced cable loss.
Tight-Buffer: A material tightly surrounding a fiber in a cable, holding it rigidly in place.
Time-Division Multiplexing (TDM): A transmission technique whereby several low-speed channels are multiplexed into a high-speed channel for transmission. Each low-speed channel is allocated a specific position based on time.
Token Ring: A ring-based network scheme in which a token is used to control access to a network. Used by IEEE 802.5 and FDDI.
Total Internal Reflection: The reflection that occurs when light strikes an interface at an angle of incidence (with respect to the normal) greater than the critical angle.
Transceiver: A device that performs, within one chassis, both telecommunication transmitting and receiving functions.
Transducer: A device for converting energy from one form to another, such as optical energy to electrical energy.
Transmitter: A device that includes a source and driving electronics. It functions as an electrical-to-optical converter.
Transponder: The part of a satellite that receives and transmits a signal.
Tree: A physical topology consisting of a hierarchy of master-slave connections between a concentrator and other FDDI nodes (including subordinate concentrators).
Trunk: A physical loop topology, either open or closed, employing two optical fiber signal paths, one in each direction (i.e. counter-rotating) forming a sequence of peer connections between FDDI nodes. When the trunk forms a closed loop, it is sometimes called a trunk ring.
TTL: Abbreviation for transistor-transistor logic.
UL: Abbreviation for Underwriter's Laboratory.
Unidirectional: Operating in one direction only.
UV: Abbreviation for ultraviolet.
V: Abbreviation for Volt.
VAC: Abbreviation for Volts, AC.
VCSEL: See vertical cavity surface emitting laser.
VDC: Abbreviation for Volts, DC.
Vertical Cavity Surface Emitting Laser: Lasers that emit light perpendicular to the plane of the wafer they are grown on. They have very small dimensions compared to conventional lasers and are very efficient.
Vestigial-Sideband (VSB) Transmission: A modified double-sideband transmission in which one sideband, the carrier, and only a portion of the other sideband are transmitted. See also sideband.
VGA: Abbreviation for video graphics array. A high-resolution color standard for computer monitors.
Video on Demand (VOD): A term used for interactive or customized video delivery service.
Videoconferencing: Conducting conferences via a video telecommunications system.
Videophone: A telephone-like service with a picture as well as sound.
Visible Light: Electromagnetic radiation visible to the human eye; wavelengths of 400-700 nm.
VOD: See video on demand.
Voice Circuit: A circuit capable of carrying one telephone conversation or its equivalent; the standard subunit in which telecommunication capacity is counted. The U.S. analog equivalent is 4 kHz. The digital equivalent is 64 kbit/s in North America and in Europe.
VSB: See vestigial-sideband transmission.
WAN: See wide area network.
Watt: Linear measurement of optical power, usually expressed in milliwatts, microwatts, and nanowatts.
Waveguide: A material medium that confines and guides a propagating electromagnetic wave. In the microwave regime, a waveguide normally consists of a hollow metallic conductor, generally rectangular, elliptical, or circular in cross-section. This type of waveguide may, under certain conditions, contain a solid or gaseous dielectric material. In the optical regime, a waveguide used as a long transmission line consists of a solid dielectric filament (optical fiber), usually circular in cross-section. In integrated optical circuits an optical waveguide may consist of a thin dielectric film. In the RF regime, ionized layers of the stratosphere and the refractive surfaces of the troposphere may also serve as a waveguide.
Waveguide Couplers: A coupler in which light is transferred between planar waveguides.
Waveguide Dispersion: The part of chromatic dispersion arising from the different speeds light travels in the core and cladding of a single-mode fiber (i.e., from the fiber's waveguide structure).
Wavelength: The distance between points of corresponding phase of two consecutive cycles of a wave. The wavelength, is related to the propagation velocity, and the frequency, by:
Wavelength = Propagation Velocity / Frequency
Wavelength-Division Multiplexing (WDM): Sending several signals through one fiber with different wavelengths of light.
Wavelength Isolation: A WDM's isolation of a light signal in the desired optical channel from the unwanted optical channels. Also called far-end crosstalk.
WDM: See wavelength-division multiplexing.
Wide Area Network: A physical or logical network that provides capabilities for a number of independent devices to communicate with each other over a common transmission-interconnected topology in geographic areas larger than those served by local area networks.
Wideband: Possessing large bandwidth.
World Wide Web (WWW): The collection of millions of graphical pages that heavily utilize HTML to provide access to information. One of the key components of the Internet.
WWW: See world wide web.
XPM: See cross-phase modulation.
XT: Abbreviation for crosstalk.
Y Coupler: A variation on the tee coupler in which input light is split between two channels (typically planar waveguide) that branch out like a Y from the input.
Zero-Dispersion Wavelength (l0): In a single-mode optical fiber, the wavelength at which material dispersion and waveguide dispersion cancel one another. The wavelength of maximum bandwidth in the fiber.