Knowledge Base

ADM - Add/drop multiplexer
AWG - Arrayed waveguide grating
Attenuator - A passive optical component that intentionally reduces the optical power propagating in a fiber.

Bend Loss - The result of macrobends (curvature of fiber) or microbends (small distortions in the fiber ) producing increased attenuation by coupling light energy from the fiber core to the cladding.
Bandpass - A range of wavelengths over which a component will meet specifications.

CATV - Cable TV
CWDM - Coarse Wavelength-Division Multiplexing
Center Wavelength(s) - The nominal operating wavelength(s).
Cladding - The outer concentric layer that surrounds the fiber core and has a lower index of refraction.
Core - The central, light carrying part of an optical fiber; it has an index of refraction higher than that of the surrounding cladding.
Coupler - A passive device that distributes optical power among two or more ports. (Can be in various ratios.) Commonly called a splitter.
Coupling Ratio - The percentage of light transferred to a receiving output port with respect to the total power of all output ports.

dB (Decibel) - Unit of measurement of signal strength.
Decibel - A standard logarithmic unit for the ratio of two powers, voltages, or currents. In fiber optics, the ratio is power.
Dispersion - A general term for those phenomena that cause a broadening or spreading of light as it propogates through an optical fiber. The three types are modal, material, and waveguide.
Directivity - Also referred to as near-end crosstalk, it is the amount of power observed at a given input port with respect to an initial input power.
Demultiplex - The process of separating optical channels.

EDFA - Erbium-doped fiber amplifier.
Erbium - doped fiber amplifier- A type of fiber that amplifies 1550-nm optical signals when pumped with a 980- or 1480-nm light source.
Excess Loss - The ratio of the total output power of a passive component with respect to the input power.

Fused Coupler - A method of making a multimode or single-mode coupler by wrapping fibers together, heating them and pulling the fibers to form a central unified mass so that light on any fiber is coupled to all output fibers.

Index of Refraction - The ratio of the velocity of light in free space to the velocity of light in a given material. Symbolized by N.
Insertion Loss (IL): - Attenuation expressed in dB for a particular path through a component. Insertion loss for Gould couplers includes excess loss, coupling loss and polarization effects.
ISO - International Standard Organization.
Isolation - Also referred to as far-end cross-talk or far-end isolation. Predominantly used in reference to WDM products, it is a measure of light at an undesired wavelength relative to the desired wavelength.

Pigtail - A short length of fiber permanently attached to a component, such as a source, detector, or coupler.
Pistoning - The movement of a fiber axially in and out of ferrule and, often caused by changes in temperature.
Polarization Sensitivity - The variation in insertion loss as the polarization state of the input light is varied.

Return Loss - Also called back reflection; is light that is reflected back along the path of transmission, from either the coupling region, the connector or a terminated fiber.
Return Reflection - Reflected optical energy that propagates backward to the source in an optical fiber.

Single - mode fiber- An optical fiber that supports only one mode of light propagation above the cutoff wavelength.
Star Coupler - A fiber-optic coupler in which power at any input port is distributed to all output ports.
Strength member - That part of a fiber-optic cable composed of Kevlar aramid yarn, steel strands, or fiberglass filaments that increase the tensile strength of the cable.

Tap Loss - In a fiber optic coupler, the ratio of power at the tap port to the power at the input port.
Tap Port - A coupler in which the splitting ratio between output ports is not equal, the output port containing the lesser power.
TDM- Time-division multiplexing
Temperature Stability - A measure of insertion loss variation as the device undergoes changes in temperature.

Uniformity - The maximum insertion loss difference between output ports of a coupler.

Wavelength - The distance between the same two points on adjacent waves; the time required for a wave to complete a single cycle.
Wavelength Dependence - The variation in an optical parameter caused by a change in the operating wavelength.
Wavelength - Division Multiplexing- A transition technique by which separate optical channels, distinguished by wavelength, are multiplexed onto an optical fiber for transmission.
WDM - Wavelength-division multiplexing

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