Photonics Dictionary

A receiver for optical communications systems consisting of a symmetric binary, pulse-code-modulated transmitter, a log-normal channel and an array of independent photocounting detectors that yield...

A fiber optic communications system that works on the principles of homodyning or heterodyning. The transmitting laser produces an optical wave that is modulated in amplitude, phase or frequency by...

A femtosecond laser is a type of laser that emits ultrashort pulses of light with durations on the order of femtoseconds, where one femtosecond is equal to 10-15 seconds. These lasers are capable of...

A communications system that can transmit in only a single direction at a time. See duplex.

A holographic grating is a type of diffraction grating that is produced using holographic recording techniques. It consists of a periodic structure of alternating transparent and opaque regions,...

In coherent optical communications systems, a laser used at the receiving end to produce a steady wave that is combined with the incoming laser signal before detection, generating a composite wave...

In fiber optic communications systems, generally one that operates between 1000 and 1700 nm.

A function that quantifies the performance degradation of coherent communications systems, imaging systems and all systems that rely on the spot size of a laser beam that has propagated along an...

The unwanted and unpredictable fluctuations that distort a received signal and hence tend to obscure the desired message. Noise disturbances, which may be generated in the devices of a communications...

In an optical fiber or waveguide communications system, an optoelectronic device or module that receives an optical signal, converts this optical signal to an electrical signal which is then...

An optical coupling device that uses light to bridge the gap between incompatible wire communications systems. It contains an input amplifier, a light-emitting diode, a photodiode and an output...

A method of coding information in a communications system where the shift in the phase of an electromagnetic wave represents a particular bit or character.

Noise generated within an optical communications system link that has both internal (dark current) and external (background noise, or noise in signal) components.

A detector and signal demodulator used in optical communications systems to receive a signal and often to translate it into an electronic signal.