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Dictionary of terms

A ­­­ · B · C · D · E · F · G · H · CH · I · J · K · L · M · N · O · P · R · r · S · S · T · U · V · W · X · Y · Z

Attenuation, Loss, Gain, Loss, Profit

Decrease resp. gain of electromagnetic or optical power between two points; Expression of power change over the optical path as a two-point ratio. Attenuation / loss / gain is usually expressed in logarithmic units – decibels (dB).

Bandwidth (of optical fiber) / Optical fiber bandwidth

The transmitting capacity of the transmitting media; A value that is numerically equal to the lowest modulation frequency at which the value of the transmission function in the baseband of the optical fiber drops to a certain level, usually half the zero frequency value. In multifilament fibers, it is predominantly distorted and dispersed in material, dispersed in In single-strand fibers, it is predominantly a material and waveguide dispersion, and the dispersion values ​​are given.

Coupler (Splitter) / Thread branch

An optical component with one or more inputs and multiple outputs which, in a defined ratio, divides incoming optical power into individual optical outputs.

Coupling Ratio / Split ratio

The ratio of optical power output from the individual output port of the fiber branch to the total output power of all outputs, expressed as a percentage.

CWDM (Coarse Wavelength Division Multiplexing) / Coarse Wavelength Multiplexing

Wave multiplex system with 18 wavelengths in the range 1270 to 1610 nm. The spacing between channels is 20 nm. It was developed as a cheaper DWDM variant. The CWDM is defined as a recommendation in the ITU-T Recommendation G.694.2 and G.695.


The amount of optical power that is transmitted from one optical input to another optical input.

DWDM (Dense Wavelength Division Multiplexing) / Dense Wavelength Multiplex

Wave multiplex with multiple transmission channels. The distance between individual optical channels is defined in GHz. The first systems used a bandwidth of 200 GHz and typically up to 20 channels. Today’s systems use a 100 GHz band, respectively. 50 GHz. The DWDM frequency raster system is defined as a recommendation in ITU-T Recommendation G.694.1.

Channel / Channel

Communication path or signal that is transmitted by the communication system. Common directions of communication (reception and broadcasting) are commonly understood. In the case of WDM with the two fibers used, one transmission channel uses one wavelength. For the WDM single-threaded system, one channel typically uses two wavelengths.

Channel Spacing

The spacing between mid wavelengths (or frequencies) between adjacent transmission channels.

Laser / Laser

Laser Light Amplification (Stimulated Emission of Radiation) – Light source generating a narrow beam of coherent light with stimulated emission.

Multiplexing / Multiplexing

A process where two or more signals are transmitted over one communication line.

nm / nm

The distance unit (one billionth of a meter). The nanometer unit is used to define the wavelength of the optical radiation.

Optical Demux / Demultiplexer

An optical component that separates two or more wavelengths from the incoming optical signal into separate output threads.

Optical Mux / Multiplexer

An optical component that combines two or more signals with different wavelengths into one optical fiber.

Optical repeater

Active devices containing one or more amplifiers, their input and output signals are optical. Mostly, the repeater is based on the conversion of the optical signal to the electrical and back to the optical. The output optical signal over the input signal may also have a different wavelength but has the same velocity and characteristic. Basically, three types of optical repeaters are distinguished by their features:

1R repeater (Reamplify)
An optical repeater that only amplifies the passing optical signal

2R repeater (Reamplify + Reshape)
Optical regeneration repeater that amplifies the passive optical signal and resets the shape of the received pulses.

3R repater (Reamplify + Reshape + Regenerate)
Optical signal repeater with gain function, resume shape, and timing of this pass signal

Transponder (DWDM) / Transponder

An optical component that combines two or more signals with different wavelengths into one optical fiber.

UDWDM (Ultra Dense Wavelength Division Multiplexing) / Ultra dense wave multiplex

Very dense wavelength multiplexes with a distance of less than 25 GHz between optical channels.

WDM (Wavelength Division Multiplexing) / Wavelength multiplex

The principle by which several independent optical signals with different wavelengths are transmitted by a common optical fiber. Typically, two to three wavelengths (e.g., 1310 nm and 1550 nm in single-stranded fibers) are used for the WDM system. For multiple transmitting signals, CWDM and DWDM systems are used.

WWDM (Wide Division Multiplexing) / Wide Multiplexing

Wave multiplex with several wavelengths with a greater spacing between channels of less than 20 nm. Eg this is a 10GBASE-LX4 Ethernet interface with four wavelengths at 25 nm.