What is dispersion compensation?
What is dispersion compensation?
Dispersion compensation essentially means canceling the chromatic dispersion of some optical element(s). Dispersion compensation is applied mainly in mode-locked lasers and in telecommunication systems, but also sometimes in optical fibers transporting light e.g. to or from some fiber-optic sensor.
What is the use of dispersion compensators for fiber optic communication?
In optical fiber communications, dispersion compensation modules (DCM) (also called dispersion compensation units, DCU) can be used for compensating the chromatic dispersion of, e.g., a long span of transmission fiber.
What is DCM in telecommunication?
The Discrete Control Module (DCM) is the perfect solution for controlling devices at remote locations if you have only a few points or have a limited budget. You can monitor 2 alarm inputs and operate up to 16 control relays.
How do you compensate chromatic dispersion?
The first type is DCF or Dispersion Compensating Fiber. This is simply a spool of a special type of fiber that has very large negative dispersion. Typically DCF dispersion can be in the range of -80 ps/(nm∙km), so a 20 km length of DCF can compensate for the dispersion in a 100 km length of NDSF.
How is dispersion compensation calculated?
Dispersion compensation distance (L(DCM)) = transmission distance (L) – OTU dispersion limit + engineering margin. A 100 km G. 652 fiber span is considered as an example: L(DCM) = transmission distance – OTU dispersion limit + engineering margin = 100 km – 40 km + (10–30 km) = 70–90 km.
What is the difference between modal and chromatic dispersion?
The key difference between modal and chromatic dispersion is that modal dispersion can occur with a monochromatic light source, whereas chromatic dispersion cannot occur with a monochromatic light source. Modal and chromatic dispersion are important terms in describing the optical properties of optical fibers.
How does a dispersion compensation module work?
A dispersion compensating module (or DCM) is used to compensate the cumulative dispersion in a single mode fiber and a dispersion coefficient is used to characterize the dispersion value. The value for regular SMF is around +16~17 ps/(nm*km) at 1550nm.
What is chromatic dispersion in fiber optics?
Chromatic dispersion is the term given to the phenomenon by which different spectral components of a pulse travel at different velocities. Chromatic dispersion arises for two reasons. The first reason is that the refractive index of silica, the material used to make optical fiber, is frequency dependent.
How many types of dispersion are there?
In an optical medium, such as fiber, there are three types of dispersion, chromatic, modal, and material. Chromatic dispersion results from the spectral width of the emitter. The spectral width determines the number of different wavelengths that are emitted from the LED or laser.
What is unit of dispersion?
The chromatic dispersion parameter is measured in units of ps/nm-km since it expresses the temporal spread (ps) per unit propagation distance (km), per unit pulse spectral width (nm).
How can we reduce dispersion?
One way to reduce modal dispersion is to use graded-index fiber. Unlike the two distinct materials in a step-index fiber, the graded-index fiber’s cladding is doped so that the refractive index gradually decreases over many layers.
What are the similarities and differences between modal dispersion and chromatic dispersion?
What are the different types of dispersion compensation?
There are primarily 3 schemes (fiber-pre, post or symmetrical) which will be used for dispersion compensation. And the dispersion compensating fibers are used extensively for upgrading the installed 1310nm optimized optical fiber links for operation at 1550nm.
How does electronic dispersion compensation ( EDC ) Work?
Electronic Dispersion Compensation (EDC) is a method using electronic filtering (also known as equalization) to compensate for dispersion in an optical communications link. The filtering can be included in a communications channel to compensate for signal degradation caused by the medium.
Which is the best way to compensate for dispersion?
Several techniques, including Dispersion Compensating Fiber or Fiber Bragg Grating, can be used to compensate the accumulated dispersion in the fiber. In the following example we will show three different schemes, pre-, post-, and symmetrical compensation, to compensate the fiber dispersion.
How is dispersion compensation used in optical fiber?
Dispersion Compensation With DCF. In DCF (Dispersion Compensating Fiber) technique, one can use a fiber having large negative dispersion alongside a typical fiber. The number of light distributed by a traditional fiber is reduced or maybe nullified by using a dispersion compensating fiber having a really giant value of dispersion