Hello there, everybody!
This post features the functions and working principle of the DCM module. Please have a read below.
FUNCTIONS
There are two types of DCM:
1. the DCM based on Dispersion Compensation Fiber (DCF);
2. the DCM based on Fiber Bragg Grating (FBG).
The DCF-based DCM and the FBG-based DCM have similar compensation features. The differences are as follows:
the insertion loss of the DCF-based DCM increases with the distance in km;
the insertion loss of the FBG-based DCM is always 4 dB regardless of the distance in km.
The DCM modules are available in different compensation distance specifications: 5 km (3.1 mi.), 10 km (6.2 mi.), 20 km (12.4 mi.), 40 km (24.8 mi.), 60 km (37.3 mi.), 80 km (49.7 mi.), 100 km (62.1 mi.), 120 km (74.6 mi.), 160 km (99.4 mi.), 200 km (124.2 mi.), and 240 km (149.1 mi.).
A DCM is located in a DCM frame that is in the lowest position of the cabinet.
APPEARANCE
WORKING PRINCIPLE
A DCM uses negative dispersion to compensate for the positive dispersion of a transmitting fiber.
A G.652 or a G.655 fiber has positive dispersion coefficient and positive dispersion slope in the 1550-nm window.
After the optical signal is transmitted over a certain distance, the accumulation of positive dispersion widens the optical signal pulse. This seriously affects the system transmission performance. To minimize such an effect, a passive DCM is used in the network.
A DCM uses negative dispersion to compensate for the positive dispersion of a transmitting fiber, so as to keep the original shape of the signal pulse.
This would be all on the functions and working principle of the DCM module. Thanks for reading this post!
