Cisco ONS 15454 DWDM - Figure 5-19 4 MD-XX.X Optical Module Functional Block Diagram

5-22
Cisco ONS 15454 DWDM Reference Manual, R8.5
78-18343-02
Chapter 5 Multiplexer and Demultiplexer Cards
5.5 4MD-xx.x Card
Figure 5-18 4MD-xx.x Block Diagram
Figure 5-19 shows the 4MD-xx.x optical module functional block diagram.
Figure 5-19 4MD-xx.x Optical Module Functional Block Diagram
The optical module shown in Figure 5-19 is optically passive and consists of a cascade of interferential
filters that perform the channel multiplexing and demultiplexing functions.
VOAs are present in every input path of the multiplex section in order to regulate the optical power of
each multiplexed channel. Some optical input and output ports are monitored by means of photodiodes
implemented both for power control and for safety purposes. An internal control manages VOA settings
and functionality as well as photodiode detection and alarm thresholds. The power at the main output
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