Optical Wavelength Conversion Unit. STM-64 Transmitting Optical Wavelength Conversion Unit with FEC Function, страница 13

Optical multiplexing/demultiplexing is accomplished by optical multipexing/ demultiplexing boards. Now OptiX BWS 320G system provide three kinds of multiplexing board: M32, M16 and three kinds of demultiplexing board: D32, D16, corresponding to the multiplexing and demultiplexing of the three channels: 32, 16. In addition, dual-path optical add/drop board MR2 is also available, and two wavelength channels can be added/dropped locally.

1. Principle

M32 board refers to the 32-channel multiplexing Unit. According to the module functions, it mainly consists of the optical module and electrical module. The optical module consists of one 32-channel optical multiplexer and two 10:90 couplers; it accomplishes the multiplex of the 32 wavelength channels and provides on-line optical monitoring interfaces. Two kinds of optical multiplexer can be used on M32 board: AWG type and coupler type. Difference of the two types lies in the fact that coupler type optical multiplexer does not need temperature control, so it is comparatively simple. In the following description, M32 board with AWG type optical multipexer will be described as an example. The circuit module mainly consists of three parts: temperature control circuit of the multiplexer, optical power detecting circuit and mailbox communication circuit. So the circuit module has the following functions: keep a constant multiplexer temperature, detect the optical power and send out alarm, and communicate with the SCC board. The principle block diagram of M32 board is shown in Figure 3-9.

Figure 3-9 Principle block diagram of M32 board

Table 3-9 shows the wavelengths and frequencies corresponding to the 32 channels of M32 board.

Table 3-9 Correlation of serial number, frequency and wavelength

2. Functions

n  Multiplex the 32 wavelength channels into the main channel.

n  Provide on-line monitoring interface: a spectrum analyzer or multi-channel processing board MS2 of OptiX BWS 320G system can be accessed through this optical interface and monitor the spectrum of the main channel without interrupting the services.