What are the performance indicators that affect the WDM wavelength division multiplexer?
1. Working band
The working band of WDM devices, such as 1550 wavelength, is divided into three bands: S band (short wavelength band 1460～1528nm), C band (conventional band 1530～1565nm), L band (long wavelength band 1565～1625nm).
2. Number of channels and channel spacing
The number of channels refers to the number of channels that can be combined or separated by the wavelength division multiplexer/demultiplexer. This number can range from 4 to 160. The design can be enhanced by adding more channels. Common channel numbers are 4, 8, 16, 32, 40, 48, etc. Channel spacing refers to the difference between the nominal carrier frequencies of two adjacent channels, which can be used to prevent inter-channel interference. According to ITU-T G． Recommendation 692, the spacing is less than 200GHz (1.6nm) are 100GHz (0.8nm), 50GHz (0.4nm) and 25GHz, etc., currently the preferred channel spacing is 100GHz and 50GHz.
3. Insertion loss
Insertion loss is the attenuation caused by the insertion of a wavelength division multiplexer (WDM) in an optical transmission system. The attenuation effect of the wavelength division multiplexer on the optical signal directly affects the transmission distance of the system. Generally, the lower the insertion loss, the less signal attenuation.
4. Isolation
Isolation refers to the degree of isolation between signals of various channels, and a high isolation value can effectively prevent crosstalk between signals from causing distortion of transmission signals.
5. Polarization dependent loss PDL
Polarization-dependent loss PDL is the distance between the maximum and minimum Loss caused by the same co-polarization state at a fixed temperature, wavelength and the same Band, that is, the maximum deviation of the insertion loss under all input polarization states.
In addition to the above, of course, there are other performance parameters that affect WDM devices, such as operating temperature, bandwidth, and so on.
