There are a lot of people who don't understand the difference between WDM and optical splitter. Simply put, WDM is to separate the multiple wavelengths of light in the line to transmit separately, of course, can also be combined with multiple wavelengths of light transmission together; Splitter is to divide a wavelength of light into multiple beams according to the use of propagation, the power of each beam according to the used splitter specifications to determine. The most important distinction between the two is that the former can composite transmission of optical signals of various business wavelengths, and the latter is only the transmission of one wavelength of light to split light in accordance with a certain proportion.
What are the performance indicators that affect WDM wavelength division multiplexer?
1. Operating 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), and L band (long wavelength band 1565~1625nm).
2. Number of channels and channel interval
The number of channels refers to the number of channels that can be combined or separated by the WDM/demultiplexer; this number can vary from 4 to 160, and the design is enhanced by adding more channels; common number of channels are 4, 8, 16, 32, 40, 48, etc. channel spacing is the difference between the nominal carrier frequencies of two adjacent channels and can be used to prevent inter-channel interference. According to the recommendation of ITU-T G.692, the channel spacing less than 200GHz(1.6nm) includes 100GHz (0.8nm), 50GHz (0.4nm) and 25GHz. At present, 100GHz and 50GHz channel spacing are preferred.
3. Insertion loss
Insertion loss is the attenuation caused by Wavelength Division Multiplexer (WDM) insertion in optical transmission systems. The attenuation effect of wavelength division multiplexer itself on optical signal directly affects the transmission distance of the system. Generally, the lower the insertion loss, the less signal attenuation.
Isolation
The isolation degree refers to the isolation degree between each channel signal. A high isolation value can effectively prevent the crosstalk between signals, which leads to the distortion of the transmission signal.
5. Polarization dependent loss PDL
Polarization dependent Loss PDL is the distance between the maximum and minimum loss caused by different polarization states under fixed temperature, wavelength and the same Band, which is the maximum deviation of insertion loss under all input polarization states.
In addition to the above, there are of course other performance parameters that affect WDM devices, such as operating temperature, bandwidth and so on.
