Introduction of CWDM system principles

CWDM mux is a low-cost WDM transmission technology for metro access layer. In principle, CWDM mux is the use of different wavelengths of light multiplexer, optical signal multiplexing to a single optical fiber transmission link on the receiving end, with the optical demultiplexer mixed-signal in the fiber is broken down into different wavelengths signal connected to the receiving device.

The main difference lies in DWDM mux: relative to DWDM systems in terms of the wavelength interval in the 0.2nm to 1.2nm, CWDM mux has a wider wavelength interval, the industry accepted standard wavelength spacing of 20nm. CWDM wavelength interval width, the technical specifications of the laser requirements are lower. The wavelength interval to reach 20nm, so the maximum wavelength shift up to -6.5 ℃ ~ +6.5 ° C, the laser emission wavelength accuracy can be relaxed to ± 3nm, and the operating temperature range (-5 ° C ~ 70 ° C), temperature changes caused by wavelength drift is still within the available range, the laser without temperature control mechanism, so the structure of the laser is greatly simplified, and the yield increase.

Besides, the larger the wavelength interval means that the optical multiplexer / demultiplexer structure greatly simplified. Of CWDM systems, for example, the filter coating layers can be reduced to about 50 layers of 100GHz DWDM system filter coating layers of about 150 layers, which result in yield improvement, cost reduction, and supplier of filter greatly increase the pro-competitive. CWDM mux costs 50% less than the cost of DWDM mux and will further reduce the automated production technology and increasing volume.