In the construction of metropolitan area networks (especially long-distance OTN optical transmission networks), wavelength division multiplexing equipment is particularly important. DWDM dense wavelength division multiplexing equipment has long-distance, high-bandwidth transmission capabilities; CWDM coarse wavelength division multiplexing equipment has a lower cost. So if you choose the right wavelength division multiplexing equipment to build a cost-effective optical transmission system?

What is the difference between CWDM/DWDM Multiplexer?

At present, the effective method to solve the continuous increase of information transmission bandwidth is to use CWDM wavelength division multiplexing equipment and DWDM wavelength division multiplexing equipment, but they are different in many aspects.

(1) Channel spacing between CWDM wavelength division multiplexing equipment and DWDM wavelength division multiplexing equipment

Channel spacing is defined as the difference in nominal carrier frequency between two adjacent optical channels, and is generally used to prevent inter-channel interference. CWDM wavelength division multiplexing equipment has a wider spacing than DWDM wavelength division multiplexing equipment. It can transmit 18 wavelengths in a spectral grid from 1271 nm to 1611 nm with a channel spacing of 20 nm. The DWDM wavelength division multiplexing equipment can transmit 40, 80 or 160 wavelengths, and the channel spacing can be 0.8 nm.

(2) Transmission distance between CWDM wavelength division multiplexing equipment and DWDM wavelength division multiplexing equipment

Because the wavelength of dense wavelength division multiplexing equipment (DWDM) is highly integrated in the optical fiber transmission process, DWDM wavelength division multiplexing equipment can transmit longer distances than CWDM wavelength division multiplexing equipment. CWDM wavelength division multiplexing equipment currently cannot achieve unlimited distance transmission, and its maximum transmission distance is only 160 kilometers, while the transmission distance of DWDM wavelength division multiplexing equipment far exceeds that of CWDM wavelength division multiplexing equipment.

(3) Modulated lasers of CWDM wavelength division multiplexing equipment and DWDM wavelength division multiplexing equipment

The system of CWDM wavelength division multiplexing equipment has low requirements on the technical indicators of the laser, and generally uses an uncooled laser; The system of DWDM wavelength division multiplexing equipment needs to use a cooling laser, and the cooling laser adopts a temperature adjustment method to ensure that the DWDM system has better performance, higher safety and longer service life, so DWDM wavelength division multiplexer It consumes more energy than CWDM wavelength division multiplexing equipment using uncooled lasers

(4) Cost of CWDM wavelength division multiplexing equipment and DWDM wavelength division multiplexing equipment

The system of DWDM wavelength division multiplexing equipment has non-uniform temperature distribution in a wide wavelength range, so when the cooling laser technology is used to adjust the temperature, the use cost of the system of DWDM wavelength division multiplexing equipment is increased. In addition, the system of DWDM wavelength division multiplexing equipment is usually four to five times more expensive than the system of CWDM wavelength division multiplexing equipment. However, with the increasing popularity of dense wavelength division multiplexers (DWDM), the price of DWDM optical modules is nearly 20%-25% lower than that of CWDM optical modules.