1.
CWDM has 18 bands, from 1270nm to 1610nm, and the interval between each band is 20nm. Each channel of DWDM has 3 kinds of spacing according to the needs: 0.4nm (50Ghz), 0.8nm (100Ghz) and 1.6nm (200Ghz), 100GHz (from C17 to C61, is the most commonly used, suitable for conventional equipment); 50GHz (from C17 to H61 for high channel devices).
2.
CWDM wavelengths from 1470nm to 1610nm generally use DFB lasers. Because of the large channel interval, CWDM devices and lasers are cheaper than DWDM devices.
3. The CWDM optical channel spacing is wider, and the number of multiplexed optical wavelengths on the same fiber is less than that of DWDM. This is the reason for the appellations of "thick" and "dense";
4. CWDM optical modulation adopts uncooled laser, which is tuned electronically; while DWDM adopts cooling laser, which is tuned by temperature.
5. Since the temperature distribution is very uneven in a wide range of optical wavelengths, it is very difficult and costly to implement temperature tuning. CWDM avoids this difficulty, thus greatly reducing the cost. At present, the cost of CWDM system is generally only 30% of that of DWDM;
6. The power consumption and physical size of the CWDM system are much smaller than those of the DWDM system.
