100G LR4 and 100G CWDM4 are two different types of 100G Ethernet optical modules. Although they are both 100G optical modules, there are some differences between them.
The first is the difference in how it works. 100G LR4 uses four wavelengths (1310nm) , each of which transmits 25G of data. The four optical signals are combined into a single beam that is transmitted through a single-mode fiber. 100G CWDM4 transmits four data signals of different wavelengths, which are 1271nm, 1291nm, 1311nm and 1331nm respectively. It works by transmitting four data signals simultaneously on an optical fiber. It uses wavelength-division multiplexing. and coherent modulation techniques to combine data signals of different wavelengths into a single fiber by multiplexing them and then transmitting them.
The second is the transmission distance. 100G LR4 is a single-mode optical module suitable for long-distance transmission with a maximum transmission distance of 10 km, while 100G CWDM4 is a wavelength division multiplexing optical module suitable for short-distance transmission, the maximum transmission distance is 2 km.
Finally, the prices are different. 100G LR4 is usually more expensive than 100G CWDM4, mainly because it is suitable for longer transmission distances.
