Currently, the commonly used central wavelengths for optical modules are primarily in three bands: the 850nm band, the 1310nm band, and the 1550nm band. Why are these three bands defined? This is related to the optical fiber loss. An optical module usually consists of an optical transmitting device (TOSA, including a laser), an optical receiving device (ROSA, including a photodetector), functional circuits,main control circuit board (PCBA), housing and optical (electrical) interface and other components. Understanding their key parameters isn't just technical jargon – it's critical for ensuring compatibility, performance, and reliability in your data center. Center Wavelength: The center wavelength of optical modules refers to the range of light waves utilized during the transmission of optical signals, measured in nanometers (nm). Commonly used wavelengths include 850nm, 1310nm, and 1550nm, as well as the CWDM wavelengths ranging from 1270nm to 1610nm. Average optical power refers to the optical power outputted by the optical module's transmitter under normal working conditions, which can be understood as the intensity of light. The unit of the center wavelength is a nanometer (nm).