Which wavelength is used in the optical module

Optical modules commonly operate at center wavelengths of 850 nm, 1310 nm, and 1550 nm, with CWDM and DWDM modules covering broader ranges from 1270 nm to 1610 nm.Standard Center WavelengthsOptical modules convert electrical signals into optical signals and transmit them through fiber. The center wavelength is the specific wavelength at which the module operates most efficiently. The commonly used wavelengths are:850 nm: Primarily used for multi-mode (MM) fiber and short-distance transmissions up to 500 meters due to low cost and sufficient performance for local networks .1310 nm: Used for single-mode (SM) fiber over medium distances, typically 500 meters to 20–40 km, offering moderate fiber loss and low dispersion .1550 nm: Used for long-distance single-mode transmission, often exceeding 40 km, with minimal fiber loss and suitable for high-capacity links .CWDM and DWDM WavelengthsFor wavelength-division multiplexing systems:CWDM (Coarse Wavelength Division Multiplexing): Operates in the range of 1270–1610 nm, suitable for short to medium distances and cost-effective multi-channel transmission .DWDM (Dense Wavelength Division Multiplexing): Operates in narrower bands, typically 1525–1565 nm or 1570–1610 nm, allowing high-density, long-distance optical communication .Practical ConsiderationsShort-distance networks (e.g., within a building) often use 850 nm multi-mode modules.Medium-distance links (e.g., campus networks) typically use 1310 nm single-mode modules.Long-haul or high-capacity networks rely on 1550 nm single-mode modules, often combined with DWDM for multiple channels.The choice of wavelength also depends on fiber type, transmission distance, and system design to minimize loss and dispersion . In summary, 850 nm, 1310 nm, and 1550 nm are the primary wavelengths for optical modules, while CWDM and DWDM systems expand the usable wavelength range for multiplexed optical communication.