1. Transmission distance
The transmission distance of sfp optical modules is divided into three types: short distance, medium distance and long distance (It is generally considered that the distance of 2km or less is short distance, the distance of 10-20km is medium distance as well as the distance of 30km, 40km and above is long distance)). The nominal transmission distance of the module model is only used as a classification method and cannot be directly applied in practical applications. On account of that the optical signal will have a certain loss and dispersion when it is transmitted in the optical fiber, which can not reach the nominal transmission distance.
The loss refers the loss of light energy due to the absorption, scattering and leakage of the medium when light is transmitted in the optical fiber, this part of the energy is dissipated at a certain rate with the increase of transmission distance.
The generation of dispersion is mainly due to the electromagnetic waves of different wavelengths travel at unequal speed in the same medium, so that the different wavelength components of the optical signal arrive at the receiving end at different times due to the accumulation of the transmission distance, resulting in pulse broadening and the inability to distinguish the signal value.
Therefore, users need to select the appropriate sfp optical module according to their own actual networking situation to meet different transmission distance requirements. The actual transmission distance depends on the actual transmission power of the corresponding SFP optical module, the transmission attenuation on the optical path as well as the receiving sensitivity of the optical port.
2. The length of optical fiber
Paying attention to the length of the optical fiber to ensure that the actual received optical power reaching the optical module is less than its optical saturation, otherwise it may cause damage to the SFP optical module.