For photoelectric converter devices, optical modules are the most common products in optical communication networks. Among the characteristics of optical modules, the transmission capacity is the most important and the most concerned parameter. In addition, the transmission distance of optical module is another key parameter that cannot be ignored. In different fields and links of optical communication network transmission, the requirements for the characteristics of optical modules are also different.

According to the different transmission distance of optical modules, they can be divided into three types: short distance optical module, medium distance optical module, and long distance optical module. The long distance optical module specifically refers to the optical module with transmission distance of more than 30km, which can meet the needs of long-distance transmission of network data.

In the actual use of long-distance optical modules, the maximum transmission distance of the module cannot be reached in many cases, because the optical signal will have a certain degree of dispersion during transmission in the optical fiber. To solve this problem, the long-distance optical module uses only one DFB laser as the light source, thus avoiding the dispersion problem.

Among SFP optical module, SFP+optical module, XFP optical module, 25G optical module, 40G optical module and 100G optical module, there are long-distance optical modules. Among them, the long distance SFP+optical module uses EML laser module and optical detector module, which reduces the power consumption of the optical module and improves the accuracy; The long-distance 40G optical module uses a driver and a modulation unit in the transmission link, and an optical amplifier and a photoelectric conversion unit in the reception link, realizing the maximum transmission distance of 80km.

However, the transmission distance of the optical module is not as far as possible, and appropriate solutions should be taken as appropriate. Long-distance applications are mainly in server ports, switch ports, network card ports, security monitoring fields, telecommunications fields, Ethernet, synchronous optical network and other fields.