Optical Modules

Brief Introduction to Optical Modules


Optical module is an optical device used for photoelectric conversion and electro-optical conversion. It is the core device of optical communication. It is composed of optoelectronic devices, functional circuits and optical interfaces. It can complete the optical-electrical/electrical-optical conversion of optical signals. The optoelectronic device includes two parts: transmitting and receiving. The transmitting end converts the electrical signal into an optical signal, that is, the input electrical signal with a certain code rate is processed by the internal driver chip and directly drives the semiconductor laser or light-emitting diode to emit modulated light at the corresponding rate. Signal, the built-in optical power automatic control circuit will keep the output optical signal power stable and realize electrical-optical conversion. After transmission through the optical fiber, the receiving end converts the optical signal into an electrical signal, that is, an optical signal with a certain code rate. After the signal is input into the module, it is converted into an electrical signal by the light detection diode, and the electrical signal of the corresponding code rate is output after the preamplifier. The output signal is generally a level signal, which realizes optical-electrical conversion, so the optical module is also called an optical transceiver integrated module. Although optical modules are small in size and relatively simple in structure, they have high technical requirements. With the accelerated growth of Internet traffic in recent years, the market demand for optical modules is also expanding rapidly.

When selecting an optical module, in addition to the type of optical fiber interface, parameters such as package, transmission rate, transmission distance, wavelength, and mode should also be considered. The specific categories are as follows:


By package: 1×9, X2, XENPARK, 300pin, GBIC, SFF, SFP, XFP, SFP+, QSFP+, QSFP28, QSFP56, QSFP-DD, etc.

By rate: 155M, 622M, 1.25G, 2.5G, 4.25G, 10G, 40G, 100G, 200G, 400G, 800G.

By wavelength: conventional wavelength, CWDM, DWDM, etc.

By mode: single-mode fiber module, multi-mode fiber module.


There are three main data transmission modes for optical modules: simplex, half-duplex and full-duplex. Simplex transmission only supports data transmission in one direction; half-duplex transmission allows data transmission in two directions, but in a certain direction. Only one direction of data transmission is allowed at a time; full-duplex transmission allows simultaneous data transmission in both directions. The transmission rate, transmission distance and application range of different types of optical modules are different. The most suitable optical module can be selected according to the actual needs. When the optical modules of the same rate have different package types, the application equipment needs to be considered Encapsulation port type. The transmission distance supported by different optical modules is different. Considering the attenuation and dispersion of the optical signal during the transmission process, the transmission distance of the optical module should be slightly larger than the actual required transmission distance. In addition, in industrial applications, industrial-grade modules with an operating temperature range of -40°C to 85°C must be used.


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