Thermistor chip of optical module produced by EXSENSE Electronics Technology Co., Ltd. can play the role of temperature monitoring and temperature controlling in the optical module, and ensure the normal operation of the optical module effectively.

Optical module is the core device of optical communication, and it is also the basis of realizing optical communication. Optical communication is composed of the "transmitter" that converts an electrical signal into a optical signal, the "receiver" that converts an optical signal into an electrical signal, and the circuit "fiber optic" that transmits optical wave.

Fiber optic is divided into multi-mode fiber and single-mode fiber. The transmission of multi-mode fiber has a variety of modes, but the high inter-mode dispersion limits the transmission frequency of digital signals, and this restriction will be more serious with the increase of transmission distance. As a result, multi-mode fiber is transmitted over relatively short distances, typically only a few kilometers. The single-mode fiber has a very small diameter and can only transmit one mode in theory, so it is suitable for remote communication.

Bare fiber of fiber optic is divided into three layers: fiber core, cladding and coating layer. The fiber core is located in the center of the fiber optic and is made of high-purity silica, glass. Its core diameter is generally 9~10μm (single mode), 50 or 62.5μm (multi-mode), the fiber core has a high refractive index, which is used to transmit optical wave. The cladding is located around the fiber core and is also made of silica glass (the diameter is generally 125μm). The cladding has a low refractive index, which, together with the fiber core, forms a total reflection condition. Coating layer is resin coating used to reinforce. Its material strength is strong, which can withstand greater impact, can protect the fiber optic from water vapor erosion and mechanical abrasion.

Transmission loss is a very important factor affecting the quality of optical communication in fiber optic transmission. The main factors that cause the attenuation of optical signal are the absorption loss of material, the scattering loss during transmission, and the loss caused by other factors such as bending, extrusion and docking loss of fiber optic. Different wavelengths of optical wave lead to different transmission losses in fiber optic. After a long period of exploration and practice, experts have gradually concluded a low-loss wavelength (1260nm~1625nm) region, the range of optical wave in this wavelength region is most suitable for transmission in fiber optic, so the optical wave used in optical communication is generally infrared band.