Temperature sensors are based on a basic physical quantity called "temperature", which refers to a sensor that senses temperature and converts it into a usable output signal. Temperature sensors are the core part of temperature measuring instruments, and there are a wide variety of them. According to the measurement method can be divided into contact and non-contact two categories, according to the sensor material and the characteristics of the electronic components are divided into two categories of RTD and thermocouple.

　　All processes in nature are closely related to temperature. Since Galileo's invention of the thermometer, people have been using temperature to make measurements.

　　Temperature sensors were the first to be developed and the most widely used type of sensor. But the real sensor that turns temperature into an electrical signal was invented by the German physicist Sébé, later known as the thermocouple sensor. 50 years later, the German Siemens invented the platinum resistance thermometer. With the support of semiconductor technology, a variety of temperature sensors, including semiconductor thermocouple sensors, were developed one after another in this century. Correspondingly, according to the wave and material interaction law, acoustic temperature sensors, infrared sensors and microwave sensors have been developed.

　　Since the advent of optical fiber in the 1970s, with the development of laser technology, from theory and practice has proved that optical fiber has a series of advantages, the application of optical fiber in the field of sensing technology is increasingly being widely valued, with the development of science and technology, the emergence of many optical fiber temperature sensors, and can be expected, in the wave of the new technological revolution, optical fiber temperature sensors will be widely used, and play a more important role.

　　The basic working principle of the fiber optic temperature sensor is the light from the light source through the optical fiber into the modulator, the parameter temperature to be measured and the light into the modulation zone interaction, leading to changes in the optical properties of light (such as light intensity, wavelength, frequency, phase, etc.), known as the modulated signal light. Then through the optical fiber into the light detector, after demodulation, to obtain the measured parameters.

　　Fiber optic temperature sensors are many types, but generally according to its working principle can be divided into functional and transmission type two. Functional fiber optic temperature sensor is the use of optical fiber characteristics (phase, polarization, intensity, etc.) with the characteristics of the temperature transformation, temperature determination. This type of sensor, although it has the characteristics of transmission, sensing a unity, but also increases the difficulty of sensitization and desensitization. The optical fiber of the transmission type fiber optic temperature sensor only plays the role of optical signal transmission, in order to avoid the complex environment of the temperature measurement area. The modulation function of the object to be measured is dependent on other sensitive elements of a physical nature. This type of sensor due to the existence of optical fiber and sensing head of the optical coupling problem, increasing the complexity of the system, and more sensitive to mechanical vibration and other interference.

　　A variety of fiber optic temperature sensors have been developed. Here are several major fiber-optic temperature sensor research status, which is representative of the fiber-optic Fabry-perot interference-type temperature sensor, semiconductor absorption fiber-optic temperature sensor, fiber-optic grating temperature sensor three.

　　Since the introduction of fiber optic temperature sensors. Mainly used in power systems, construction, chemical, aerospace, medical and marine development and other fields, and has achieved a large number of reliable application achievements. Its application is an emerging field, with very broad prospects for development, so far, there have been a lot of related research at home and abroad, although the sensitivity, measurement range, resolution and other aspects of great development, but I believe that with the depth of research, according to the specific application purposes, there will be more and more higher precision, simpler structure, lower cost, more practical programs proposed, and further! Promote the development of temperature sensors.