A New Type Of Sensitivity Adjustable Fiber Bragg Grating Sensor

As the fiber optic sensor can be used for large area monitoring, and the advantage of high sensitive, good shape adaptability, resistance to electromagnetic interference, light weight, wide dynamic ranges, the fiber Bragg grating sensors are widely applied in various fields. At the moment fiber-optic sensing technology has been developed to a mature stage, and the most important develop technology is fiber bragg grating sensor. With the development of sensor signal demodulation technology and the designing of fiber sensors, fiber Bragg grating sensor is regarded as a mature technology as a kind of sensors, and the number of publications based on this field is considerable. The fiber sensor has a wide application area, such as temperature sense, pressure sense, stress sense, strain sense, vibration sense, displacement sense, refractive index sense, voltage sense, and so on. There are many ways for fiber bragg grating to sensing the external environment variables, and the application environment of it and the style of their sense is mostly not the same. The most important factor on estimation of the performance of a sensor is the sensitivity, which is determined by different design options. Different design aspects of the sensor lead to different sensing results and the sensitivity of the sensor also vary. Most of the sensors were designed to a particular environment and have a definite environment to measure, also have a confirmatory sensitivity. It could not achieve the other measurement environmental requirements which corresponding to the different sensitivity. Design a sensitivity adjustable sensor structure and adjust the sensitivity as needed to adapt to different measurement environment, can greatly increase the applicability of the sensor and saving the measurement cost.In this paper we mainly design a new type of fiber Bragg grating sensor with adjustable sensitivity. The fiber Bragg grating (Fiber Bragg grating, FBG) were used as the sensor component, an intensity beam length adjustment method is applied to achieve the purpose of adjustable sensitivity. The main method is to design a sensor to an arm cantilever sensor with embedded structure. The embedded part of the length of the sensor chip in the main structure, like a part of structure, is designed without affecting the sensing side of the sensor. The length of cantilever arm can be adjusted to change the sensitivity of the sensor, with the purpose to achieve the effect of adjust the sensitivity. In this way, one sensing architecture can be used to measurement a variety of different environment variables, and adjust the sensitivity depending on the actual needs, so it has much practical value.From the theoretical analysis and the experimental of vibration and displacement verification confirmed that the design of the sensitivity adjustable fiber grating sensor structure in this paper is feasible. In the future this structure could be applied to the bridge or machine conditional monitoring. The purposes of a sensor structure fixed to multi-environment can be achieved, without using additional sensing structure to measure the different environment variables. It can reduce the cost of the sensing.