Research On Multiplexing Technology Of Optical Fiber Reverberation Cavity Sensor

Fiber cavity ring-down sensors have been widely paid attention by scientists due to their intrinsic advantages of the traditional cavity ring-down spectroscopy, such as high precision, fast dynamic response, and no requiring complex optical alignment equipment. But, up to now, most fiber cavity ring-down sensors can only measure a single target, which does not show the superiority of fiber sensor which can be multiplexed. In order to meet the demands of increasing complex measurement, fiber cavity ring-down sensing technology urgently needs to solve the problem that achieves multiple sensors multiplexing and multiple parameters measurement.This thesis proposes the fiber cavity ring-down sensor multiplexing technology with the capable of simultaneous measurement of pressure and temperature. The wavelength-swept fiber laser(WSFL), which is designed based on the fiber Fabry-Perot tunable filter, provides the continuous wavelength tunable laser to fiber cavity ring-down sensors array, and the light with designed wavelength is coupled into a certain fiber cavity ring-down by fiber Bragg grating(FBG) served as wavelength selection device. According to the different time of the light signal reflected by the FBG with different wavelength, every sensor is distinguished in sensors array. The wavelength shift of the FBG induced by temperature change is transformed into the time change of the pulse light signal reflected by the FBG. Accurate temperature information can be achieved based on the time delay of the pulse light reflected by the FBG. The mixing information of temperature and pressure is obtained in the microbend area of sensor based on ring-down time. The simultaneous measurement of pressure and temperature can be achieved by removing temperature influence on pressure measurement. This proposed system greatly reduces the cost and promotes the practical application of fiber cavity ring-down sensor.