Optical fibre temperature sensing method and sensor based on SAGNAC interferometer

Abstract

In the present invention, a small section of polarization preserving fiber transducing head is added into closed light path of total polarization SAGNAC interferometer applying Y waveguide modulator and wide spectrum light source to create condition for generating polarization nonreciprocal after certain process is applied, generated polarization nonreciprocal phase-shift and temperature acted on transducing head is presented in linear ratio relationship when light path is in operation so phase shift can be measured accurately by utilizing circuit the same as used in close ring optical fibre gyro detection and furthermore temperature measurement is realized.

Description

technical field [0001] The invention relates to an optical fiber temperature sensing method based on a SAGNAC interferometer and a sensor thereof. Background technique [0002] SAGNAC interferometer is a typical interferometer, which is the basic structure of all optical gyroscopes. When the optical path is formed with optical fiber and equipped with a special detection circuit, it becomes a fiber optic gyroscope. For the principle and technology of fiber optic gyroscope, please refer to Herve C. Lefever's monograph "The Fiber-Optic Gyroscope" or its translation: Zhang Guicai, Wang Wei, "Fiber Optic Gyroscope", the following related discussions will be based on this. figure 1 It is a typical SAGNAC interferometer. The broadband light emitted by the broadband light source 1 passes through the optical fiber 2 to the coupler 3 and then enters the Y waveguide modulator 5 through the optical fiber 4. After passing through the Y waveguide modulator 5, the light is divided into two...

AI Technical Summary

Problems solved by technology

In the fiber optic gyro, only one polarization mode is required to propagate. Although the polarization maintaining fiber is used to ensure the single polarization mode transmission, due to the defects in the polarization maintaining fiber, there are often more mode polarization couplings, resulting in non-reciprocal phase shift. This kind of non-reciprocity caused by the unsatisfactory polarization-maintaining ability of polarization-maintaining fiber is defined as polarization non-reciprocity (PNR)

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