Optical Fiber Sensing Unit and Its Application in Simultaneous Measurement of Refractive Index and Temperature

Abstract

The invention discloses an optical fiber sensing unit and its application for simultaneously measuring the temperature of the refraction index. The optical fiber sensing unit includes input single-mode optical fiber, micro-nano multi-mode optical fiber, reflection single-mode optical fiber and a reflection end face. The wide-spectrum light emitted by the signal light source enters the optical fiber sensing unit through the optical fiber coupler to generate an interference spectrum, and then the interference spectrum is transmitted to the reflective end face of the optical fiber sensing unit for partial reflection, and the reflected interference spectrum is received by the demodulation device; The demodulation device demodulates the wavelength and intensity variation of the reflected interference spectrum, that is, realizes the simultaneous measurement of the refractive index and temperature. The invention can simultaneously measure external refraction index and temperature value, has high sensitivity and reliability, strong anti-interference ability, low cost and easy realization. It can be used not only for atmospheric environment, soil water quality monitoring, but also for research in the fields of biomedicine, life science and human body detection.

Description

technical field [0001] The present invention relates to the technical field of optical fiber sensing, in particular to the optical fiber sensing unit and its application for monitoring the refractive index and temperature in a local area, which can be applied in the fields of atmospheric environment, soil water quality, biomedicine, life science and human body detection . Background technique [0002] The refractive index can reflect certain properties of substances, such as the humidity in the atmosphere, the impurities and microbial content in soil water quality, and the blood sugar content in human blood, so it is very meaningful to measure the refractive index. The traditional method of measuring the refractive index is to use an Abbe refractometer, but this method requires sampling to measure the refractive index, and does not have the ability of remote monitoring and real-time measurement. At the same time, the refractive index measurement method based on optical fibe...

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Problems solved by technology

However, the above methods have certain disadvantages. For example, the preparation of the grating requires an ultraviolet laser and a phase mask to engrave the grating, which requires high costs and a relatively complicated preparation process; based on the sensing of the thermo-optic coefficient of the optical fiber itself, the obtained sensitivity value is very low.

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