Wavelength division multiplexing device for distributed optical fiber temperature sensor

Abstract

The invention discloses a wavelength division multiplexing device for a distributed optical fiber temperature sensor in the field of optical fiber sensors. The device comprises four ports formed on a shell; an optical circulator with four ports is arranged in the shell; first and second ports of the optical circulator are directly connected to a port 1 and a port 2 on the shell respectively; a fiber Bragg grating with Rayleigh scattering wavelength, a fiber Bragg grating with Stokes wavelength and a band-pass filter with anti-Stokes wavelength are connected in series between a third port of the optical circulator and a port 3 on the shell; the fiber Bragg grating with the Rayleigh scattering wavelength, a fiber Bragg grating with the anti-Stokes wavelength and a band-pass filter with the Stokes wavelength are connected in series between a fourth port of the optical circulator and a port 4 on the shell; and a light path in the optical circulator circulates from the first port to the fourth port step by step. The device can reliably separate anti-Stokes light from Stokes light, the accurate temperature information can be acquired further, and the temperature resolution of the system is improved.

Description

Technical field [0001] The invention relates to a wavelength division multiplexing device, in particular to a wavelength division multiplexing device for a distributed optical fiber temperature sensor, and belongs to the technical field of optical fiber sensors. Background technique [0002] Since JPDakin et al. successfully realized the distributed temperature measurement technology based on Raman scattering for the first time in 1985, people have carried out extensive research on various technologies for realizing distributed optical fiber temperature sensing. Sensing technology has the most extensive practical application. Compared with traditional sensors, distributed optical fiber temperature sensors have many outstanding advantages: the optical fiber itself is used as the sensing medium, and thousands of points of temperature information distributed along the optical fiber can be obtained in one measurement, which realizes continuous distributed measurement and reduces Mea...

AI Technical Summary

Problems solved by technology

First of all, this wavelength division multiplexing device uses a 1X3 bidirectional coupler, which will introduce an additional loss of about 9.5dB (10log(1 / 9)=9.5dB), which greatly weakens the available anti-Stokes light and Stokes light intensity; Secondly, the isolation of the device is difficult to exceed 40dB, unless a very special filter is designed, the reason is the same as above

[0007] If the above-mentioned conventional wavelength division multiplexing device is used in a distributed optical fiber temperature sensor, usually due to insufficient isolation, it will cause mutual crosstalk between anti-Stokes light and Stokes light, and interference of Rayleigh scattered light, In this case, it is difficult to obtain accurate temperature information and high resolution. In severe cases, the temperature curve may even be distorted, and the system cannot work normally.

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