Few-mode fiber based Raman distributed temperature measurement system and temperature measurement method

Abstract

The invention discloses a few-mode fiber based Raman distributed temperature measurement system and a temperature measurement method. The temperature measurement system comprises a pulse laser light source, a coupler, special connector, a few-mode fiber, a Raman filter, two photoelectric detectors and a signal processor, and is characterized in that pulse laser outputted by the coupler gets into the few-mode fiber through the special connector, and back-scattering light is generated in the transmission process of the pulse laser in the few-mode fiber; the back-scattering light is inputted into the Raman filter through a back output port of the coupler, and the Raman filter carries out filtering on Raman Stokes light and Raman anti-Stokes light respectively; the two photoelectric detector respectively receive scattered light outputted from the two ports and carry out photoelectric conversion; and the signal processor carries out processing on outputted electric signals so as to acquire temperature information. According to the invention, the few-mode fiber is low in transmission loss, and the intermodal dispersion is far less than that of a multi-mode fiber, thereby not only increasing the detecting distance of the temperature measurement system, but also improving the spatial resolution of the temperature measurement system.

Description

technical field [0001] The invention relates to the technical field of distributed optical fiber temperature measurement systems, in particular to a Raman distributed temperature measurement system and temperature measurement method based on few-mode optical fibers. Background technique [0002] Temperature sensing systems are widely used in infrastructure such as roads, tunnels, bridges, water conservancy projects, high-voltage cables, underground coal mines, and petrochemical fields. The traditional single-point mobile or distributed measurement methods realized by networking of multiple electronic sensors have disadvantages such as difficult installation, difficult maintenance, and susceptibility to electromagnetic interference. Optical fiber-based distributed temperature sensor is an effective means to improve the shortcomings of the above-mentioned sensing system, and the optical fiber has the advantages of low insertion loss, long detection distance, easy laying, etc. ...

AI Technical Summary

Problems solved by technology

For the distributed Raman sensing system based on multimode fiber, its advantage is that multimode fiber has a large mode field area and high Raman gain coefficient, and its disadvantage is that the loss of multimode fiber is large, resulting in a limited detection distance. Insufficient spatial resolution of sensing due to crosstalk introduced by intermodal dispersion

For the distributed Raman sensing system based on single-mode fiber, its advantage is that the loss is small, and its disadvantage is that the mode field area is small, so the input optical power is limited and the detection distance is limited

Images