Long-distance Raman distributed temperature sensing system

Abstract

The invention relates to a long-distance Raman distributed temperature sensing system which comprises an optical fiber pulse laser, an electrooptic modulator, a pump light source of 1480nm, wavelength division multiplexers, circulators, a signal processing and displaying module which are arranged at a front end of the system; the system is characterized by further comprising at least one stage of calibrating module, a sensing optical fiber and a relay amplifying module which are arranged at a rear end of the system and are connected with the wavelength division multiplexers at the front end of the system; the calibrating module, the sensing optical fiber and the relay amplifying module are connected in sequence; the relay amplifying module comprises a coupler, an Er-doped optical fiber amplifier, a first wavelength division multiplexer and a second wavelength division multiplexer are respectively provided with four channels, and a first circulator and a second circulator. The system has the beneficial effects that compared with a traditional Raman distributed optical fiber sensing system, the Raman distributed optical fiber temperature sensing system provided by the invention adds multiple stages of amplification, sensing distances are extended remarkably, and moreover, precision on temperature calibration is improved.

Description

technical field The invention belongs to the technical field of optical fiber sensing, and in particular relates to a long-distance distributed optical fiber Raman temperature sensing system capable of multi-stage optical amplification and multi-stage temperature calibration using a fiber Bragg grating (Fiber Bragg Grating, FBG). Background technique In recent years, the distributed optical fiber Raman temperature sensor based on the principle of spontaneous Raman scattering is able to monitor the temperature in a wide range along the optical fiber in real time online, and compared with the distributed optical fiber sensor based on the principle of Brillouin scattering, it has low cost and is not Due to the advantages of cross-interference by strain, it is widely used in distributed temperature monitoring fields such as oil pipelines, power lines, and geological investigations. Compared with the distributed optical fiber sensor based on the Brillouin scattering principle, t...

AI Technical Summary

Problems solved by technology

Another factor that limits the application of centralized optical amplification technology in Raman distributed temperature sensors is: after adding optical amplification, the temperature calibration at the incident end of the optical fiber is not suitable for the scattered light in the optical fiber after optical amplification, thus Unable to perform accurate temperature demodulation of amplified Raman scattered light

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