Distributed optical fiber sensing system and method based on multi-pulse and multi-wavelength

Abstract

The invention discloses a distributed optical fiber sensing system and a method based on multi-pulse and multi-wavelength, belongs to the technical filed of distributed optical fiber sensors. The system comprises a light source module, a modulation module, a delay module, a coupling module, a pulse amplification module, a preamplifier amplification module, a splitting system, an interference module, a signal detection module, and a data processing terminal. The distributed optical fiber sensing method uses a plurality of light source combinations to inject n wavelengths of light in one cycle T, and controls the delay time through a optical fiber delay line, so that a light pulse is sequentially injected into a sensing optical fiber in a specific order. A backward Rayleigh scattered light generated by the n light pulse is separated by gratings of different central reflection wavelengths, and photoelectrically converted after entering the photodetector. N OTDR curves independent of eachother are obtained after AD acquiring. By demodulating n OTDR curves, n phase information with repetition frequency f is obtained, and n demodulated curves are interleaved by array to form a final result.

Description

technical field [0001] The invention belongs to the technical field of distributed optical fiber sensors, and in particular relates to a distributed optical fiber sensing system and method based on multi-pulse and multi-wavelength. Background technique [0002] Distributed optical fiber sensing is an important application in the field of optical fiber sensing. Compared with point sensors, distributed sensors have obvious advantages, such as low cost and convenient processing, which have gained many application advantages. In perimeter security, pipeline detection, Geological exploration, distributed temperature measurement and other fields already have obvious market advantages. It can detect physical quantities such as vibration, temperature, and strain along the optical cable in real time, and the market prospect is good. [0003] At present, the distributed measurement system is mainly based on the principle of backscattering. The principle of this system is to use the pr...

AI Technical Summary

Problems solved by technology

After splitting the power of a single light source N times by using a single light source with a frequency shifter combined with balanced detector demodulation, the power will drop to SNR will degrade rapidly as N increases

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