Light pulse external modulation type distributed optical fiber temperature sensing device

Abstract

The invention discloses a light pulse external modulation type distributed optical fiber temperature sensing device. An external modulation light-emitting unit is used for outputting the high-power narrow pulsed light needed by the system. The device has the following advantages and positive effects: the effects caused by instability of the light source and coupling loss, optical fiber splice loss, optical fiber bending loss, optical fiber transmission loss and the like in the optical fiber transmission process can be effectively eliminated by adopting Rayleigh scattering light as the contrast signal; and the Raman scattering light after combination and the Rayleigh scattering light are stronger, and the stronger scattering light signal can be detected if the input light source power is lower, thus overcoming the contradiction between the incident light power and the nonlinearity of scattering light and improving the temperature measuring sensitivity of the system.

Description

Distributed optical fiber temperature sensing device with external modulation of optical pulse technical field The invention relates to the technical field of optical fiber sensing, in particular to the technical field of distributed optical fiber temperature sensing. Background technique The index of the incident pulsed laser is the key factor affecting the performance of the distributed optical fiber sensor, and the basic condition for the distributed optical fiber sensor to respond to changes in light scattering, and the narrower the pulsed light, the more stable the spectral width, and the higher the sensitivity of the system; The spectral drift of the light source is also very important, because the frequency drift will cause the backscattering curve of the distributed optical fiber temperature sensor to jitter, so that the temperature-induced changes in the backscattering curve will be submerged, seriously affecting the performance of the system. High-power incident...

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Problems solved by technology

However, when the modulation rate increases to 200MHz, this method encounters many limitations, the signal rate, the average output power and the extinction ratio are all limited.

In addition, direct modulation will distort the analog signal and shift the output wavelength of the pulse, the so-called "chirp" effect

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