Research for Thermal Drift of APD Gain in Distributed Temperature Sensing System Based on the Raman Back-Scattering

Abstract

In the temperature measurement system of distributed optical fiber based on Raman back-scattering, the temperature measurement depends on a series of laser pulses in the optical fiber, which produces anti-stokes and stokes lights of Raman back-scattering at various points. By using the ratio of them, the measurement of temperature field space can be realized. But the signals that can be gained are quite weak in practice, and there are interferences of noises and external signals, therefore APD is selected (Avalance Photodiode) to amplify the weak signals. Because the gain characteristics of APD are vulnerable to the influences of temperature and bias voltage, so in this paper the experiments were carried on about the effects of temperature, bias voltage, incident power etc. on APD, and a substantive discussion was discussed.