Distributed Temperature Sensor Interrogator Based on Polarization-Sensitive Reflectometry

In this paper, a polarization-sensitive reflectometry technique has been investigated in order to serve as an interrogating device in distributed sensing applications. As the sensing fiber has a beat length of about a few centimeters, a high-resolution reflectometer was required. A coherent optical frequency-domain reflectometer (OFDR) was used from this perspective. The principle is based on the linear dependence of fiber beat length on temperature. The reported experimental results detail the calibration method and discuss the features of the interrogating device in terms of temperature threshold and spatial resolution. The proposed system, exploiting the Rayleigh backscatter signal, offers an interesting alternative to existing systems, mainly based on nonlinear effects.