Distributed Temperature Sensing through Network Analysis Frequency-Domain Reflectometry

• DOI: 10.20944/preprints202402.1445.v1
• Publication Date: 2024-03-04T06:16:57Z
• Authors: Rizwan Zahoor; Raffaele Vallifuoco; Luigi Zeni; Aldo Minardo
• Keywords: distributed temperature sensing; optical frequency-domain reflectometry; rayleigh scattering; distributed temperature sensing; optical frequency-domain reflectometry; Chemical technology; TP1-1185; 01 natural sciences; Article; rayleigh scattering; 0104 chemical sciences

In this paper, we propose and demonstrate a network analysis optical frequency domain reflectometer (NA-OFDR) for distributed temperature measurements at high spatial (down to 3 cm) and temperature resolution. The system makes use of a frequency-stepped, continuous-wave (cw) laser, whose output light is modulated using a vector network analyzer. The latter is also used to demodulate the amplitude of the beat signal obtained by coherently mixing the Rayleigh backscattered light with a local oscillator. The system is capable of high measurand resolution (50 mK at 3-cm spatial resolution), thanks to the high sensitivity of coherent Rayleigh scattering to temperature. Furthermore, compared to the conventional optical-frequency domain reflectometry (OFDR), the proposed system does not rely on the use of a tunable laser, therefore it is less prone to limitations related to the laser coherence or sweep nonlinearity. Two configurations are analyzed, both numerically and experimentally, based on either a double sideband or single sideband modulated probe light. The results confirm the validity of the proposed approach.