Distributed Vibration Sensing Through a Network Analysis Optical Frequency-Domain Reflectometer

In this article, we demonstrate the use of a network analysis optical frequency domain reflectometer (NA-OFDR) for distributed vibration sensing at a spatial resolution of ≈3 cm and an acquisition rate up to ≈80 Hz. The system makes use of a continuous-wave (CW) laser, whose amplitude is modulated using a vector network analyzer. The latter is also used to demodulate the amplitude and phase of the beat signal obtained by coherently mixing the backscattered light with a local oscillator. Two configurations are considered, based on either double sideband or single sideband modulation of the probe light. The single sideband modulation is shown to possess superior performance in terms of localization capabilities of the applied perturbation.