Phase matching sampling algorithm for sampling rate reduction in time division multiplexing optical fiber sensor system

Time division multiplexing (TDM) architecture is an important approach to creating sensor arrays for massive scale monitoring. But it is paradoxical for the TDM interferometric sensor array to keep a short delay fiber for high sensing resolution and meanwhile use low sampling rate for practical applications. In this paper, a phase matching sampling (PMS) paradigm is proposed to address the above contradiction. By matching the phase of the sampling clock with the delay fiber length, combining with multiple-pulses sampling strategy, the proposed PMS method can avoid collecting the redundant information, facilitating the decreasing of sampling rate as well as delay fiber length of the TDM sensing system. The proof-of-concept experiments on an 8-channel TDM interferometric system demonstrate that when the sampling rate is fixed at 20 MS/s, by applying the PMS algorithm, the delay fiber length can be shortened from 100 m to 1 m, compared with applying the conventional sampling method. It reduced the phase noise of the system by a factor of 10 at 1 mHz and by a factor of 50 at 1 Hz. The PMS algorithm for greatly reducing the sampling rate is expected to fuel the TDM interferometric sensor arrays for many applications.