Measurement of External Impact by an Intermodal Fiber Interferometer with Spectral Interrogation and Fourier Transform of Output Signals

The approach to measuring external impact by measuring the phase difference of excited mode groups of an intermodal fiber interferometer has been experimentally investigated. The proposed approach is based on obtaining the phase spectrum of the spectral transfer function of an intermodal fiber interferometer. The results of measuring the external impact (the change in the length of the multimode fiber according to the triangular law) by the proposed approach are presented. It is shown that the method of measuring the phase difference of excited mode groups provides a linear response to external impact in a large dynamic range.