Reflectometry based on a frequency-shifted interferometer using sideband interference

Frequency-shifted interferometry has shown great potential in optical fiber sensor multiplexing. In this letter, we propose and demonstrate a frequency-shifted interferometer (FSI) based on sideband interference. Comparing with previous implementation of FSI based on a Sagnac interferometer, this scheme is much simpler and compact. By scanning the driving frequency of a LiNbO3 phase modulator in the range of 4.5-5.5 GHz, we demonstrate a spatial resolution of 0.1 m, which is 50 times better than the previously reported results.