Abstract

The frequency-modulated continuous-wave (FMCW) technique, which was originally investigated in radar technology, has been successfully used to construct various fiber-optic interferometers and sensors. The advantages of this technology include easy calibration and counting fringes, absolute measurement and simple signal processing. Recently, there is a growing interest in the application of the FMCW technique to rotation sensing [1,2]. However, the problem in the existing fiber-optic FMCW Sagnac interferometers is that the initial optical path difference in the interferometer introduces an unexpected non-reciprocal phase drift if the environmental conditions are unstable. This paper reports a differential birefringent fiber FMCW Sagnac interferometer, which, due to the nature of the differential structure, can automatically eliminate the unexpected non-reciprocal phase drift and make the resolution of the interferometer doubled.

© 2004 Optical Society of America