Optical low-coherence reflectometer for differential phase measurement

A birefringent-fiber-based dual-channel optical low-coherence reflectometer capable of differential phase measurement is described. Phase noise owing to environmental perturbations that is common to both channels is canceled, resulting in accurate measurement of the phase difference between light backscattered from two spatially separated sites. Results are presented that demonstrate the accuracy and sensitivity of the system. (C) 2000 Optical Society of America OCIS codes: 120.3180, 120.5050, 110.4500, 120.1840, 060.2430.