Satoshi Tanaka and Yoshihiro Ohtsuka

Department of Applied Physics, Faculty of Engineering, Hokkaido University, Sapporo, 060 Japan

(Received November 8, 1996; Accepted December 20, 1996)

This paper describes a double fiber-coiled interferometric deformation sensor fabricated using paired polarization maintaining single-mode fibers. A change in bending-induced birefringence plays a fundamental role in the sensor performance as the fiber-coil is being deformed across its cross-section. Differential optical heterodyne detection processes allow us to implement two-mode operations; one is widely dynamic operation and the other highly sensitive operation around a target region. The deformation sensitivity for one-turn fiber-coil is 2.5 deg/mm for the widely dynamic operation, whereas 9.5×10 deg/mm for the highly sensitive operation. The double fiber-coiled deformation sensor can eliminate external, undesirable temperature disturbances.

Key words : double Mach-Zehnder interferometry, optical heterodyne detection, immunity from environmental disturbances, polarization maintaining single-mode fiber, fiber-coil deformation sensor