Satoshi TANAKA,¹ Kazuaki YOSHIDA,² Seiichiro KINUGASA¹ and Yoshihiro OHTSUKA¹

¹Department of Applied Physics, Faculty of Engineering, Hokkaido University, Sapporo, 060 Japan, ²Yokohama R & D Laboratories, The Furukawa Electric Co., Ltd., 2-4-3, Okano, Nishi-ku, Yokohama 220 Japan

(Received July 1, 1996; Accepted September 12, 1996)

Novel birefringent single-mode fibers are fabricated with a vacant hole on either side of the central elliptical core, referred to as side-hole fiber, and their intrinsic and tension-induced modal birefringences are measured to know their characteristic properties for the purpose of making a strain sensor. Five sampled side-hole fibers are prepared for measurements. The sensitivity of the strain sensor is primarily determined by two parameters, tension-induced and intrinsic modal birefringences. Tension-induced modal birefringence is controllable by optimal arrangement of the size and location of the side-holes in the cross-section of the fiber. A sensitivity diagram for designating and fabricating side-hole fibers is presented.

Key words : birefringent single-mode side-hole fiber, parameter measurements and analysis, polarimetric strain sensor, tension-induced modal birefringence, polarization maintaining single-mode fiber