An in situ birefringence measurement in conjunction with an atomic force microscope study shows that the geometric asymmetry of the side-writing process is a major cause of the induced birefringence in grating-based fiber devices. Measured refractive-index profiles of UV-exposed fibers clearly show the asymmetry in the induced index change. We demonstrate the use of a dual-exposure technique for producing low-birefringence devices.
© 1994 Optical Society of America
Ashish M. Vengsarkar, Qian Zhong, Daryl Inniss, W. A. Reed, Paul J. Lemaire, and S. G. Kosinski, "Birefringence reduction in side-written photoinduced fiber devices by a dual-exposure method," Opt. Lett. 19, 1260-1262 (1994)