We present two novel schemes for refractometry based on a long-period fiber grating- (LPG-) based Michelson interferometer. These schemes are designed to overcome the measurement dependence of previously demonstrated LPG-based refractometry on the immersion depth. The first utilizes an unshielded LPG and the second, a shielded one. Both schemes were tested over a certain refractive-index range, and the measurement of glucose concentration in water was experimentally demonstrated. In addition, the temperature sensitivity of the two schemes is discussed.
© 2005 Optical Society of America
(060.2340) Fiber optics and optical communications : Fiber optics components
(060.2370) Fiber optics and optical communications : Fiber optics sensors
(350.2770) Other areas of optics : Gratings
Dae Woong Kim, Yan Zhang, Kristie L. Cooper, and Anbo Wang, "In-fiber reflection mode interferometer based on a long-period grating for external refractive-index measurement," Appl. Opt. 44, 5368-5373 (2005)