[OPTICAL REVIEW Vol. 4, No. 5 (1997) 578-583]
Coupling-Wave Structures for Optical Waveguide Sensors
De-Kui QING,1 Ichirou YAMAGUCHI,1 Kiminori ITOH2 and Masayuki MURABAYASHI2
1The Institute of Physical and Chemical Research (RIKEN), Hirosawa, 2-1, Wako, Saitama, 351-01 Japan, 2Institute of Environmental Science and Technology, Yokohama National University, Tokiwadai, 79-7, Hodogaya-ku,Yokohama, Kanagawa, 240 Japan
(Received May 14, 1997; Accepted June 27, 1997)
An optical waveguide sensor structure, i.e. a coupling-wave structure, is presented and analyzed on the basis of a codirectional coupler. Potential uses for absorption-and fluorescence based sensors are theoretically explained by the group index method (D.-K. Qing, X-.M-. Chen, K. Itoh, M. Murabayashi: J. Lightwave Technol. 14 (1996) 1907). Refractive-index-based sensors were also analyzed. An actual coupling-wave structure was realized by combining the ion-exchange and the sol-gel methods. The coupling-wave structure that provides effective sensing interaction is easy to fabricate and can be used to realize optical waveguide chemical or biological sensors.
Key words : codirectional coupler, coupling wave, optical waveguide sensors, absorption-based sensors, fluorescence-based sensors, refractive-index-based sensors