[OPTICAL REVIEW Vol. 4, No. 3 (1997) 354-357]

Absorption Measurement Using a Leaky Waveguide Mode

Takayuki OKAMOTO* and Ichirou YAMAGUCHI

The Institute of Physical and Chemical Research (Riken), Wako, Saitama, 351-01 Japan

(Received June 10, 1996; Accepted March 18, 1997)

We propose an optical waveguide sensor using a leaky mode for absorption measurement of liquid samples. This sensor uses a single coupling prism. A cladding layer and a waveguide layer are directly deposited on the reflecting surface of the prism. The intensity of the internally reflected beam at an appropriate incident angle is very sensitive to the imaginary part of the sample attached to the surface of the waveguide layer. The sensitivity of this sensor is controlled by the thicknesses of both cladding and waveguide layers. We studied the performance of the sensor by numerical calculation.

Key words : optical waveguide, optical chemical sensor, leaky mode, single coupling prism, absorption measurement