[OPTICAL REVIEW Vol. 18, No. 6 (2011) 430-435]
© 2011 The Japan Society of Applied Physics

Vertical Input Optical Ring Resonator with Differential Operation for Optical Sensor

Hideaki OKAYAMA1*, Motoki MIYAZAKI, and Hirochika NAKAJIMA

RISE, School of Science and Engineering, Waseda University, Shinjuku, Tokyo 169-8555, Japan
1Research & Development Center, Oki Electric Industry Co., Ltd., Warabi, Saitama 335-8510, Japan

(Received November 15, 2010; Accepted August 22, 2011)

A novel waveguide ring resonator optical sensor with two resonant wavelength channels is proposed for a refractive index measurement of a test sample placed on the sensor substrate and its performance characteristics are investigated analytically and numerically. The waveguide device consists of a ring resonator, a split-ring-shaped loop waveguide, and a vertical input/output grating coupler, in which the loop waveguide acts as an additional resonator and provides another output wavelength channel of the sensor. The differential detection between the two wavelength channels enables the highly sensitive detection with temperature compensation. A numerical simulation based on a finite difference time domain (FDTD) method shows that a precise index change detection with a resolution of 10-6 can be achieved using of the proposed device.

Key words: optical waveguide, optical resonator, grating, optical sensor

*E-mail address: okayama575@oki.com