[OPTICAL REVIEW Vol. 13, No. 4 (2006) 292-296]
© 2006 The Optical Society of Japan

Self-Modulation of Scattering Intensity from a Silica Sphere Coated with a Sol–Gel Film Doped with J-Aggregates

Kenzo YAMAGUCHI*, Masamitsu FUJII1, Tadanobu NIIMI, Masanobu HARAGUCHI, Toshihiro OKAMOTO and Masuo FUKUI

Department of Optical Science and Technology, Faculty of Engineering, Univerity of Tokushima, 2-1 Minamijosanzima, Tokushima 770-8506, Japan
1Department of Electronics and Mechanics, Toba National College of Maritime Technology, 1-1 Ikegami, Toba, Mie 517-8501, Japan

(Received November 15, 2005; Accepted March 16, 2006)

A micrometer-sized nonlinear optical resonator constituted of a silica microsphere coated with J-aggregates has been fabricated by the sol–gel process. We determined the scattering light spectrum and discuss the application of the observed effect for the realization of an optical switching element. Optical evaluation of the sphere has been performed in the attenuated-total-reflection (ATR) configuration. We excited a whispering gallery mode and measured the nonlinear ATR signal dependence on excitation intensity. The experimental result agrees very well with the simulation results obtained using the Mie theory and the finite-difference time-domain method taking into account optical Kerr nonlinearity. The permittivity of the film of J-aggregates was measured by ATR method at several wavelengths and the value at the desired wavelength was determined by extrapolation using the Lorentz function.

Key words: optical switching, optical Kerr nonlinearity, whispering gallery mode, J-aggregates, microsphere, FDTD method

*E-mail address: kenzou@opt.tokushima-u.ac.jp