Eur. Phys. J. Special Topics 223, 1959–1969 (2014)
https://doi.org/10.1140/epjst/e2014-02239-2

Regular Article

Whispering gallery mode profiles in a coated microsphere

¹ Institut Ruder Bošković, Bijenička cesta 54, 10000 Zagreb, Croatia
² IFN – CNR CSMFO Lab., Via alla Cascata 56/C Povo, 38123 Trento, Italy
³ IFAC – CNR, MDF Lab., 50019 Sesto Fiorentino, Italy
⁴ Enrico Fermi Centre, Piazza del Viminale 1, 00184 Roma, Italy
⁵ FOTON-Systèmes Photoniques (CNRS-UMR 6082), ENSSAT, 6 rue de Kerampont, CS 80518, 22305 Lannion Cedex, France
⁶ Centre National d'Etudes Spatiales (CNES), 31401 Toulouse Cedex 9, France

^a e-mail: ivanda@irb.hr

Received: 15 May 2014
Revised: 4 August 2014
Published online: 6 October 2014

Abstract

The properties of whispering gallery modes (WGM) of a microsphere can be tailored by coating the resonator with a thin film. If the coating has a higher refractive index than the microsphere core, the resulting structure will have a configuration which has similarities both with a classical WGM resonator and with a planar waveguide. By choosing the film thickness and refractive index we can tailor the degree of confinement of the WGMs inside the sphere core, coating and surrounding medium, which will in turn influence the WGMs contact with its surroundings. We present a study of the effect of the coating on the WGM mode profiles in particular of a silicon coating on a silica sphere.