Pressure tuning of whispering gallery mode resonators

The effect of hydrostatic pressure on solid and hollow microsphere optical resonators was investigated. The primary goal was to explore the feasibility of a micro-optical pressure sensor based on whispering gallery modes (WGMs) and to quantify the deleterious effect of environmental pressure changes on other WGM-based sensors. Expressions were developed for WGM shifts due to changes in hydrostatic pressure of the environment surrounding the spherical resonators. These expressions were validated through experiments in which the pressure-induced WGM shifts of hollow polymethyl methacrylate microspheres were monitored. The effect of atmospheric pressure variations on silica resonators is negligible, but hydrostatic pressure may be effective in the optical tuning of hollow polymer spheres. © 2007 Optical Society of America OCIS codes: 120.0280, 120.4880, 120.5475, 130.6010.