Quantitative measurements of the vibrational eigenmodes in ultrahigh-Q silica microspheres are reported. The modes are excited via radiation-pressure-induced dynamical backaction of light confined in the optical whispering-gallery modes of the microspheres (i.e., via the parametric oscillation instability). Two families of modes are studied and their frequency dependence on sphere size investigated. The measured frequencies are in good agreement both with Lamb's theory and numerical finite-element simulation and are found to be proportional to the sphere's inverse diameter. In addition, the quality factors of the vibrational modes are studied.
© 2007 Optical Society of America
Original Manuscript: February 20, 2007
Revised Manuscript: June 1, 2007
Manuscript Accepted: June 4, 2007
Published: July 24, 2007
R. Ma, A. Schliesser, P. Del'Haye, A. Dabirian, G. Anetsberger, and T. J. Kippenberg, "Radiation-pressure-driven vibrational modes in ultrahigh-Q silica microspheres," Opt. Lett. 32, 2200-2202 (2007)