title: Imaging arbitrary acoustic whispering-gallery modes in the gigahertz range with ultrashort light pulses.
abstract: Using an ultrafast optical technique with enhanced frequency control, we image surface-acoustic whispering-gallery-like modes in a microscopic disk at various frequencies up to 1 gigahertz (GHz), allowing experimental determination of their dispersion. This is made possible by intensity-modulated optical pumping and probing with a periodic femtosecond light source. Spatiotemporal Fourier transforms of the two-dimensional acoustic fields measured to micron resolution allow us to isolate individual whispering-gallery modes of first and second radial order as well as their mode patterns and Q factors to unprecedented frequency resolution. We thereby demonstrate arbitrary-frequency ultrafast control and imaging of a micro-acoustic system with an optical time-resolved technique. Applications include quality control of surface acoustic wave filters in telecommunications.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Mezil
authors.forename: Paul H
authors.initials: PH
authors.lastname: Otsuka
authors.forename: Shogo
authors.initials: S
authors.lastname: Kaneko
authors.forename: Oliver B
authors.initials: OB
authors.lastname: Wright
authors.forename: Motonobu
authors.initials: M
authors.lastname: Tomoda
authors.forename: Osamu
authors.initials: O
authors.lastname: Matsuda