Excitation of high-frequency surface acoustic wave pulses with tapered fibers

Abstract Tapered fiber tips with 1–2 μm aperture were used to excite broadband surface acoustic wave (SAW) pulses with frequency spectra up to 800 MHz, this limit being set by interferometric detection. The spatial confinement of the laser pulses by the fiber source in the near field is demonstrated by a shortening of the elastic pulse profile and extension of its frequency spectrum with decreasing tip–surface distance. The method provides a new imaging technique for detecting the confinement of pulsed radiation and extends the SAW technique.