Fiber-integrated microcavities for efficient generation of coherent acoustic phonons

Coherent phonon generation by picosecond optical pumpprobe spectroscopy is an important experimental tool for studying acoustic properties at the nanoscale. In this work, we integrate semiconductor micropillar cavities confining near-infrared light and 18 GHz acoustic phonons with single-mode fibers. This approach solves a major challenge of existing pump-probe experiments using mechanical delay lines: maintaining the spatiotemporal overlap of pump and probe beams on a micro-object to achieve well-controlled, reproducible mode matching conditions.