A new class of hybrid systems that couple optical and mechanical nanoscale devices is under development. According to their interaction concepts, two groups of opto-mechanical systems are summarized as mechanically tunable and radiation pressure-driven optical resonators. On account of their high-quality factors and small mode volumes as well as good on-chip integrability with waveguides/circuits, photonic crystal (PhC) cavities have attracted great attention in sensing applications. Benefitting from the opto-mechanical interaction, a PhC cavity integrated opto-mechanical system provides an attractive platform for ultrasensitive sensors to detect displacement, mass, force, and acceleration. In this review, we introduce basic physical concepts of opto-mechanical PhC system and describe typical experimental systems for sensing applications. Opto-mechanical interaction-based PhC cavities offer unprecedented opportunities to develop lab-on-a-chip devices and witness a promising prospect to further manipulate light propagation in the nanophotonics.
On-chip spectroscopy with thermally tuned high-Q photonic crystal cavities