Nanophotonic Structures for Cavity Optomechanics

In this contribution, we will show how nanophotonic structures can be used to gain access to previously inaccessible regimes in cavity optomechanics [1] . We introduce a novel optomechanics platform, built from two photonic crystal membranes [2] , one of which is freely suspended (see Fig. 1 ). This cavity supports a series of photonic bound states in the continuum (BICs) that, in principle, trap light forever [3] and can be favourably used together with evanescent coupling for realizing various types of optomechanical couplings, such as linear or quadratic coupling of either dispersive or dissipative type, by tuning the photonic crystal patterning and cavity length. By combining light propagation in both free-space (between the photonic-crystal membranes) and guided-mode (over the photonic-crystal membranes) form, our platform merges the strengths offered by in-plane and out-of-plane optomechanical systems.