Fig. 1

Schematic diagram of the composite photonic-molecule cavity optomechanical system including two WGM cavities. The first WGM cavity with high-cavity dissipation κ is optomechanical cavity c driven by a pump laser, and radiation pressure force induces the mechanical mode b coupling to cavity c with coupling strength g. The second WGM cavity a is an auxiliary cavity driven by a probe laser with high-quality factor (Q). The optomechanical cavity c is coupled to cavity a via evanescent field, and we introduce a parameter J to describe the coupling strength of the two cavities, which can be controlled by varying the separation between them [26]