Single-pole double-throw–type optomechanically induced transparency

We propose a scheme for achieving twofold nonreciprocal optomechanically induced transparency (OMIT) in a three-cavity optomechanical system. In this system, an optical microring resonator is evanescently coupled to two microring optomechanical resonators simultaneously, and a beam splitter is utilized to establish two distinct optical paths. By utilizing a strong control laser and a weak probe laser to drive the resonators, a twofold nonreciprocal OMIT phenomenon can be observed. Specifically, the distinct propagation direction of the control laser will result in nonreciprocal OMIT in the two different paths, respectively. In contrast to two-cavity optomechanical systems, the OMIT can be significantly enhanced through indirect coupling, resulting in an $\sim 23.4\%$ increase at the frequency resonance. This unique structure of a three-cavity system renders it an ideal optical single-pole double-throw (SPDT) switch or an ideal optical SPDT-like isolator, which can play an pivotal role in optical communication networks and present exciting opportunities in quantum technologies.