Optical nonreciprocity and optomechanical circulator in three-mode optomechanical systems

We demonstrate the possibility of optical nonreciprocal response in a three-mode optomechanical system where one mechanical mode is optomechanically coupled to two linearly coupled optical modes simultaneously. The optical nonreciprocal behavior is induced by the phase difference between the two optomechanical coupling rates which breaks the time-reversal symmetry of the three-mode optomechanical system. Moreover, the three-mode optomechanical system can also be used as a three-port circulator for two optical and one mechanical modes, which we refer to as optomechanical circulator.