Nonreciprocal transmission characteristics in double-cavity double-optomechanical system

Abstract

<sec>Optical non-reciprocal devices such as the isolators are quite important components in optical systems. To realize the non-reciprocal transmission of the light, the Lorenz reciprocity theorem must be broken first and the main method is that Faraday magnetic rotation effect is used to change the polarization state of the signal through magneto-optical materials. However, this method is difficult to achieve on-chip integration. So using optomechanical system is presented to overcome the difficulty.</sec><sec>In order to improve the isolation characteristics of the device, a double-cavity double-optomechanical system, which is coupled to two optical modes by two mechanical oscillators with two different optomechanical coupling strengths, is proposed. Driven by the red detuning field in such a system, the non-reciprocal phenomenon can be realized by regulating the phase difference, and the direction of light transmission and isolation can be determined as well. This property is determined by the quantum interference effect between the optomechanical coupling strengths and the couplings of the optical cavity modes. The method is that the relative operators are represented by their average value plus their relative fluctuations, and then according to the input-output relationship the transmission amplitude and the isolation rate are obtained.</sec><sec>We mainly discuss the distribution of the isolation rate as a function of the optomechanical coupling strength. The results are that the combined action of two mechanical modes can make the system have higher fault tolerance rate. The other mechanical mode can make the system achieve a large isolation rate at two specific frequencies and the reverse transmission in the resonant frequency signals at the same time.</sec>