Theoretical Research Of Optical Nonreciprocal In Hybrid Cavity Systems

Because of directional control of light,nonreciprocal devices play an extremely impor-tant role in processing optical signals and information.In recent years,the hybrid cavity sys-tems based on atom-cavity or optomechanical interaction have excellent performance in many fields,such as quantum information processing,construction of controllable quantum network and precise measurement.Therefore,in this thesis,we mainly study the realization of optical nonreciprocal transmission by the hybrid cavity systems.First,we consider the nonlinear system of atom ensemble coupled with cavity mode.By using the atom ensemble to enhance the nonlinear interaction with the cavity,the optical isolator with high isolation rate is realized.We find that the increase in the number of atoms will lead to the enhancement of nonlinear effects in the system,resulting in an increase in the isolation rate of the system.Secondly,we study the nonreciprocal transmission in the three mode optomechanical system.It is found that when the impedance matching condition in the system is broken,the optical isolator of strong light signal can be realized.Furthermore,by introducing optical gain into the system,the signal can be directional amplified.At the same time,we derived the analytical expression of the optimal transmission coefficient and the corresponding isolation rate in the amplification direction,which provides a clear theoretical basis for choosing the appropriate parameters in the experiment to achieve both high amplification coefficient and isolation rate at the same time.In addition,we propose a theoretical scheme to realize phase-insensitive or phase-sensitive directional amplification in three-cavity optomechanical system by using the effect of composite magnetic field.By adjusting the system parameters,we can make the system have the characteristics of optical circulator,cyclic amplifier and directional amplifier,which provides the theoretical foundation for future experiments.In summary,we have studied a variety of theoretical schemes to realize optical nonreciprocal transmission in hybrid cavity systems,which provides a theoretical basis for the realization of an optical nonreciprocal transmission schemes that are easier to control and integrate.