Theoretical Study Of Optical Bistability Based On Confined Atomic Systems

The cavity optomechanical system can confine photons in a small volume for a long time and significantly enhance the interaction between light and matter,which has aroused great research interest of researchers.With the continuous development and progress of semiconductor and nano process technology,cavity optomechanical systems are gradually miniaturized in scale,which makes the quantum effects of cavity optomechanical systems become more and more obvious.Among the many quantum nonlinear optical properties in cavity optomechanical system,optical bistability,an interesting quantum nonlinear property that has been paid attention to many scholars.This is because optical bistable devices manufactured using the principle of optical bistability can be widely used in optical storage,optical communications,optical logic components,and optical image processing.They can also be used in the manufacture of all-optical switches,optical amplification and other optical devices.However,the controllability of the optical bistability is still insufficient,which limits its potential applications in fields such as abnormal switching and phototransistors.Based on the above,this paper mainly studies the optical bistability in the atom-assisted hybrid cavity optomechanical system,mainly for two cavity optomechanical systems,one of which contains the N-type four-level atomic ensemble,and the other contains the inverted V-type three-level atomic ensemble,and the system couples with double oscillators.The specific research work and results are as follows:In the third chapter,we explore the optical bistability in the hybrid optomechanical system containing the N-type atomic ensemble.Through theoretical calculation and numerical analysis,it is found that the introduced control field interacts with atoms to produce the atomic coherence effect,which enhances the nonlinear effect of the system,and we can easily realize the bistable behavior of the steady-state photon number.At the same time,you can also change the size and switch of the cavity bistability by controlling the pump field power,the cavity field-pump field detuning amount,the cavity field-atom coupling strength,and the other classical field-atom coupling strength.Compared with the two-level atomic ensemble,our multi-level system provides more means to change the threshold and width of optical bistability.In the fourth chapter,we study the optical bistability in a hybrid optomechanical system that includes the inverted V-shaped atomic ensemble and couples with double oscillators.Through theoretical calculation and numerical analysis,it is found that changing the mass ratio or resonant frequency ratio of the two movable micromechanical membranes can effectively adjust the bistable behavior exhibited by the average photon number in the cavity.At the same time,adjusting the coupling strength between the control field and atoms can increase or decrease the nonlinearity of the system,so as to control the opening and closing of the bistable behavior.In the study of this hybrid optomechanical system,we provides more methods to control the behavior of optical bistability,which may have potential application prospects in all-optical switches,and to some extent,it also provides directions for the preparation of new optical bistable devices.