Theoretical Investigate Of The Optical Respond In The Nonlinear Optomechanical Cavity

In recent years,the optomechanical system has attracted widespread concern in both theory and experiment due to its high quality factor,high frequency,low spatial scale and high sensitivity.The rapid development of nano technology and semiconductor technology has brought a strong impetus which makes the quantum effect more remarkable in optomechanical cavity system such as slow and fast light,optomechanically induced transparency(OMIT).These quantum effects have opened up a new scientific gate brought a ray of light to the research field for the realization of high precision measurement,faster quantum information processing and verification of the basic principles of quantum science.In addition,when considering the coupling of cavity field and other quantum systems such as quantum wells and quantum dots,we can give more freedom in quantum manipulation,so that the convenience of control can be improved obviously;At the same time,these coupling systems can provide an effective way for the classical quantum information conversion.In this paper,we investigate the OMIT and tunable slow and fast light and the ground-state cooling of a mechanical oscillator in a hybrid atom-optomechanical systems based on the high-order-excitation approximation.Some of the main works are as follows:(1)We investigate the optical response of the output field and the tunable slow and fast light in a nonlinear optomechanical cavity with a degenerate optical parametric amplifier(OPA)and a higher order excited atomic ensemble.Studies show that the high-order-excitation atom which is similar to the degenerate OPA that acts as a nonlinear medium,induces an additional dip in absorption spectrum of the probe field.The coherence of the mechanical oscillator leads to split the peak in absorption in the probe field spectrum so that the phenomenon of optomechanical induced transparency(OMIT)is generated from the output probe field.In particular,the presence of nonlinearities with the degenerate OPA and the higher order excited atoms can affect significantly the width of the transparency windows,providing an additional flexibility for controlling optical properties.Furthermore,in the presence of the degenerate OPA,the optical-response properties for the probe field become phase-sensitive so that a tunable switch from slow to fast light can be realized.(2)We discuss the ground-state cooling characteristics and the dynamic equation of the mechanical oscillator in a hybrid optomechanical cavity system mixed with the atomic ensemble.In this system,the ensemble atomic in the cavity are treated as two-level atoms and we consider they meet the high-excitation condition.The results show that with the increase of the coupling strength of the atomic field,the cooling process of the mechanical oscillator is accelerated,the driving force becomes larger and the detuning becomes smaller.