在含有克尔介质和光学参量放大器(OPA)的光机械系统中，腔中的光学双稳性与纠缠特性会受到这两种介质较大的影响。当调节非线性晶体与腔场的耦合常数时，OPA 晶体的非线性增益对系统的双稳性影响与入射光强度对双稳性的影响是相似的，然而克尔介质的三阶非线性系数对系统双稳性却有着明显不同的影响。对系统纠缠特性的研究结果表明：OPA 晶体的非线性增益系数对腔场与振动镜之间的纠缠有着增强的作用，而克尔介质的三阶非线性系数对纠缠却有着减弱的效果。

In a nonlinear optomechanical system which contains a Kerr medium and a degenerate optical parametric amplifier (OPA), optical bistability and entanglement are affected largely by these two kinds of medium. When adjusting the coupling constant of nonlinear crystal and the cavity field, the nonlinear gain of OPA crystal and the intensity of incident light have similar effects on the optical bistability, while the third-order nonlinear susceptibility of Kerr medium has obviously different effects. The calculation results of entanglement in this system show that the nonlinear gain coefficient of OPA crystal can increase the entanglement between cavity field and vibrating mirror, while the third-order nonlinear susceptibility of Kerr medium can reduce the entanglement.