Optical levitation of mechanical oscillators has been suggested as a promising way to decouple the environmental noise and increase the mechanical quality factor. Here, we investigate the dynamics of a free-standing mirror acting as the top reflector of a vertical optical cavity, designed as a testbed for a tripod cavity optical levitation setup. To reach the regime of levitation for a milligram-scale mirror, the optical intensity of the intracavity optical field approaches 3 MW cm⁻². We identify three distinct optomechanical effects: excitation of acoustic vibrations, expansion due to photothermal absorption, and partial lift-off of the mirror due to radiation pressure force. These effects are intercoupled via the intracavity optical field and induce complex system dynamics inclusive of high-order sideband generation, optical bistability, parametric amplification, and the optical spring effect. We modify the response of the mirror with active feedback control to improve the overall stability of the system.

已经提出了将机械振荡器的光学悬浮作为消除环境噪声并增加机械品质因数的有前途的方法。在这里，我们研究用作垂直光学腔顶部反射镜的独立反射镜的动力学特性，该反射镜被设计为三脚架腔光学悬浮装置的试验台。为了达到毫克级镜子的悬浮状态，腔内光场的光强度接近3 MW cm ^-2。我们确定了三种不同的光机械效应：声振动的激发，由于光热吸收引起的膨胀以及由于辐射压力而引起的镜的局部剥离。这些效应通过腔内光场相互耦合，并引起复杂的系统动力学，包括高阶边带生成，光学双稳态，参数放大和光学弹簧效应。我们使用主动反馈控制来修改反射镜的响应，以提高系统的整体稳定性。