强耦合光机械腔中的简正模式分裂和冷却

摘要

研究由辐射压力与驱动Fabry-Perot光学腔相耦合而产生的腔光机械动力学行为.通过量子朗之万方程具体研究了机械振子的涨落光谱、机械阻尼与共振频移和基态冷却.随着输入激光功率的增加,振子的涨落光谱呈现简正模式分裂的现象,并且数值模拟结果和实验结果相符合.同时推导了有效机械阻尼和共振频移.红移边带导致了机械模的冷却,蓝移边带引起了机械模的放大.此外,引入一种近似机制来研究振子的基态冷却,并且考虑在解析边带机制下简正模式分裂对机械振子冷却的影响.最后,数值讨论了初始浴温度、输入激光功率和机械品质因数这三个因素对机械振子冷却的影响.%A model describing optomechanical dynamics via radiation-pressure coupling with a driven optical cavity is investigated by a linearized quantum Langevin equation.The spectrum of the oscillator presents normal mode splitting with the increase of the input laser power in strong coupling regime and our results are in good agreement with the experimental results.The effective mechanical damping and the resonance frequency shift are derived.The redshifted sideband leads to the cooling of the mechanical oscillator,and the blueshifted motional sideband results in amplification.Furthermore,an approximate mechanism is introduced to analyze the cooling of the mechanical oscillator.Since both the normal mode splitting and cooling require working in the resolved sideband regime,whether the normal mode splitting influences the cooling of the mirror is considered.Meanwhile,we give three key factors influencing the cooling of mechanical oscillator,these being initial bath temperature,input laser power and mechanical quality factor.