非线性光学腔响应中的机械品质因子估计
Mechanical quality factor estimation from a nonlinear optical cavity response
- Technical University of Denmark（丹麦技术大学）
- James C. Wyant College of Optical Sciences, The University of Arizona（亚利桑那大学詹姆斯·C·怀安特光学科学学院）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文提出一种基于非线性光学腔响应的全光学振铃衰减方法，通过跟踪双峰轮廓峰间距估计调制幅度，从而在不分辨机械振荡的情况下测定内禀阻尼率，并实验验证了其准确性与鲁棒性。
AI中文摘要：
内禀阻尼率和品质因子（$Q$）是光机系统中的关键参数。然而，在高品质因子器件中，其测量往往具有挑战性，因为探针引起的动态反作用（DBA）以及分辨并精确跟踪机械共振的需求限制了现有技术的性能。在此，我们提出了一种在未分辨边带区域内的全光学振铃衰减方法，该方法利用了强机械运动引起的非线性、时间平均光学响应。我们推导了一个解析模型，用于描述由弱频率扫描激光探测的时间平均光学腔响应。在机械振子演化过程中，激发运动将洛伦兹线形调制成双峰轮廓，其峰间距能够精确估计调制幅度。在机械振铃衰减期间跟踪该响应，可以在不分辨机械振荡的情况下确定内禀阻尼率。我们将该方法应用于放置在高精细度腔内的密度调制声子晶体薄膜，获得的机械品质因子与同一平台上的独立测量结果一致。我们的方法需要最简的光学设置，同时提供原位诊断，并降低探针引起的DBA的影响，且对测量噪声具有鲁棒性。最后，该模型可以描述其他与相干频率调制色散耦合的谐振系统，为超越光机平台提供新的见解和测量策略。
英文摘要：
Intrinsic damping rate and quality factor ($Q$) are key parameters in optomechanical systems. However, in high-Q devices, their measurement is often challenging because probe-induced dynamical backaction (DBA) and the need to resolve and accurately track the mechanical resonance limit the performance of state-of-the-art techniques. Here, we introduce an all-optical ringdown method in the unresolved-sideband regime that exploits the nonlinear, time-averaged optical response induced by strong mechanical motion. We derive an analytical model of the time-averaged optical cavity response probed by a weak frequency-scanning laser. During the evolution of the mechanical oscillator, the excited motion modulates the Lorentzian lineshape into a double-horned profile whose peak separation enables an accurate estimation of the modulation amplitude. Tracking this response during the mechanical ringdown allows the intrinsic damping rate to be determined without resolving the mechanical oscillation. We apply the method to a density-modulated phononic crystal membrane placed inside a high-finesse cavity and obtain mechanical quality factors consistent with independent measurements on the same platform. Our method requires a minimal optical setup, while offering an in situ diagnostic and reduced impact from probe-induced DBA and robustness against measurement noise. Finally, the model can describe other resonant systems dispersively coupled to coherent frequency modulations, providing new insights and measurement strategies that expand beyond the optomechanical platform.
