色散光力耦合系统中微悬臂梁囚禁与冷却的实验研究

This project dedicates to study the method of trapping micro-resonator via dispersive optomechanical coupling mechanism and realizing the high efficient optomechanical cooling. In the traditional micro-resonator-based two-mirror-cavity optomechanical system, there exist two drawbacks-the technical challenge of simultanously increasing the optical properties of micro-cavity and mechanical performance of micro-resonator; and limitation imposed on the optomechanical cooling limit by the optomechanical induced bistability effect. Studies have showed that the resonator-based dispersive optomechanical system can successfully resolve the conflict between optics and mechanics of optomechanical system and offer more optomechanical coupling mechanisms. In this project, a dispersive optomechanical system is constructed by inserting a micro-cantilever into a traditional Fabry-Perot optical cavity. Our researches focus on employing the dispersive coupling mechanism to achieve micro-cantilever trapping, which will benefit surmounting the bistability effect imposed limit of cooling operation. And we will further study of simultaneously trapping and cooling of the micro-cantilever and achieving a high efficient cooling with the optomechanical trapped micro-cantilever. Besides, we will cooperate with theoretical groups to investigate the impacts of different coupling mechanisms on the dynamics of the micro-cantilever, and obtain the optimal cooling condition for the dispersive optomechanical system.

本项目旨在研究利用色散光力耦合实现微纳共振器的囚禁并进而实现高效光力冷却的实验方法。对于利用基于共振器的两镜面光腔构成的光力耦合系统而言，一方面光腔光学性能与共振器力学性能之间的矛盾限制了光力耦合效率的提高，另一方面光力诱导的双稳效应也限制了光力冷却的冷却极限。研究表明基于共振器的色散光力耦合系统在成功解决了光力系统光学性能与力学性能之间矛盾的同时还提供了更加丰富的光力耦合机制。本项目通过将一个高灵敏单晶硅悬臂梁插入到传统的Fabry-Perot光腔中间构筑一个色散光力耦合系统，重点研究利用色散光力耦合实现悬臂梁囚禁的方法，解决双稳效应对光力冷却极限的限制问题。并进一步开展同时实现悬臂梁囚禁与冷却的研究，探索利用光力囚禁悬臂梁实现高效冷却。同时，我们还将与国内理论小组开展合作，深入研究色散光力耦合系统中不同光力耦合机制对悬臂梁动力学性能的影响，分析得到色散光力系统中的优化冷却条件。

本项目旨在基于三镜面光腔的色散光力系统中利用二次光力耦合作用实现机械振子的光学囚禁，并利用光学囚禁效应重点研究机械振子光力冷却新方法。项目自2013年实施以来进展顺利，按照项目任务书的要求，我们研究了光腔中机械振子的振动势能，并通过构造基于悬臂梁的色散光力耦合系统研究了振子的最佳光学囚禁条件，成功实现了悬臂梁的光学囚禁。在此基础之上，我们利用光学囚禁快速调谐悬臂梁的共振频率，在基于耦合悬臂梁的两模光力系统中研究了机械声子的Landau-Zener隧穿，为进一步探索基于非绝热操控的快速冷却新机制奠定了基础。

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