具有振动免疫特性光学谐振腔设计方法研究

Study on the design of vibration-immune optical resonator

窄线宽稳频激光是研制光学原子钟、引力波探测、光学频率合成器以及低噪声微波源等研究的核心部分,由振动噪声引起的频率噪声已成为实现具有更窄线宽、更高频率稳定度激光的主要限制性因素。本文利用Ansys有限元分析的方法,通过优化参考腔的切割深度和支撑位置以及ULE环的尺寸,使得腔镜在振动作用下保持平行同时腔镜各点均具有较低的振动敏感度,避免了由于装配误差引起腔长变化的问题。在对光学参考腔几何尺寸优化设计后,对光学谐振腔不同频率处的振动敏感度进行测试及分析,结果表明在最佳支撑位置下空间三轴方向的振动敏感度均可被抑制至10^-10 g^-1量级,实验结果和仿真结果相吻合。此方法为振动免疫结构腔体的设计提供了一种思路,也为进一步实现具有更高频率稳定度、更窄线宽激光奠定了基础。

Lasers with ultra-narrow linewidth and high frequency stability are the critical component for the development of optical atomic clocks,gravitational wave detection,optical frequency synthesizers and low-noise microwave sources.Vibration-induced frequency noise has become a major limitation for lasers with narrower linewidth and higher frequency instability.In this paper,we optimize the cutting depth and support positions of the reference cavity and the size of the ULE ring by utilizing Ansys finite element analysis.The cavity mirrors are parallel with each other and each point of the cavity mirror has low vibration sensitivity,avoiding the problem of cavity length variation due to assembly errors.After optimizing the geometry of the optical cavity,we measured and analyzed frequency response of the vibration sensitivity of the reference cavity,the experimental results show that the vibration sensitivity of the cavity in three dimensional axes can be suppressed to the order of 10^-10 g^-1 with the optimal support position,and the experimental and simulation results are in good agreement.This work provides a method for the design of vibratory-immune cavity and lays a foundation for the realization of laser with higher frequency stability and narrower linewidth.