基于高阶模激光稳频的热噪声分析  

Thermal Noise Analysis Based on Higher-Order Mode Laser Frequency Stabilization

作　　者：杜联联 刘静芳 刘佳敏 杨荣国 孙恒信[1,2] 郜江瑞[1,2] Du Lianlian;Liu Jingfang;Liu Jiamin;Yang Rongguo;Sun Hengxin;Gao Jiangrui(State Key Laboratory of Quantum Optics and Quantum Optics Devices,Institute of Opto-Electronics,Shanxi University,Taiyuan 030006,Shanxi,China;Collaborative Innovation Center of Eatreme Optics,Shani University,Taiyuan 030006,Shanxi,China;College of Physics and Electronic Engineering,Shani University,Taiyuan 030006,Shanxi,China)

机构地区：[1]山西大学光电研究所量子光学与光量子器件国家重点实验室,山西太原030006 [2]山西大学极端光学协同创新中心,山西太原030006 [3]山西大学物理与电子工程学院,山西太原030006

出　　处：《光学学报》2024年第13期153-162,共10页Acta Optica Sinica

基　　金：国家重点研发计划(2021YFC2201802);山西省回国留学人员科研资助项目(2021-005)。

摘　　要：理论分析高阶激光模式在激光稳频系统中的热噪声,并给出模式类型和阶数、激光功率、分析频率等参数对热噪声、散粒噪声以及总噪声的影响。给出激光稳频系统的一般噪声模型,将其应用于高阶模式的稳频系统并分析噪声传递过程。理论计算高阶模稳频系统中参考腔的热噪声,对比高阶厄米-高斯和拉盖尔-高斯模式的基底热噪声,在同一阶数下,拉盖尔模式比厄米模式的热噪声更低。LG_(10,0)模式在1 Hz处产生的热噪声相比于基模热噪声降低了16%。综合散粒噪声的影响,得到LG_(p,0)模式在0≤p≤25范围内参考腔的最低总噪声在1 Hz处可以达到0.022 Hz/Hz^(1/2),相比于基模总噪声降低了23%。使用该方式可以很好地控制激光器频率噪声以减少对引力波探测的影响。Objective Laser frequency stabilization is an essential technology in various applications, including optic communication,quantum metrology, and space-borne gravitational wave detection. Conventionally, the laser for use is frequency stabilized to an ultra-stable reference cavity. However, the frequency noise due to the cavity length noise of the reference cavity still limits the application of the ultra-high-precision measurement of space-time strain with a magnitude of the order of 10^(-18)-10^(-20 )in the frequency range of mHz-Hz. Before application in such high-precision measurements, extensive suppression of frequency noise is mandatory. The thermal noise of the reference cavity is typically a predominant source that necessitates reduction. Higher-order laser transverse modes, characterized by a larger transverse intensity distribution, yield a lower spatially averaged thermal noise. The integration of higher-order modes into frequency stabilization with ultra-stable cavities has not been exhaustively explored in the literature.Methods We first introduce a generalized noise model for frequency stabilization based on a reference cavity. Then we apply this model to higher-order mode reference cavities to scrutinize the influence of the mode transformation noise on the final frequency noise. By controlling a series of technical noises of the cavity such as vibration, temperature, and electronic noise, the thermal noise and shot noise emerge as the two dominant noise sources. According to the fluctuation dissipation theorem, we calculate and compare the thermal noises of higher-order Hermite-Gaussian(HG) and Laguerre-Gaussian(LG) modes, using parameters of a regular ultra-stable cavity. We also delve into the mode coupling efficiencies of different LG_(p,0) modes based on the scheme of mode-mismatching for mode transformation. The shot noise, attributable to the limited mode coupling efficiency, is also taken into account. By compromising the thermal noise and shot noise, we propose some optimal mode orders for

关 键 词：激光光学 激光稳频 高阶模 热噪声 散粒噪声 

分 类 号：O436[机械工程—光学工程]