30cm超稳腔的振动、热分析及稳定度评估

Vibration,Thermal Analysis and Stability Evaluation of 30 cm Transportable Ultra-Stable Cavity

高性能的超稳腔是实现高稳定度光钟的关键。振动噪声和温度波动噪声是影响超稳腔稳定度的主要因素。本文利用Pound-Drever-Hall(PDH)技术实现了171Yb光钟钟激光与30 cm可搬运超稳腔的锁定,并对超稳腔的振动噪声、温度波动噪声以及超稳腔稳定度的评估进行了研究。通过对超稳腔施加主动振动激励的方式得到该腔在三个正交方向上的振动敏感度分别为5.6×10^(−10)/g,4.8×10^(−10)/g,1.5×10^(−10)/g。通过测量腔谐振频率随腔体温度的变化,拟合得到其零膨胀温度点为34.0(0.4)℃。最后通过与两套独立的30 cm超稳腔的三角帽比对,对该超腔的稳定度进行了评估,采用去关联算法得到2 s平均时间下的稳定度为4.1×10^(-16)。噪声谱分析表明该稳定度主要受限于振动噪声。这些研究为我们进一步优化可搬运超稳钟激光的稳定度提供了方向。

A high-performance transportable ultra-stable cavity is the key to achieve the high-stability transportable optical clock.Vibration noise and temperature fluctuation noise are the main factors that affect the stability of the ultra-stable cavity.In this paper,we used the Pound-Drever-Hall(PDH)technique to achieve the locking of the 171Yb optical clock laser to a 30 cm transportable ultra-stable cavity,and studied the evaluation method of the vibration noise,temperature fluctuation noise and stability of the ultrastable cavity.By applying active vibration excitation to the cavity,we obtained the vibration sensitivities of the cavity in three orthogonal directions as 5:6×10^(−10)=g,4:8×10^(−10)=g and 1:5×10^(−10)=g,respectively.By measuring the change of the cavity resonance frequency with the cavity temperature,we fit its zero-crossing temperature to be 34:0(0:4)℃.Finally,by comparing with two independent 30 cm ultra-stable cavities with three-cornered hat method,we evaluated the independent stability of this ultra-stable cavity,and obtained a stability of 4:1×10^(−16) at an averaging time of 2 s by using correlation removed algorithm.Noise spectrum analysis shows that stability of cavity is mainly limited by vibration noise.These studies provide us with directions for further optimizing the stability of the transportable ultra-stable clock laser.