Cavity-stabilized ultra-stable optical oscillators are one of the core ingredients in the ground-based or spaceborne precision measurements such as optical frequency metrology, test of special relativity, and gravitational wave observation. We report in detail the development of two ultra-stable systems based on 1064-nm neodymium-doped yttrium aluminum garnet lasers and 20-cm optical cavities. The optical cavities adopt ultra-low-loss silica mirrors with compensating rings. An electro-optic crystal with a wedged angle is used to reduce the residual amplitude modulation. Using two-stage thermal control, long-term stabilities of 100 µK are achieved for the outer wall of the vacuum chamber housing the optical cavity. Two additional thermal shields increased the time constant of the optical cavities to 70 h. By operating the optical cavity at the temperature of zero coefficient of thermal expansion, the frequency stability reaches 2.5 × 10⁻¹⁶ at 10 s averaging time and remains below 5 × 10⁻¹⁶ with an extended time of 1000 s after removing the first- and second-order drifts. The dependence of the laser linewidth on the measurement time is tested against a simplified theoretical model.

中文翻译：

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具有2.5×10-16频率不稳定性的超稳定的1064nm掺钕钇铝石榴石激光器

腔稳定的超稳定光学振荡器是地面或星载精度测量（例如光频率计量，狭义相对论测试和引力波观测）中的核心成分之一。我们详细报告了基于1064 nm掺钕钇铝石榴石激光器和20 cm光腔的两个超稳定系统的开发。光腔采用带补偿环的超低损耗石英镜。具有楔角的电光晶体用于减少残余振幅调制。采用两阶段热控制，长期稳定性为100 µ对于容纳光学腔的真空室的外壁，获得K。两个附加的隔热罩将光腔的时间常数增加到70 h。通过在零热膨胀系数的温度下操作光腔，频率稳定性在10 s的平均时间达到2.5×10 ^-16，并在去除第一和第二个后的1000 s内保持低于5×10 ^-16的延长时间。二阶漂移。根据简化的理论模型测试了激光线宽对测量时间的依赖性。