Weng Wenle, Light Philip S, Luiten Andre N
Opt Lett. 2018 Apr 1;43(7):1415-1418. doi: 10.1364/OL.43.001415.
We exploit the strong polarization dependence of the thermooptic coefficients in a lithium niobate whispering-gallery-mode resonator to create a self-referenced thermometer. An unprecedented temperature sensitivity of 3.0 GHz/K in the frequency difference between modes of orthogonal polarizations is demonstrated. In order to lock the lasers to the mode resonances, we use a simple intracavity phase modulation approach that provides for superbly low frequency instability. We demonstrate a record room-temperature thermometer detectivity of 40 nK with 1 s of averaging time. Simulations based on the fluctuation-dissipation theorem are performed to calculate the fundamental thermorefractive noise, showing that the detectivity could be improved with reduced laser-locking instabilities.
我们利用铌酸锂回音壁模式谐振器中热光系数的强偏振依赖性来创建一个自参考温度计。在正交偏振模式之间的频率差中展示出了前所未有的3.0 GHz/K的温度灵敏度。为了将激光器锁定到模式谐振上，我们采用了一种简单的腔内相位调制方法，该方法具有极低的频率不稳定性。我们展示了在1秒平均时间下创纪录的室温温度计探测率为40 nK。基于涨落耗散定理进行了模拟，以计算基本的热折射噪声，结果表明，降低激光锁定不稳定性可提高探测率。
