Kaufer Steffen, Willke Benno
Opt Lett. 2019 Apr 15;44(8):1916-1919. doi: 10.1364/OL.44.001916.
Optical AC coupling (OAC) has been established as a highly sensitive alternative to multi-photodiode arrays in the detection of laser power noise. Previous experiments were limited by the linewidth of the resonators used in these experiments. This Letter describes a dedicated setup, which uses an optical resonator with a linewidth of 4 kHz which is one magnitude smaller than in earlier experiments. To optimize the OAC gain, the novel approach of using a tunable impedance matching is described. An OAC coupling-based power stabilization feedback control loop is set up and characterized at frequencies overlapping with the terrestrial gravitational wave detection band. The performance of the new experiment is mainly limited by expected noise sources down to frequencies of about 1 kHz and about 7 dB better than its traditional equivalent at frequencies between 8 and 60 kHz.
光学交流耦合（OAC）已被确立为在检测激光功率噪声方面比多光电二极管阵列更具高灵敏度的替代方案。先前的实验受到这些实验中所使用谐振器线宽的限制。本信函描述了一种专门的装置，它使用了线宽为4kHz的光学谐振器，这比早期实验中的线宽小一个数量级。为了优化OAC增益，描述了使用可调阻抗匹配的新方法。建立了基于OAC耦合的功率稳定反馈控制回路，并在与地面引力波探测频段重叠的频率上对其进行了表征。新实验的性能主要受限于约1kHz频率以下的预期噪声源，并且在8至60kHz频率之间比其传统等效物性能好约7dB。
