Abstract

The development of an optical clock with ultimate accuracy and stability requires lasers with very narrow linewidths. We present two ultrastable laser systems based on 48-cm-long Fabry–Perot cavities made of ultralow expansion glass in horizontal and vertical configurations operating at 698 nm. Fractional frequency instability of the beat signal between the two lasers reaches ${1.6} \times {{10}^{- 15}}$ at the averaging time of 1 s. We experimentally characterized the contribution of the different noise sources (power fluctuations, residual amplitude modulation, the Doppler noise, and sensitivity to the shock impact) and found that in our case the laser frequency instability to a large extent is determined by an optoelectronic feedback loop. Although the vertical configuration was easier to manufacture and transport, it is much more sensitive to acoustics and horizontal accelerations compared to the horizontal one. Both laser systems were transported over a 60 km distance from the Lebedev Physical Institute to the All-Russian Scientific Research Institute for Physical-Engineering and Radiotechnical Metrology (VNIIFTRI), where they serve as local oscillators for spectroscopy of the clock transition in the recently developed strontium optical clock.

© 2021 Optical Society of America

Stability improvement of ⁴⁰Ca⁺ optical clock by using a transportable ultra-stable cavity

Yanmei Hao, Ruming Hu, Baolin Zhang, Mengyan Zeng, Huaqing Zhang, Zixiao Ma, Yao Huang, Qunfeng Chen, Kelin Gao, and Hua Guan
Opt. Express 32(3) 4081-4092 (2024)

Optical frequency synthesizer referenced to an ytterbium optical clock

Yuan Yao, Bo Li, Guang Yang, Xiaotong Chen, Yaqin Hao, Hongfu Yu, Yanyi Jiang, and Longsheng Ma
Photon. Res. 9(2) 98-105 (2021)

Dual-axis cubic cavity for drift-compensated multi-wavelength laser stabilisation

Ian R Hill, Richard J Hendricks, Sean Donnellan, Paul Gaynor, Ben Allen, Geoffrey P Barwood, and Patrick Gill
Opt. Express 29(22) 36758-36768 (2021)

Continuous optical generation of microwave signals for fountain clocks

Burghard Lipphardt, Patrick Walkemeyer, Michael Kazda, Johannes Rahm, and Stefan Weyers
Appl. Opt. 62(29) 7628-7632 (2023)

Compact optically pumped cesium beam atomic clock with a 5-day frequency stability of 7×10⁻¹⁵

Xuan He, Shengwei Fang, Zhichao Yuan, Weibin Xie, Nan Chen, Zezheng Xiong, Qing Wang, Xianghui Qi, and Xuzong Chen
Appl. Opt. 60(34) 10761-10765 (2021)