Matei D G, Legero T, Häfner S, Grebing C, Weyrich R, Zhang W, Sonderhouse L, Robinson J M, Ye J, Riehle F, Sterr U
Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany.
JILA, National Institute of Standards and Technology and University of Colorado, Department of Physics, 440 UCB, Boulder, Colorado 80309, USA.
Phys Rev Lett. 2017 Jun 30;118(26):263202. doi: 10.1103/PhysRevLett.118.263202. Epub 2017 Jun 28.
We report on two ultrastable lasers each stabilized to independent silicon Fabry-Pérot cavities operated at 124 K. The fractional frequency instability of each laser is completely determined by the fundamental thermal Brownian noise of the mirror coatings with a flicker noise floor of 4×10^{-17} for integration times between 0.8 s and a few tens of seconds. We rigorously treat the notorious divergences encountered with the associated flicker frequency noise and derive methods to relate this noise to observable and practically relevant linewidths and coherence times. The individual laser linewidth obtained from the phase noise spectrum or the direct beat note between the two lasers can be as small as 5 mHz at 194 THz. From the measured phase evolution between the two laser fields we derive usable phase coherence times for different applications of 11 to 55 s.
我们报告了两台超稳激光器，每台都稳定在独立的硅法布里-珀罗腔上，工作温度为124K。每台激光器的频率不稳定度完全由镜面涂层的基本热布朗噪声决定，在0.8秒至几十秒的积分时间内，闪烁噪声本底为4×10⁻¹⁷。我们严格处理了与相关闪烁频率噪声相关的臭名昭著的发散问题，并推导了将这种噪声与可观测且实际相关的线宽和相干时间联系起来的方法。从相位噪声谱或两台激光器之间的直接拍频得到的单个激光线宽在194THz时可小至5mHz。从测量的两个激光场之间的相位演化，我们推导出了适用于不同应用的11至55秒的可用相位相干时间。
