Hannemann S, Salumbides E J, Ubachs W
Laser Centre, Department of Physics and Astronomy, Vrije Universiteit, De Boelelaan 1081, Amsterdam, The Netherlands.
Opt Lett. 2007 Jun 1;32(11):1381-3. doi: 10.1364/ol.32.001381.
We demonstrate a technique to reduce first-order Doppler shifts in crossed atomic/molecular and laser beam setups by aligning two counterpropagating laser beams as part of a Sagnac interferometer. Interference fringes on the exit port of the interferometer reveal minute deviations from perfect antiparallelism. Residual Doppler shifts of this method scale with the ratio v/(4d) of the typical atomic/molecular velocity v and the laser beam diameter d. The method is implemented for precision frequency calibration studies at deep-UV wavelengths, both in one- and two-photon excitation schemes: the 6s(2) --> 6s30p(3/2)J=1 line in Yb at 199 nm and the 4p(6) --> 4p(5)p1/2 transition in Kr at lambda=212 nm. The achieved precision of 6 x 10(-10) is limited by the characteristics of the laser system.
我们展示了一种通过将两束反向传播的激光束对准作为萨格纳克干涉仪的一部分，来减少交叉原子/分子与激光束装置中一阶多普勒频移的技术。干涉仪出射端口上的干涉条纹揭示了与完美反平行状态的微小偏差。该方法的残余多普勒频移与典型原子/分子速度v和激光束直径d的比值v/(4d)成比例。此方法应用于深紫外波长下的精密频率校准研究，包括单光子和双光子激发方案：199nm波长下镱原子的6s(2) --> 6s30p(3/2)J = 1跃迁线，以及212nm波长下氪原子的4p(6) --> 4p(5)p1/2跃迁。所达到的6×10^(-10)的精度受激光系统特性限制。
