Locking the laser frequency to an atomic transition

N. P. Wells, James C. Camparo

To overcome the temperature sensitivity of lasers locked to Doppler-broadened transitions, we propose a scheme in which the laser is locked to an isoclinic point of the atom's spectrum: a frequency at which the first derivative of the absorption spectrum does not change upon a physical change of the sample. Here, we demonstrate that an isoclinic point exists in the Rb87D1spectrum at 795 nm, and that it is located midway between the Fg=2 → Fe=1 and Fg=2 → Fe=2 transitions. Locking a VCSEL diode laser to this isoclinic point, we have been able to demonstrate a very low sensitivity of the locked laser's frequency to temperature variations of the atomic vapor.

J. T. Malos

Jipeng Wang, Bangcheng Han, Jinhai Bai

Atomic interferometric gravity gradient measurement enables atomic interference by manipulating atoms with lasers of specific frequencies. Thus, the frequency and phase−locking performance of the laser system exerts a significant impact on key experimental parameters, including the loading rate and ultimate cooling temperature of atomic clouds, the state selection efficiency of Raman transitions, the contrast of atomic interference fringes, and the level of detection noise. As atomic interferometric gravity gradient measurement transitions from static laboratory measurements to mobile field operations, conventional laser frequency and phase−locking methods struggle to meet the demand for rapid re−locking after device movement and cannot achieve timely system recovery in the event of laser unlocks. This work proposes an automatic laser frequency and phase−locking system that can detect real−time deviations in laser frequency and phase and implement rapid and precise corrections. Meanwhile, by utilizing the reference signal source in the optical phase−locked loop, the system realizes laser frequency hopping to satisfy the diverse laser frequency requirements across all stages of atomic interferometric gravity gradient measurement.

J H Hannay, Daniel E. Field

William D. Phillips, John V. Prodan, Harold J. Metcalf

Taro Hasegawa, Mitsuyasu Deguchi

A robust laser-frequency-locking scheme to atomic transitions is proposed and demonstrated. In this scheme, dispersion of the Zeeman-shifted atoms instead of absorption in the dichroic atomic vapor laser lock (DAVLL) [Appl. Opt.37, 3295 (1998)] is measured and used as an error signal for stabilization feedback. The error signal of the proposed scheme can provide a wide locking range. Experimental demonstration with the transition between 5d 2D3/2 and 6p 2P1/2 of Ba+ is carried out for a grating feedback external-cavity laser diode at 650 nm.