Robust Characterization Of Microfabricated Atomic Beams On A Six-Month Time Scale

Miniature atomic beams can provide new functionalities for atom-based sensing instruments such as atomic clocks and interferometers. We recently demonstrated a planar silicon device for generating well-collimated thermal atomic beams [Nat. Commun. 10, 1831 (2019)]. Here we present fluorescence spectroscopy studies on atomic beams emitted from an array of thin silicon capillaries. These microfabricated rubidium beams work stably over six months at different temperatures above 100 degrees C. At an oven temperature of 150 degrees C, the calibrated throughput of the miniature source is 7 x 10(11) atoms/s/channel with a typical beam brightness of 6 x 10(14) atoms per second per steradian per unit source area [s(-1) sr(-1) mm(-2)]. We also present a recipe for evaluating the fluorescence spectra given the Monte Carlo-simulated angular distribution function, even under conditions of strong laser saturation of the probing transition. Monte Carlo simulations together with multilevel master equation calculations fully account for the influence of optical pumping and spatial extension of the Gaussian laser beam. A notable consequence of this work is the agreement between theory and experimental data that has allowed fine details of the angular distribution of the collimator to be resolved over three decades of dynamic range of atomic beam output flux.