An all-optical velocity filter and beam splitter for generating cold molecular beams: a proposal and simulation

Abstract

In order to generate one or two cold molecular beams that have neither a permanent electric dipole moment nor a magnetic dipole one, a controllable scheme to form an all-optical velocity filter and molecular beam splitter by using two red-detuned, crossing and cavity-enhanced guiding laser beams is proposed, and both the dynamic velocity filtering and beam splitting processes of the guided cold I2 molecular beam are studied by using the three-dimensional Monte Carlo method. Our study shows that by adjusting the laser power difference between the two guiding laser beams from −124 W to 124 W, a splitting ratio of the two-arm output molecular beams from about 10.3% to 89.7% can be obtained. Also, by adjusting the intersection angle between the two standing wave cavities from 80° to 10°, an adjustable splitting ratio from about 1.6% to 98.4% can be obtained. If the intersection angle between the guided oblique beam and the guided straight beam is set to 80°, a cold I2 molecular beam with a full-width at half-maximum longitudinal velocity of 1 m s−1 and a longitudinal temperature of 8 mK can be generated by using an all-optical velocity filter.