Magneto-optic trapping of lithium using semiconductor lasers

Abstract

We present an experimental investigation of a magneto-optical trap for 7 Li atoms which is operated exclusively with low-power single-mode diode lasers. A master-slave scheme based on injection locking of two diode lasers is employed to reach sufficiently high power of tunable narrowband radiation. The trap is loaded from an atomic beam which is decelerated in a compact Zeeman-slower with decreasing field resulting in trap loading rates close to 10 8 atoms/s. The dependence of loading rate, trap spring constant, temperature, number and density of trapped atoms on the laser parameters is studied. More than 10 9 atoms are accumulated at a density approaching 10 11 atoms/cm 3. Since the highest particle numbers are achieved at trap laser detunings of several linewidths from resonance, light-assisted inelastic collisions are of minor importance, and the number of trapped atoms is mainly limited by background gas collisions. The volume occupied by the trapped atoms is found to be independent of the particle number for densities up to 10 10 atoms/cm 3 and particle numbers up to 10 8. The lowest measured temperature 300±50 μK corresponds to a momentum spread of 7 photon recoil momenta.