Building Cesium Blue Magneto-Optical Trap

Magneto-optical traps (MOT) are apparatus to laser cool and spatially trap neutral atoms with scattering forces and a spatially varying magnetic field. It has a wide application in variety of AMO experiments such as ultracold atom experiments, optical lattice clocks, neutral atom quantum computing, etc. Our goal is to construct the world's first Cesium MOT with a blue cooling transition, $6S_{1/2} F=4\rightarrow7S_{3/2} F=5$ , to make a visible optical cooling transition MOT available for undergraduate advanced laboratory classes. A Cesium MOT with this cooling transition has a loss channel due to occasional excitation of atoms to the $F=4$ state and subsequent decay to the $F=3$ ground state. We constructed an $852 $ nm tunable external cavity diode laser (ECDL) to drive the $6S_{1/2} F=3\rightarrow6S_{3/2} F=4$ transition. Using the constructed ECDL, we performed saturated absorption spectroscopy on the $6S_{1/2} F=3\rightarrow6S_{3/2} F=2, 3 ,4$ transitions to frequency stabilize the laser to the repump transition.