Direct semiconductor diode laser system for an optical lattice clock based on neutral strontium for future tests of fundamental physics in space

We present the design and the status of an optical lattice clock at NASA’s Jet Propulsion Laboratory based on bosonic 88Sr atoms and its laser system. The design of the clock aims for future sensitive tests of fundamental physics in space. The atomic source employs a two-dimensional magneto-optical trap realized with permanent magnets and a simple dispenser-based atomic oven. This design results in a low system size, weight and power, suppresses thermal atoms in the clock interrogation zone and eliminates hot blackbody radiation in the science cell. The laser system utilizes exclusively direct diode lasers without second harmonic generation to minimize the complexity and power consumption of the overall system. The clock interrogation laser at 698 nm and the laser for the second cooling stage at 689 nm are both locked to the same high finesse optical cavity to further reduce the size of the system. Future paths to system miniaturization are also discussed.