Radiation Exposure of Distributed-Feedback Lasers for Use in Atom Trapping and Atom Interferometry

Semiconductor DFB lasers are compact, efficient, robust light sources suitable for use in laser trapping and cooling and for atom interferometry using alkali atoms. Two commercially available DFB lasers (LD-0852-0150-DFB, Eagleyard Photonics) emitting at 852 nm were subjected to gamma and flash x-ray (FXR) radiation, to a total dose of 200 krad (in two exposures) and a prompt dose of 1.2 krad per shot, respectively. We measured frequency shifts and output power before, during and after exposures with the lasers tuned to the Cs D2 resonance. Radiation induced frequency excursions were smaller than the Doppler broadened linewidth. Radiation induced output power losses were negligible in flash x-ray and 1.8 dB after each of the two 100 krad gamma exposures. These results demonstrate that spectroscopy-grade DFB lasers can survive and function in very adverse radiation environments, making possible the radiation-hard implementation of cold atom based clocks and atom interferometer inertial sensors.