Sub-megahertz linewidth 780.24  nm distributed feedback laser for ⁸⁷Rb applications

A distributed feedback GaAs-based semiconductor laser with a laterally coupled grating is demonstrated at a wavelength of 780.24 nm with up to 60 mW power. A mode expander and aluminum-free active layers have been used to reduce the linewidth to 612 kHz while maintaining high output power. The laser demonstrates over 40 dB side-mode suppression ratio with >0.3nm of tuning suitable for atom cooling experiments with the D2 ⁸⁷Rb atomic transition. This laser has substantial potential to be integrated into miniaturized cold atom systems.