Sub-megahertz linewidth 780.24 nm distributed feedback laser for<sup>87</sup>Rb applications
Eugenio Di Gaetano, Scott Watson, Euan McBrearty, Marc Sorel, Douglas J. Paul
Abstract
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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow class="MJX-TeXAtom-ORD"><mml:mo>></mml:mo></mml:mrow><mml:mrow class="MJX-TeXAtom-ORD"><mml:mn>0.3</mml:mn></mml:mrow><mml:mspace width="thickmathspace"/><mml:mrow class="MJX-TeXAtom-ORD"><mml:mi mathvariant="normal">n</mml:mi><mml:mi mathvariant="normal">m</mml:mi></mml:mrow></mml:math> of tuning suitable for atom cooling experiments with the D2 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow class="MJX-TeXAtom-ORD"><mml:msup><mml:mi/><mml:mrow class="MJX-TeXAtom-ORD"><mml:mn>87</mml:mn></mml:mrow></mml:msup><mml:mrow class="MJX-TeXAtom-ORD"><mml:mi mathvariant="normal">R</mml:mi><mml:mi mathvariant="normal">b</mml:mi></mml:mrow></mml:mrow></mml:math> atomic transition. This laser has substantial potential to be integrated into miniaturized cold atom systems.