We report and characterize sub-kHz linewidth operation of an AlGaInP-based VECSEL system suitable for addressing the narrow cooling transition of neutral strontium atoms at 689 nm. When frequency-stabilized to a standard air-spaced Fabry-Perot cavity (finesse 1000) via the Pound-Drever-Hall (PDH) technique, it delivers output power >150 mW in a circularly-symmetric single transverse mode with low frequency and intensity noise. The optical field was reconstructed from the frequency noise error signal via autocorrelation and the Wiener-Khintchine theorem, leading to an estimated linewidth of (125 ± 2) Hz. Optical beat note measurements were performed against a commercial locked laser system and a second, almost identical, VECSEL system resulting in linewidths of 200 Hz and 160 Hz FWHM, respectively. To the best of our knowledge, this is the first demonstration of a VECSEL compatible with the narrowest of lines (few hundred Hz) used for cooling and trapping atoms and ions.
Bibliographical noteFunding Information:
Engineering and Physical Sciences Research Council (EP/I022791/1, EP/M013294/1). The laser gain structures were grown by Dr Andrey Krysa at the EPSRC National Centre for III-V Technologies. The laser enclosure for the second VECSEL, used in the beat note measurement system, was supplied by Dr Peter Schlosser of the Fraunhofer Centre for Applied Photonics. Data related to this publication have been made available at the University of Strathclyde data repository .
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ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics