21 February 2013 Tunable high-purity microwave signal generation from a dual-frequency VECSEL at 852 nm
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We describe the dual-frequency operation of an optically-pumped vertical external cavity semiconductor laser (VECSEL) stabilized onto an Cs atomic transition. It is based on the simultaneous emission of two cross-polarized adjacent longitudinal modes inside the same laser cavity, which provides a strong correlation between the two laser lines. The frequency difference, in the GHz range, is fixed by the intracavity phase anisotropy, and precisely tuned with an electro-optic modulator (EOM). For this work, we additionally take benefit of the class-A dynamical behaviour of VECSEL which results in a shot-noise limited relative-intensity-noise on a wide spectral range.

The GaAs/AlGaAs active structure is pumped with a 1W-fiber coupled laser diode at 670 nm. The laser cavity has been carefully designed for improved thermal and mechanical stability, and compactness. It consists in a 15-mm concave output coupler, a glass Fabry-Perot etalon, a YVO4 birefringent plate and a MgO:SLT EOM. The output power at each frequency reaches 20 mW. The frequency difference is phase-locked to a microwave reference source through the EOM voltage with a MHz bandwidth, resulting in a high-purity optically-carried microwave signal. Simultaneously, one laser line is locked on a Cs atomic hyperfine transition at 852 nm through a low-bandwidth servo-loop on the cavity length. The performance of our laser source is thus fully compatible with the excitation of Cs atoms in coherent population trapping atomic clocks.

© (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
F. A. Camargo, F. A. Camargo, N. Girard, N. Girard, J. M. Danet, J. M. Danet, G. Baili, G. Baili, L. Morvan, L. Morvan, D. Dolfi, D. Dolfi, D. Holleville, D. Holleville, S. Guérandel, S. Guérandel, I. Sagnes, I. Sagnes, P. Georges, P. Georges, G. Lucas-Leclin, G. Lucas-Leclin, "Tunable high-purity microwave signal generation from a dual-frequency VECSEL at 852 nm", Proc. SPIE 8606, Vertical External Cavity Surface Emitting Lasers (VECSELs) III, 86060S (21 February 2013); doi: 10.1117/12.2014240; https://doi.org/10.1117/12.2014240


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