[1] A. Laurain, M. Myara, G.Beaudoin, I. Sagnes, and A. Garnache, "Multiwatt--power highly--coherent compact single--frequency tunable Vertical--External--Cavity--Surface-- Emitting--Semiconductor--Laser," Optics Express, vol. 18, iss. 14, pp. 14627–14636, July 2010.

Abstract : We demonstrate high power (2.1 W) low noise single frequency operation of a tunable compact verical–external–cavity surface–emitting– laser exhibiting a high beam quality. We took advantage of thermal lens–based stability to develop a short (3−10 mm) plano–plano external cavity without any intracavity filter. The semiconductor structure emitting at 1μm is optically pumped by a 8W commercial 808 nm multimode diode laser at large incidence angle. For heat management purpose the GaAs-based VECSEL membrane was bonded on a SiC substrate. We measured a low divergence quasi-circular TEM00 beam (^ = 1.2) close to diffraction limit, with a linear light polarization (>30 dB).We simulated the steady state laser beam of this unstable cavity using Fresnel diffraction. The side mode suppression ratio is > 45 dB. The free running laser linewidth is 37 kHz limited by pump induced thermal fluctuations. Thanks to this high-Q external cavity approach, the frequency noise is low and the dynamics is in the relaxation-oscillation-free regime, exhibiting low intensity noise (< 0.1%), with a cutoff frequency ~ 41MHz above which the shot noise level is reached. The key parameters limiting the laser power and coherence are studied. This design/properties can be extended to other wavelengths.

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