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A cold-atom random laser

2013; Nature Portfolio; Volume: 9; Issue: 6 Linguagem: Inglês

10.1038/nphys2614

1745-2481

Quentin Baudouin, Nicolas Mercadier, Vera Guarrera, William Guerin, Robin Kaiser,

Cold Atom Physics and Bose-Einstein Condensates

Random lasing, where light is amplified through multiple scattering in a gain medium, could occur naturally in astrophysical environments. Experimental evidence for random lasing in a cloud of cold atoms may lead to a better understanding of these astrophysical lasers. In conventional lasers optical cavities are used to provide feedback to gain media. Mirrorless lasers can be built by using disordered structures to induce multiple scattering, which increases the path length in the medium, providing the necessary feedback1. Interestingly, light or microwave amplification by stimulated emission also occurs naturally in stellar gases2,3,4 and planetary atmospheres5,6. The possibility of additional scattering-induced feedback4,7—random lasing8,9,10,11,12,13,14—could explain the unusual properties of some space masers15. Here, we report experimental evidence of random lasing in a controlled, cold atomic vapour, taking advantage of Raman gain. By tuning the gain frequency in the vicinity of a scattering resonance, we observe an enhancement of the light emission due to random lasing. The unique possibility to both control the experimental parameters and to model the microscopic response of our system provides an ideal test bench for better understanding natural lasing sources, in particular the role of resonant scattering feedback in astrophysical lasers.