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Spatial Beam Self-Cleaning in Second-Harmonic Generation

2020; Nature Portfolio; Volume: 10; Issue: 1 Linguagem: Inglês

10.1038/s41598-020-64080-7

2045-2322

Katarzyna Krupa, R. Fona, Alessandro Tonello, Alexis Labruyère, Badr Mohamed Ibrahim Shalaby, S. Wabnitz, Fabio Baronio, Alejandro B. Aceves, G. Millot, Vincent Couderc,

Laser-Matter Interactions and Applications

Abstract We experimentally demonstrate the spatial self-cleaning of a highly multimode optical beam, in the process of second-harmonic generation in a quadratic nonlinear potassium titanyl phosphate crystal. As the beam energy grows larger, the output beam from the crystal evolves from a highly speckled intensity pattern into a single, bell-shaped spot, sitting on a low energy background. We demonstrate that quadratic beam cleanup is accompanied by significant self-focusing of the fundamental beam, for both positive and negative signs of the linear phase mismatch close to the phase-matching condition.