Stability of an efficient optical parametric chirped pulse amplification

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Optical parametric chirped pulse amplification (OPCPA) is one of possible technologies to produce an ultrahigh power laser with a compact size, a high pulse contrast, and a large spectral bandwidth. The OPCPA is generally divided into two geometries to achieve the large bandwidth phase-match : a near-collinear geometry that the nonlinear optical process is closed-to-degeneracy and a noncollinear geometry that the amplification process is away from degeneracy. Based on these two geometries, some novel ideas for the OPCPA were proposed to replace conventional regenerative or rod disk amplifiers. For the collinear geometry, the OPCPA process can be evaluated with one-dimensional coupled wave-equation. Also with one-dimensional calculations, angular effects of beam divergences and beam quality were discussed by introducing the angular effects into the phase-mismatching factor, in which the frequency chirp of the signal pulse was ignored in that analysis. For the noncollinear geometry, spat … More ial effects should be considered and evaluated by introducing the walk-off angle and transverse displacement into multi-dimensional coupled wave-equations.We developed a multi-dimensional simulation code of coupled wave-equations for optical parametric chirped pulse amplification involving effects of frequency chirp, beam divergence, walk-off, group-velocity mismatch, and diffraction. Based on a conventional noncollinear geometry, we show some typical numerical results, such as spatially shaped effect in signal beam due to the spatial separation between pump and signal beams, and central wavelength shift effect in the signal pulse due to the walk-off and beam divergence.We propose a novel scheme for ultra-broadband phase-matching optical parametric chirped pulse amplification with an angularly-diverged pump beam. This scheme has some advantages such as an ultra-broadband phase-matching range, a stable amplification for signal beam and a stable pulse compression subsequently, and a simple experimental configuration. The proposed scheme is expected to amplify a signal pulse shorter than 10 fs around an 800-nm wavelength. Less