Stability of an efficient optical parametric chirped pulse amplification

光参量啁啾脉冲放大(OPCPA)是一种可以产生体积小、脉冲对比度高、光谱带宽大的超高功率激光器的技术。为了实现大带宽相位匹配，OPCPA通常分为两种几何结构：一种是非线性光学过程接近简并的近共线几何结构，另一种是放大过程远离简并过程的非共线几何结构。在这两种几何结构的基础上，提出了用OPCPA取代传统的再生或棒状盘形放大器的一些新想法。对于共线几何结构，OPCPA过程可以用一维耦合波动方程来计算。在一维计算中，通过在相位失配因子中引入角度效应，忽略了信号脉冲的频率啁啾，讨论了光束发散和光束质量的角度效应。对于非共线几何体，SPAT…在多维耦合波方程中引入走离角和横向位移，需要考虑和评估更多的光学效应。我们开发了一个多维耦合波方程的模拟程序，该程序考虑了频率啁啾、光束发散、走离、群速度失配和衍射的影响。基于传统的非共线几何模型，我们给出了一些典型的数值结果，如由于抽运光和信号光的空间分离而产生的信号光束的空间整形效应，以及由于走离和光束发散引起的信号脉冲的中心波长漂移效应。该方案具有超宽带相位匹配范围、信号波束稳定放大和后续脉冲压缩稳定等优点，且实验结构简单。该方案有望在800 nm波长附近放大短于10ps的信号脉冲。较少

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