BBO晶体Ⅰ类相位匹配从可见光到近红外光宽带参量放大的带宽研究

Investigation of Spectral Bandwidth of BBO-Ⅰ Phase Matching Noncollinear Broadband Optical Parametric Amplification from Visible to Near-Infrared

超快激光的应用,需要有高功率、窄脉宽和宽调谐的激光光源。飞秒光参量放大是产生可调谐、短至几个飞秒光脉冲的一种重要方法。为获得极窄的飞秒光脉冲,飞秒光参量放大器就应该有尽可能大的本征带宽。理论研究了BBO晶体在Ⅰ类非共线相位匹配条件下的宽带参量放大特性。将多色相位匹配技术应用于飞秒光参量放大,推导出信号光带角色散时的宽带运转条件。分别介绍了从可见光到近红外光选取合适的参数实现宽带运转的方法。基于400nm蓝光抽运的BBO晶体光参量放大器（OPA）,系统地分析了非共线角和信号光角色散值对相位失配和参量带宽的影响。研究结果表明选取适当非共线角和在近红外光中引入适当的角色散可极大提高参量带宽。

Laser sources that are high power, short time duration and broadly tunable are needed for the application of ultra-fast laser. Femtosecond optical parametric amplification is one of the important techniques to produce broadly tunable and several femtoseconds pulse. To produce extremely short laser pulse, the femtosecond optical parametric amplification should support large spectral bandwidth enough. The ultra-broadband optical parametric amplification of BBO type-Ⅰ phase matching is theoretically investigated. The achromatic phase matching technology is introduced in femtosecond optical parametric amplification, and broadband phase matching condition with angular dispersion of signal beam is given. The effects of noncollinear angle and angular dispersion of signal pulse on the phase mismatching and parametric bandwidth are also discussed. The results indicate that a suitable noncollinear angle of signal pulse and introducing suitable angular dispersion in near-infrared signal pulse can increase the parametric bandwidth dramatically. As an example, phase-matched noncollinear optical parametric amplifiers （NOPAs） pumped by the blue light of 400 nm are discussed. The method and the analysis results provide a theoretical guidance for obtaining broadband parametric amplifiers.