讨论了若干利用二阶非线性效应的飞秒激光技术研究进展。基于传统的钛宝石飞秒激光器,提出了可产生稳定的1μm波段可调谐飞秒激光的新型注入式飞秒光参量放大(OPA)系统。结合相位匹配折返原理,用部分氘化KDP晶体作为二阶非线性介质,实现了对20nm带宽的1mm波段飞秒激光的高效宽带倍频,倍频效率达到55%。最后介绍了具有脉冲扩展功能的时间望远镜系统。

The recent progress of the authors′ group on developing quadratic nonlinear technologies for femtosecond lasers is reviewed. A novel injective femtosecond optical parametric amplifier(OPA) is developed, which can produce tunable femtosecond laser with central wavelength at 1μm, based on the traditional Ti:sapphine laser. A wideband frequency doubling efficiency, as high as 55%, for femtosecond pulsed laser with central wavelength at 1μm is realized, by using the phase matching reentry principle and adopting partially deuterated KDP crystal as the quadratic nonlinear medium. Finally, a time telescope of femtosecond laser with functions of pulse expanding and spectral narrowing is demonstrated.