Opt Lett. 2018 Aug 1;43(15):3706-3709. doi: 10.1364/OL.43.003706.
We propose a broadband pumped optical parametric amplification scheme for the generation of a micojoule few-cycle pulse centered at 1.8 μm. Owing to the opposite chirp of the broadband pump and seed pulses, an idler pulse with an FWHM bandwidth of 434 nm is obtained, which can be effectively compressed to a near-transform-limited duration of 13.1 fs by simply compensating for the linear chirp. The picojoule-level seed is amplified to microjoule level in a single stage with a pump pulse of 100 μJ, corresponding to an overall conversion efficiency of 9%. The presented scheme is potentially applicable in various nonlinear crystals with different kinds of femtosecond laser systems, which provides not only an efficient approach of down-converting a near-infrared laser with moderate energy to the mid-infrared region, but also a suitable seeding source in high-energy OPCPA systems.
我们提出了一种宽带抽运光参量放大方案，用于产生中心波长为 1.8μm 的微焦耳级少周期脉冲。由于宽带抽运光和种子光的相反啁啾，获得了 FWHM 带宽为 434nm 的闲频光脉冲，通过简单补偿线性啁啾，可将其有效压缩至近变换极限的 13.1fs 脉冲宽度。在 100μJ 的抽运脉冲作用下，皮焦耳级的种子光在单级放大中被放大到微焦耳级，整体转换效率为 9%。该方案可应用于各种不同种类的飞秒激光系统中的非线性晶体中，不仅为从中红外区域向下转换具有中等能量的近红外激光提供了一种有效的方法，而且为高能 OPCPA 系统提供了合适的种子源。
