Tamer Issa, Hellwing Marco, Azamoum Yasmina, Hornung Marco, Keppler Sebastian, Schorcht Frank, Hein Joachim, Kaluza Malte C
Opt Express. 2020 Jun 22;28(13):19034-19043. doi: 10.1364/OE.388344.
A compact, femtosecond-pumped noncollinear optical parametric amplifier (NOPA) is presented with a passive spectral shaping technique, employed to produce a flat-top-like ultrabroadband output spectrum. The NOPA is pumped by a dedicated 2 mJ, 120 fs Yb-based CPA system, which generates both the second harmonic pump pulse and white light supercontinuum as the signal pulse. A chirped mirror pair pre-compensates the material GVD within the optical path of the signal pulse to produce a near-FTL pulse duration at the OPA crystal output. By optimizing both the pump/signal cross angle and the pump/signal delay, the 40 cm × 40 cm footprint, single-pass, fs-pumped, direct NOPA (non-NOPCPA) system generates a record 20 µJ, 11 fs pulses at 820 nm central wavelength with a bandwidth of 230 nm FWHM, to be used as an ultrashort optical probe pulse for relativistic laser-plasma interactions at the petawatt-class POLARIS laser system.
本文介绍了一种紧凑的、飞秒泵浦的非共线光学参量放大器（NOPA），它采用了一种被动光谱整形技术，用于产生平顶状的超宽带输出光谱。该NOPA由一个专门的2 mJ、120 fs的基于镱的啁啾脉冲放大（CPA）系统泵浦，该系统产生二次谐波泵浦脉冲和白光超连续谱作为信号脉冲。一对啁啾镜在信号脉冲的光路中对材料的群速度色散（GVD）进行预补偿，以在光学参量放大器（OPA）晶体输出端产生近傅里叶变换极限（FTL）的脉冲持续时间。通过优化泵浦/信号交叉角和泵浦/信号延迟，这个占地40 cm×40 cm的单通、飞秒泵浦、直接NOPA（非NOPCPA）系统在中心波长820 nm处产生了创纪录的20 μJ、11 fs脉冲，其半高全宽（FWHM）带宽为230 nm，可作为拍瓦级北极星（POLARIS）激光系统中相对论激光-等离子体相互作用的超短光学探测脉冲。
