Ovchinnikov A V, Chefonov O V, Agranat M B, Fortov V E, Jazbinsek M, Hauri C P
Opt Express. 2020 Nov 9;28(23):33921-33936. doi: 10.1364/OE.405545.
The ideal laser source for nonlinear terahertz spectroscopy offers large versatility delivering both ultra-intense broadband single-cycle pulses and user-selectable multi-cycle pulses at narrow linewidths. Here we show a highly versatile terahertz laser platform providing single-cycle transients with tens of MV/cm peak field as well as spectrally narrow pulses, tunable in bandwidth and central frequency across 5 octaves at several MV/cm field strengths. The compact scheme is based on optical rectification in organic crystals of a temporally modulated laser beam. It allows up to 50 cycles and central frequency tunable from 0.5 to 7 terahertz, with a minimum width of 30 GHz, corresponding to the photon-energy width of ΔE=0.13 meV and the spectroscopic-wavenumber width of Δ(λ)=1.1 cm. The experimental results are excellently predicted by theoretical modelling. Our table-top source shows similar performances to that of large-scale terahertz facilities but offering in addition more versatility, multi-colour femtosecond pump-probe opportunities and ultralow timing jitter.
用于非线性太赫兹光谱学的理想激光源具有很大的通用性，既能产生超宽带单周期脉冲，又能产生线宽窄且用户可选择的多周期脉冲。在此，我们展示了一个高度通用的太赫兹激光平台，它能提供峰值场强达数十MV/cm的单周期瞬态以及光谱窄脉冲，在数MV/cm的场强下，带宽和中心频率可在5个倍频程范围内调谐。该紧凑方案基于对时间调制激光束在有机晶体中的光学整流。它能产生多达50个周期，中心频率可在0.5至7太赫兹之间调谐，最小宽度为30 GHz，对应光子能量宽度ΔE = 0.13 meV以及光谱波数宽度Δ(λ)= 1.1 cm。理论建模出色地预测了实验结果。我们的桌面型光源展现出与大型太赫兹设施相似的性能，但还具有更多的通用性、多色飞秒泵浦 - 探测机会以及超低定时抖动。
