Koulouklidis Anastasios D, Gollner Claudia, Shumakova Valentina, Fedorov Vladimir Yu, Pugžlys Audrius, Baltuška Andrius, Tzortzakis Stelios
Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology - Hellas (FORTH), P.O. Box 1527, GR-71110, Heraklion, Greece.
Photonics Institute, TU Wien, Gusshausstrasse 27-387, A-1040, Vienna, Austria.
Nat Commun. 2020 Jan 15;11(1):292. doi: 10.1038/s41467-019-14206-x.
Extreme nonlinear interactions of THz electromagnetic fields with matter are the next frontier in nonlinear optics. However, reaching this frontier in free space is limited by the existing lack of appropriate powerful THz sources. Here, we experimentally demonstrate that two-color filamentation of femtosecond mid-infrared laser pulses at 3.9 μm allows one to generate ultrashort sub-cycle THz pulses with sub-milijoule energy and THz conversion efficiency of 2.36%, resulting in THz field amplitudes above 100 MV cm. Our numerical simulations predict that the observed THz yield can be significantly upscaled by further optimizing the experimental setup. Finally, in order to demonstrate the strength of our THz source, we show that the generated THz pulses are powerful enough to induce nonlinear cross-phase modulation in electro-optic crystals. Our work paves the way toward free space extreme nonlinear THz optics using affordable table-top laser systems.
太赫兹（THz）电磁场与物质的极端非线性相互作用是非线性光学的下一个前沿领域。然而，在自由空间中进入这一前沿领域受到现有缺乏合适的强大太赫兹源的限制。在此，我们通过实验证明，3.9μm飞秒中红外激光脉冲的双色成丝能够产生能量亚毫焦且太赫兹转换效率为2.36%的超短亚周期太赫兹脉冲，从而产生高于100 MV/cm的太赫兹场振幅。我们的数值模拟预测，通过进一步优化实验装置，所观测到的太赫兹产率能够显著提高。最后，为了展示我们太赫兹源的强度，我们表明所产生的太赫兹脉冲强大到足以在电光晶体中诱导非线性交叉相位调制。我们的工作为使用经济实惠的桌面激光系统实现自由空间极端非线性太赫兹光学铺平了道路。
