Generation of midwave- and longwave infrared few-cycle multi-mJ pulses for the study of soliton-induced ultrafast nonlinear phenomena in atomic and molecular gases by using dielectric-coated metallic hollow-core fibers

该项目旨在利用已有的工作在1 kHz的新型多MJ超短脉冲中波红外(MWIR)OPCPA系统(3 MJ，5微米)，并将其扩展到长波IR(LWIR)范围(覆盖7-12微米)，用于研究介质涂覆金属空芯光纤(DM-HCF)的非线性过程。这种独特的激光光源和DM-HCF的探索为中红外非线性光学提供了一个新的领域，例如，在迄今为止在其他波导中无法实现的反常色散范围内，研究新的光谱和时间区域以及超快非线性过程。特别是无失真孤子脉冲传输、少周期孤子自压缩和孤子诱导超连续谱产生等5-12微米光谱范围内的孤子现象，将从理论和实验两个方面进行研究。个人目标是：(1)扩展现有的几个周期的MWIR OPCPA系统，以产生7-12微米范围的超短脉冲，使脉冲能量达到MJ-范围。(2)用于反常色散区中、长波红外脉冲自压缩的DM-HCFS的理论和实验研究。在所考虑的5-12微米的波长范围内，一种无与伦比的新压缩技术有望问世。此外，DM-HCF允许以比玻璃HCF高得多的能量压缩脉冲。(3)利用高能中波和长波红外脉冲在充气DM-HCFS中产生超连续谱的理论和实验研究。这种泵浦脉冲的应用应该可以产生扩展到太赫兹光谱范围的极宽的超连续谱。(4)研究充气DM-HCF中MWIR和LWIR脉冲的无失真孤子传输与波长和脉冲能量的关系。目标波长范围在3-12微米之间的孤子还没有实现。(5)利用双色脉冲技术在气体中产生高能太赫兹脉冲。人们可以预期，与近红外泵浦脉冲相比，在MWIR和LWIR中使用毫焦耳脉冲，太赫兹产额将增加两个数量级。

The project aims at the use of an already existing novel multi-mJ ultrashort pulse midwave IR (MWIR) OPCPA system (3 mJ, 5 micrometers) operating at 1 kHz and its extension to longer wavelengths in the longwave IR (LWIR) range (covering 7-12 micrometers) for the study of nonlinear processes in dielectric-coated metallic hollow-core fibers (DM-HCF). This unique laser source and the exploration of DM-HCFs grant access to a new segment of mid-IR nonlinear optics, e.g., to investigate new spectral and temporal regimes and ultrafast nonlinear processes in the anomalous dispersion range hitherto inaccessible in other waveguides. In particular solitonic phenomena in the 5-12 micrometers spectral range for distortion-less soliton pulse delivery, few-cycle soliton self-compression and soliton-induced supercontinuum generation will be studied from both a theoretical and experimental perspective. The individual goals are:(1) Extending the existing few-cycle MWIR OPCPA system for the generation of ultrashort pulses in the range of 7-12 micrometers, enabling pulse energies in the mJ-range. (2) Theoretical and experimental study of DM-HCFs for MWIR and LWIR pulse self-compression in the anomalous dispersion regime. In the considered wavelength range from 5-12 micrometers an unrivaled new compression technique is expected. Furthermore, DM-HCFs allow the compression of pulses with much higher energy compared to glass HCFs. (3) Theoretical and experimental study of supercontinuum generation in DM-HCFs filled with a gas using the high-energy MWIR and LWIR pulses. The application of such pump pulses should allow the generation of extremely broadband supercontinua extending into the THz spectral range.(4) Distortion-less soliton propagation of MWIR and LWIR pulses in gas-filled DM-HCFs will be studied in dependence on wavelength and pulse energy. Solitons in the targeted wavelength range between 3-12 micrometers have not been realized yet. (5) Generation of high-energy THz pulses in gases by using the two-color pulse technique. One can expect that with millijoule pulses in the MWIR and LWIR the THz yield will be increased by up to two orders of magnitude compared to near-IR pump pulses.