Titanium-sapphire femtosecond laser amplifier system

Lange教授团队要求的激光放大系统可提供持续时间为35 fs、脉冲能量为4.5 mJ、中心波长为800 nm、重复频率为3 kHz的超短光脉冲。利用激光的基本原理，强太赫兹（THz）脉冲仅由一个振荡周期组成，峰值场超过1 MV/cm，将通过倾斜脉冲前光学整流产生。此外，使用所要求的双光参量放大器，将产生强锁相中红外脉冲，其峰值场高达100 MV/cm，中心频率范围为15至100太赫兹。时域光谱同时跟踪太赫兹脉冲的幅度和相位，将实现线性表征以及强场测量，包括幅度分辨，二维光谱。此外，在另一项单独的提案中，要求定制的磁性低温恒温器系统将实现磁场和低温下的光谱。我们的小组研究了光-物质相互作用的极端极限，其中光学非线性发生在明显短于光的单周期的时间尺度上。最近的成就包括观察动态布洛赫振荡和高谐波的产生，拓扑绝缘体中狄拉克电子的光波加速，强天线增强太赫兹近场自旋的最小耗散开关，超越Kohn定理的非微扰非线性，以及专用太赫兹谐振器中深强光-物质耦合电子的非绝热开关。所要求的激光系统将使我们能够继续这项研究并探索凝聚态系统中太赫兹亚周期物理的新方向。最近在腔量子电动力学（cQED）的实验中，利用光学谐振器的真空模式来控制电子输运、化学反应或超导性。虽然这些研究集中在平衡状态下的强或超强光-物质耦合，但我们将研究一般的高场动力学，特别是以前无法达到的耦合强度，其中真空拉比频率超过光的振荡周期。为此，我们将进一步提高我们已经建立的腔耦合朗道电子的耦合强度，研究深强耦合半导体子带间跃迁的非线性，并探索cQED的新概念，包括超导谐振器或原子薄电子系统，如过渡金属二硫族化物。当我们系统地探索从线性到非线性再到非摄动动力学的转变时，我们预计会出现大量的新现象，包括高阶非线性、非经典光的产生、非线性相互作用产生的新共振和相变。子周期分辨率将在揭示相关量子动力学方面发挥关键作用。

The laser amplifier system requested by the group of Prof. Lange provides ultrashort optical pulses with a duration of 35 fs, a pulse energy of 4.5 mJ, a center wavelength of 800 nm, and a repetition rate of 3 kHz. Using the laser’s fundamental, strong terahertz (THz) pulses consisting only of a single oscillation cycle, and with peak fields exceeding 1 MV/cm will be generated by tilted pulse-front optical rectification. Moreover, strong, phase-locked mid-infrared pulses with peak fields of up to 100 MV/cm and tuneable center frequencies ranging from 15 to 100 THz will be generated using the requested dual optical parametric amplifier. Time domain spectroscopy tracing the amplitude and phase of THz pulses simultaneously will enable linear characterization as well as strong-field measurements including amplitude-resolved, two-dimensional spectroscopy. In addition, a custom-cut magnet cryostat system, requested in a separate proposal, will enable spectroscopy at magnetic fields and cryogenic temperatures.Our group investigates extreme limits of light-matter interaction in which optical nonlinearities occur on time scales significantly shorter than a single cycle of light. Recent achievements include the observation of dynamical Bloch oscillations and high-harmonics generation, lightwave acceleration of Dirac electrons in topological insulators, minimally dissipative switching of spins by strong, antenna-enhanced THz near fields, non-perturbative nonlinearities beyond Kohn’s theorem, and non-adiabatic switching of deep-strongly light-matter coupled electrons in specialized THz resonators.The requested laser system will allow us to continue this research and explore novel directions of THz subcycle physics in condensed matter systems. Recent experiments in cavity quantum electrodynamics (cQED) have utilized the vacuum modes of optical resonators to control electronic transport, chemical reactions, or superconductivity. While these studies have focused on strong or ultrastrong light-matter coupling in equilibrium, we will investigate high-field dynamics in general, and in particular for previously inaccessible coupling strengths, where the vacuum Rabi frequency exceeds the oscillation period of light. To this end, we will further boost the coupling strength of our established cavity-coupled Landau electrons, investigate nonlinearities of deep-strongly coupled semiconductor intersubband transitions, and explore novel concepts for cQED including superconducting resonators or atomically thin electronic systems such as transition metal dichalcogenides. As we systematically explore the transition from linear to nonlinear to non-perturbative dynamics, we expect a wealth of novel phenomena including high-order nonlinearities, generation of non-classical light, novel resonances generated by nonlinear interactions, and phase transitions to unfold. Subcycle resolution will play a key role in unravelling the relevant quantum dynamics.