Titanium-sapphire femtosecond laser amplifier system

兰格教授课题组要求的激光放大系统提供的超短光脉冲的持续时间为35fs，脉冲能量为4.5mJ，中心波长为800 nm，重复频率为3 kHz。利用激光器的基本原理，通过倾斜的脉冲前沿光学整流，将产生仅由一个振荡周期组成的峰值场超过1 mV/cm的强太赫兹(THz)脉冲。此外，使用所要求的双光学参数放大器将产生峰值场高达100 mV/cm、中心频率在15至100太赫兹之间可调的强锁相中红外脉冲。同时跟踪太赫兹脉冲的幅度和相位的时间域光谱学将使线性表征以及包括幅度分辨的二维光谱学在内的强场测量成为可能。此外，在另一份提案中要求的定制切割磁铁低温恒温器系统将能够在磁场和低温下进行光谱分析。我们的团队研究了光-物质相互作用的极端极限，其中光学非线性发生在比单个光周期短得多的时间尺度上。最近的成就包括动态布洛赫振荡和高次谐波的观测，狄拉克电子在拓扑绝缘体中的光波加速，强天线增强的太赫兹近场对自旋的最小耗散切换，超越科恩定理的非微扰非线性，以及在专门的太赫兹谐振器中深-强轻质耦合电子的非绝热切换。所要求的激光系统将使我们能够继续这一研究，并探索凝聚态物质系统中太赫兹亚循环物理的新方向。最近在腔量子电动力学(CQED)中的实验利用光学谐振腔的真空模式来控制电子输运、化学反应或超导。虽然这些研究集中在平衡状态下强或超强的光-物质耦合，但我们将研究一般的高场动力学，特别是以前无法获得的耦合强度，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建立的腔耦合朗道电子的耦合强度，研究深-强耦合半导体亚带间跃迁的非线性，并探索用于cQED的新概念，包括超导谐振器或原子薄电子系统，如过渡金属二卤化物。随着我们系统地探索从线性到非线性再到非微扰动力学的转变，我们期待着丰富的新现象，包括高阶非线性，非经典光的产生，由非线性相互作用产生的新的共振，以及相变。子周期分辨率将在解开相关量子动力学的过程中发挥关键作用。

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.