Intense few-cycle mid-infrared laser source

对固体中强场现象的研究可以极大地受益于在光谱的中红外部分使用强的、几个周期的激光光源。中红外激光更适合于在半导体、捕光钙钛矿、二维材料以及具有生物意义的材料等低禁带材料中使用强场。由于半导体的平均带隙能量约为1-2 eV量级，暴露在光场(1 eV-2 eV)中的半导体在能够有效地触发极端非线性响应之前遭受光学损伤。中红外脉冲可以克服这一障碍。中红外场和光场将允许激发和探测更多自由度，而不是电子响应，如声子。中红外脉冲和光学阿秒脉冲的结合可以使动力学显像术的发展成为可能，即探索物质中的电子动力学在空间和时间上的能力。纳米结构材料驱动强场发射的可能性--我们团队中一条新的、非常有希望的研究路线--可以再次受益于超短光脉冲的持续时间，但它们的能量非常接近固体(&lt；5 eV)的典型功函数，再次对可以行使的最大电场施加了可怕的限制。我们将在下面看到，如果驱动场的载流子能量向光谱的中红外部分移动，提供产生和控制电子脉冲的潜力的光电子发射实验可以显著地提高。我们建议采购一个中红外(2微米)，相位稳定，少周期激光系统，能量在~250微焦耳的范围内。该系统将对固体中强场现象的一系列研究起到至关重要的作用。

The study of strong field phenomena in solids can tremendously benefit from the use of intense, few-cycle laser sources in the mid-infrared part of the spectrum. Lasers at the mid-infrared are more appropriate for exercising strong fields in low band gap materials such as semiconductors, light-harvesting perovskites, 2-D materials, as well as materials of biological interest. With an average bandgap energy of the order of 1-2 eV, semiconductors exposed to optical fields (1 eV -2 eV) suffer optical damage before an extreme nonlinear response can be efficiently triggered. Mid-infrared pulses can allow overcoming this barrier. Mid-infrared field and optical fields will allow excitation and probing of more degrees of freedom other than electronic response such as phonons. The combination of mid-infrared pulses and optical attosecond pulses could allow the development of dynamics picoscopy, that is the capability to explore electron dynamics in matter both in space and time. The possibility to drive strong-field emission from nanostructured materials—a new and highly promising research route in our group, can once again benefit from the duration of ultrashort optical pulses but their energy is very close to the typical work function of solids (< 5 eV) imposing once again a formidable limit as to the maximum electric field that can be exercised. We will see bellow that photoemission experiments offering the potential for generating and controlling electron pulses can be dramatically improved if the carrier energy of the driving field shift towards the mid-infrared part of the spectrum. We propose the procurement of a mid-infrared (2 microns), phase-stabilized, few-cycle laser system with energy in the range of ~250 microjoule. This system will play an essential role for a range of studies of strong field phenomena in solids.