Löhr Alexander Gabriel, Ivanov Misha Yu, Khokhlova Margarita A
Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Berlin, Germany.
Department of Physics, Humboldt University, Berlin, Germany.
Nanophotonics. 2023 Mar 9;12(14):2921-2928. doi: 10.1515/nanoph-2022-0818. eCollection 2023 Jul.
Control over the time dependence of the refractive index of a material allows one to modify and manipulate the properties of light propagating through it. While metamaterials provide a promising avenue in this context, another route has been extensively explored by the ultrafast community - the so-called molecular modulators. Indeed, impulsively-aligned diatomic molecules provide a unique medium, where periodic rotational revivals induced by a pump pulse persist for tens of picoseconds, offering an excellent opportunity for the controlled modification of the refractive index and, therefore, of femtosecond laser pulses propagating through these media. Here we present an analytical theory which describes this process and stumble across a novel mechanism revealing exponential transformations of the probe pulse - its compression, amplification and frequency up-conversion. In particular, our analytical results predict the generation of amplified ultrashort (about 20 fs) ultraviolet pulses centered around 550 nm, starting with near infrared input pulses centered on 1 μm of about 30 fs duration, under very realistic experimental conditions.
对材料折射率的时间依赖性进行控制，能够使人们改变和操控通过该材料传播的光的特性。虽然超材料在这方面提供了一条很有前景的途径，但超快领域的研究人员也广泛探索了另一条途径——所谓的分子调制器。实际上，脉冲对齐的双原子分子提供了一种独特的介质，泵浦脉冲引发的周期性旋转复兴会持续数十皮秒，这为控制折射率以及因此对通过这些介质传播的飞秒激光脉冲进行控制提供了绝佳机会。在此，我们提出一种解析理论，该理论描述了这一过程，并偶然发现了一种揭示探测脉冲指数变换的新机制——其压缩、放大和频率上转换。特别是，我们的解析结果预测，在非常现实的实验条件下，从持续时间约30飞秒、中心波长为1微米的近红外输入脉冲开始，能够产生中心波长约为550纳米、脉宽约20飞秒的放大超短紫外脉冲。
