Yessenov Murat, Faryadras Sanaz, Benis Sepehr, Hagan David J, Van Stryland Eric W, Abouraddy Ayman F
Opt Lett. 2022 Apr 1;47(7):1630-1633. doi: 10.1364/OL.450828.
Space-time (ST) wave packets are a class of pulsed optical beams whose spatiotemporal spectral structure results in propagation invariance, tunable group velocity, and anomalous refractive phenomena. Here, we investigate the refraction of ST wave packets normally incident onto a planar interface between two dispersive, homogeneous, isotropic media. We formulate a new, to the best of our knowledge, refractive invariant for ST wave packets in this configuration, from which we obtain a law of refraction that determines the change in their group velocity across the interface. We verify this new refraction law in ZnSe and CdSe, both of which manifest large chromatic dispersion at near-infrared frequencies in the vicinity of their band edges. ST wave packets can thus be utilized in nonlinear optics for bridging large group-velocity mismatches in highly dispersive scenarios.
时空（ST）波包是一类脉冲光束，其时空光谱结构导致传播不变性、可调群速度和反常折射现象。在此，我们研究了垂直入射到两种色散、均匀、各向同性介质之间平面界面上的ST波包的折射。据我们所知，我们针对这种配置下的ST波包制定了一种新的折射不变量，从中我们得到了一个折射定律，该定律确定了它们的群速度在界面处的变化。我们在ZnSe和CdSe中验证了这一新的折射定律，这两种材料在其带边附近的近红外频率下都表现出很大的色散。因此，ST波包可用于非线性光学，以弥合高色散情况下的大群速度失配。
