Yessenov Murat, Abouraddy Ayman F
CREOL, The College of Optics and Photonics, University of Central Florida, Orlando, Florida 32816, USA.
Phys Rev Lett. 2020 Dec 4;125(23):233901. doi: 10.1103/PhysRevLett.125.233901.
Although a plethora of techniques are now available for controlling the group velocity of an optical wave packet, there are very few options for creating accelerating or decelerating wave packets whose group velocity varies controllably along the propagation axis. Here we show that "space-time" wave packets in which each wavelength is associated with a prescribed spatial bandwidth enable the realization of optical acceleration and deceleration in free space. Endowing the field with precise spatiotemporal structure leads to group-velocity changes as high as ∼c observed over a distance of ∼20 mm in free space, which represents a boost of at least ∼4 orders of magnitude over X waves and Airy pulses. The acceleration implemented is, in principle, independent of the initial group velocity, and we have verified this effect in both the subluminal and superluminal regimes.
尽管现在有大量技术可用于控制光波包的群速度，但能够创建群速度沿传播轴可控变化的加速或减速波包的方法却很少。在此我们表明，每个波长都与规定的空间带宽相关联的“时空”波包能够在自由空间中实现光的加速和减速。赋予场精确的时空结构会导致在自由空间中约20毫米的距离上观察到高达约c的群速度变化，这比X波和艾里脉冲至少提高了约4个数量级。原则上，实现的加速度与初始群速度无关，并且我们已在亚光速和超光速两种情况下验证了这一效应。
