利用局部弯曲的时空波包在130米处选择性避开多个视线障碍物
Selective avoidance of multiple line-of-sight obstacles at 130~m using locally bending space-time wave packets
AI总结：
研究利用时空波包局部绕过障碍物的方法，通过对脉冲光束时空频谱工程设计，在130米露天环境实验，实现避开多个LoS障碍物并选择性到达目标，有望用于多种涉及LoS障碍物的应用场景。
AI中文摘要：
自加速光束沿弯曲轨迹传播而非直线传播，这为避开阻挡光路的视线（LoS）障碍物带来了前景。然而，若传统激光束在射向目标途中被障碍物拦截，仅用弯曲光束替换是不够的，需要能在局部绕过障碍物的激光束。本文表明，对脉冲光束的时空频谱进行工程设计可产生时空波包，其传播动力学可随意调整以局部绕过一个或多个障碍物，从而避开它们并选择性地到达指定目标。我们在距离光源130米的露天环境中进行实验。在一种场景中，光束入射到位于两个LoS障碍物之间的目标上，前后两个障碍物均被避开；在另一种场景中，局部弯曲的光束避开了目标前方的一个和两个LoS障碍物。这些结果可能有助于遥感、远距离探测、定向能量、存在LoS障碍物时的光通信和射频通信以及选择性放射治疗等需要对目标进行选择性入射的应用。
英文摘要：
Self-accelerating optical beams follow curved trajectories rather than propagating rectilinearly, which raises the prospect for avoiding line-of-sight (LoS) obstacles blocking the beam path. However, if a conventional laser beam is intercepted by an obstacle en route to an intended LoS target, then replacing this beam with a bending beam is not adequate: the obstacle is avoided but the target cannot be concomitantly reached. Rather, a laser beam that \textit{locally} bends around the obstacle -- before continuing along its rectilinear path -- is needed. Here we show that engineering the spatiotemporal spectrum of a pulsed beam yields a space-time wave packet whose propagation dynamics can be tuned at will to locally bend around one or multiple obstacles, thereby avoiding them, to selectively reach a designated target. We carry out our experiments over distances extending to 130~m from the source, carried out in an open-air environment. In one scenario, the beam is incident on a target placed between two LoS obstacles, one preceding it and one following it -- both of which are avoided. In a second scenario, the locally bending beam avoids one and then two LoS obstacles preceding the intended target. These results may contribute to applications requiring selective incidence on targets in remote sensing, stand-off detection, directed energy, for optical and radio-frequency communications in presence of LoS obstacles, and for selectively delivered radiation therapies.
