Ultrathin entirely flat Umklapp lenses
Ultrathin entirely flat Umklapp lenses
复制标题
DOI：
10.1103/physrevb.101.155430
复制
发表时间：
2020-04-28
影响因子：
3.7
通讯作者：
Craster, Richard, V
中科院分区：
文献类型：
--
作者：
Chaplain, Gregory J.;Craster, Richard, V
我们设计超薄，完全平坦，电介质透镜使用晶体动量转移，所谓的Umklapp过程，实现所需的波控制的平面透镜的新机制;物理上，这些透镜利用结构化线阵列的周期性的突变，所以有一个介质的第一布里渊区与另一个的第二布里渊区之间的重叠。在不同周期性的区域之间的界面处，表面阵列导波混合成被引导到阵列外部的材料中的反向传播光束。波的这种控制和重定向使该装置能够模拟Pendry-Veselago透镜，该透镜的宽度为一个晶胞，而不需要明确的负折射率。使用嵌入在空气中的氮化硅（Si 3 N4）的理想化板中的阵列进行模拟，在420-500 THz之间的可见波长下工作，证明了这种效果。
We design ultra-thin, entirely flat, dielectric lenses using crystal momentum transfer, so-called Umklapp processes, achieving the required wave control for a new mechanism of flat lensing; physically, these lenses take advantage of abrupt changes in the periodicity of a structured line array so there is an overlap between the first Brillouin zone of one medium with the second Brillouin zone of the other. At the interface between regions of different periodicity, surface, array guided waves hybridize into reversed propagating beams directed into the material exterior to the array. This control, and redirection, of waves then enables the device to emulate a Pendry-Veselago lens that is one unit cell in width, with no need for an explicit negative refractive index. Simulations using an array embedded in an idealized slab of silicon nitride (Si3N4) in air, operating at visible wavelengths between 420-500 THz demonstrate the effect.