Luo Hailu, Ren Zhongzhou, Shu Weixing, Li Fei
Department of Physics, Nanjing University, Nanjing 210008, China.
Phys Rev E Stat Nonlin Soft Matter Phys. 2007 Feb;75(2 Pt 2):026601. doi: 10.1103/PhysRevE.75.026601. Epub 2007 Feb 5.
We propose to employ the quasi-isotropic metamaterial (QIMM) slab to construct a polarization insensitive lens, in which both E- and H-polarized waves exhibit the same refocusing effect. For shallow incident angles, the QIMM slab will provide some degree of refocusing in the same manner as an isotropic negative index material. The refocusing effect allows us to introduce the ideas of paraxial beam focusing and phase compensation by the QIMM slab. On the basis of angular spectrum representation, a formalism describing paraxial beams propagating through a QIMM slab is presented. Because of the negative phase velocity in the QIMM slab, the inverse Gouy phase shift and the negative Rayleigh length of paraxial Gaussian beam are proposed. We find that the phase difference caused by the Gouy phase shift in vacuum can be compensated by that caused by the inverse Gouy phase shift in the QIMM slab. If certain matching conditions are satisfied, the intensity and phase distributions at object plane can be completely reconstructed at image plane. Our simulation results show that the superlensing effect with subwavelength image resolution could be achieved in the form of a QIMM slab.
我们建议采用准各向同性超材料（QIMM）平板来构建一个偏振不敏感透镜，其中E偏振波和H偏振波都表现出相同的重新聚焦效果。对于浅入射角，QIMM平板将以与各向同性负折射率材料相同的方式提供一定程度的重新聚焦。这种重新聚焦效果使我们能够引入近轴光束聚焦和QIMM平板相位补偿的概念。基于角谱表示，提出了一种描述近轴光束通过QIMM平板传播的形式体系。由于QIMM平板中的负相速度，提出了近轴高斯光束的逆古依相移和负瑞利长度。我们发现真空中由古依相移引起的相位差可以由QIMM平板中的逆古依相移引起的相位差来补偿。如果满足某些匹配条件，则物平面处的强度和相位分布可以在像平面处完全重建。我们的模拟结果表明，以QIMM平板的形式可以实现具有亚波长图像分辨率的超透镜效应。
