Hakkarainen Timo, Setälä Tero, Friberg Ari T
Department of Applied Physics, Helsinki University of Technology, P. O. Box 3500, FI-02015 TKK, Finland.
J Opt Soc Am A Opt Image Sci Vis. 2009 Oct;26(10):2226-34. doi: 10.1364/JOSAA.26.002226.
We investigate near-field imaging of a point dipole by a lossy, nanoscale metamaterial slab. Making use of the electromagnetic angular-spectrum representation, we derive the Green tensor for the field transmission through the metamaterial slab, duly considering multiple reflections, polarizations, and wave-vector signs. With this general formalism, we calculate the point-spread function of the imaging system, which enables us to assess, for instance, resolution and image brightness. Our results demonstrate that with the metamaterial-slab lens one achieves resolution beyond the conventional diffraction limit of half the wavelength. In general, the resolution and image brightness are degraded when the slab thickness and absorption increase, but we show that in some cases the resolution is rather insensitive to the magnitude of the losses in the metamaterial.
我们研究了有损纳米级超材料平板对点偶极子的近场成像。利用电磁角谱表示，我们推导了通过超材料平板的场传输的格林张量，充分考虑了多次反射、偏振和波矢符号。借助这种通用形式，我们计算了成像系统的点扩散函数，这使我们能够评估例如分辨率和图像亮度。我们的结果表明，使用超材料平板透镜可实现超越传统半波长衍射极限的分辨率。一般来说，当平板厚度和吸收率增加时，分辨率和图像亮度会降低，但我们表明在某些情况下，分辨率对超材料中的损耗大小相当不敏感。
