科研之友
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摘要
We study the influences of the graded index on Pendry's perfect lens. A perfect lens, in its idealized case, is a slab of material with both the electric permittivity. and the magnetic permeability mu being -1. In the graded-index lens discussed here the., as well as mu, gradually changes from -1 in the main body of the slab to + 1 in the vacuum. During this process of changing, the. will inevitably touch the zero value, which introduces singularities in the corresponding wave equations. We analytically discuss the imaging properties of the graded-index lens by use of confluent hypergeometric Kummer functions and discover that the limit of resolution of the lens has a logarithmic dependence on the graded-index regions. This logarithmic dependence implies that the hyper resolution of a "perfect" lens can only be obtained if the negative-to-positive transition layers are exponentially thin compared with the wavelength as well as the thickness of the lens. Similar effects in a metal slab lens are also discovered.
- 出版日期2016-6-1
- 单位北京大学
