Photonic crystals: imaging by flat lens using negative refraction.

Parimi, Patanjali V; Lu, Wentao T; Vodo, Plarenta; Sridhar, Srinivas · Nature · 2003

basic_science · Level V

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Abstract

The positive refractive index of conventional optical lenses means that they need curved surfaces to form an image, whereas a negative index of refraction allows a flat slab of a material to behave as a lens and focus electromagnetic waves to produce a real image. Here we demonstrate this unique feature of imaging by a flat lens, using the phenomenon of negative refraction in a photonic crystalline material. The key advance that enabled us to make this observation lies in the design of a photonic crystal with suitable dispersion characteristics to achieve negative refraction over a wide range of angles.