Dual-band flat lens with negative index for silicon photonics.

We have designed a photonic crystal flat lens with negative index operating at λ = 1.55 μ m for silicon photonics. It focuses an incident plane wave while it collimates the wave emitted by a point source. Its focal length is 4 λ , and it is 4.4 λ thick. Thus, it acts as a convex lens. It consists of a graded photonic crystal and its operating frequency is set in the second band of photonic crystals, so that the effective index is negative. It also operates in the first band, where it also focuses a plane wave and collimates a point source wave. In both cases, the resolution is subwavelength. It is at the wavelength scale and it has been designed so as it can be fabricated via the silicon-on-insulator CMOS technology. This compact photonic integrated circuit is for optical communications applications, optical interconnects, sensing and lab-on-chip. [ABSTRACT FROM AUTHOR]