Dielectric photonic crystal with a near-zero effective refractive index in the microwave range

Abstract

The microwave propagation in a 3D dielectric photonic crystal at the frequency range from 8.5 to 12GHz has been investigated. A frequency range where effective refractive index n_ef of the crystal approaches zero is found. In the frequency range where n_ef <0.2, themicrowave beam becomes collimated, sharpened, and free of diffraction noise. An excitation of a surface wave, propagating along the external surface of the structure, is revealed in same frequency range. This property of the photonic crystal structure can be used to screen and mask objects scanned by external radiation.