Induced Birefringence in Electrooptical Photonic bi-oriented Crystals

摘要

Electrically induced birefringence in Photonic bi-oriented Crystals (PBC) is dcmonstrated assuming a regular assembly of dielectric anisotropic grains. Regions of alternating high and 1ow optical constants are achieved due to a periodic twist between the grains. The dielectric contrast at the grain boundaries varies according to the directions of light propagation. In directions of large dielectric contrast, modes of the lightflow are confined and photonic bandgaps are generated. In directions of low or zero dielectric contrast, the artificial crystal is optically transparent. The generation of bandgaps in the photonic bandstructure can be induced by imposing external fields to PBC. If an electric field is applied to the PBC, the dielectric indcxcllipsoid of each twisted grain is deformed. For explicit bi-crystalline geometry and direction of lightflow, PBC are optically transparent at no external field. Conversely, at high external fields a periodic dielectric contrast is observed at the grain boundaries. If the electrically induced dielectric contrast is sufficiently large, photonic confinement is observed. Thus, the optical transmission can be directed by the intensity of the imposed electric field. The electrically induced birefringence in one-dimensional PBC may have possible applications for optical switches and modulators. In two-dimensional PBC, the induced birefringence may be applicable to tune the directions in optical waveguides.