Unidirectional and bidirectional light beam splitting in photonic crystal with elliptical and circular scatterers

The light beam splitting characters of the two-dimensional asymmetric photonic crystal structures are studied, which are composed of elliptical and circular silicon rods immersed in air. Through interlacing the elliptical and circular silicon rods along the interface of the two photonic crystals, the unidirectional light splitting phenomena are achieved, where the light beam propagates towards two opposite directions within different frequency regions. A bidirectional three-channel light beam splitting behavior is also observed within another frequency region. The light transmission characters can be altered by rotating the elliptical rods in the unit cell. The unidirectional three-output-channel beam splitting behavior is achieved, while the light beam propagating along the opposite direction experiences a self-collimation behavior and keeps its transmitting direction unchanged.