MULTI-REFRACTION WITH SAME POLARIZATION STATE IN TWO DIMENSIONAL TRIANGULAR PHOTONIC CRYSTALS

Multi-refraction effects with one polarization in a two-dimensional triangular photonic crystal (PhC) were systematically studied by theoretical analysis and numerical simulation. The more complicated refraction behaviors can be excited in the higher band regions based on the intricate undulation of one band or the overlap of different bands. A novel non-handedness effect is proposed for the first time with group velocity perpendicular to phase velocity. Furthermore, triple refraction phenomena and special collimation effects of symmetrical positive-negative refraction with the loose incident conditions have been found in different band regions of this PhC. These unique features will provide us with more understanding of electromagnetic wave propagation in PhCs and give important guideline for the design of new type optical device.