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

Multi-refraction efiects 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 difierent bands. A novel non-handedness efiect is proposed for the flrst time with group velocity perpendicular to phase velocity. Furthermore, triple refraction phenomena and special collimation efiects of symmetrical positive-negative refraction with the loose incident conditions have been found in difierent 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 devices.