Positive-negative refraction effect based on overlapping bands in a two-dimensional photonic crystal

Positive-negative refraction based on overlapping bands in a two-dimensional square lattice photonic crystal was studied by theoretical analysis and numerical simulation. An incident beam launching into this photonic crystal under certain conditions will excite simultaneously the negative refracted mode at the second band and the positive refracted mode at the third band, which overlaps with the second band. This positive-negative refraction effect can be manipulated by adjusting the incident angle. This special mechanism of positive-negative refraction can be used to realize beam splitting with more design flexibilities and more excellent properties. (c) 2008 Optical Society of America