Theoretical study on the propagation of self-collimated beams in two-dimensional photonic crystals

Abstract

We have investigated the propagation of self-collimated beams in two dimensional photonic crystals using the plane wave expansion method and the FDTD simulations. We have verified that self-collimated propagation is achieved at the flat region on the equi-frequency contour, and the self-collimated beam undergoes sharp 90˚ bending through (10) photonic crystal-air interface. However, a novel discovery is that by introducing a line defect, we can obtain a beam splitting phenomena .Furthermore, we have demonstrated that by varying the radius of defect rods $γ_d$, we can divide an input beam into two output beams with an arbitrary power ratio. Then using this beam into many output beams with the same power. Also the fact is verified that the adjacent or crossed self-collimated beams do not couple each other.