Engineering of directional emission from photonic crystal waveguides

We analyze, by the finite-difference time-domain numerical methods, several ways to enhance the directional emission from photonic crystal waveguides through the beaming effect recently predicted by Moreno et al. [Phys. Rev. E 69, 121402(R) (2004)], by engineering the surface modes and corrugation of the photonic crystal surface. We demonstrate that the substantial enhancement of the light emission can be achieved by increasing the refractive index of the surface layer. We also measure power of surface modes and reflected power and confirm that the enhancement of the directional emission is related to the manipulation of the photonic crystal surface modes.