  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.
