Theoretical Study of Directional Emission Enhancement From Photonic Crystal Waveguides With Tapered Exits

We utilize an approach based on the idea of tapering waveguide exits to increase the directional emission of the light waves emitted from photonic crystal waveguides. It is shown that the enhancement of the directional beaming can be achieved under certain tapered configurations due to the interference pattern created at the exit of the waveguide. The output radiation profile is observed with the finite-difference time-domain method and a 75% reduction in the divergence angle of the out-coupled beam is achieved with the modified waveguide ends.