Highly directional emission from photonic crystals with a wide bandwidth

The authors numerically and experimentally demonstrated highly directional emission from photonic crystals. This was achieved by first splitting the incident electromagnetic wave into multiple beams using photonic crystal waveguide structures. The beams were then emitted out of the surface of a photonic crystal with the same phase, which resulted in a highly directional radiation pattern. The measured half power beam width was 4.8 degrees, which was in good agreement with the calculated value of 4.1 degrees. In contrast to the traditional beaming structures, their design did not involve gratinglike structures, which resulted in a wider operation bandwidth. (c) 2007 American Institute of Physics.