Three-dimensional photonic-bandgap crystals are used to design and fabricat
e uniquely directional sources and receivers. By utilizing the resonances o
f a Fabry-Perot cavity formed with photonic-bandgap crystals, we were able
to create exceptionally directional sources by placing the sources within s
uch a cavity. Very good agreement between finite-difference time-domain cal
culations and the experiment is obtained. Radiation patterns with half-powe
r beam widths of less than 12 degrees were obtained. (C) 2001 Optical Socie
ty of America.