We utilize the anomalous dispersion of planar-photonic crystals (PhCs) near the dielectric band edge to control the wavelength-dependent propagation of light. Light beams with up to 20° divergence were collimated over a 25-nm (1285 nm to 1310 nm) bandwidth using a triangular lattice. The"superprism"phenomenon is demonstrated in the same configuration, simply by tuning the wavelength. Sources of loss are discussed. Both the plane-wave expansion calculation and finite-difference time-domain simulation match well with the experimental results. This is the first experimental demonstration of self-collimating phenomena in a PhC configuration.
Lijun Wu, Michael Mazilu, and Thomas F. Krauss, "Beam Steering in Planar-Photonic Crystals:From Superprism to Supercollimator," J. Lightwave Technol. 21, 561- (2003)