Reflectivity studies of photonic band structure effects in two-dimensional air/semiconductor lattices

We report an experimental and theoretical investigation of the near infra-red reflectivity properties of two-dimensional (2D) photonic crystals obtained by deep reactive ion etching of AlGaAs planar waveguides. It is shown that coupling of incident radiation to the folded band structure of photonic crystal waveguides allows sharp resonance features to be observed in the reflectivity spectra. By determining the energy dependence of the resonant features on the angle of incidence along different symmetry directions we are able to map out the photonic band structure. Theoretical spectra obtained from a numerical solution of Maxwell's equations for the periodically patterned waveguide were found to be in very good agreement with experiment.