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

We report an experimental and theoretical investigation of the near infra-r ed reflectivity properties of two-dimensional (2D) photonic crystals obtain ed by deep reactive ion etching of AlGaAs planar waveguides. It is shown th at coupling of incident radiation to the folded band structure of photonic crystal waveguides allows sharp resonance features to be observed in the re flectivity spectra. By determining the energy dependence of the resonant fe atures 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 patte rned waveguide were found to be in very good agreement with experiment.