Dielectric materials that exhibit periodic structuring on the length-scale of the operation wavelength exhibit an energy band structure for light. The multi-branch dispersion relation of these Photonic Crystals induces unusual diffractive properties and may even exhibit a complete photonic band gap, i.e., a range of frequencies for which propagation is forbidden irrespective of direction. In turn, such a band gap facilitates the realization of high-Q cavities and complex wave-guiding circuitry, leads to strong modifications of the nonlinear properties of constituent materials and considerably modifies the radiation dynamics of embedded emitters. Over the years, these concepts have been expanded to include the so-called metamaterials which, in the long-wavelength limit, exhibit unusual effective material parameters that are unavailable in ordinary materials.

​Comparison of the experimental and theoretical frequency-resolved reciprocal space mapping of spontaneous emission from 3D visible-wavelength titania woodpile photonic crystals (adapted from Advanced Optical Materials 2, 849 (2014)).

Our activities in this research area are concerned with the development and characterization of three-dimensional Photonic Crystals, the theory of Photonic-Crystal-based optical circuitry, and the modification of nonlinear properties and radiation dynamics in Photonic Crystals. Very recently, we have begun to investigate the properties of hyperbolic metamaterials.