Photonic Band Gap Materials

Photonic band gap materials are solids that strongly diffract light, ideally at visible and near-infrared wavelengths. They are ordered composite dielectric structures, such as silica-air or titania-polymer, with sub-micron periodic length scales. Many exciting applications have been proposed for these materials, including cavities for thresholdless lasing, planar waveguiding, and photon localization. The efforts of Vicki Colvin's group are focused on the development of new materials and strategies for fabrication of the required sub-wavelength-scale periodicity. Much of this work involves a newly developed method for the self-assembly of spherical colloids. A variety of new and interesting structures have been created using these highly ordered colloidal crystals. Several projects are exploring the use of these materials as membranes or as high surface-area electrodes. In a collaboration with Daniel Mittleman, the optical properties of these photonic crystals are being characterized, and compared with photon band structure calculations. Other projects include using unconventional selfassembled crystals, such as protein crystals, to form new diffractive materials for the soft x-ray region of the spectrum.

Diverse colloidal photonic band gap materials