Optical characterization of active photonic crystals

Photonic crystals have so far mainly been used in passive devices such as optical fibers, miniaturized waveguides and dielectric mirrors. These applications are primarily based on engineering allowed defect propagation modes within the forbidden photonic band gap. Potentially far more revolutionary are the devices that could make use of another property of the photonic crystal - nonlinear dispersion. At the edge of the photonic bandgap, propagating photons are predicted to experience an anomalously low group velocity. Such "slow photons", during interaction with matter such as emitting or absorbing centers, could give rise to new phenomena in optical absorption and emission, characteristics that cannot be obtained in any traditional optical material. This is a great opportunity to break new ground in optical materials science. In this project, we propose to extend previous work and capability on surface plasmons to include 3D photonic crystals and derivative classes of active materials. Firstly, we propose to fabricate and test dye-sensitized photoelectrochemical Gratzel solar cells using a photonic crystal architecture. To do this, we propose to add facilities for measuring and testing solar cells. This part will focus on the absorption properties of materials when embedded within a photonic crystal cavity. Secondly, we propose to investigate the emissive properties of semiconductor quantum dots embedded in photonic crystals by means of time-resolved photoluminescence. Emission and Absorption of materials are intimately related through the physics of recombination kinetics - that is why they have to be investigated as a pair.RG 105/0