Light trapping and solar energy harvesting in thin film photonic crystals

Photonic crystals are widely known for their light-trapping capabilities. This is often associated with the occurrence of a photonic band gap or other suppression in the electromagnetic density of states [1-3]. This also enables unprecedented forms of strong coupling between light and matter. A less studied form of light-trapping occurs in the higher bands of a photonic crystal, where the electromagnetic density of states is enhanced rather than suppressed. This enables strong absorption of light from a broadband source over a wide acceptance angle in a material with weak intrinsic absorption [4].