Dennis M. Callahan is a Ph.D. candidate at the California Institute of Technology. He is a member of the Light-Materials Interactions in Energy Conversion, an Energy Frontier Research Center, under the advisement of Harry Atwater. His research focuses on design and fabrication of novel solar cells in which the electromagnetic environment has been intentionally engineered to enhance performance. This includes solar cells incorporating elements of plasmonics, photonic crystals, optical resonators and other nanophotonic elements.