Optics plays an increasingly important role for power generation, transmission, and storage. Optics is at the heart of solar devices and modules that efficiently convert the solar spectrum into electrical power, and not just because light is the input to solar cells. Exciting research on the use of plasmonics to enhance photovoltaic efficiency is described in a paper contributed by K. R. Catchpole and A. Polman, while Rühle et al. discuss the use of optical waveguides for better solar cells. Luminescent materials can be used as optical frequency shifters to boost solar cell performance, and van Sark and his co-workers have authored a paper that describes the use of luminescent materials for planar optical concentrators.
On the power storage front, there is substantial research activity on solar hydrogen - the use of solar radiation to create hydrogen fuel. Efforts have focused on solar photolysis (solar induced splitting of water to form hydrogen and oxygen) as the well as the development of biological agents that use sunlight to produce hydrogen and other fuels. A paper by M. Mitra and A. Melis shows how the optical properties of biofuel producing algae can be tailored for best absorption of sunlight. Optical power transmission is proving to be a valuable way to provide power to remote equipment such as video cameras, and a contribution by Freude et al. describes optically powered fiber optic networks. Light emitting diodes are deployed worldwide to replace inefficient incandescent lighting and toxic fluorescent tubes. A contribution by J. K. Kim and E. F. Schubert describes the emergence of light emitting diodes as “smart” light sources that have enhanced functionality such as color temperature control. Finally, as in other industries, optical instruments are proving invaluable for materials and device development, for process monitoring, and for characterization of the performance of energy devices and systems. A contribution by Domínguez et al. describes a solar simulator for characterizing solar cells for concentrating photovoltaics.
The invited papers in this focus issue on Optics for Energy highlight several ways that optics is used for power generation, transmission, and storage. The authors are recognized as leaders in their fields. The collection of topics is by no means exhaustive, but together the papers provide a glimpse into the many ways that optics is making a difference in energy technology.