Through advanced calculations physicists and mathematicians have discovered that a thin, diamond-like photonic nanostructure reflects a surprisingly broad range of colors of light, from all angles. This causes the material to have great potential as a back reflector to enhance the efficiency of solar cells or tiny on-chip light sources. The efficiency of solar cells depends on trapping and absorbing light and can be increased by using a back reflector: a mirror behind the solar cell material that reflects light that was not absorbed and leads it back into the solar cell. The ideal mirror reflects light incident from any angle, known as omnidirectional reflectance, and for all frequencies (or colors) of light. Such omnidirectional reflectance for dielectric structures is associated with three-dimensional photonic crystal nanostructures that sustain a so-called complete photonic band gap. However, researchers always thought such structures would have a narrow frequency range of o...