Two-Photon Photovoltaic Effect

The two photon photovoltaic effect is a way of generating electricity from light in which two photons are absorbed by a semiconductor at the same time, together exciting an electron hole pair, rather than the single photon absorption that drives an ordinary photovoltaic cell. Because it is a nonlinear optical process, its absorption rate rises with the square of the light own intensity, so it is normally far weaker than ordinary single photon absorption at everyday light levels but becomes the dominant effect once the light is intense enough. This intensity dependence makes the effect of interest for converting very high intensity optical signals, rather than ordinary sunlight, into electrical power. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/