By aiming high- and low-frequency laser beams at a semiconductor, physicists at UC Santa Barbara have produced multiple frequencies of light simultaneously, with the potential to significantly increase the speed of data communication. The above picture shows near-infrared (amber rods) and terahertz (yellow cones) radiation interact with a semiconductor quantum well (tiles). The near-IR radiation creates excitons (green tiles) consisting of a negative electron and a positive hole (dark blue tile at center of green tiles) bound in an atom-like state. Intense terahertz fields pull the electrons (white tiles) first away from the hole and then back towards it (electron paths represented by blue ellipses). Electrons periodically recollide with holes, creating periodic flashes of light (white disks between amber rods) that are emitted and detected as sidebands.