Light Well: A Tunable Free-Electron Light Source on a Chip

The passage of a free-electron beam through a nanohole in a periodically layered metal-dielectric structure creates a new type of tunable, nanoscale radiation source-a light well. In the reported demonstration, tunable light is generated at an intensity of similar to 200 W/cm(2) as electrons with energies in the 20-40 keV range are injected into gold-silica well structures with a lateral size of just a few hundred nanometers.