Duke Free-Electron Laser Breaks 2000-Angstrom Barrier

DURHAM, N.C., Oct 14 -- Duke University reports that its Russian-built free-electron laser (FEL) has emitted at deep-UV wavelengths shorter than 2000 angstroms. According to Vladimir Litvinenko, associate director for light sources at Duke's Free-Electron Laser Laboratory, the OK-4 -- one of two FELs at the lab -- successfully lased at 1937 angstroms.
Litvinenko explained that 2000 angstroms is considered a significant technical barrier because the mirrors commonly used to create FEL light lose considerable reflectivity and degrade quickly at such short wavelengths. Some lasers such as excimers can operate at short wavelengths by using mirrors composed of different materials; as those materials are damaged by the x-ray radiation produced by the magnets FELs use to generate light, they are not an option for FELs. The team of Duke researchers used new mirrors able to handle x-ray and UV radiation and enhanced the quality of the electron beam powering the OK-4 in order to achieve short wavelength emission.