Ultrashort light pulses are powerful tools for time-resolved studies of molecular and atomic dynamics. They arise in the visible and infrared range from femtosecond lasers, and at shorter wavelengths, in the ultraviolet and X-ray range, from synchrotron sources and free-electron lasers. Recent progress in laser wakefield accelerators has resulted in electron beams with energies from tens of mega-electron volts (refs 5,6,7) to more than 1 GeV within a few centimetres, with pulse durations predicted to be several femtoseconds. The enormous progress in improving beam quality and stability makes them serious candidates for driving the next generation of ultracompact light sources. Here, we demonstrate the first successful combination of a laser-plasma wakefield accelerator, producing 55–75 MeV electron bunches, with an undulator to generate visible synchrotron radiation. By demonstrating the wavelength scaling with energy, and narrow-bandwidth spectra, we show the potential for ultracompact and versatile laser-based radiation sources from the infrared to X-ray energies.     «

Ultrashort light pulses are powerful tools for time-resolved studies of molecular and atomic dynamics. They arise in the visible and infrared range from femtosecond lasers, and at shorter wavelengths, in the ultraviolet and X-ray range, from synchrotron sources and free-electron lasers. Recent progress in laser wakefield accelerators has resulted in electron beams with energies from tens of mega-electron volts (refs 5,6,7) to more than 1 GeV within a few centimetres, with pulse durations predict...     »