A compact synchrotron radiation source driven by a laser-plasma wakefield accelerator

Ultrashort light pulses are powerful tools for time-resolved studies of molecular and atomic dynamics(1). They arise in the visible and infrared range from femtosecond lasers(2), and at shorter wavelengths, in the ultraviolet and X-ray range, from synchrotron sources' and free-electron lasers(3). Recent progress in laser wakefield accelerators has resulted in electron beams with energies from tens of mega-electron volts (refs 5-7) to more than 1 GeV within a few centimetres(4), with pulse durations predicted to be several femtoseconds(9). The enormous progress in improving beam quality and stability(5-8,10) makes them serious candidates for driving the next generation of ultracompact light sources(11). 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.