The Shanghai Deep Ultraviolet Free-Electron Laser (SDUV-FEL) reaches saturation with High-Gain Harmonic-Generation (HGHG) scheme in mid-December, 2010.

FEL may currently emit ultra high brightness X-rays through Self-Amplified Spontaneous Emission (SASE) or HGHG. The latter, though technically more complicated, shows better performance especially on temporal coherence than the former.

Recognized as one potential candidate for the next generation high-brightness x-ray sources, HGHG based FEL attracts more and more attentions internationally. The saturation of HGHG-based SDUV-FEL makes China the second country that has mastered this technique in the world after the United States.

The SDUV-FEL project was proposed by Shanghai Institute of Applied Physics, National Synchrotron Radiation Laboratory, and Institute of High Energy Physics in 1998. It has achieved a lot after a series of experiments, among which SASE was first observed in later 2009, seeded FEL experiment began in early 2010 and the first echo signal from echo-enabled harmonic generation was observed in May 2010.