Laser-driven parametric amplification of soft X-rays

For time-resolved spectroscopy, ultra-short pulses can be directly generated with lasers and the wavelength range can be extended with nonlinear frequency conversion techniques. For covering the shorter wavelength range, XFEL's and plasma based x-ray lasers are attractive candidates. However their stability, coherence and beam quality is limited and can be improved e.g. by seeding with coherent high harmonic radiation [1]. Another route is the nonlinear frequency conversion of laser pulses into the XUV range by high order harmonic generation resulting very short XUV or soft-x-ray pulses in a laser like beam. The major drawback of high harmonics is their low conversion efficiency.