Phase-matched high-order harmonic generation of soft and hard X-rays is accomplished using infrared driving lasers in a high-pressure non-linear medium. The pressure of the non-linear medium is increased to multi-atmospheres and a mid-IR (or higher) laser device provides the driving pulse. Based on this scaling, also a general method for global optimization of the flux of phase-matched high-order harmonic generation at a desired wavelength is designed.
This invention was made with government support under grant number DE-FG02-04ER15592 awarded by the Department of Energy and grant number EEC 0310717 awarded by the National Science Foundation. The government has certain rights in the invention.