All-optical quasi-phase matching (QPM) uses a train of counterpropagating pulses to enhance high-order harmonic generation (HHG) in a hollow waveguide. A pump pulse enters one end of the waveguide, and causes HHG in the waveguide. The counterpropagation pulses enter the other end of the waveguide and interact with the pump pulses to cause QPM within the waveguide, enhancing the HHG.
The present invention was made with government support as follows, and the U.S. Government has certain rights in the invention.
National Science Foundation Cooperative Agreement No. EEC-0310717, "NSF Engineering Research Center in Extreme Ultraviolet Science and Technology."
Department of Energy, National Nuclear Security Administration, Grant No. DE-FG52-06NA26151, "Investigations of Laser Materials Interactions using Ultrafast Short-Wavelength Light."