Abstract: A cryogenic cooling apparatus for high average power laser oscillator or amplifier, wherein the oscillator or amplifier material is in direct contact with a flowing cryogenic liquid cooled to below its boiling point is described. This method of cooling overcomes the limit in heat flux due to the onset of film boiling, thereby allowing for increased laser average power.

Abstract: A pre-ionized medium created by a capillary discharge results in more efficient use of laser energy in high-order harmonic generation (HHG) from ions. It extends the cutoff photon energy, and reduces the distortion of the laser pulse as it propagates down the waveguide. The observed enhancements result from a combination of reduced ionization energy loss and reduced ionization-induced defocusing of the driving laser as well as waveguiding of the driving laser pulse. The discharge plasma also provides a means to spectrally tune the harmonics by tailoring the initial level of ionization of the medium.

Abstract: An extreme ultraviolet/soft x-ray laser driven by a compact solid-state chirped pulse amplification laser system entirely pumped by laser diodes is described. The solid-state pump laser generates compressed pulses of sub-10 ps duration with energy greater than 1 J at a chosen repetition rate in a cryogenically cooled Yb:YAG system. Lasing in the 18.9 nm line of Ni-like Mo was observed. The diode-pumped laser has the potential to greatly increase the repetition rate and average power of lasers having a variety of EUV/SXR wavelengths on a significantly smaller footprint.