Ultrashort pulse driven optical-field-ionization x-ray lasers

摘要

Efficient optical-field-ionization x-ray lasers driven by femtosecond laser pulses have been demonstrated in clustered gas jets. With a tight focusing configuration, near saturation outputs of Pd-like xenon laser at 41.8 nm and Ni-like krypton laser at 32.8 nm are generated at low pump energy of 200 mJ. By using the axicon-ignitor-heater scheme to produce a 9-mm-long plasma waveguide in a pure krypton gas jet, the lasing photon number of Ni-like Kr laser at 32.8 nm is dramatically enhanced by about three orders of magnitude in comparison to that without plasma waveguide, resulting in a photon number of 8×10~(10) and an energy conversion efficiency of 2×10~(-6) with a pump pulse of just 235 mJ. Besides for producing various OFI collisional-excitation x-ray lasers of sufficient photon number for practical applications, an optically-preformed plasma waveguide may also be a favorable choice for achieving OFI recombination x-ray lasers and inner-shell x-ray lasers.