High-energy ultrashort laser pulse compression in hollow planar waveguides

Abstract

We demonstrate compression of high energy ultrashort laser pulses by nonlinear propagation inside gas-filled planar hollow waveguides. We adjust the input beam size along the non-guiding dimension of the planar waveguide to restrain the intensity below photoionization, while the relatively long range guided propagation yields significant selfphase modulation (SPM) and spectral broadening. We compare the compression in different noble gases and obtain 13.6 fs duration with output pulse energy of 8.1 millijoule (mJ) in argon, and 11.5 fs duration with 7.6 mJ energy in krypton. The broadened spectra at the output of the waveguide are uniform over more than 70 % of the total pulse energy. Shorter duration could be obtained at the expense of introduction of spatial structure in the beam (and eventual formation of filaments) resulting from small-scale self focusing in the non-guided direction. OCIS codes: 320.5520, 320.7110 The advent of high energy laser pulses with durations of few optical cycles provided scientists with very high electric fields, sufficient to suppress the Coulomb potential in atoms, accelerate electrons up to keV energies and produce coherent intense UV and XUV radiation with duration