Pulse propagation in hollow-core fiber at high-pressure regime: application to compression of tens of μJ pulses and determination of nonlinear refractive index of xenon at 103 μm

Abstract

Classical expression for the propagation constant and absorption coefficient derived by Narcatilli and Schmeltzer for hollow-core fiber (HCF) has been slightly modified to account for noble gas material dispersion at high gas pressure. As a proof of concept, the nonlinear refractive index of xenon (Xe) gas has been investigated by numerically fitting to experimentally obtained spectral broadening in HCF under intense high repetition rate pulses. By varying the Xe pressure inside the HCF, a pressure-dependent nonlinear refractive index value of κ₂=(50.1±0.3)×10^-20 cm²/W atm at 1.03 μm is obtained, which compares favorably with literature reported values. Finally, temporal compression of 50 μJ, 320 fs pulses at 0.6 MHz repetition rate to 61 fs with 0.29 GW peak power in a HCF filled with 5 bars of Xe gas has been demonstrated using a single HCF compression stage.