Phase-matched high-order harmonic generation in a semi-infinite gas cell with absorbing gaseous media

We experimentally study the pressure dependent high-order harmonic generation in a semi-infinite gas cell with different absorbing gaseous media in order to reveal the influence of absorption in the high harmonic generation (HHG) process. Theoretical fits to the experimental results allow us to measure the absorption cross-section of the harmonics and to investigate the pressure independent phase mismatches. Our findings provide a better understanding about HHG in absorbing media and show that a sharp and intense harmonic spectrum can be generated as phase-matched and absorption-limited in a long interaction length geometry