High-order harmonic generation in a hollow fiber filled with a weakly ionizing gas is theoretically analyzed within the framework of the slowly varying envelope approximation. The gas pressure that corresponds to maximum efficiency of frequency conversion, the absorption coefficient, the phase mismatch owing to gas dispersion, and the enhancement of harmonic-generation efficiency owing to waveguide phase matching are estimated for 27th-harmonic generation in hollow fibers filled with helium, neon, argon, krypton, or xenon. As a result of the ionization-induced self-phase modulation of the pump pulse in a hollow fiber filled with a weakly ionizing gas, the phase mismatch changes within the pump pulse, decreasing the overall efficiency of harmonic generation and making the harmonic-generation efficiency less sensitive to the gas pressure in the hollow fiber.
© 2001 Optical Society of America
A. N. Naumov, A. M. Zheltikov, A. B. Fedotov, D. A. Sidorov-Biryukov, A. P. Tarasevitch, Ping Zhou, and D. von der Linde, "Pressure control of phase matching in high-order harmonic generation in hollow fibers filled with an absorbing weakly ionizing gas," J. Opt. Soc. Am. B 18, 811-817 (2001)