Abstract

In order to improve high-harmonic generation efficiency, both reduction of the macroscopic phase mismatching between the pump and harmonic waves and increase of interaction length are crucial¹. We have found that the phase matching can be achieved using hollow fiber by examining third-harmonic generation in a hollow fiber in room air². The phase matching mechanism in the fiber is that a nonlinear refractive index change for the fundamental pulse compensates a dispersion induced by a free electrons. Also demonstrated was that a beam quality of the third harmonic was nearly single mode when it converted in a hollow fiber.

© 1998 IEEE