Quasi-phase matching and characterization of high-order harmonic generation in hollow waveguides using counterpropagating light.

Probe of high-order harmonic generation in a hollow waveguide geometry using counterpropagating light.

We use counterpropagating light to directly observe the coherent buildup of high harmonic generation in a hollow waveguide geometry. We measure, for the first time, coherence lengths for high photon energies that cannot be phase matched using conventional approaches. We also probe the transition through phase matching, the ionization level at which different harmonic orders are generated, and t...

High-order harmonic generation in crossed laser beams

We investigate laser high-order harmonic generation in the presence of interfering light. A relatively weak interfering pulse intersects the primary harmonic-generating laser pulse at the focus. The influence on the harmonic-generation process is studied at near-counterpropagating and at perpendicular angles. The interfering beam creates a standing intensity and phase modulation, which disrupts...

Quasi-phase-matching and dispersion characterization of harmonic generation in the perturbative regime using counterpropagating beams.

It is shown theoretically that second harmonic generation can be quasi-phase-matched by using a pump beam consisting of a forward propagating field and a counterpropagating pulse train. The counterpropagating setup can also be used for direct measurement of the coherence length of the nonlinear process which can determine the dispersion properties of the medium.

Phase Matching and Coherence of High-Order Harmonic Generation in Hollow Waveguides

Type-II quasi phase matching in periodically intermixed semiconductor superlattice waveguides.

Second-harmonic generation using the type-II polarization configuration is demonstrated in quasi-phase-matched GaAs radicalAlGaAs superlattice waveguides. Phase-matching wavelengths and conversion efficiencies were determined for several quasi-phase-matching periods using 1.9 ps pulses. Saturation effects at high input power were concluded to be the result of third-order nonlinear effects.