Quantum path interferences of high-order harmonic generation in two-color Gaussian beams

The phase matching of the quantum paths in high-order harmonic generation is investigated in two-color laser fields. The results show that the spatial distribution of the laser field is optimized by adjusting the laser beam waist, the phase-matching properties of the long trajectories can be modulated effectively, and then good phase matching for both the two paths can be achieved from on-axis region to off-axis region. A radial clear interference fringe induced by the well phase-matching of two paths can be observed by placing a near-field filter, which has great potential for distinguishing clearly different interference effects and observing higher order trajectories with improved detection sensitivity.