Phase-matched nonlinear wave-mixing processes in XUV region with multicolor lasers

TL;DR

This paper experimentally investigates phase-matched nonlinear wave-mixing in the extreme ultraviolet region using multicolor lasers, revealing new spectral components and demonstrating control over mixing processes in krypton gas.

Contribution

It introduces experimental evidence of phase-matched wave-mixing in the XUV region with multicolor lasers, including the observation of new spectral components and analysis of phase-matching conditions.

Findings

Observation of new spectral components in XUV wave-mixing

Demonstration of phase-matched generation of mixing fields

Analysis of intensity and focus position effects on wave-mixing

Abstract

We report here experimental results of perturbative nonlinear optical wave-mixing processes in the extreme ultraviolet region by using two-color and three-color laser fields. Besides the usual odd-harmonic spectrum of high harmonic generation, new spectral components are observed when multiple incommensurate lasers (one driving plus one or two control field) interact with neutral krypton gas. To demonstrate the wave-mixing process underlying such an observation, we firstly couple the driving field with either the signal or the idler field of an optical parametric amplifier in the gaseous ensemble to generate certain mixing frequencies. The two control fields are then simultaneously combined with the driving field to produce broad and distinguishable mixing peaks that clearly reveal the contribution of each control laser. Finally, the variation of the intensity of the mixing waves with the intensity of each control field, the gas density, and the relative focus position is examined for signatures of phase-matched generation of the mixing fields in this spectral region.