Harmonic Generation Via χ3Intermodal Phase Matching in Microfibers

Voltage-controlled phase matching in quadrupole second-harmonic generation.

We have observed strong phase-matched (PM) quadrupole optical second-harmonic generation (SHG) from nematic liquid crystals that possess inversion symmetry. PM conditions were achieved for two configurations by voltage control of the molecular orientation and thus of the refractive indices. Quadrupole SHG was separated from electric-field-induced dipole-type SHG with the help of time-gated meas...

Intensity-dependent phase-matching effects in harmonic generation

In high-order harmonic generation by an intense laser, intrinsic phases can develop at the atomic level between the laser field and the individual emitted harmonics. Because intrinsic phases can vary rapidly with the laser intensity, they can strongly influence phase matching to the extent that the laser intensity varies within the generating medium. Previously reported measurements of broad fa...

Collinear phase matching for second harmonic generation using conoscopic interferometry

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

We review recent experimental and theoretical work on the use of counterpropagating light to enhance high-order harmonic generation through all-optical quasi-phase matching. Also presented is a new technique for measuring the coherence of high harmonics in the nonlinear medium. This information is crucial for understanding the process of harmonic generation over extended distances, as well as f...

Non-critical phase-matching fourth harmonic generation of a 1053-nm laser in an ADP crystal

In current inertial confinement fusion (ICF) facilities, KDP and DKDP crystals are the second harmonic generation (SHG) and third harmonic generation (THG) materials for the Nd:glass laser (1053 nm). Based on the trend for the development of short wavelengths for ICF driving lasers, technical solutions for fourth harmonic generation (FHG) will undoubtedly attract more and more attention. In thi...