Quasi-phase Matched Harmonic Generation Research Articles

30 W all-fiber supercontinuum generation via graded-index multimode fiber pumped by picoseconds laser pulse

We demonstrated an over 30 W all-fiber supercontinuum source based on a four-mode graded-index multimode fiber (GIMF) pumped by around 5 picoseconds laser pulse. Following the evolution of the supercontinuum, it is reasonable to conclude that the discrete spectral peaks in the range 350–700 nm were generated owing to the geometric parametric instability effect and quasi-phase matched harmonic generation, whereas the radiation of dispersive waves, stimulated Raman scattering, and relative effects of optical soliton caused spectral broadening ranging from 700 nm to 1750 nm (and even to 2400 nm). Furthermore, the properties of the supercontinua generated in the four-mode GIMF and the 50/125 standard GIMF were experimentally compared. This comparison implied that the wavelengths radiated by the geometric parametric instability differed owing to different dispersion values. And the supercontinuum generated by the four-mode GIMF had a flatter spectral profile and a wider wavelength range.

High-order quasi-phase matching harmonic generation in two-dimensional nonlinear photonic crystal

The high-order collinear and non-collinear quasi-phase matching harmonic generations were realized in a two-dimensional periodically poled LiNbO3 wit h square lattice by tuning the input wavelength. The output spots lay at different symme tric positions with respect to the input beam of picosecond pulse, and the relat ive intensities of spots at certain wavelengths were measured. The high-order no nlinear harmonic processes were also realized by tuning the input angle. The exp erimental and theoretical results are in good agreement with each other. Our stu dies might be beneficial to the development of optics integration and compact de vices.

Dispersion-controlled hollow core fiber for phase matched harmonic generation

We describe theoretically the performance of a new design for quasi-phase matched harmonic generation in a gas medium. A hollow core fiber in which thick glass plates are periodically introduced allows good phase control of the fundamental light. The generated x-rays are transmitted throught small holes in the plates. An increase of the harmonic yield of up to three orders of magnitude is predicted as a result of the structure. This esign can be considered as a phase-locked travelling-wave x-ray laser.