Generation of light with controllable spatial patterns via the sum frequency in quasi-phase matching crystals

TL;DR

This paper demonstrates a novel method to generate light beams with controllable complex spatial patterns using sum frequency generation in quasi-phase matching crystals, with potential applications in advanced optical technologies.

Contribution

It introduces a new approach to produce and control complex light spatial structures via crystal phase mismatching in SFG, supported by experimental and numerical validation.

Findings

Controllable multi-ring Bessel-Gaussian beams created

Donut-like Laguerre-Gaussian beams generated

Spatial structures tuned by pump frequency and temperature

Abstract

Light beams with extraordinary spatial structures, such as the Airy beam (AB), the Bessel-Gaussian beam (BGB) and the Laguerre-Gaussian beam (LGB), are widely studied and applied in many optical scenarios. We report on preparation of light beams with controllable spatial structures through sum frequency generation (SFG) using two Gaussian pump beams in a quasi-phase matching (QPM) crystal. The spatial structures, including multi-ring-like BGB, donut-like LGB, and super-Gaussian-like beams, can be controlled periodically via crystal phase mismatching by tuning the pump frequency or crystal temperature. This phenomenon has not been reported or discussed previously. Additionally, we present numerical simulations of the phenomenon, which agree very well with the experimental observations. Our findings give further insight into the SFG process in QPM crystals, provide a new way to generate light with unusual spatial structures, and may find applications in the fields of laser optics, all-optical switching, and optical manipulation and trapping.