Third-harmonic generation of spatially structured light in a quasi-periodically poled crystal

TL;DR

This paper demonstrates third-harmonic generation of spatially structured light, including vector optical fields, in a quasi-periodically poled crystal, enabling new wavelength manipulation and potential quantum information applications.

Contribution

First experimental demonstration of third harmonic generation of vector optical fields in a quasi-periodically poled crystal, aligning with theoretical predictions.

Findings

Successful third harmonic generation of vector optical fields.

Good agreement between experimental results and theory.

Potential for generating higher orbital angular momentum photons.

Abstract

Nonlinear optical processes of spatially structured light, including optical vortex and vector optical fields, have stimulated a lot of interesting physical effects and found a variety of important applications ranging from optical imaging to quantum information processing. However, high harmonic generation of vector optical fields with space-varying polarization states is still a challenge. Here we demonstrate third harmonic generation of spatially structured light including vector optical fields, in a nonlinear Sagnac interferometer containing a carefully designed quasi-periodically poled potassium titanyl phosphate for the first time. The experimental results are in good agreement with the theoretical predictions. Our results will enable to manipulate spatially structured light or photons at new wavelengths and carrying higher orbital angular momentum. Our approach has the potential applications for the research of optical skyrmions and may open up new opportunities to produce spatially structured entangled photons for quantum communication and computation.