Resonantly tunable second harmonic generation from lithium niobate metasurfaces

TL;DR

This paper demonstrates lithium niobate metasurfaces with tunable second harmonic generation, achieving enhanced efficiency at Mie-resonances and enabling flexible, compact nonlinear light sources for applications like biosensing and optical communications.

Contribution

It introduces experimentally tunable lithium niobate metasurfaces that control SHG efficiency via geometric parameters, a novel approach for nonlinear light source development.

Findings

SHG efficiency is enhanced at Mie-resonances.

Resonance tuning allows selective wavelength boosting.

Potential applications in biosensing and optical communications.

Abstract

Second harmonic generation (SHG) is a coherent nonlinear phenomenon that plays an important role in laser color conversion. Lithium niobate (LN), which features both a large band gap and outstanding second-order nonlinearities, acts as an important optical material for nonlinear frequency conversion covering a wide spectral range from ultraviolet to mid-infrared. Here we experimentally demonstrate LN metasurfaces with controllable SHG properties. Distinct enhancements for the SHG efficiency are observed at Mie-resonances. And by changing the geometric parameters thus the resonances of the metasurfaces, we manage to selectively boost the SHG efficiency at different wavelengths. Our results would pave a way for developing with high flexibility the novel compact nonlinear light sources for applications, such as biosensing and optical communications.