Second harmonic generation in nano-structured thin-film lithium niobate waveguides

TL;DR

This paper demonstrates efficient second harmonic generation in nano-structured thin-film lithium niobate waveguides, achieving high conversion efficiency through modal and quasi-phase matching techniques.

Contribution

It introduces a novel integrated platform with lithographically-defined waveguides that enable high-efficiency wavelength conversion.

Findings

Achieved normalized conversion efficiencies up to 41% W-1cm-2.

Demonstrated both modal phase matching and quasi-phase matching.

Low propagation loss of approximately 3.0 dB/cm.

Abstract

Integrated thin-film lithium niobate platform has recently emerged as a promising candidate for next-generation, high-efficiency wavelength conversion systems that allow dense packaging and mass-production. Here we demonstrate efficient, phase-matched second harmonic generation in lithographically-defined thin-film lithium niobate waveguides with sub-micron dimensions. Both modal phase matching in fixed-width waveguides and quasi-phase matching in periodically grooved waveguides are theoretically proposed and experimentally demonstrated. Our low-loss (~ 3.0 dB/cm) nanowaveguides possess normalized conversion efficiencies as high as 41% W-1cm-2.