High system efficiency nonlinear frequency conversion on thin-film lithium niobate

TL;DR

This paper demonstrates a highly efficient integrated thin-film lithium niobate frequency converter with a record conversion efficiency of 152%/W, achieved through innovative waveguide and coupler design, promising scalable photonic devices.

Contribution

The work introduces a novel combination of periodically poled waveguides and laser-written out-of-plane couplers for high-efficiency nonlinear frequency conversion.

Findings

Achieved 152%/W conversion efficiency including losses

Demonstrated scalable integrated photonic device approach

Enhanced light confinement improves nonlinear process efficiency

Abstract

Integrated photonic platforms can greatly enhance the efficiency of nonlinear frequency conversion processes by tightly confining light on a sub-micron scale. However, this advantage is often reduced by large fiber-to-chip coupling losses which drastically reduce the overall performance. Here we demonstrate a highly efficient thin-film lithium niobate frequency converter based on periodically poled waveguides combined with direct laser written out-of-plane couplers. Including on-chip and fiber-to-chip losses we obtain a conversion efficiency of 152 %/W, thus demonstrating a promising approach for future scalable integrated devices.