Tungsten disulfide-gold nanohole hybrid metasurfaces for nonlinear metalens in the visible region

TL;DR

This paper introduces a novel nonlinear hybrid metasurface combining tungsten disulfide and gold nanoholes for efficient second-harmonic generation in the visible spectrum, enabling advanced nonlinear optical devices.

Contribution

It demonstrates the first visible-region nonlinear hybrid metasurface with significantly enhanced SHG efficiency using WS2 and gold nanoholes, and fabricates nonlinear metalenses for beam manipulation.

Findings

Achieved large SHG susceptibility (~0.1 nm/V) at 810 nm.

Demonstrated nonlinear metalenses with focal lengths of 30, 50, and 100 μm.

Showed potential for integrated nonlinear optical devices.

Abstract

Recently, nonlinear hybrid metasurface comes into an attractive new concept in the research of nanophotonics and nanotechnology. It is composed of semiconductors with an intrinsically large nonlinear susceptibility and traditional plasmonic metasurfaces, offering opportunities for efficiently generating and manipulating nonlinear optical responses. A high second-harmonic generation (SHG) conversion efficiency has been demonstrated in the mid-infrared region by using multi-quantum-well (MQW) based plasmonic metasurfaces. However, it has yet to be demonstrated in the visible region. Here we present a new type of nonlinear hybrid metasurfaces for the visible region, which consists of a single layer of tungsten disulfide (WS2) and a phased gold nanohole array. The results indicate that a large SHG susceptibility of ~0.1 nm/V at 810 nm is achieved, which is 2~3 orders of magnitude larger than that of typical plasmonic metasurfaces. Nonlinear metalenses with the focal lengths of 30 {\mu}m, 50 {\mu}m and 100 {\mu}m are demonstrated experimentally, providing a direct evidence for both generating and manipulating SH signals based on the nonlinear hybrid metasurfaces. It shows great potential applications in designing of integrated, ultra-thin, compacted and efficient nonlinear optical devices, such as frequency converters, nonlinear holography and generation of nonlinear optical vortex beam.