Scalable, polarization-insensitive broadband nonlinear metasurfaces for weak-light applications

Area of Science:

• Nanophotonics
• Materials Science
• Nonlinear Optics

Background:

• Metasurfaces offer unique light manipulation capabilities.
• Indium tin oxide (ITO) is a transparent conductive oxide with potential for nonlinear applications.
• Disordered silver nanoparticles (DSNPs) can enhance light-matter interactions through plasmonic effects.

Purpose of the Study:

• To develop an ITO-based metasurface integrated with DSNPs.
• To investigate the nonlinear optical properties of the developed metasurface.
• To demonstrate its potential for low-power, high-integration-density nanophotonic devices.

Main Methods:

• Fabrication of an ultrathin metasurface (∼35 nm) comprising ITO and DSNPs.
• Characterization of localized plasmon resonance coupling between DSNPs and the ITO layer.
• Measurement of nonlinear optical responses across the visible-to-near-infrared spectrum.

Main Results:

• The DSNPs coupled and confined incident light within the ITO layer, inducing strong nonlinear responses.
• Minimal polarization dependence (<15% fluctuation) was observed across a broad spectrum.
• A high nonlinear refractive index (>0.1 cm²/GW, max 1.24 cm²/GW) was achieved at a low pump intensity (0.2 GW/cm²).

Conclusions:

• The developed ITO-based metasurface with DSNPs enables efficient nonlinear light-matter interactions.
• This technology offers a promising solution for low-power, high-integration-density nonlinear nanophotonic devices.
• It paves the way for advanced all-optical control applications.