Full-color enhanced second harmonic generation using rainbow trapping in ultrathin hyperbolic metamaterials

Area of Science:

• Nonlinear Optics
• Metamaterials Science
• Nanophotonics

Background:

• Metasurfaces offer subwavelength nonlinearity enhancement but are limited by narrow bandwidths due to sharp resonant features.
• Hyperbolic metamaterials show potential for enhanced light-matter interactions.

Purpose of the Study:

• To achieve broadband enhanced second-harmonic generation (SHG) in metasurfaces.
• To overcome the conventional bandwidth limitations in nonlinear optical devices.

Main Methods:

• Fabrication of a nanostructured gold/zinc oxide (Au/ZnO) multilayer.
• Utilizing nanopatterning to access modes with large momentum for light trapping.
• Investigating nonlinear light-matter interactions in the visible spectrum.

Main Results:

• Demonstrated broadband enhanced second-harmonic generation (SHG) in the visible range (400-650 nm).
• Achieved an enhancement factor over 50 within the 470-650 nm wavelength range.
• Obtained a maximum SHG conversion efficiency of 1.13×10^-6 at 8.80 mW pump power.

Conclusions:

• Nanopatterned hyperbolic metamaterials enable broadband enhanced nonlinearities.
• This approach provides an effective and robust method for developing broadband nonlinear optical devices.
• The findings pave the way for advanced photonic technologies utilizing enhanced nonlinear light-matter interactions.