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A multi-mode super-fano mechanism for enhanced third harmonic generation in silicon metasurfaces
David Hähnel1, Christian Golla2, Maximilian Albert3
1Theoretical Electrical Engineering & CeOPP, Paderborn University, 33098, Paderborn, Germany. hdavid@mail.upb.de.
Light, Science & Applications
|April 20, 2023
Summary
Researchers achieved significant third harmonic generation enhancement using amorphous silicon metasurfaces. This breakthrough stems from a novel multi-mode Fano resonance, enabling high nonlinear optical performance for future applications.
Area of Science:
- Photonics and Nanotechnology
- Nonlinear Optics
- Materials Science
Background:
- Metasurfaces offer tunable optical properties.
- Third harmonic generation (THG) is crucial for frequency conversion.
- Fano resonances in nanostructures can enhance nonlinear optical effects.
Purpose of the Study:
- To investigate and demonstrate strong enhancement of third harmonic generation (THG) in amorphous silicon metasurfaces.
- To identify and characterize the underlying physical mechanism responsible for the enhanced THG.
- To experimentally validate the theoretical predictions and quantify the nonlinear performance.
Main Methods:
- Fabrication of amorphous silicon metasurfaces with elliptical nano resonators.
- Numerical simulations using full-wave electromagnetic solvers to study Fano resonances.
- Linear and nonlinear transmission spectroscopy for experimental verification.
- Quantitative nonlinear optical measurements to determine conversion efficiency.
Main Results:
- Observed strong enhancement of third harmonic generation (THG) in the amorphous silicon metasurface.
- Identified a novel multi-mode Fano mechanism, termed 'Super-Fano' resonances, responsible for the enhancement.
- Experimentally verified the predicted behavior and achieved a maximum absolute conversion efficiency of approximately 2.8 x 10-7.
- Demonstrated amplification factors up to ~900 compared to an unpatterned silicon film.
Conclusions:
- Amorphous silicon metasurfaces with elliptical nano resonators exhibit significantly enhanced THG.
- The 'Super-Fano' resonance mechanism provides a pathway for efficient nonlinear frequency conversion.
- These findings open possibilities for advanced photonic devices utilizing strong Fano-type multi-mode coupling.
