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Multipolar Effects in the Optical Active Second Harmonic Generation from Sawtooth Chiral Metamaterials
Huimin Su1,2, Yuxiang Guo1, Wensheng Gao1
1Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, P. R. China.
Scientific Reports
|February 26, 2016
Summary
Chiral nanostructures can amplify chiroptical effects beyond natural materials. This study reveals how multipolar interactions in sawtooth gratings enhance nonlinear optical activity, offering new pathways for giant chiroptical responses.
Area of Science:
- Plasmonics
- Metamaterials
- Nonlinear Optics
Background:
- Chiroptical effects are crucial for analyzing molecular chirality and controlling reactions.
- Chiral plasmonic metamaterials offer amplified chiroptical responses compared to natural materials.
- Current research often focuses on field enhancement, overlooking other factors for giant chiroptical effects.
Purpose of the Study:
- To investigate optical-active second harmonic generation (SHG) in chiral sawtooth gratings.
- To explore the role of multipolar effects in enhancing nonlinear optical activity.
- To identify novel strategies for achieving giant chiroptical responses in metamaterials.
Main Methods:
- Fabrication and optical characterization of planar sawtooth gratings with mirror-imaged patterns.
- Analysis of polarization-dependent second harmonic generation (SHG) curves.
- Theoretical investigation of electric-dipole and multipolar contributions to chiroptical effects.
Main Results:
- Observed significant multipolar effects in polarization-dependent SHG.
- Demonstrated that nanostructure chirality induces nonzero chiral susceptibility components.
- Showed that multipolar interactions differ for orthogonal circular polarizations, enhancing nonlinear optical activity.
Conclusions:
- Nanostructure chirality and multipolar interactions are key to giant chiroptical effects.
- Multipolar effects offer a novel route to optimize nonlinear plasmonic structures.
- This work provides new insights into achieving enhanced nonlinear optical activity and chiroptical responses.
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