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Second harmonic generation from gold meta-molecules with three-fold symmetry
Renjie Hou1, Vasyl Shynkar2, Clément Lafargue2
1Department of Chemistry, Department of Physics and Astronomy, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 5B7, Canada. flagugne@uwo.ca.
Physical Chemistry Chemical Physics : PCCP
|March 10, 2016
Summary
Metallic nanostructures exhibit unique optical properties for advanced applications. This study details their nonlinear optical behavior, focusing on second-harmonic generation microscopy and electromagnetic field modeling.
Area of Science:
- Nanophotonics and Plasmonics
- Nonlinear Optics
- Materials Science
Background:
- Metallic nanoparticle arrays possess unique optical properties valuable for data storage, sensing, and optoelectronics.
- Nonlinear optical phenomena can be significantly modified by metallic nanostructures, enabling novel applications.
- Understanding these properties is crucial for advancing spectroscopic techniques and device performance.
Purpose of the Study:
- To design and fabricate gold nanostructures with specific symmetry for nonlinear optical investigations.
- To explore the nonlinear optical properties, particularly second-harmonic generation (SHG), of these nanostructures.
- To correlate SHG signals with the structural symmetry and electromagnetic field distribution.
Main Methods:
- Fabrication of non-centrosymmetric gold nanostructures using electron beam lithography.
- Investigation of nonlinear optical properties using second-harmonic generation microscopy (SHGM) with femtosecond laser excitation.
- Electromagnetic field modeling via the Finite Difference Time Domain (FDTD) method.
- Polarization-resolved measurements and lifetime measurements to distinguish SHG from two-photon induced photoluminescence (TPPL).
Main Results:
- Successfully designed and fabricated gold nanostructures with three-fold axial symmetry.
- Observed and characterized second-harmonic generation (SHG) signals, demonstrating confinement and polarization dependence.
- FDTD modeling accurately predicted electromagnetic field distribution and SHG signal behavior.
- Distinguished SHG from TPPL through lifetime measurements, confirming the dominance of nonlinear optical effects.
Conclusions:
- Engineered metallic nanostructures exhibit tunable nonlinear optical responses.
- SHG microscopy combined with FDTD modeling provides a powerful tool for characterizing nanostructure optical properties.
- These findings pave the way for enhanced spectroscopic measurements and novel optoelectronic devices.
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