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Nonlinear Thermoplasmonics in Graphene Nanostructures.
Line Jelver1, Joel D Cox1,2
1POLIMA─Center for Polariton-driven Light-Matter Interactions, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark.
Nano Letters
|October 17, 2024
Summary
Researchers activated thermoplasmons in narrow graphene nanoribbons using moderate energy. This enables significant nonlinear optical effects like third-harmonic generation and optical Kerr nonlinearities in the mid- and near-infrared spectrum.
Area of Science:
- * Condensed matter physics
- * Plasmonics
- * Nonlinear optics
Background:
- * Graphene's linear electronic dispersion provides significant intrinsic optical nonlinearity.
- * Graphene nanostructures enhance nonlinear optical phenomena via plasmons.
- * Achieving mid- and near-infrared resonances requires nanoscale patterning (~10 nm), where quantum finite-size effects are critical.
Purpose of the Study:
- * To investigate the activation of thermoplasmons in narrow graphene nanoribbons.
- * To explore the potential for driving nonlinear optical effects using photothermal excitation.
- * To assess the feasibility of avoiding electrical gating or high doping levels for nonlinear plasmonics.
Main Methods:
- * Fabrication of narrow graphene nanoribbons.
- * Excitation of thermoplasmons using ultrashort optical pulses.
- * Measurement of third-harmonic generation and optical Kerr nonlinearities.
Main Results:
- * Thermoplasmons were successfully activated in narrow graphene nanoribbons at mid- and near-infrared frequencies with moderate absorbed energy.
- * Substantial third-harmonic generation and optical Kerr nonlinearities were observed.
- * Photothermal excitation proved effective in driving these nonlinear plasmonic phenomena.
Conclusions:
- * Photothermal excitation is a viable method for activating nonlinear plasmonic phenomena in nanostructured graphene.
- * This approach bypasses the need for invasive electrical gating or excessive charge carrier doping.
- * The findings pave the way for practical applications of nonlinear plasmonics in graphene at technologically relevant IR frequencies.
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