A distant-neighbor quantum-mechanical method is used to study the nonlinear optical wave mixing in graphene nanoflakes(GNFs),including sum-and difference-frequency generation,as well as four-wave mixing.Our analysis s...A distant-neighbor quantum-mechanical method is used to study the nonlinear optical wave mixing in graphene nanoflakes(GNFs),including sum-and difference-frequency generation,as well as four-wave mixing.Our analysis shows that molecular-scale GNFs support quantum plasmons in the visible spectrum region,and significant enhancement of nonlinear optical wave mixing is achieved.Specifically,the second-and third-order wave-mixing polarizabilities of GNFs are dramatically enhanced,provided that one(or more) of the input or output frequencies coincide with a quantum plasmon resonance.Moreover,by embedding a cavity into hexagonal GNFs,we show that one can break the structural inversion symmetry and enable otherwise forbidden second-order wave mixing,which is found to be enhanced by the quantum plasmon resonance too.This study reveals that the molecular-sized graphene could be used in the quantum regime for nanoscale nonlinear optical devices and ultrasensitive molecular sensors.展开更多
We study the nonlinear optical properties of heterojunctions made of graphene nanoribbons(GNRs)consisting of two segments with either the same or different topological properties.By utilizing a quantum mechanical appr...We study the nonlinear optical properties of heterojunctions made of graphene nanoribbons(GNRs)consisting of two segments with either the same or different topological properties.By utilizing a quantum mechanical approach that incorporates distant-neighbor interactions,we demonstrate that the presence of topological interface states significantly enhances the second-and third-order nonlinear optical response of GNR heterojunctions that are created by merging two topologically inequivalent GNRs.Specifically,GNR heterojunctions with topological interface states display third-order harmonic hyperpolarizabilities that are more than two orders of magnitude larger than those of their similarly sized counterparts without topological interface states,whereas the second-order harmonic hyperpolarizabilities exhibit a more than ten-fold contrast between heterojunctions with and without topological interface states.Additionally,we find that the topological state at the interface between two topologically distinct GNRs can induce a noticeable red-shift of the quantum plasmon frequency of the heterojunctions.Our results reveal a general and profound connection between the existence of topological states and an enhanced nonlinear optical response of graphene nanostructures and possible other photonic systems.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11947007)the Natural Science Foundation of Guangdong Province,China(Grant No.2019A1515011499)the Department of Education of Guangdong Province,China(Grant No.2019KTSCX087)。
文摘A distant-neighbor quantum-mechanical method is used to study the nonlinear optical wave mixing in graphene nanoflakes(GNFs),including sum-and difference-frequency generation,as well as four-wave mixing.Our analysis shows that molecular-scale GNFs support quantum plasmons in the visible spectrum region,and significant enhancement of nonlinear optical wave mixing is achieved.Specifically,the second-and third-order wave-mixing polarizabilities of GNFs are dramatically enhanced,provided that one(or more) of the input or output frequencies coincide with a quantum plasmon resonance.Moreover,by embedding a cavity into hexagonal GNFs,we show that one can break the structural inversion symmetry and enable otherwise forbidden second-order wave mixing,which is found to be enhanced by the quantum plasmon resonance too.This study reveals that the molecular-sized graphene could be used in the quantum regime for nanoscale nonlinear optical devices and ultrasensitive molecular sensors.
基金funding provided by Shanghai Jiao Tong Universitysupported by the National Natural Science Foundation of China(Grant Nos.12104104,62175042)+5 种基金the Natural Science Foundation of Guangdong Province(Grant No.2019A1515011499)the Department of Education of Guangdong Province(Grant No.2019KTSCX087)the Start-up Funding of Guangdong Polytechnic Normal University(Grant No.2021SDKYA165)the Guangdong Department of Education Projects of Improving Scientific Research Capabilities of Key Subjects Construction(Grant No.2022ZDJS016)the European Research Council(ERCGrant No.ERC-2014-CoG-648328).
文摘We study the nonlinear optical properties of heterojunctions made of graphene nanoribbons(GNRs)consisting of two segments with either the same or different topological properties.By utilizing a quantum mechanical approach that incorporates distant-neighbor interactions,we demonstrate that the presence of topological interface states significantly enhances the second-and third-order nonlinear optical response of GNR heterojunctions that are created by merging two topologically inequivalent GNRs.Specifically,GNR heterojunctions with topological interface states display third-order harmonic hyperpolarizabilities that are more than two orders of magnitude larger than those of their similarly sized counterparts without topological interface states,whereas the second-order harmonic hyperpolarizabilities exhibit a more than ten-fold contrast between heterojunctions with and without topological interface states.Additionally,we find that the topological state at the interface between two topologically distinct GNRs can induce a noticeable red-shift of the quantum plasmon frequency of the heterojunctions.Our results reveal a general and profound connection between the existence of topological states and an enhanced nonlinear optical response of graphene nanostructures and possible other photonic systems.
