Optical Response of Hybrid Plasmon–Exciton Nanomaterials in the Presence of Overlapping Resonances

J. Phys.: Condens. Matter

Nitzan

2017

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This review provides a brief introduction to the physics of coupled exciton-plasmon systems, the theoretical description and experimental manifestation of such phenomena, followed by an account of the state-of-the-art methodology for the numerical simulations of such phenomena and supplemented by a number of FORTRAN codes, by which the interested reader can introduce himself/herself to the practice of such simulations. Applications to CW light scattering as well as transient response and relaxation are described. Particular attention is given to so-called strong coupling limit, where the hybrid exciton-plasmon nature of the system response is strongly expressed. While traditional descriptions of such phenomena usually rely on analysis of the electromagnetic response of inhomogeneous dielectric environments that individually support plasmon and exciton excitations, here we explore also the consequences of a more detailed description of the molecular environment in terms of its quantum density matrix (applied in a mean field approximation level). Such a description makes it possible to account for characteristics that cannot be described by the dielectric response model: the effects of dephasing on the molecular response on one hand, and nonlinear response on the other. It also highlights the still missing important ingredients in the numerical approach, in particular its limitation to a classical description of the radiation field and its reliance on a mean field description of the many-body molecular system. We end our review with an outlook to the near future, where these limitations will be addressed and new novel applications of the numerical approach will be pursued.

Section: Nonlinear Molecular Plasmonicsmentioning

confidence: 99%

Optics of exciton-plasmon nanomaterials

J. Phys.: Condens. Matter

Nitzan

2017

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“…This makes it possible to address the regime of strong exciton-plasmon coupling, where the molecular species does not only modify the plasmon-plasmon coupling but becomes an active component of the transmitting system. We note in passing that the latter procedure can also describe the molecular system in the non-linear response regime [79][80][81][82], although we do not address this regime in the present study.…”

Section: Introductionmentioning

confidence: 95%

Plasmon transmission through excitonic subwavelength gaps

The Journal of Chemical Physics

Nitzan

2016

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We study the transfer of electromagnetic energy across a subwavelength gap separating two coaxial metal nanorodes. The absence of spacer in the gap separating the rods the system exhibits the strong coupling between longitudinal plasmons in the two rods. The nature and magnitude of this coupling is studied by varying various geometrical parameters. When the length of one rod is varied this mode spectrum exhibits the familiar anti-crossing behavior that depends on the coupling strength determined by the gap width. As a function of frequency the transmission is dominated by a splitted longitudinal plasmon peak. The two hybrid modes are the dipole-like "bonding" mode characterized by a peak intensity in the gap, and a quadrupole-like "antibonding" mode whose amplitude vanishes at the gap center. When off-resonant 2−level emitters are placed in the gap, almost no effect on the frequency dependent transmission is observed. In contrast, when the molecular system is resonant with the plasmonic lineshape, the transmission is strongly modified, showing characteristics of strong exciton-plasmon coupling, modifying mostly the transmission near the lower frequency "bonding" plasmon mode. The presence of resonant molecules in the gap affects not only the molecule-field interaction but also the spatial distribution of the field intensity and the electromagnetic energy flux across the junction.

“…15 Various research groups investigated how such systems respond to external intense probes assuming that molecules are the main source of the nonlinear response. [16][17][18][19][20][21] One may note, however, that combining the nonlinear response of metal with that of molecules in the strong coupling regime obviously requires treating both subsystems on equal footing.…”

Section: Introductionmentioning

confidence: 99%

Plasmon enhanced second harmonic generation by periodic arrays of triangular nanoholes coupled to quantum emitters

Drobnyh

The Journal of Chemical Physics

2020

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Linear and nonlinear optical response of periodic arrays of nanoholes of triangular shape is examined using experimentally realizable parameters. Utilizing a three dimensional fully vectorial approach based on the nonlinear hydrodynamic Drude model describing metal coupled to Maxwell's equations and Bloch equations for molecular emitters we analyze linear transmission, reflection, and nonlinear power spectra. Three lowest energy electromagnetic modes are identified as a localized surface plasmon, a first order Bragg plasmon, and a guiding mode. When molecules are resonant with the Bragg plasmon the Rabi splitting of 138 meV is observed. We observe the blue shift of linear absorption, which is associated with the strong molecules-plasmon coupling. Rigorous numerical calculations demonstrating second and third harmonic generation by the triangular hole arrays are performed. It is shown that both the Coulomb interaction of conduction electrons and the convective term contribute on equal footing to the nonlinear response of metal.When molecular emitters are placed on a surface of hole arrays calculated second harmonic response exhibits three peaks corresponding to second harmonics of hybrid exciton-plasmon states.