Space and time-varying electromagnetic structures give access to regimes of operation and effects that ordinarily do not occur in their time-invariant counterparts due to modal orthogonality constraints. Here, we present the theory of intermodal energy transfer in time-varying plasmonic structures. After identifying a suitable physical mechanism of permittivity modulation, we introduce an appropriate time-domain formalism to study the evolution of the dielectric polarization density in the system. Using a perturbative approach, we obtain closed-form solutions describing the intermodal energy transfer between a directly excited dipolar mode and a higher order subradiant mode. We further show that the modal amplitudes reach a steady state and determine the optimal modulation conditions that maximize the amplitude of the high-order mode. Finally, we identify a coherent control strategy to enhance the conversion efficiency to higher order modes.
Intermodal excitation in time-varying plasmonic structures
Note: This paper is part of the APL Special Collection on Time Modulated Metamaterials.
R. S. Rafi, S. Fardad, A. Salandrino; Intermodal excitation in time-varying plasmonic structures. Appl. Phys. Lett. 23 January 2023; 122 (4): 041701. https://doi.org/10.1063/5.0132243
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