What is Active Plasmonics?
Plasmonics
Plasmon is a collective oscillation of electrons in the metal in response to an incident electromagnetic wave and have received great attention due to their remarkable proficiency in modulating electromagnetic waves. Surface Plasmon Polariton (SPP) emerges at the metal-dielectric interface, propagating along this boundary, while Localized Surface Plasmon (LSP) arises through the interplay of electromagnetic waves with sub-wavelength-sized metallic features. In principle, plasmon resonance could be tuned if there are changes in (1) geometry, (2) surroundings, and (3) carrier density. However, pragmatic applications have been restricted because of the daunting challenge of the adaptively manipulating optical properties of plasmonic materials.
Active Plasmonics
Active plasmonics is a promising and challenging field that aims for utilizing plasmonic materials in materials and devices through providing active functionality. For example, electrochemistry offers an exquisite avenue to exploit active functionality (1) through (3) by inducing both chemical and electrical stimuli in a controlled way. Other stimulies, such as heat, mechanical, electric field, magnetic field, and etc, also could be considerd as a stimuli. Active electrochemical plasmonic is one of the potent methodologies to drive the active functionality toward next generation plasmonic materials.
FDTD (Finite-difference time-domain) Electromagnetic Simulations
According to the Faraday's and Ampere's law, change of electric field induces magnetic field change and vice versa. Therefore, electromagnetic property of plasmonic material can be anticipitated or analyzed using appropriate approximations (mainly, update equation and time discretization). Electric & magnetic field profile, transmission, reflection, absorption, scattering, and etc. can be obtained from the simulation.
Combination with Photonic Nanostructures
Plasmonic property of nanostructure could be enhanced by combining with photonic structures. Representatively, six photonic structures are mainly considered, That is scatters, photonic crystals, multillayer film, Fabry-Perot cavity, dielectric/metallic metasurface, and diffractive surface.
