Dark and bright modes, and their coherent control in dipolar metasurface bilayers

Several plasmonic nanoparticles supporting dipolar resonances can couple to form normal modes. Here, we develop an analytical model to explain the formation of nonradiative dark and radiative bright modes through radiative coupling in bilayers consisting of dipolar nanoantenna arrays that are separated by a subwavelength distance. We also include near-field contributions in our model and show that the absorption and reflectance spectra obtained from our model agree reasonably well with the respective finite-difference time-domain simu-lation results for both perfectly aligned and misaligned bilayers. The ability to vary the reflection and absorption spectra of these bilayers by changing the material and geometrical parameters has potential applications in the design of efficient spectral filters. We also show that we can selectively excite these modes by adjusting the phase between two counterpropagating normally incident fields, which has applications in all-optical modulators and switches based on purely linear interferometric effects.

Automated summary

Several plasmonic nanoparticles can couple to form nonradiative dark and radiative bright modes through radiative coupling. We develop an analytical model to explain the formation of these modes in bilayers consisting of dipolar nanoantenna arrays. Our model includes near-field contributions and shows good agreement with finite-difference time-domain simulation results. Changing the material and geometrical parameters can vary the reflection and absorption spectra of the bilayers, making them useful for designing efficient spectral filters. By adjusting the phase between two counterpropagating normally incident fields, we can selectively excite these modes, which has applications in all-optical modulators and switches based on linear interferometric effects.