Polarization conversion in plasmonic nanoantennas for metasurfaces using structural asymmetry and mode hybridization

Peter Wiecha (1) , Leo-Jay Black (2, 3) , Yudong Wang (2) , Vincent Paillard (1) , Christian Girard (1) , Otto L. Muskens (2) , Arnaud Arbouet (1)

1 CEMES-NeO - Nano-Optique et Nanomatériaux pour l'optique
2 University of Southampton
3 CEMES - Centre d'élaboration de matériaux et d'études structurales

Polarization control using single plasmonic nanoantennas is of interest for subwavelength optical components in nano-optical circuits and metasurfaces. Here, we investigate the role of two mechanisms for polarization conversion by plasmonic antennas: Structural asymmetry and plasmon hybridization through strong coupling. As a model system we investigate L-shaped antennas consisting of two orthogonal nanorods which lengths and coupling strength can be independently controlled. An analytical model based on field susceptibilities is developed to extract key parameters and to address the influence of antenna morphology and excitation wavelength on polarization conversion efficiency and scattering intensities. Optical spectroscopy experiments performed on individual antennas, further supported by electrodynamical simulations based on the Green Dyadic Method, confirm the trends extracted from the analytical model. Mode hybridization and structural asymmetry allow addressing different input polarizations and wavelengths, providing additional degrees of freedom for agile polarization conversion in nanophotonic devices.

Mots clés: birefringence; scattering; assemblies; nanoparticles; arrays; spectroscopy; resonances; light; antenna; side

Domaines: Matière Condensée [cond-mat]; Optique [physics.optics]

Peter Wiecha, Leo-Jay Black, Yudong Wang, Vincent Paillard, Christian Girard, et al.. Polarization conversion in plasmonic nanoantennas for metasurfaces using structural asymmetry and mode hybridization. Scientific Reports, 2017, 7 (1), pp.40906. ⟨10.1038/srep40906⟩. ⟨hal-01739803⟩