Strong, spectrally-tunable chirality in diffractive metasurfaces.
Metamaterials and metasurfaces provide a paradigm-changing approach for manipulating light. Their potential has been evinced by recent demonstrations of chiral responses much greater than those of natural materials. Here, we demonstrate theoretically and experimentally that the extrinsic chiral response of a metasurface can be dramatically enhanced by near-field diffraction effects. At the core of this phenomenon are lattice plasmon modes that respond selectively to the illumination's polarization handedness. The metasurface exhibits sharp features in its circular dichroism spectra, which are tunable over a broad bandwidth by changing the illumination angle over a few degrees. Using this property, we demonstrate an ultra-thin circular-polarization sensitive spectral filter with a linewidth of ~10 nm, which can be dynamically tuned over a spectral range of 200 nm. Chiral diffractive metasurfaces, such as the one proposed here, open exciting possibilities for ultra-thin photonic devices with tunable, spin-controlled functionality.
Department of Physics and Max Planck Centre for Extreme and Quantum Photonics, University of Ottawa, 25 Templeton, Ottawa, ON, K1N 6N5, Canada.
Israel
I
De Leon
Department of Physics and Max Planck Centre for Extreme and Quantum Photonics, University of Ottawa, 25 Templeton, Ottawa, ON, K1N 6N5, Canada.
Matthew J
MJ
Horton
Department of Physics and Max Planck Centre for Extreme and Quantum Photonics, University of Ottawa, 25 Templeton, Ottawa, ON, K1N 6N5, Canada.
Sebastian A
SA
Schulz
Department of Physics and Max Planck Centre for Extreme and Quantum Photonics, University of Ottawa, 25 Templeton, Ottawa, ON, K1N 6N5, Canada.
Jeremy
J
Upham
Department of Physics and Max Planck Centre for Extreme and Quantum Photonics, University of Ottawa, 25 Templeton, Ottawa, ON, K1N 6N5, Canada.
Peter
P
Banzer
Department of Physics and Max Planck Centre for Extreme and Quantum Photonics, University of Ottawa, 25 Templeton, Ottawa, ON, K1N 6N5, Canada.|Institute of Optics and Department of Physics and Astronomy, University of Rochester, Rochester NY, 14627.
Robert W
RW
Boyd