Spin-Polarization-Selective Lattice Plasmon Modes

Israel De Leon Department of Physics, University of Ottawa, Ottawa, Ontario, Canada Matthew Horton Department of Physics, University of Ottawa, Ottawa, Ontario, Canada Sebastian A. Schulz Department of Physics, University of Ottawa, Ottawa, Ontario, Canada Jeremy Upham Department of Physics, University of Ottawa, Ottawa, Ontario, Canada Peter Banzer Department of Physics, University of Ottawa, Ottawa, Ontario, Canada Robert W. Boyd Department of Physics, University of Ottawa, Ottawa, Ontario, Canada The Institute of Optics, University of Rochester, Rochester, New York, USA

Two dimensional metamaterials, or metasurfaces, offer the possibility to manipulate the properties of light with unprecedented flexibility using planar geometries, [1,2] providing a new route to develop ultra-thin optical devices with sophisticated functionality [3,4]. Metasurfaces with lattice spacings comparable to the optical wavelength can support delocalized plasmon-photon modes that propagate along the lattice. These hybrid modes, known as lattice plasmon modes (LPMs), result from coherent interactions between the nanoparticles via diffractive coupling. [5]. LPMs have attracted much attention recently because of their relatively large quality factors and broad spectral tunability, which hold potential for biosensing applications and enhanced fluorescence emission [6,7]. Here, we show that a metasurface consisting of a periodic array of split-ring resonators (SRRs) embedded in a homogeneous medium can support LPMs that respond selectively to the handedness of circularly polarized light. These modes exhibit a number of important properties, such as a propagation direction dictated by the handedness of the polarization, and a sensitive dependence upon the angle of illumination. A preliminary experimental result is given in Fig. 1, which shows the metasurface’s transmittance spectra for circularly polarized light at oblique incidence. The two absorption features located around 910 nm and 990 nm, denote the spin-polarization-selective LPMs (note that each of them is excited only with a particular polarization handedness). We discuss the physical mechanism behind these LPMs, as well their dispersive properties.

LSM_spectra

Fig. 1: Transmittance spectra of a metasurface consisting of an array of SRRs, obtained for circularly polarized illumination at oblique incidence (angle of incidence is 3 deg.). LCP: Left-circular polarization; RCP: Right-circular polarization.

References:
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ideleon@uottawa.ca