Enhanced Faraday rotation by dielectric metasurfaces with Bayesian shape-optimized scatterers.

In this Letter, we demonstrate how to optimize the magneto-optic response of a Huygens metasurface composed of square arrays of all-dielectric nano-disk scatterers. We compare cylindrical and shape-modified disks. Both provide a strongly enhanced Faraday rotation that is accompanied by almost 100% transmittance. The shape modification obtained via a Bayesian optimization algorithm results in a 50% increase in the magneto-optic response compared to the best cylindrical disk, providing 15° of polarization rotation for a 260 nm thick metasurface.

Dispersion control in a near-infrared subwavelength resonator with a tailored hyperbolic metamaterial.

We demonstrate experimentally and computationally an intricate cavity size dependence of the anomalous near-infrared mode spectrum of an ordinary optical resonator that is combined with a ZnO:Ga-based hyperbolic metamaterial (HMM). Specifically, we reveal the existence of a resonance in subwavelength-sized cavities and demonstrate control over the first-order cavity mode dispersion. We elaborate that these effects arise due to the HMM combining the mode dispersions of purely metallic and purely dielectric cavity cores into a distinct intermediate regime. By tailoring the HMM fill factor, this unique dispersion of a subwavelength resonator can be freely tuned between these two limiting cases.

Mid-infrared beam splitter for ultrashort pulses.

A design is presented for a beam splitter suitable for ultrashort pulses in the mid-infrared and terahertz spectral range consisting of a structured metal layer on a diamond substrate. Both the theory and experiment show that this beam splitter does not distort the temporal pulse shape.

Near-field study on the transition from localized to propagating plasmons on 2D nano-triangles.

In this manuscript we report on a near field study of two-dimensional plasmonic gold nano-triangles using electron energy loss spectroscopy in combination with scanning transmission electron microscopy, as well as discontinuous Galerkin time-domain computations. With increasing nano-triangle size, we observe a transition from localized surface plasmons on small nano-triangles to non-resonant propagating surface plasmon polaritons on large nano-triangles. Furthermore we demonstrate that nano-triangles with a groove cut can support localized as well as propagating plasmons in the same energy range.