Tunable and switchable polarization rotation with non-reciprocal plasmonic thin films at designated wavelengths

Abstract

We experimentally demonstrate an ultra-thin plasmonic optical rotator in the visible regime that induces a polarization rotation that is continuously tunable and switchable by an external magnetic field. The rotator is a magneto-plasmonic hybrid structure consisting of a magneto-optical EuSe slab and a one-dimensional plasmonic gold grating. At low temperatures, EuSe possesses a large Verdet constant and exhibits Faraday rotation, which does not saturate over a regime of several Tesla. By combining these properties with plasmonic Faraday rotation enhancement, a large tuning range of the polarization rotation of up to 8.46 for a film thickness of 220 nm is achieved. Furthermore, through experiments and simulations, we demonstrate that the unique dispersion properties of the structure enable us to tailor the wavelengths of the tunable polarization rotation to arbitrary spectral positions within the transparency window of the magneto-optical slab. The demonstrated concept might lead to important, highly integrated, non-reciprocal, photonic devices for light modulation, optical isolation, and magnetic field optical sensing. The simple fabrication of EuSe nanostructures by physical vapor deposition opens the way for many potentially interesting magneto-plasmonic systems and three-dimensional magneto-optical metamaterials.

Plasmonic Analog of Electromagnetically Induced Absorption Leads to Giant Thin Film Faraday Rotation of 14°

“…By tuning this coupling carefully, a high-Q absorptive hybrid mode is realized, which can be used to resonantly amplify the Faraday rotation response. Furthermore, the EIA mechanism allows us to utilize the high oscillator strength of the plasmonic resonance, leading to an efficient coupling of the incident light into the structure without reducing the effective Q factor due to the broad plasmonic resonance, as was the case in previous approaches [7,14,47]. Although being only less than 200 nm thick, our novel structure design exhibits an order of magnitude better rotation capability than previous Ansätze that resulted in only fractions of degree rotation [13,14,[41][42][43].…”

“…Considerable attention was received by a recent approach where the MO response of a dielectric thin film is enhanced by the attachment of a plasmonic grating [13,14]. This technique also allows the amplified MO response to be spectrally tailored by tuning the grating parameters [47]. Very recently, the underlying enhancement mechanism has also been described analytically using a simple oscillator model based on the Lorentz force [48].…”

On‐Chip Polarization Rotators

“…As for the insertion loss induced by the twisting, we measured a loss of 0.096 dB for polarization rotator with l = 500 µm, which is negligible. Similar to the polarization rotators at telecom wavelength, a polarization rotator at visible wavelength also plays an important role in information processing . However, the reduction in wavelength means a reduction in the waveguide size as well, which imposes higher demands on the fabrication precision.…”

Plasmonic‐Assisted Graphene Oxide Artificial Muscles

“…The addition of AuNRs with various plasmonic absorption peaks can tailor the strength of grip and hence control the function of the robot. With the plasmonic‐reprogrammable strategy, the artificial muscle can be applied for different purposes, e.g., a light‐assisted hand as shown in Figure c. The bending areas are actually synthesized by the bilayer HAM, instead of traditional joints.…”