Plasmonic enhancement of mid- and far-infrared acousto-optic interaction [Invited].

We present a concept of an acousto-optical device with plasmonic efficiency enhancement at a 10.6 µm wavelength. Interaction of light, Rayleigh surface acoustic wave, and surface plasmon polariton excited via prism coupling using Otto geometry enhances the diffraction efficiency. In the case of Otto geometry, the surface acoustic wave affects both the refraction index of the optical medium and the air gap thickness between the prism and the metal. Dependencies of the reflective coefficient of the prism-air-metal system on gap thickness and dielectric permittivity modulation were analyzed. The analytical results were confirmed by experimental measurements of the angular spectrum of the reflected beam.

Magneto-optical plasmonic heterostructure with ultranarrow resonance for sensing applications.

Currently, sensors invade into our everyday life to bring higher life standards, excellent medical diagnostic and efficient security. Plasmonic biosensors demonstrate an outstanding performance ranking themselves among best candidates for different applications. However, their sensitivity is still limited that prevents further expansion. Here we present a novel concept of magnetoplasmonic sensor with ultranarrow resonances and high sensitivity. Our approach is based on the combination of a specially designed one-dimensional photonic crystal and a ferromagnetic layer to realize ultralong-range propagating magnetoplasmons and to detect alteration of the environment refractive index via observation of the modifications in the Transversal Magnetooptical Kerr Effect spectrum. The fabrication of such a structure is relatively easy in comparison with e.g. nanopatterned samples. The fabricated heterostructure shows extremely sharp (angular width of 0.06°) surface plasmon resonance and even sharper magnetoplasmonic resonance (angular width is 0.02°). It corresponds to the propagation length as large as 106 µm which is record for magnetoplasmons and promising for magneto-optical interferometry and plasmonic circuitry as well as magnetic field sensing. The magnitude of the Kerr effect of 11% is achieved which allows for detection limit of 1∙10(-6). The prospects of further increase of the sensitivity of this approach are discussed.