The amorphous films show many physical properties which differ from the crystalline state. One of these is the optical transparency photoinduced by light with photon energies higher than optical bandgap. The phenomenon is especially large in amorphous chalcogenide films. However, the changes of optical constants are too small for optoelectronic applications. In this paper we consider structure were the amorphous As<sub>2</sub>S<sub>3</sub> film is placed in a structure which forms a surface plasmon resonance structure. The reflected light is coupled with waveguide modes. The experimental studies show that high nonlinear changes may be achieved for the light intensity of 10- 12 mW when the incident angle is close to resonance. For some film thicknesses the SPR resonance was achieved with prism made from BK7 glass, which is important opportunity for applications.
In this paper we present several numerical simulations of the surface plasmon resonance for Kretschmann type configuration in a metal-chalcogenide waveguide. We assume that the chalcogenide (GaLaS) waveguide layer have finite thickness, whereas the gold film layer and the air cover layer are semi-infinite layers (from an optical point of view). We determined the thickness of the chalcogenide film for which plasmonic resonant coupling of the incident radiation to the waveguide occurs. We calculated the propagation constant for the TE- and TM- modes (both for visible and IR domain), the attenuation coefficient and the electromagnetic field distribution within the waveguide. The obtained results provide the conditions for design an optical memory device 2D based on light-light interaction in plasmonic configuration.
In report is made the synthesis of the surface plasmon polariton propagation phenomenon. Methods such as Maxwell equations, Drude model used to describe the light confinement at the interface between two media are analyzed. Simulation techniques such as the transfer matrix formalism and the dispersion equation are examined. Finally are presented the results of our own investigations aiming plasmonic structure containing a film of amorphous chalcogenide material. It is shown the structure is very sensitive to the modifications of the refractive index that may be used for the design of the optical memory.
Preliminary results obtained in investigating a plane electromagnetic wave incident on a metal nanowire grating formed on a dielectric substrate, using FEM, are presented. The numerically simulated model is developed considering Cu, Au, Ag or other metal nanowire having a diameter of 40 nm - 800 nm, formed on dielectric substrates with a refractive index between 1.4 and 2.4. The transmission and reflection coefficients for refraction, specular reflection and first order diffraction are computed. The cases of dielectric substrate with metallic layers of different thicknesses deposited on the opposite side are also investigated.
Metamaterials are artificially designed media that show averaged properties not yet encountered in nature. Among such
properties, the possibility of obtaining optical magnetism and negative refraction are the ones mainly exploited but
epsilon-near-zero and sub-unitary refraction index are also parameters that can be obtained. Such behaviour enables
unprecedented applications. Within this work, we will present various aspects of metamaterials research field that we deal with at our department. From the modelling part, we will present tour approach for determining the field enhancement in slits that have
dimensions in the 10<sup>4</sup> times smaller than the incident wavelength. This huge difference makes it almost impossible for
commercial software to handle thus analytical approached have to be employed. From the fabrication point of view, various 2D and 3D high resolution patterning techniques are used. The talk will describe the ones available within our group. We will present the electron-beam lithography approach for fabricating nano-antennae to be used in coupling of plasmonics waveguides to/from free space. Also, a 3D technique based on twophoton-polymerisation and isotropic metal deposition to fabricate metal-covered 3D photonic crystals will be discussed. From the measuring side we will present two THz based setups for obtaining material’s characteristics, both in the low as well as in the high THz range, thus having the possibility of describing a material from 0.1 to 10THz.
The modulation of infrared radiation ((lambda) equals 1150 nm) in waveguides of glassy semiconductors As<SUB>2</SUB>Se<SUB>3</SUB> and As<SUB>2</SUB>Se<SUB>3</SUB>Sn<SUB>0.175</SUB> has for the first time been investigated experimentally. The measurement of frequency-response characteristic shows that there are two relaxation constans-fast and slow. The rise time of optical modulator with arsenic selenide waveguides having tin additions is nearly 10<SUP>-3</SUP>s. The origin of additional absorption can be explained in the framework of two-steps transition models. The first one is the excitation of excess carriers into the conducting band by highly absorbed pump beam and theirs partial capturing on localized states. The second is the re-excitation of trapped carriers and restoration of optical absorption by signal waveguided beam.