Strong coupling between excitons in organic semiconductors and Bloch Surface Waves

We report on the strong coupling between the Bloch surface wave supported by an inorganic multilayer structure and $J$-aggregate excitons in an organic semiconductor. The dispersion curves of the resulting polariton modes are investigated by means of angle-resolved attenuated total reflection as well as photoluminescence experiments. The measured Rabi splitting is 290 meV. These results are in good agreement with those obtained from our theoretical model

Optical properties of materials

The optical properties of macroscopic materials are described, basing only on classical arguments. Starting from Maxwell’s equations in a medium, the propagation of electromagnetic (em) waves in isotropic, linear and homogeneous materials is treated. To this aim, complex macroscopic quantities as the dielectric function, the optical conductivity, and the refractive index are introduced, together with the dispersion relations which they obey. Some hints at their extensions to anisotropic and nonlinear materials are given

Optical study of intersubband transitions in GaSb/AlGaSb systems for QWIPs

The realization of long-wavelength normal-incidence photodetectors relying on interconduction subband absorption in GaSb-based multi-quantum well (MQW) systems has been proven to be possible. High efficiencies can be achieved based on the size-induced Γ-to-L subband crossover in GaSb wells with an electron spill-over from the Γ to the ellipsoidal L conduction subbands. A systematic study of the intersubband absorption in n-GaSb/AlGaSb MQWs as a function of the n-doping and temperature is presented. In particular, medium-infrared transmittance measurements at normal-incidence evidenced sharp bands, corresponding to a peak fractional absorption per well which is higher than that reported in literature on similar systems

Influence of the preparing conditions on the physicochemical characteristics of glasses for thick film hybrid microelectronics

Seven batches of a high-lead glass were used for the preparation of RuO2-based thick film resistors. Investigation of their electrical properties showed a lack of reproducibility of results whose origin was related to changes of the physicochemical properties of the glassy matrix. A systematic investigation of the glass batches, both in form of frit powders and screen printed and fired layers, was carried out with several spectroscopies to detect changes in composition and structure. The spectroscopic methods included x-ray Energy Dispersive Fluorescence (EDS), Scanning Electron Microscopy (SEM), Atomic Absorption (AA), diffuse optical reflection of the powders and specular reflection of the layers, optical transmission, and other complementary methods. The dissolution of Al, due to interaction between the glasses and the alumina substrate, as well as the diffusivity and solubility of Ag due to interaction with the Ag-bearing terminations were measured. The results demonstrated that, apart from small compositional differences, the various batches were characterized by differences in residual stresses, redox reactions, and ''microstructure.'' The latter was responsible for very notable differences in the optical properties of the glasses, which in turn are closely related with the difference in atomic solubility and diffusivity. Optical spectroscopies have been found to be a suitable means for testing reproducible preparation methods of glass frits for thick-film hybrid microelectronics