Anomalies In Optical Properties Research Articles

Ordered PbHPO4 nanowires: Crystal structure, energy bands and optical properties from first principles

Structural, electronic and high-frequency dielectric properties of both the bulk crystal and the ordered nanostructured metamaterials, nanolayers (NLs) and nanowires (NWs) of hydrogen-bonded PbHPO4 are studied within the density functional theory. We have shown that all artificial structures considered by us may be equilibrated regarding the maximal forces acting on each atom up to the value not worse than 10-6eV/Å. The monoclinic symmetry not higher than the symmetry of the bulk PbHPO4 crystal, P2/c, is imposed both on each NL/NW proper and on their mutual space arrangement. Electronic band structure, density of states and partial densities of states, optical refractive indices and extinction coefficients have been calculated. We have displayed the evolution of electronic band properties going from the bulk single crystal to periodically ordered nanostructures, NLs and NWs. We have found significant anomalies in optical properties in visible and ultraviolet ranges of NWs studied in our research compared with those of bulk crystal.

Role of Wood anomalies in optical properties of thin metallic films with a bidimensional array of subwavelength holes

Recents works dealt with the optical transmission on arrays of subwavelength holes in a metallic layer deposited on a dielectric substrate. Making the system as realistic as possible, we perform simulations to enlighten the experimental data. This paper proposes an investigation of the optical properties related to the transmission of such devices. Numerical simulations give theoretical results in good agreement with experiment, and we observe that the transmission and reflection behavior correspond to Fano's profile correlated with resonant response of the eigen modes coupled with nonhomogeneous diffraction orders. We thus conclude that the transmission properties observed could conceivably be explained as resulting from resonant Wood's anomalies.

Anomalies in optical properties of metal-doped lithium niobate single crystals

In this paper we discuss the possibility of phase transitions in doped LiNbO3 at temperatures much lower than the Curie temperature. We found an anomalous temperature behavior of the refractive index of metal-doped LiNbO3 crystals. The anomalies have non-equilibrium character.

Exciton effects in disordered semiconductors

Experimental data on optical and photoelectric properties of molecular (polymeric) disordered semiconductors of inorganic and organic nature are analyzed. It is shown that anomalies in optical properties and in the structure of the internal photoeffect quantum-yield spectrum can be understood by assuming the existence of exciton states in disordered semiconductors.