Reflection spectra of 1D photonic crystals based on aluminum oxide

Optical properties (transmission and reflection) of 1D photonic crystals (PCs) based on mesoporous anodic aluminum oxide with the lattice periods of 188 and 194nm are investigated. The experimentally measured reflection spectrum is compared in its first bandgap region with the theoretical dependence obtained from the dispersion relation for the 1D PC. Angular dependence is established for spectral positions of bandgaps in the 1D PC. A possibility of using mesoporous aluminum-oxide-based 1D PCs as narrow-band filters, narrow-band mirrors, and refractive sensors of molecular compounds is analyzed.     

On the possibility of detecting low-energy scalar and pseudo-scalar bosons

The properties of the conversion of “cold” extra-light scalar or pseudo-scalar bosons weakly interacting with material media to photons with energies of 0.001–1.0 meV are analyzed. Various possible experimental schemes including closed resonant cells at low temperatures and highly sensitive receivers of radio-frequency photons are presented. The existence of such elementary particles is predicted in various expansion versions of the “standard model”. Their direct or indirect detection would make it possible to clarify the nature of the “dark matter” phenomenon.     

Vibrational spectrum of Li2B4O7 crystals

The polarized infrared reflection spectra of Li₂B₄O₇ were studied in the spectral range 80–1600 cm^?1 and compared with Raman spectra. From the spectrum dispersion analysis, the frequencies, damping, and dielectric oscillator strengths were determined for all vibrational modes observed. A calculation of the effective charges and an analysis of the chemical-bond types of the Li₂B₄O₇ crystal structural units were carried out on the basis of the obtained data.     

Overtone Raman Scattering in Lithium Niobate Single Crystals Doped with Terbium

Crystallography Reports - Overtone bands in the spectral range of 1300?1950 cm–1 have been found in Raman scattering spectra of lithium niobate single crystals doped with terbium. The...     

Semimicroscopic Description of Isoscalar Giant Multipole Resonances in the $${}^{\mathbf{208}}$$ Pb Nucleus

Physics of Atomic Nuclei - An approach to describing main properties of isoscalar giant multipole resonances in medium-heavy closed-shell nuclei is proposed within the particle–hole...     

Localized Second Optical Harmonic in Nonlinear Optical Ceramics Excited by a Femtosecond Laser

Optics and Spectroscopy - Second harmonic generation is studied in samples of LiTaO3 powder ceramics with different lithium concentrations (48.8 and 49.3%) under excitation by a femtosecond laser...     

Secondary Radiation in Microdiamonds with NV Centers

Crystallography Reports - The regularities in the secondary radiation (fluorescence and Raman) spectra of single diamond microcrystals have been investigated. The Raman spectrum excited by infrared...     

Analysis of photoluminescence spectra of anthracene traces in photon traps

Photoluminescence spectra of small amounts of anthracene being in the photon trap, a specific type of the resonant cavity, were measured. In photon traps, radiation is input and output by optical waveguides. The use of ultraviolet light-emitting-diode sources of exciting radiation and a minipolychromator allowed photoluminescence spectra measurements in the range of 340–500 nm at an exposure of ～ 10^?3 s.     

Secondary emission of globular photonic crystals based on the opal-POPOP composite

The spectra of secondary emission of a globular photonic crystal such as the opal matrix filled with the POPOP aromatic compound (a known luminophore) and initial materials excited by semiconductor light-emitting diodes were studied. It was found that the luminescence spectrum of opal filled with POPOP significantly differs from luminescence spectra of POPOP itself and initial opal. It was shown that the observed luminescence in the visible region is mostly caused by three-photon parametric light scattering. In this case, the spectral shape is controlled by the photon density of states, differing from the photon density of states of pure opal. The shape of the secondary emission spectrum of artificial opal filled with POPOP was calculated. The effect of the photonic bandgap position on the intensity distribution of spontaneous emission of used luminophore was established.