V. A. Aseev

Holographic characteristics of a modified photothermorefractive glass

The spectral and holographic characteristics of classical and modified photothermorefractive glass are compared. It shows that modified photothermorefractive glass has no additional absorption bands in the blue–green region, as is the case in classical photothermorefractive glass. This makes it possible to record purely phase holograms in modified photothermorefractive glass. The refractive-index increment is a factor of 2 greater in modified photothermorefractive glass than in classical photothermorefractive glass.

Spectral Luminescence Properties of Transparent Lead Fluoride Nanoglassceramics Doped with Erbium Ions

Transparent nanoglassceramics has been synthesized based on lead fluoride silicate glass doped with erbium ions. It is shown that heat treatment of lead fluoride silicate glass leads to the formation of nanoscale (16–40 nm) crystalline phase of lead fluoride. X-ray diffraction analysis and measurement of spectral luminescence properties have revealed that the erbium ions enter the crystalline phase of lead fluoride.

Spectroluminescence properties of photothermorefractive nanoglass-ceramics doped with ytterbium and erbium ions

Comprehensive studies of the spectroluminescence and laser properties of high-concentration photothermorefractive nanoglass-ceramics doped with ytterbium and erbium ions for integrated-optics amplifiers and minilasers have been carried out for the first time. The limiting concentrations of erbium for which amplification is observed have been established, and the influence of the pump power on the gain has been investigated.

Spectral luminescence and information characteristics of transparent lead fluoride nano-glass-ceramics doped with erbium ions

Spectral luminescence properties of synthesized transparent nano-glass-ceramics doped with erbium ions are studied. It is shown that, as a result of the secondary heat treatment of nano-glass-ceramics, the width of the luminescence spectrum at half maximum increases more than by 15 nm. Luminescence life-time dependences of erbium ions in studied samples are measured, their absorption cross-sections are determined, and their emission cross-sections are calculated by the McCumber method. Spectral and ultimate information characteristics of erbium-doped fiber amplifiers based on synthesized nano-glass-ceramics are numerically simulated. It is shown that, in the unsaturated gain regime, a substantial ripple of the absorption and emission cross-section spectra and shorter lifetime of the metastable level of the erbium ion reduce the pumping radiation power that is required for obtaining the given peak gain, narrow the gain spectra, and lower the transmission capacity of devices based on nano-glass-ceramics compared to the initial glass. Conversely, fiber amplifiers based on calcium fluoride glass-ceramics, for which the lifetime of the metastable level increases with increasing annealing temperature, have an advantage in the transmission capacity over devices based on the primary glass.

Lead lanthanide oxyfluorides in a glasslike matrix

The crystalline phases formed upon thermal treatment of glasses of composition 18PbF2 · 30SiO2 · 5ZnF2 · 29CdF2 · 15AlO3/2 · (2–5.5)Ln(Y)F3 (mol %) at the crystallization onset temperature have been investigated. The possibility of obtaining nanosized crystals of a new class of PbLnOF3 compounds, in which Ln are lanthanides from Ce to Lu, with a fluorite structure (cubic crystal system, face-centered, space group Fm3m) in a glasslike matrix has been demonstrated. The unit cell size depends on the lanthanide type (ionic radius).

Luminescent properties of ytterbium-erbium nanostructured lead fluoride silicate glass-ceramics at low temperatures

We have studied the luminescent properties of lead fluoride silicate nanostructured glass-ceramics doped with ytterbium and erbium ions. We have measured luminescence spectra of glass-ceramics in the visible and near-IR ranges at temperatures of 300 and 77 K and under their pumping at a wavelength of 975 nm. We have examined changes in the luminescence spectra of glass-ceramics depending on the time of their secondary thermal treatment, concentration of dopant ions, specimen temperature, and power of excitation radiation.

Fluorophosphate glasses activated by rare-earth ions and AgBr

Analysis of the absorption band position for colloidal silver in fluorophosphate glasses of the composition (0.95 − x − y)(MgCaBaSrAl2F14)-0.05Ba(PO3)2-xPbF2-yLnF3 (where Ln = Eu, Ce, Sm, Tb; 0 ≤ x ≤ 0.2; y = 0.01, 0.02) with small additives of AgBr (0.04 wt % above 100%) has been performed. It has been shown that joint introduction of AgBr and EuF3 with additional heat treatment of the glasses below the temperature of the onset of crystallization leads to a rise of the plasmon absorption band of silver nanoparticles. It has been assumed that the reason for the observed shift of the plasmon absorption band is the formation of a ∼0.5-nm-thick shell of AgBr on the surface of a metallic Agn0-cluster.

Application of projection on latent structures for determining temperature of erbium-doped lead fluoride nano-glass-ceramics from upconversion fluorescence spectra

The temperature of erbium-doped lead fluoride nano-glass-ceramics in the range from 44 to 150°C is determined by constructing a projection on latent structures of upconversion fluorescence spectra in violet, green, and red bands. It is shown that the four-dimensional space of latent structures provides the best accuracy of temperature measurements. This space allows one to determine (using a training set of fluorescence spectra with a step of 10°C) temperatures above 70°C with a relative error not larger than 0.5%.

Design and fabrication of optical devices based on new polyfunctional photo-thermo-refractive glasses

Novel optical elements and devices (holographic volume Bragg gratings, gradient optical elements, optical and plasmonic waveguides, hollow structures, thermo-and biosensors, phosphors for LEDs, down-converters for solar cells) have been designed and fabricated based on new polyfunctional photo-thermo-refractive glasses. Some technologies (photo-thermo-induced crystallization, holograms recording, laser treatment, ion exchange, chemical etching) have been used. Shown that photo-thermo-refractive glasses can be used as a basic optical material for many photonics applications with the characteristics comparable with other commercially available materials.

Inorganic phosphors in lead–silicate glass for white LEDs

Luminescent composites of the “phosphor-in-glass” type, based on a highly reflective lead–silicate matrix and fine-grained powders of YAG:Ce3+ and SiAlON:Eu2+ crystals, are developed and synthesized. Phosphor and glass powders are sintered at a temperature of 550°C to obtain phosphor samples for white LEDs. The composites are analyzed by X-ray diffraction and luminescence spectroscopy. The dependence of the light quantum yield on the SiAlON:Eu2+ content in the samples is investigated. A breadboard of a white LED is designed using a phosphor-in-glass composite based on lead–silicate glass with a low glasstransition temperature. The total emission spectra of a blue LED and glass-based composites are measured. The possibility of generating warm white light by choosing an appropriate composition is demonstrated.