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Donato M.G.,CNR Institute for Chemical and Physical Processes | Gagliardi M.,CNR Institute for Microelectronics and Microsystems | Sirleto L.,CNR Institute for Microelectronics and Microsystems | Messina G.,University of Reggio Calabria | And 3 more authors.
Applied Physics Letters | Year: 2010

In this paper, the optical dispersion properties and the Raman gain of sodium phosphate glasses containing niobium oxide at increasing concentrations have been systematically investigated, with the aim of establishing a potential enhancement of the Raman gain and its bandwidth with respect to silica. A broadening of the bandwidth and a higher peak Raman gain (approximately 17 times) than in silica glass have been observed at high niobium oxide molar content. Our findings point out that sodium-niobium-phosphate glasses could be utilized for the realization of Raman amplifiers. © 2010 American Institute of Physics. Source

Gaponenko M.S.,Belarusian National Technical University | Lutich A.A.,Ludwig Maximilians University of Munich | Tolstik N.A.,Belarusian National Technical University | Onushchenko A.A.,Research and Technological Institute of Optical Materials Science | And 3 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

We report experimental evidence of the lowest exciton state splitting and carrier trapping in PbS quantum dots (QDs) in glass matrix. Our measurements of photoluminescence (PL) of PbS QDs using steady-state and time-resolved PL spectroscopy reveal strong temperature dependences of the PL intensity and decay kinetics. We find that consistent quantitative description of our experimental results can be achieved using a simple model taking into account the lowest 1S-1S exciton state splitting and multiphonon-assisted carrier trapping to states outside a PbS QD. Using our model, we estimate the lowest exciton splitting energy and lifetimes of the dark and bright exciton states of PbS QDs. Consistent with our model, the PL transition energy of PbS QDs deviates at higher temperatures from the one predicted based on the bulk PbS band-gap dependence due to the lowest 1S-1S exciton state splitting. Temperature-induced broadening of the PL spectrum of PbS QDs is explained by the exciton-phonon interaction. © 2010 The American Physical Society. Source

Lipovskii A.A.,Saint Petersburg State Polytechnic University | Rusan V.V.,Research and Technological Institute of Optical Materials Science | Tagantsev D.K.,Saint Petersburg State University
Solid State Ionics | Year: 2010

A new technique to imprint phase and amplitude patterns into glass is proposed. The technique is based on the thermal poling of oxide glasses via a figurate plane anode which has a relief with a given 2D modulation of the pattern depth. Poling with such an anode results in the subsurface layer depleted of high-mobility ions and characterized by 2D modulation of its thickness directly determined by the relief of the anode pattern. Due to the 0.02 difference in refractive indices of the depleted layer and bulk glass, glasses poled via the figurate anode operate like optical phase structures, e.g. diffraction phase gratings in the case of a regular pattern. It is found that phase contrast in such structures (for the glasses used in this work) increases linearly with the total charge passing through the glass sample in the process of poling, with the maximal achieved phase contract of 1.32π. If initial glass contains silver ions, the bottom of the depleted layer can be treated as a latent relief image of the anode relief pattern, which can be visualized by heat treatment in H2 atmospheres due to the formation of silver nanoparticles absorbing visible light. Physico-chemical processes involved in the structure formation are discussed. © 2010 Elsevier B.V. All rights reserved. Source

Gaponenko M.S.,Belarusian National Technical University | Gaponenko M.S.,University of Neuchatel | Tolstik N.A.,Belarusian National Technical University | Tolstik N.A.,Norwegian University of Science and Technology | And 3 more authors.
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2013

Following the long dominance of CdSe quantum dots as the paradigm semiconductor nanocrystals for investigating of strong quantum confinement phenomena, attention is paid to the lead chalcogenide quantum dots which possess a level of carrier confinement unachievable in quantum dots of other materials. However, the energy level structure of the lowest 1S-1S exciton in these quantum dots is not defined well. Here, we report on the experimental investigation of absorption and photoluminescence of PbS quantum dots with a mean radius of 2.4 nm and show that the 1S-1S absorption and photoluminescence band maxima obey different temperature dependences. The temperature decrease leads to the increase of the Stokes shift. The results are in qualitative agreement with the assumption that different inherent exciton states within the split 1S-1S exciton state are responsible for the absorption and emission of light by PbS quantum dots. © 2013 Published by Elsevier B.V. Source

Buganov O.V.,B. I. Stepanov Institute of Physics | Nguyen D.H.,Vietnam Academy of Science and Technology | Tikhomirov S.A.,B. I. Stepanov Institute of Physics | Onuschenko A.A.,Research and Technological Institute of Optical Materials Science
Advances in Natural Sciences: Nanoscience and Nanotechnology | Year: 2011

The parameters of a solid-state PbS quantum dot saturable absorber, optical elements, resonator and feedback circuit have been adjusted for stable and highly efficient hybrid mode-locking Nd :YAG laser operation. A highly stable microsecond pulse train (40-50μs) containing about 5000 ps pulses and 3 mJ total train energy was generated with a repetition rate of 10 Hz. This all solid-state hybrid mode-locked Nd :YAG laser was used for synchronous pumping of a femtosecond Ti : Sapphire laser. © 2011 Vietnam Academy of Science & Technology. Source

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