One-dimensional disordered photonic structures with two or more materials

Here we would like to discuss the light transmission modulation by periodic and disordered one dimensional (1D) photonic structures. In particular, we will present some theoretical and experimental findings highlighting the peculiar optical properties of: i) 1D periodic and disordered photonic structures made with two or more materials; ii) 1D photonic structures in which the homogeneity or the aggregation of the high refractive index layers is controlled. We will focus also on the fabrication aspects of these structures.Comment: 6 pages, 4 figure

SnO2 based glasses : A viable photonic system

The present work focuses on sol-gel derived SnO2-based thin glass-ceramic films doped with Er3+ ions, fabricated by dipcoating technique. Our goal is to find a viable fabrication protocol to obtain them. Thin films with a variety of composition were synthesized and their structural, optical and spectroscopic properties were investigated. The FTIR spectra and X-ray diffraction patterns were used to characterize the structure of the thin films. The transparency of the thin film was tested by UV-Vis transmittance measurements. The energy transfer dynamic was investigated by time-resolved spectroscopy and photoluminescence measurements

Polyglycerol coated polypropylene surfaces for protein and bacteria resistance

Polyglycerol (PG) coated polypropylene (PP) films were synthesized in a two- step approach that involved plasma bromination and subsequently grafting hyperbranched polyglycerols with very few amino functionalities. The influence of different molecular weights and density of reactive linkers were investigated for the grafted PGs. Longer bromination times and higher amounts of linkers on the surface afforded long-term stability. The protein adsorption and bacteria attachment of the PP-PG films were studied. Their extremely low amine content proved to be beneficial for preventing bacteria attachment

Synthesis, structure and spectroscopic properties of luminescent GdVO4:Dy3+ and DyVO4 particles

Part of this research was done during visit of D.J. to IFN-CNR CSMFO Lab. and FBK Photonics Unit, Povo-Trento, Italy, in the framework of the STSM (Grant No. 38223) from the project: COST Action MP 1401 Advanced Fibre Laser and Coherent Source as tools for Society, Manufacturing and Lifescience” (2014e2018). The authors from Vinca Institute of Nuclear Sciences acknowledge the financial support of the Ministry of Education, Science and Tech-nological Development of the Republic of Serbia (Project No: 45020 and 172056). L.T.N. Tran acknowledges the scholarship of the Ministry of Education and Training, Vietnam International Education Development. T. G. acknowledges the ERDF PostDoc project No. 1.1.1.2/VIAA/1/16/215 (1.1.1.2/16/I/001).In this work, we focused on the syntheses, structure and spectroscopic properties of GdVO4:Dy3+ and DyVO4 (nano)particles of different sizes and shapes (spherical nanoparticles of 2 nm, 4 nm, and 20 nm in size, nanorods with a few nanometers in diameter and up to 10–20 nm in length and microparticles of 1–8 μm) obtained by four synthetic methods. The size effect on the structure, Raman active modes, and photoluminescence emission intensities was analyzed by X-ray diffraction, Raman and photoluminescence spectroscopy, scanning and transmission electron microscopy, and diffuse reflection spectroscopy. All X-ray diffraction patterns clearly indicated presence of a single tetragonal zircon-type phase; absence of impurity phases indicate that the dopant Dy3+ ions were successfully and uniformly incorporated into the GdVO4 host lattice due to the equal valence and similar ionic radii. Micro-Raman measurements support the XRD measurements and showed Raman-active modes of the REVO4 systems (RE = Gd, Dy). The difference between the two hosts in the diffuse reflectance spectra was observed and it could be attributed to more effective Gd3+ ions on the charge transfer bands and different polarization (compared to bulk material) in smaller nanoparticles. Photoluminescence spectroscopy showed several bands in the visible and near-infrared regions which can be exclusively attributed to the f–f transitions of Dy3+ ions.STSM (Grant No. 38223); COST Action MP 1401 (2014e2018); Ministry of Education, Science and Tech-nological Development of the Republic of Serbia (Project No: 45020 and 172056); ERDF PostDoc project No. 1.1.1.2/VIAA/1/16/215 (1.1.1.2/16/I/001); Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

Glass-based 1-D dielectric microcavities

We have developed a reliable RF sputtering techniques allowing to fabricate glass-based one dimensional microcavities, with high quality factor. This property is strongly related to the modification of the density of states due to the confinement of the gain medium in a photonic band gap structure. In this short review we present some of the more recent results obtained by our team exploiting these 1D microcavities. In particular we present: (1) Er3+ luminescence enhancement of the 4I13/2 → 4I15/2 transition; (2) broad band filters based on disordered 1-D photonic structures; (3) threshold defect-mode lasing action in a hybrid structure

Ferromagnetic-like behavior of Bi0.9La0.1FeO3-KBr nanocomposites

We studied magnetostatic response of the Bi0.9La0.1FeO3-KBr composites (BLFO-KBr) consisting of nanosized (about 100 nm) ferrite Bi0.9La0.1FeO3 (BLFO) conjugated with fine grinded ionic conducting KBr. When the fraction of KBr is rather small (less than 15 wt percent) the magnetic response of the composite is very weak and similar to that observed for the BLFO (pure KBr matrix without Bi1-xLaxFeO3 has no magnetic response as anticipated). However, when the fraction of KBr increases above 15percent, the magnetic response of the composite changes substantially and the field dependence of magnetization reveals ferromagnetic-like hysteresis loop with a remanent magnetization about 0.14 emu/g and coercive field about 1.8 Tesla (at room temperature). Nothing similar to the ferromagnetic-like hysteresis loop can be observed in BLFO ceramics, which magnetization quasi linearly increases with magnetic field. Different physical mechanisms were considered to explain the unusual experimental results for BLFO-KBr nanocomposites, but only those among them, which are highly sensitive to the interaction of antiferromagnetic Bi0.9La0.1FeO3 with ionic conductor KBr, can be relevant. An appropriate mechanism turned out to be ferro-magneto-ionic coupling.Comment: 24 pages, 4 figures in the main text, and supplement with 4 figure

Red photonic glasses and confined structures

We present some recent results obtained by our team in rare earth doped photonic glasses and confined structures, in order to give some highlights regarding the state of art in glass photonics. To evidence the unique properties of transparent glass ceramics we compare spectroscopic and structural properties between the parent glass and the glass ceramics. Starting from planar waveguides we move to spherical microresonators, a very interesting class of photonic confined structures. We also conclude the short review with some remarks about the perspective for glass photonics

Analytical modelling of Tm-doped tellurite glass including cross-relaxation process

In this paper, we present a comprehensive analytical model of Tm able to take into account direct cross-relaxation process. We show that by using an appropriate set of parameters the model is able to properly fit the first part of the fluorescence decay of Tm-doped tellurite glasses for different dopant concentration values. We also compare the model with a full numerical model to investigate its limitations. We assess the model is a valid tool to fit fluorescence properties but for precisely predicting population inversion is limited to doping level up to about 1%. In fact, we show the reverse cross-relaxation process becomes significant in case of higher doping level

Coherent emission from fully Er 3+ doped monolithic 1-D dielectric microcavity fabricated by rf-sputtering

All Er3+ doped dielectric 1-D microcavity was fabricated by rf sputtering technique. The microcavity was constituted by half wave Er3+ doped SiO2 active layer inserted between two Bragg reflectors consists of ten pairs of SiO2/TiO2 layers also doped with Er3+ ions. The scanning electron microscopy was used to check the morphology of the structure. Transmission measurements confirm the third and first order cavity resonance at 530 nm and 1560 nm, respectively. The photoluminescence measurements were obtained by optically exciting at the third order cavity resonance using 514.5 nm Ar+ laser with an excitation angle of 30°. The Full Width at Half Maximum of the emission peak at 1560 nm decrease with the pump power until the spectral resolution of the detection system of ∼1.0 nm. Moreover, the emission intensity presents a non-linear behavior with the pump power and a threshold at about 24 mW was observed with saturation of the signal at above 185 mW of pump power

New genetic loci implicated in fasting glucose homeostasis and their impact on type 2 diabetes risk.

Levels of circulating glucose are tightly regulated. To identify new loci influencing glycemic traits, we performed meta-analyses of 21 genome-wide association studies informative for fasting glucose, fasting insulin and indices of beta-cell function (HOMA-B) and insulin resistance (HOMA-IR) in up to 46,186 nondiabetic participants. Follow-up of 25 loci in up to 76,558 additional subjects identified 16 loci associated with fasting glucose and HOMA-B and two loci associated with fasting insulin and HOMA-IR. These include nine loci newly associated with fasting glucose (in or near ADCY5, MADD, ADRA2A, CRY2, FADS1, GLIS3, SLC2A2, PROX1 and C2CD4B) and one influencing fasting insulin and HOMA-IR (near IGF1). We also demonstrated association of ADCY5, PROX1, GCK, GCKR and DGKB-TMEM195 with type 2 diabetes. Within these loci, likely biological candidate genes influence signal transduction, cell proliferation, development, glucose-sensing and circadian regulation. Our results demonstrate that genetic studies of glycemic traits can identify type 2 diabetes risk loci, as well as loci containing gene variants that are associated with a modest elevation in glucose levels but are not associated with overt diabetes