Advances on functional doped glasses: technologies, properties and applications

Resume : Development of new optoelectronic devices based on optical fibres is possible thanks to constant searching for advanced materials adapted to specific applications of optical fibre structures and also due to the development of technological processes used for their production or further processing. Special constructions of active optical fibres allow to optimise their parameters with regard to application of these fibres used in optoelectronic systems as lasers, amplifiers or sensors. Simultaneously, developing of glasses co-doped with RE ions leads to the constructions of new photonic devices required in integrated optics and sensor applications. The presentation will be dealt with optical and thermal properties of RE co-doped fluorophosphate glasses with the attention to their application in optical fibres. Presented glass system co-doped with Nd3+/Yb3+ as a result of excitation at the wavelength of 808 nm characterized strong and wide ( = 100 nm) emission in the 1m region corresponding to the superposition of optical transitions 4F3/2 → 4I11/2 (Nd3+) and 2F5/2 → 2F7/2 (Yb3+). The optimization of Nd3+ → Yb3+ resonant energy transfer in glass was possible because of a small difference in energy (~ 1190 cm-1) between the laser levels of neodymium and ytterbium. Described in the paper good thermal and luminescent properties of glass enable to manufacture optical fibers with amplified spontaneous emission (ASE) at 1.1 μm. Acknowledgments The research activity was performed in the Bialystok University of Technology project S/WE/4/2013 and the CNR-PAS joint project “Nanostructured systems in opal configuration for the development of photonic devices” (2014-2016). The COST Action MP1401 Advanced fibre laser and coherent source as tools for society, manufacturing and life science is also acknowledged.

Resume : Glass-ceramics are nanocomposite materials which offer specific characteristics of capital importance in photonics. This kind of two-phase materials is constituted by nanocrystals embedded in a glass matrix and the respective composition and volume fractions of crystalline and amorphous phase determine the properties of the glass-ceramic. Among these properties transparency is crucial, in particular when confined structures, such as dielectric optical waveguides, are considered, and several works have been devoted to this topic. Another important point is the role of the nanocrystals when activated by luminescent species, as rare earth ions, and their effect on the spectroscopic properties of the glass-ceramic. The presence of the crystalline environment around the rare earth ion allows high absorption and emission cross sections, reduction of the non-radiative relaxation thanks to the lower phonon cut-off energy, and tailoring of the ion-ion interaction by the control of the rare earth ion partition. Fabrication, assessment and application of glass-ceramic photonic systems, especially waveguides, deserve an appropriate discussion which is the aim of this communication, focused on luminescent glass-ceramics. A brief historical review, consolidated results and recent advances in this important scientific and technological area will be presented, and some perspectives will be outlined. Acknowledgements This research was performed in the framework of the MAE Significant Bilate

Resume : The investigation of the differences between ordered and disordered materials (in the hundreds of nanometer lengthscale) is a crucial topic for a better understanding of light transport in photonic media. In this work, we study the light transmission properties of disordered one dimensional photonic structures in which disorder is introduced by a random variation of layer thickness. The structures have been fabricated by rf-sputtering technique. The transmission spectrum of the disordered structure has been carefully simulated by taking into account the refractive index dispersion of silicon dioxide and titanium dioxide, resulting in a very good agreement between the experimental data and the simulations. We found that the transmission of the photonic structure in the range 300 – 1200 nm is lower with respect the corresponding periodic photonic crystal. This study envisages the use of disordered one dimensional photonic structures for the modelization and realization of broad band filters. Acknowledgments The research activity was performed in the framework of CNR-PAS joint project Nanostructured systems in opal configuration for the development of photonic devices (2014-2016) and Progetto Premiale “Strutture risonanti per la rivelazione di biomarkers precursori della sepsi”. The COST Action MP1401 Advanced fibre laser and coherent source as tools for society, manufacturing and life science is also acknowledged.

Resume : In the last decades erbium-containing materials have been widely used as active media in large-scale communication systems, due to the fact that Er emission at 1.54 micron corresponds to a minimum of loss in silica optical fibers. However, the low Er content that can be insert without precipitation in optically inactive Er-clusters and the low Er excitation cross section are limiting factors for its optical efficiency. A possible approach to overcome the solubility limit is the development of yttrium-erbium based compounds in which Er concentration can be modulated, by replacing Y in substitutional positions. In this way up to 10E22 Er/cm3 can be introduced in Y-Er oxides and silicates. To further enhance Er excitation cross section, we propose the insertion of bismuth in Er-Y oxide thin film deposited by magnetron co-sputtering. The Bi influence on structural and optical properties of the compound will be widely discussed. In particular Bi will be demonstrated to act as an efficient sensitizer for Er, when Bi3+ oxidation state is favored, by determining an increase of more than three order of magnitude of Er effective excitation cross section. Moreover, we will evaluate the effects of Ag and Au nanoparticles with different sizes and shapes for tuning their plasmon resonance in the energy range of Bi and Er levels, in order to induce plasmon-photon coupling. The results suggest Bi-doped Y-Er compounds as novel and efficient emitter at 1.54 micron for photonic applications.

Resume : In 1969, when Miller proposed to mimic the new born integrated circuit and create integrated optical devices, he already identified « doped » glass substrates as potential candidates for this new type of circuitry. After years of research and development on both material science, guided wave theory and microtechnology, the many devices that have been realized and, for some of them, commercialized proved Miller’s vision was right. In this article, we will review the field of glass integrated optic, from the very first results of the late 1970’s to the most recent developments concerning biochips, optofluidic devices in harsh environment, integrated lasers and amplifiers as well as 3D integration. Finally, we will identify and put emphasis on some of the many challenges that need to be addressed in the future, trying to propose some potential solutions.

Resume : An optical fibre based dosimeter consists of a small scintillator coupled to a passive fibre of suitable length for remote signal transport to an optical detector. Such configuration has several advantages in radiation dosimetry. Indeed, the small volume of the sensor makes the radiation field perturbation negligible, leading to high spatial resolution and point dose evaluations. These systems may enable a real-time measurement of the dose, providing a direct feedback to the medical physician during a radiation therapy treatment as well as dosimetric information during diagnostic irradiations. In this work the recent progresses in the development of rare-earth doped silica fibers are shown. In particular, the main purpose was the production of scintillating fibers with an emission spectrum which can be easily distinguished from that of spurious luminescent signals originated in the fiber material as a consequence of the exposition to ionizing radiations (e.g. Cherenkov light and intrinsic fluorescence). Therefore, rare earth dopants like Eu and Yb were considered for the scintillating fiber development, and the results were compared to those obtained on previously investigated Ce-doped fibers. A study of the luminescent and dosimetric properties of these new systems was carried out by using X and gamma rays of different energies. Furthermore, a detailed investigation of the mechanisms responsible for possible sensitivity changes upon accumulated dose was performed.

Resume : The purpose of this presentation is to analyse ways for design and synthesis new nanocomposite materials based on chalcogenide glass semiconductor (ChGS). Additive component may be organic dye, chalcogene, transitional or rare-earth metals. Thermal evaporation of ChGS and additive component was carried out in vacuum using two evaporators, with their power carefully regulated. Molecular beams of two components were measured separately by quartz microbalance. Hardware-software system was used to correct evaporators power in real time, allowing to hold molecular ratio of the composite during film growth. The spatial arrangement of the two evaporators and substrates in a vacuum chamber provided simultaneous production of a set of samples with composite ratio that varied over a wide range. Such technique allows change properties of obtained media predictably changing their physical and chemical properties. Structural studies were carried with the use of Raman and IR spectroscopy and X-ray diffraction, films morphology with the use of AFM microscopy. Enclosure of organic dye and other dopants in the chalcogenide glass matrix can generate new energy states in the forbidden gap, significantly change their optical, luminescent, magnetic, thermal and non-linear optical properties. Possible mechanism of the observed direct relief formation can be molar volume change of composite nanomultilayer system under the action of light. These media can be used for the fabrication of different optical elements including direct one-step relief formation with the use of amorphous chalcogenide multilayers and in other applications. The research was supported by the project FP–7 SECURE–R21