Symposium CL
Inorganic Materials Systems for Advanced Photonics

Session CL-1 -  Photonic Nanomaterials and Nanostructures

CL-1:IL01  Synthesis of Nanoparticles: the Role of Chemical Parameters Toward Functional Materials
A. LAURIA, Laboratory for Multifunctional Materials, Swiss Federal Institute of Technology (ETH-Zurich), Zürich, Switzerland

Several materials express unique properties when their dimensions are confined at the nanoscale. Nanoparticle-based functional materials require to preserve at the macroscale such properties as a key factor for its performance. Colloidal syntheses of nanoparticles, and in particular the nonaqueous sol-gel route, enable high control over size, shape, structure, and composition of the produced materials, allowing to tune their functional (e.g. optical and photocathalythic) properties. At the same time, the rich chemistry involved in such synthetic strategies permits the control of the particle surface chemistry which determines either their stability or their assembly, crucial features toward homogeneous dispersions and multifunctional mixtures rather than more rational architectures such as porous superstructures. In this talk the sol-gel synthesis methods for obtaining metal oxide nanoparticles will be described. The importance of their peculiar chemical characteristics in order to process nanoparticle-based functional materials like optical polycrystalline ceramics, hybrid composites and aerogels will be reviewed.


CL-1:IL02  Yb3+ Photoluminescence Enhancement by Disordered Plasmonic Networks Assembled on Anisotropic Crystals
L. SANCHEZ-GARCIA, M.O, RAMIREZ, L.E. BAUSA, Dept. Fisica de Materiales, Universidad Autónoma de Madrid, Madrid, Spain; J.J. CARVAJAL, R. SOLE, M. AGUILO, F. DIAZ, Fisica i Cristal·lografia de Materials i Nanomaterials, Universitat Rovira i Virgili, Tarragona, Spain

Designing metallic nanoparticle arrangements to enhance the optical properties of Yb3+ ions is a challenge relevant to a variety of fields such as bio-imaging, photovoltaics, photocatalysis, or ultra-short solid state lasers. Here, metallic nanoparticles connected forming disordered plasmonic networks (DPNs) are assembled onto the polar surface of Yb3+ doped RbTiOPO4 (RTP) crystals. The plasmonic response of DNPs in the near infrared region is exploited to obtain up to a 5-fold enhancement of the photoluminescence (PL) of Yb3+, depending on the polarization of the excitation and emission beams. The anisotropic character of the PL enhancement is analyzed by means of the near field components of the DPNs, and the experimental absorption cross-section values of the electric-dipole transitions of Yb3+ ions along the different crystallographic directions of RTP. We show that in the near field regime, the DPNs generate additional polarization field components to that of the incident field, which allow the access to the largest transition dipole component of Yb3+ in configurations which are not available in the bare crystal. The work provides fundamental insights for controlling the emitter’s properties at the nanoscale.


CL-1:IL04  Colloidal Nanocrystals: Functional Materials for Photonic Applications
M. STRICCOLI¹, E. FANIZZA^{2, 1}, A. PANNIELLO¹, N. DEPALO¹, M. CORRICELLI¹, C. INGROSSO¹, R. COMPARELLI¹, A. AGOSTIANO^{2, 1}, M. L. CURRI¹, ¹CNR IPCF Bari c/o Chem. Dept., University of Bari, Bari, Italy; ²Chemistry Dept., University of Bari, Bari, Italy

The design of innovative materials joining original tailored properties with versatile and reliable processing capabilities, represents one of the most crucial challenges in modern material science. Improved chemistry protocols allow the synthesis of colloidal functional nanocrystals (NCs) in a large variety of shapes, sizes and compositions with tunable chemical and physical properties. In particular, semiconductor inorganic NCs have been widely exploited as quantum optical emitters, thanks to their high quantum yield, chemical stability, low tendency to photobleaching and possibility to be tuned in a large spectral range. Also, recently, perovskite NCs and carbon dots have attracted great attention due to their very intense emission and to the low toxicity, respectively. In addition, post-synthetic functionalization procedures allow to manipulate such nano-objects, integrating them in solid matrices, assembling on substrates, or conjugating with organic molecules, preserving their original optical properties and adding new ones. The nanoscale emitters can be effectively used as nanosized building blocks to fabricate optically active materials for photonic devices by exploiting their controlled organization on surfaces or their dispersion in polymeric matrices.


CL-1:IL05  Integrated Lithium Niobate Photonics
M.A. BAGHBAN, K. GALLO, Department of Applied Physics, KTH-Royal Institute of Technology, Stockholm, Sweden

Lithium niobate (LiNbO3) is a ferroelectric material which intrinsically affords superb electro-optic, acousto-optic and nonlinear optical properties, still setting the standards for telecommunications and quantum optics in critical applications such as high-speed modulation, frequency conversion and antenna remoting devices in RF photonics. This talk will provide a review on current status and development prospects of integrated photonic devices in LiNbO3 platforms, afforded by the deployment of nanotechnology tools in this material. The intrinsic nonlinear- and electro-optic properties of LiNbO3 can be combined with the high index contrast in thin-film LiNbO3 structures amenable to integration with silicon, to realize small-footprint integrated optical devices such as photonic crystals, resonators, filters and wavelength converters with various applications in telecom and quantum optics. Such devices can be further combined with other platforms such as single photon detectors and superconducting materials in order to provide higher degrees of freedom and enhanced functionalities for advanced classical and quantum applications.

 
Session CL-2 - Luminescent and Chromogenic Ceramics and Glass Systems

CL-2:IL01  Ceramic Phosphor Development for Solid State Lighting (SSL)
I. KINSKI, M. ARNOLD, Fraunhofer Institute for Ceramic Technologies and Systems, Hermsdorf, Germany; M. Fries, U. Partsch, Fraunhofer Institute for Ceramic Technologies and Systems, Dresden, Germany

Technological approaches for high performance application for lighting tend to use polycrystalline ceramic phosphor converter materials in order to overcome degradation of polymers and glasses used in conventional indoor lighting. Ceramic discs applied in SSL are exposed to high power fluence and therefore the excitation source and the optical system are crucial parameters defining the requirements on the ceramic light converters. The tailoring of the ceramic microstructure depends strongly on the excitation source whether a light-emitting diode (LED) or laser diode (LD) is used and has to be adjusted and optimized, accordingly. The optical pathways and thermal heat management has to be taken into account regarding the different possibilities of arrangement in the system of the light-converting ceramic to the excitation source. For all applications the adjustment of scattering centers is most essential for the intended use. Different processing routes for the ceramic phosphors have been developed, followed by an upscaling of the ceramic discs and finishing processes to a size of 4 inch in order to realize a wafer to wafer process to build up a full ceramic hermetically sealed package.


CL-2:IL02  Rare-earth-doped Glass and Glass-ceramic Phosphors for Radiation Imaging and Dosimetry
GO OKADA¹, F. CHICILO², JUMPEI UEDA³, S. TANABE³, A. EDGAR⁴, G. BELEV², T. WYSOKINSKI⁵, D. CHAPMAN², T. YANAGIDA¹, S. KASAP², ¹Nara Institute of Science and Technology, Nara, Japan; ²University of Saskatchewan, Canada; ³Kyoto University, Japan; ⁴Victoria University of Wellington, New Zealand; ⁵Canadian Light Source, Canada

Radio-photoluminescence (RPL) is a phenomenon in which luminescent centres are generated in phosphor materials by incident ionizing radiation. The generated centres can be easily observed via photoluminescence (PL) and the intensity is proportional to the incident radiation dose. Therefore, the RPL response signal can be utilized as a probe of incident radiation dose. In addition, the signal is stable at room temperature and under excitation light, and can be read out by confocal microscope so as to obtain the spatial variation of a radiation dose on a microscopic scale. We are currently particularly interested in RPL phenomenon in Sm-doped materials. Samarium exhibits intra-valence reduction of Sm (Sm3+ -> Sm2+) following irradiation (eg. with X-rays). As a result, a PL signal of Sm2+ emerges and can be utilized as a probe of radiation dose. This phenomenon was successfully proven to be an effective tool in Microbeam Radiation Therapy (MRT), which employs an array of micro X-ray beams and an extremely high X-ray dose for radiotherapy.


CL-2:IL03  GGAG Nanoceramics Doped with Rare Earth for Application in LED Lighting
P. GLUCHOWSKI, W. STREK, W. RYBA-ROMANOWSKI, P. SOLARZ, Institute of Low Temperature and Structure Research PAS, Wrocław, Poland

The GGAG:RE3+ (RE: Ce, Dy, Eu-Tb-Ce) ceramics were fabricated by low temperature high pressure technique from the respective phosphors synthesized using modified Pechini method. The nanocrystals obtained with this method have the size from tens to hundreds nanometers. Small size of grains, cubic structure of the GGAG garnet and high pressure sintering method allow to obtain translucent ceramics that can be successfully used in LED devices. The impact of grain size and morphology, RE3+ concentration and nanoceramic sintering conditions on the spectroscopic properties of GGAG:RE3+ was checked and analysed. The spectroscopic properties of the nanopowders and nanoceramics were compared to the single crystal. In the GGAG ceramics co-doped with different lanthanide pairs energy transfer processes were investigated. The spectroscopic properties of GGAG:RE3+ suggest that this material can be used as a potential phosphor with multicolor emission used in white LED systems.
This work was supported by the National Science Centre, Poland under grant number DEC-2014/15/B/ST5/05062.


CL-2:IL04  Optical, Luminescent and Mechanical Properties of SPSed Ceramics Based on YSZ and MgAl2O4
E.S. DVILIS, O.L. KHASANOV, E.F. POLISADOVA, V.D. PAYGIN, Tomsk Polytechnic University, Tomsk, Russia

Sintering kinetics of YSZ, MgAl2O4 commercial nanopowders was studied by the dilatometry. Shrinkage, activation energy of the grain-boundary diffusion, thermal expansion coefficient were determined. The studied samples were compacted as by the static uniaxial pressing so by the compaction using non-cavitation powerful ultrasound assistance (PUA). PUA compaction allows to increase the density of YSZ green compacts, sintered ceramics and optical transmittance. Transmittance 12% at 555 nm, 79% at 2700 nm for YSZ ceramics and 73% at 555 nm, 77% at 750 nm for MgAl2O4 were achieved by SPS. Microhardness, fracture toughness, creep at indentation of sintered transparent samples were determined by the nanohardness and microhardness testers. Using 3D profilometer the dynamic evolution of the swelling areas with time after local indentation of transparent YSZ ceramics was shown. Approach to optimize the SPS regimes to sinter ceramics with improved transmittance in the selected wavelength range was suggested. The approach does not use the microstructure characteristics of sintered samples but applies the optimization criteria based on the equation describing the dependence of optical density normalized by sample thickness versus wavelength.


CL-2:IL05  Theoretical Modeling of Optical Properties of Red Phosphors for White LEDs
M.G. BRIK, College of Sciences, Chongqing University of Posts and Telecommunications, Chongqing, P.R. China; Institute of Physics, University of Tartu, Tartu, Estonia; Institute of Physics, Jan Długosz University, Czestochowa, Poland

In the recent years active research is focused on the red phosphors for solid state lighting. One of the most important applications of these phosphors is connected with the white LEDs. The main targets are lowering the correlated color temperature and increasing the color rendering index. The ions of choice for such phosphors are often Mn4+ and Eu3+. Several models that allow to calculate the electronic and optical properties of these impurities in various solids will be discussed in the present talk. Special attention will be paid to the relations between the structural/chemical properties of the host materials and positions of the emission lines. Several trends across large groups of phosphor materials were revealed based on the systematic analysis of the obtained results. A few practical recommendations how to tune red emission of the Mn4+ ions will be formulated. Presentation will be supported by recent publications combining experimental and theoretical results.


CL-2:L06  Morfological, Photoluminescent and Structural Properties Study of Pr3+-Doped α-Ag2WO4 Synthesized by the Coprecipitation Methodology
I.L.V. ROSA¹, C.L. CORREA¹, I.M. PINATTI¹, R. ROMANCINI¹, E. LONGO^{1, 2}, ¹CDMF, LIEC, Chem. Depart., Federal University of São Carlos (UFSCar), São Carlos, Brazil; ²CDMF, LIEC, São Paulo State University (UNESP), Araraquara, Brazil

Among the semiconductor oxides with AWO4 formula, silver tungstate is a material with monovalent cation (Ag+) and present the crystallographic forms α-, β- and γ-Ag2WO4, being the α (orthorhombic), the most thermodynamically stable form, the focus of this study. Silver tungstate has been used for the chemical fixation of CO2, catalyst in organic chemistry, light detector and microbial agent. The rare earth (RE) ion Pr³+ stands out due to the possibility of simultaneous emissions in the blue, green and red region for use in lasers, as well as for its emission in the infrared for optical amplification. Praseodymium doped silver tungstate (Ag2WO4:Pr3+) powders were synthesized by the coprecipitation method at 90 °C for 30 minutes using Na2WO4.2H2O, AgNO3 and Pr2O3 as precursors. The powders were prepared with different concentrations of RE ions, in order to study their structural, photoluminescent and morphological properties. The X-ray diffraction patterns agree with a single phase (α), while the Raman spectroscopy showed the vibrational modes B1g, A1g and A2g, indicating order at long and short range for all samples. Photoluminescence spectroscopy showed characteristic transitions of RE ions, such as 1D2-3H4, 3P0-3H6 and 3P0-3F2 of Pr3+ in the red region.


Session CL-3 - Transparent Conducting and Non-conducting Ceramics

CL-3:IL02  Chalcogenide Glass-ceramics Transparent in the Infrared
L. CALVEZ, Glass and ceramic team UMR-CNRS 6226, Institute of Chemical Sciences of Rennes, Université de Rennes 1, Rennes, France

Chalcogenide glass (ChG) shows excellent IR transmission ranging from 0.8 μm up to 20 μm, thus becoming a valuable building block in IR optics. However, the advantages of ChG are largely inhibited by their relatively weak thermo-mechanical properties. Fortunately, glass-ceramics with crystal phases of different physicochemical properties give a route for the enhancement of mechanical properties, meanwhile keeping the usual advantage of fabrication versatility. The crystallization behavior of Ge(S/Se)2-based ChG were firstly focused on the addition of (Ga2S/Se)3 with or without the addition of alkali halide. However, chalcogenide glass-ceramics (ChGC) are not only dedicated to the enhancement of mechanical properties. In fact, depending on the glass composition, ‘a la carte‘ properties can be obtained. Thus, the possibility to strongly increase the luminescence efficiency by controlled crystallization within ChGC doped with rare-earth will be developped. Moreover, by controlling the generated crystalline species, some ChGC present outstanding properties such as photo-carrier generation, potentially leading to novel generation of photosolar cells. Finally, the possibility to fasten the crystallyzation process by using sintering process such as SPS will be demonstrated.


CL-3:IL03  Transparent Ceramics Based on Rare Earth Ions-doped Cubic Tungstate/Molybdate Matrices: A Challenge and Prospect for New Efficient Optical Materials?
M. GUZIK¹, M. BIEZA¹, E. TOMASZEWICZ², Y. GUYOT³, G. BOULON³, ¹Faculty of Chemistry, University of Wrocław, Wrocław, Poland; ²Department of Inorganic and Analytical Chemistry, West Pomeranian University of Technology, Szczecin, Poland; ³Univ Lyon, Université Claude Bernard Lyon1, CNRS, Institut Lumière Matière, Villeurbanne, France

Surprisingly, today available rare earth (RE3+) luminescent ions-doped cubic optical transparent ceramics used as laser sources or phosphors for lighting are limited to a very small number. The main objective of this project is to select carefully new RE3+ luminescent ions-doped tungstate/molybdate chemical compositions, fulfilling two conditions, cubic crystallographic system and size of the crystallites up to 100 nm, different of usual garnets, sesquioxides or fluorites, owing to their long longevity, low cost, and excellent chemical stability. The choice of RE3+ ions has been Nd3+ and Yb3+ for IR and visible lasers and Eu3+ for red phosphors. The host lattices, in which the substitution of optically un-active trivalent La3+ or Y3+ by RE3+ ions will take place have been preferred. For each composition, nano-powder materials are researched by various methods: Pechini, combustion, hydrothermal, methods and high-temperature solid state reaction. Results on both synthesis and spectroscopic characterizations of Eu3+, Nd3+ and Yb3+-doped La2MoWO9, La2Mo2O9 and Y6MoO12 cubic compounds will be presented. Our attention now is focused on both the crystal growth by using the micro-pulling down method (µ-PD) and the fast SPS (Spark Plasma Sintering) technique for transparent ceramics.


CL-3:L04  Spark Plasma Sintering (SPS) of Alumina-based Transparent Ceramics
A. PILLE¹, A. KANAEV¹, T. BILLETON², E. FELDBACH³, F. SCHOENSTEIN¹, ¹Laboratoire de Sciences des Procédés et des Materiaux, CNRS UPR-3407, Université Paris 13, Sorbonne Paris Cité, Villetaneuse, France; ²Laboratoire de Physique des Lasers, CNRS UMR-7538, Université Paris 13, Sorbonne Paris Cité, Villetaneuse, France; ³Institute of Physics, University of Tartu, Tartu, Estonia

Polycrystalline alumina and spinel ceramics are abundantly used in industry due to their chemical inertness, good insulating qualities and fascinating mechanical, thermal, and optical properties. They have lately been in the limelight because of their promising nanoscale self-healing properties and possible applications in hazardous environments. In this work we put emphasis on improving the transparency and decreasing the grain size of sintered ceramics. We use self-synthesised starting powders and make a comparison with commercially available powders. The powders are consolidated using novel reactive Spark Plasma Sintering (SPS) approach. We discuss the importance of the phase, crystallite and particle size of the starting powders, as well as the sintering cycle and show different options to produce transparent ceramics via SPS. Investigation of the effect of proton irradiation on the luminescence of ceramics with various grain sizes will be presented.

 
Session CL-4 - Laser Materials

CL-4:IL01  Optical Ceramics for High Energy Lasers
J. SANGHERA¹, WOOHONG KIM¹, G. VILLALOBOS¹, S. BAYYA¹, C. BAKER¹, M. HUNT¹, B. SHAW¹, J. FRANTZ¹, B. SADOWSKI², R, MIKLOS², L. BUSSE¹, D. BOYD¹, I. AGGARWAL², C. ASKINS¹, J. MYERS¹, J. PEELE², D. RHONEHOUSE¹, R. THAPA², S. BOWMAN¹, ¹Naval Research Laboratory, Optical Science Division, Washington, DC, USA; ²Sotera Defense Solutions, Herndon, VA, USA

We report our recent progress in the development of high quality transparent ceramic window materials and laser gain materials for high energy laser (HEL) systems. NRL had previously demonstrated technology to make spinel ceramic with an absorption loss of 6 ppm/cm at 1.06 µm in small size samples. In this presentation, we provide an update of the results of the scale up process with a goal of 30 cm diameter windows by hot press method. We also demonstrate high optical transparency from various ceramics fabricated by microwave sintering process. High efficiency laser oscillations from various rare-earth sesquioxides are also presented. Antireflective surface structures (ARSS), fabricated directly into the surface of various substrates including transparent ceramics, single crystals, and fused silica windows, lenses, and fibers are also demonstrated. Very low reflection losses as well as high laser damage thresholds have been measured for optics with ARSS. Furthermore, these structures can be chemically modified to impart superhydrophobic character to the surface which is very important and beneficial for many military and commercial applications. We present our recent progress in the development of cladded single crystal fibers for high power single frequency lasers. Both high quality transparent ceramics and commercial single crystals have been successfully used as feed stocks to grow high quality rare earth doped crystal fibers using Laser Heated Pedestal Growth (LHPG) method. Various fabrication methods, optical characterization and gain measurements are presented on these single and double clad fibers.


CL-4:IL02  Yb:CaF2 Laser Ceramics: Synthesis and Physical Characterizations
M. MORTIER, J. SARTHOU, P. GREDIN, Institut de Recherche de Chimie Paris, CNRS - Chimie ParisTech, PSL Research University France; F. DRUON, J. HOSTALRICH, P. GEORGES, Laboratoire Charles Fabry, UMR 8501, Institut d’Optique, CNRS, Univ. Paris Sud, Palaiseau, France

Recently, Yb:CaF2 crystal has demonstrated its potential as near-IR high power amplifier pumped with diode around 980 nm. CaF2 gathers high physical properties (thermal conductivity, laser damage threshold) and attractive optical properties (broad bands) because of the specific organization of rare earths as hexameric clusters in fluorite. These properties are promising for short pulses with high repetition rates or widely tunable laser systems. If these crystals have demonstrated significant results toward power and fluence scaling-up, the challenge would now lies in the transposition of these results to a ceramic form, which would provide new advantages: easier production, few size or shape restrictions and enhanced fracture resistance. We report the preparation and characterization of Yb:CaF2 ceramics synthesized from raw nanopowders obtained through soft chemistry route. The preparation of the green body uses a new pressureless method. The densification of the green body involves no additional pressure assistance, and requires moderated temperature. The laser properties of the obtained ceramics were measured and physical properties, such as thermal conductivities and lattice dynamics, were explored after a careful study of the structure and chemical composition.


CL-4:IL04  Vision for Advanced Laser Materials
J. BALLATO, M. CAVILLON, P.D. DRAGIC, Clemson University, Clemson, SC, USA; University of Illinois at Urbana-Champaign, Urbana, IL, USA

Sustained progress in solid state laser has led to the present state where further performance improvements are limited by intrinsic optical nonlinearities. This is particularly true in optical fiber-based lasers. This paper treats a simple and direct solution: mitigate nonlinearities at their fundamental origin - the material with which the light interacts. Such a materials approach permits greater reductions to nonlinearities than other present methods. Simpler geometries and ease of manufacturing are additional benefits of this unified materials approach. More specifically, the material properties that give rise to Brillouin, Raman, and Rayleigh scattering, transverse mode instabilities (TMI), and n2-mediated nonlinear effects will be reviewed and results discussed with a focus on trends with glass family. Optical power scaling estimations as well as binary and ternary property diagrams associated with parasitic nonlinearities are employed to graphically represent compositional trends and targets for an intrinsically low nonlinearity, silica-based optical fiber. While optical fibers will be used as an example, the materials approach can be broadened to other solid state laser materials and systems.


CL-4:IL05  Mid-infrared Transition Metal Doped Chalcogenide Laser Materials and Lasers
S.B. MIROV^1,2, I.S. MOSKALEV², M.S. MIROV², S. VASILYEV², V.V. FEDOROV^1,2, D.V. MARTYSHKIN^1,2, O. GAFAROV¹, V. SMOLSKI², ¹Center for Optical Sensors and Spectroscopies and the Department of Physics, University of Alabama at Birmingham, CH 310, Birmingham, AL, USA; ²IPG Photonics Corporation, Southeast Technology Center, Birmingham, AL, USA

We report on unique process of recrystallization and effective doping of ZnS ceramics under hot isostatic pressing resulting in a large cm-scale monocrystalline domains formation and an increase of the Fe diffusion coefficient by three orders of magnitude. We also present a breakthrough in high-power CW Cr:ZnS/Se laser systems, enabling output power levels of up to 140 W near 2500 nm, and 32 W at 2940 nm with corresponding optical efficiencies of 62% and 29%. This talk also summarizes recent improvements of output characteristics of polycrystalline Cr:ZnS/Se master oscillators in Kerr-Lens-Mode-Locked regime. Current research efforts include power scaling of fs Cr:ZnS/Se lasers beyond the 7 W level, development of octave-spanning oscillators, further power and energy scaling of fs Cr:ZnS/Se laser amplifiers, and extension of ultrafast laser oscillations to 3 – 10 µm spectral range, including a first ultrafast optical parametric oscillator based on random phase matching in disordered polycrystal, ZnSe ceramic.


CL-4:L06  Recent Progress on Fabrication of Rare-earth Doped Sesquioxide Laser Ceramics
J. WANG^{1, 2}, D.L. YIN¹, P. LIU ², J. MA^{1, 2}, Z.L. DONG³, L.B. KONG³, DINGYUAN TANG^{1, 2}, ¹School of Electrical and Electronic Engineering, Nanyang Technogical University, Singapore; ²Jiangsu Key Laboratory of Advanced Laser Materials and Devices, Jiangsu Normal University, China; ³School of Materials Science and Engineering, Nanyang Technological University, Singapore

Sesquioxide ceramics, such as Y2O3, Lu2O3, and Sc2O3, have excellent thermal conductivity, thermal expansion coefficient, and relatively small phonon energy. They are desired host materials for high power lasers. In this talk, we will present our works on the fabrication of various rare-earth doped sesquioxide laser ceramics, such as Yb3+:Y2O3, Yb3+:Lu2O3, Nd3+:Y2O3, Ho3+:Y2O3, and Er3+:Y2O3. Well dispersed Y2O3 and Lu2O3 nano-powders with good dispensability were synthesized by using the chemical co-precipitation method. The influences of different sintering aids and sintering conditions on densification and microstructure evolution of the ceramics were investigated. High optical quality sesquioxide laser ceramics were produced, especially, high efficient laser operations at 1.0µm, 2.0µm, 3.0µm based on our fabricated laser ceramics were successfully demonstrated.


CL-4:L07  Nd3+-doped Lu2O3 Laser Materials as Ceramics (SPS, HIP) and Single Crystals (µ-Pulling Down). Spectroscopic Properties and Comparison of Laser Outputs
G. BOULON, G. ALOMBERT-GOGET, Y. GUYOT, Institute Light Matter, UMR5306 CNRS, UCBLyon1, University of Lyon, Villeurbanne, France; M. GUZIK, Faculty of Chemistry, University of Wrocław, Poland; J. PEJCHAL, A. YOSHIKAWA, A. ITO, T. GOTO, Institute for Materials Research,Tohoku University, Sendai, Japan; A. IKESUE, World Lab. Co., Ltd., Nagoya, Japan; G. TOCI, National Institute of Optics, NRC, INO-CNR, Sesto Fiorentino, Italy

The research activity on advanced laser materials is greatly increasing with the availability of transparent sintered polycrystalline ceramics [1]. Our research approach is under progress with laser materials at the frontier of materials science as for example Lu₂O₃ sesquioxyde of melting point higher than garnets. It has been suggested to be suitable host materials in high power laser applications due to the highest thermal conductivity (12.5 W/m/K) compared with YAG (10.8 W/m/K). However, it is extremely difficult to grow Lu₂O₃ single crystal by the LHPG and the µ-Pulling Down techniques because of its high melting point (2490 °C). Indeed, it is much easier to fabricate Lu2O3 into a ceramic structure -solid-state reaction process- because the sintering temperature is about 700 °C lower than its melting point. This is why we are involved with the fabrication and the comparison of spectroscopic properties, thermal conductivities and laser outputs of Nd³⁺-doped Lu₂O₃ transparent ceramics by both SPS and HIP techniques [2-5].
[1] J. Sanghera et al. Opt. Mater. 35 (2013) 693–699. [2] G. Alombert-Goget et al, Opt.Mat., 41 (2015) 3-11. [3] G. Toci, et al Opt. Mat., 41 (2015) 12–16. [4] M. Guzik et al, J. of Lum 169 (2016) 606–611. [5] L. An et al, Vol.4 Opt. Mat. Ex. (2014) 1420.


CL-4:L08  Effect of Gd3+ on Yb3+ Emission in Gd Admixed Yb:YAG at Cryogenic Temperature
S.P. DAVID, V. JAMBUNATHAN, F. YUE, P. NAVRATIL, M. MIKA; A. LUCIANETTI, T. MOCEK, HiLASE Centre, Institute of Physics CAS, Dolní Brežany, Czech Republic; Department of Glass and Ceramics, University of Chemistry and Technology, Prague, Prague, Czech Republic

Mixed garnet materials doped with laser active ions are relatively a new class of materials which find applications for ultra-short lasers due to their inhomogeneous broadening. Recently, we found that the addition of Ga3+ in YAG results in maintaining the spectral broadening of Yb3+ emission even at cryogenic temperature. This confirmed Y3Al5-xGaxO12 a promising material for generating ultra-short pulses at cryogenic temperature compared to YAG. To further explore this idea of multicomponent garnets, efforts were made to prepare Gd3+ admixed YAG garnets doped with Yb3+ ion. With a fixed Yb3+ concentration, the ceramics pellets were made by solid state reaction with different concentration of Gd. The prepared samples were subjected to structural and emission studies. Compared to YAG, the Yb3+ emission spectra recorded for Gd admixed YAG at cryogenic temperature shows around ~20% broadening and a shift in emission peak towards the longer wavelength with the increase in Gd concentration. The crystal field due to Gd3+ addition is different from that of Y3+ which results in inhomogeneous broadening. Gallium occupies Al3+ site whereas Gd3+ occupies Y3+ site. Measurements were made at different cryogenic temperatures and the results will be discussed in detail.


Session CL-5 - Inorganic Optical Fibers

CL-5:IL01  Optical Fiber Materials and Process Innovations for Next Generation Telecommunication Systems
P. TANDON, Corning Inc., Corning, NY, USA

Optical fibers have been extensively used in telecommunication systems for decades. Most of the optical fibers used are silica based glass fibers and are made using chemical vapor deposition (CVD) process. The talk focuses on the trends in telecommunication industry, particularly concentrating on the requirements on the optical fibers to meet the growing capacity demand of fiber optic systems. Optical fiber materials and process innovations are discussed that are essential for developing optical fiber technologies for next generation telecommunication systems. Role of glass science and technology is highlighted as the key enabler in the development of these fibers, along with a discussion of future areas of interest.


CL-5:IL02  Shining a Light on Disease with Mid-infrared Fibreoptics
A.B. SEDDON, Ł. SOJKA, T.M. BENSON, D. FURNISS, Z.Q. TANG, H. PARNELL, D. JAYASURIYA, Y. FANG, M. SHEN, S. SUJECKI, Mid-Infrared Photonics Group, George Green Institute for Electromagnetics Research, University of Nottingham, Nottingham, UK

Our vision is of a new paradigm of portable, real-time mid-infrared molecular sensing and imaging in medicine and healthcare, including for early cancer detection and screening. We are developing long-wavelength mid-infrared chalcogenide-glass optical fibres for passive, nonlinear and luminescent optical behaviour to create new devices which are robust, functionally-designed, safe, compact and cost-effective. Our latest results in developing mid-infrared chalcogenide glass optical-fibre as coherent sources and for passive transmission will be presented along with competing technologies. In addition, recent results in mid-infrared sensing and tissue imaging using chalcogenide glass fibre systems will be described.


CL-5:IL04  Composite Material Optical Fibres - Functionalisation with Semiconductors and 2D Materials
P.J.A. SAZIO, A. LEWIS, F. DE LUCIA, W. BELARDI, F. POLETTI, C.C. HUANG, D. HEWAK, ORC, University of Southampton, UK; V. GOPALAN, J.V. BADDING, Dept. of Chemistry and Materials Research Institute, Pennsylvania State University, State College, PA, USA

Over the past decade a new field of semiconductor-based optical fibre has emerged. Using high pressure chemical deposition technology developed by our groups at Penn State and ORC Southampton, semiconductors such as Si or Ge have been grown inside hollow silica glass fibres, allowing the properties of these materials to be exploited for applications such as all-fibre optoelectronics. The high-pressure technique is simple, low cost, and flexible so that it can be modified and extended to fill the large number of micro- and nanoscale pores in microstructured optical fibres, including the latest Hollow-core Antiresonant (ARF) structures thus providing flexibility to enhance the potential application base of these devices. Recent work has seen the integration of silicon into ARFs, demonstrating that these novel Composite Material ARFs can be fabricated in relatively long lengths (> 30cm) and could exhibit negligible attenuation levels. Work has also been undertaken on the deposition of the TMD materials inside CM-ARFs. The transmission spectra of these novel CM-ARFs has been analysed, exhibiting little additional loss compared with control samples. I will discuss the optical fibres we have fabricated to date and the prospects for using them in the manipulation and generation of light.

 
Session CL-6 -  Photons Management

CL-6:IL01  Whispering Gallery Mode Resonator Based Sensors
T. IOPPOLO, Southern Methodist University, Dallas, TX, USA

All-photonic micro-sensor based on the optical resonance (commonly referred to as the whispering gallery modes, WGM) shifts of dielectric spherical and dome shaped resonators will be presented. The WGM possess very large optical quality factors which allow for the development of miniaturized, extremely high-resolution sensors. Tethered and untethered sensors will be presented. Tethered sensors are mainly spherical micro cavities that are coupled evanescently to a single mode optical fiber. The optical fiber serves as input output port to excite and interrogate the optical modes. Untethered sensors are essentially spherical or dome shaped microscale lasers that are excited using an external light source. The emission spectrum of the microscale laser is observed using a spectrometer. This last configuration allows for a remote excitation and interrogation of the optical modes. In both configurations, a change in the morphology of the micro cavity due to an external effect leads to a shift in its optical modes. The optical shift in turn is monitored and related to the external effect. Sensors based on this concept will be presented for different applications.


CL-6:IL02  Rare Earth Microcavity Lasers for Silicon Nanophotonics
J.D.B. BRADLEY, McMaster University, Hamilton, Ontario, Canada

In this presentation I will discuss our recent work on ultra-compact rare-earth-doped dielectric microlasers integrated on silicon photonic chips. We achieve laser action using a novel monolithically integrated high-Q microresonator design. The resonator structure includes a circular trench filled with rare-earth-doped glass beside a co-integrated silicon nitride bus waveguide for on-chip laser output. In passive (undoped) microresonators we measure internal quality factors > 1e6 at a wavelength of 1.5 µm. We show lasing at 1.0, 1.5 and 1.9 µm in ytterbium, erbium, and thulium-doped microcavities, respectively, and in devices with diameters ranging from 80 to 200 µm. We observe sub-milliwatt lasing threshold powers, approximately 10 times lower than previously demonstrated in rare-earth-doped waveguide lasers on silicon. The microlaser fabrication process is CMOS-compatible and allows for integration of such lasers within integrated silicon photonic circuits for optical communications and sensing.


CL-6:IL03  Efficient Frequency Conversion in PhoXonic Cavities Based on Whispering Gallery Mode Resonators
D. FARNESI, G. RIGHINI, G. NUNZI CONTI, S. SORIA, CNR-IFAC, Institute of Applied Physics "N. Carrara", Sesto Fiorentino, Italy

Whispering gallery mode resonators (WGMR) because of their extraordinary high quality factors and small mode volumes strongly enhance light-matter interactions and are ideally suited for nonlinear optical interactions They can be specifically exploited for low power continuous wave (CW) nonlinear frequency conversion, which is still a challenge in nonlinear optics. We report on nonlinear optical effects on phoxonic cavities based on hollow whispering gallery mode resonators pumped with a continuous wave laser. We observed stimulated scattering effects such as Brillouin and Raman, Kerr effects such as degenerated and non-degenerated four wave mixing, and dispersive wave generation. These effects happened concomitantly. Hollow resonators give rise to a very rich nonlinear scenario due to the coexistence of several family modes.
 
 
Session CL-7 - Advances in Characterization Techniques

CL-7:IL03  The Role of Computations in Complex Optical Problems
L. RAMUNNO, A. CALÀ LESINA, P. BERINI, University of Ottawa, Ottawa ON, Canada

Computational electrodynamics provides an important tool for understanding light-matter interaction in complex nanoscale systems. Simulations bring insight to experimental results by allowing one tease out the most relevant underlying phenomena in very complex scenarios. In this talk, I will focus on two problems we were able to tackle by large scale computational approaches. The first is understanding why metal surfaces appear coloured after exposure to intense ps laser pulses. While the colours are quite reproducible, SEM images reveal a very complex surface, including random distributions of nanoparticles and underlying structures. Our computations show that plasmonic effects are key to the generation of colour, and from this we are able to detangle what features on the complex surfaces were responsible for particular colors. The second problem is understanding why strong birefringence is observed in a new carbon allotrope material randomly intercalated with silver/gold alloy nanoparticles. By developing a Clausius-Mossotti theory for arbitrary atomic lattices and a model for the metal alloy, then using these in our computations, we explain experimental measurements and develop an understanding of the optical properties of this new complex material.


CL-7:L04  Ultrafast Scanning Electron Microscopy (USEM) to Probe Charge Dynamics in Oxide Thin Films
S.M. PIETRALUNGA^{1, 2}, V. SALA^{2, 3}, G. CERULLO^{1, 3}, G. LANZANI^{2, 3}, G. IRDE^2,3, M. ZANI³, A. TAGLIAFERRI^{2, 3}, ¹CNR-IFN, Milano, Italy; ²CNST@Polimi, IIT, Milano, Italy; ³Department of Physics, Politecnico di Milano, Milano, Italy

Photon—assisted Ultrafast Scanning Electron Microscopy (USEM) is a novel stroboscopic pump-probe technique to probe charge carrier dynamics, featuring ps time resolution, nanoscale spatial resolution and surface sensitivity. It employs synchronized pulsed laser and electron beams, respectively to excite optical transitions and to probe their dynamical effects in terms of Secondary Electron (SE) contrast. A USEM setup has been devised, excited by an UV laser beam and operating in Ultra-High Vacuum regime. By a lock-in detection scheme, fast dynamical SE signal in the picosecond and nanosecond scale can overpass charging effects and optically induced CW contributions. In this way USEM becomes a successful tool -complementary to time resolved PL and CL- also for oxide thin films and wide bandgap insulators, to visualize the SE dynamics proceeding from optically active defects and charge traps. We show USEM dynamics in the case of color centers in Al2O3 – on-Silicon thin film. UV excitation of an oxygen vacancy state at surface as well as hot electron photoemission from color centers excited by the electron beam are probed by SE contrast evolution. SE depletion, acting at short positive delays, was attributed to fast laser-induced surface charging in the tens of ps range.

 
Session CL-8 - Ongoing Applications and Forecasts

CL-8:IL01  Transparent Ceramics: Materials, Engineering Progress and Applications
A.E. GOLDSTEIN, Israel Ceramics and Silicates Institute, Haifa, Israel

This communication intends to provide a state of the art review - of the field of transparent ceramics (TCs). First, after a brief recapitulation of the evolution of transparency, in ceramics - the main materials, now achievable in transparent state ( 0.15-15 micron range ), will be presented. Then the progress made in understanding, processing and characterization of the TCs will be exemplified. For instance the theories developed - for the quantitative treatment of the effect of factors like ceramics porosity, birefringence or transition cation absorption, on the incident electromagnetic radiation attenuation - will be discussed. The fact that green-body configuration is the key to full densification was, gradually, realized. As a result new powder processing, correlated with improved forming methods were put forward; the main developments will be treated, together with new processing methods (non sintering) like CVD or full glass-crystallization. The TCs found already many applications like envelopes for Na vapor based street lamps, solid state lasers, Q-switches, phosphors, scintillators, electro - optic components (based on transparent perovskites), transparent armor etc.; these apps will be discussed. Future perspectives, of TCs, will be also considered.


CL-8:IL02  Progress in Transparent Ceramic Development and its Laser Applications
M. DUBINSKII, US Army Research Laboratory, Adelphi, MD, USA

Rare-earth doped transparent ceramics are uniquely positioned as gain media for a wide variety of laser applications. Presented here is an overview of ARL activities in spectroscopic research of laser ceramics, their laser performance and novel laser ceramic development with major emphasis on highly scalable resonantly-pumped eye-safe lasers and Mid-IR lasers. The concept and the benefits of ultra-low quantum defect laser operation are illustrated by our experimental data. The results of laser experiments with concentration-composite ceramics, waveguided ceramic designs and Mid-IR lasers are presented. There has been significant emphasis lately on highly thermo-conductive transparent ceramics as the gain media the most amenable to power scaling. This paper also presents our most recent results in highly thermo-conductive rare-earth doped transparent ceramic development, including Er-doped Aluminum Nitride, sapphire and Magnesium Oxide ceramics. Below one can find a list of some publications by the ARL research team pertaining to the results presented in this overview presentation.
References: [1] T. Sanamyan,…M. Dubinskii, Las. Phys. Letters 11 (2014) 065801-1. [2] T. Sanamyan,…M. Dubinskii, Opt. Materials 35 (2013) 821. [3] N. Ter-Gabrielyan,…M. Dubinskii, Opt. Express 20 (2012) 25554. [4] L. D. Merkle,…M. Dubinskii, Opt. Mat. Express 2 (2012) 78. [5] T. Sanamyan,…M. Dubinskii, Opt. Express 19 (2011) A1082. C[6] N. Ter-Gabrielyan,…and M. Dubinskii, Opt. Mater. Express 1 (2011) 503.


CL-8:IL03  Additive Manufacturing of Ceramic and Glass Materials for Photonics Applications
SHUO LI¹, RAN ZOU¹, MOHAN WANG¹, SHENG HUANG¹, MING-JUN LI², M. BURIC³, P. OHODNICKIC³, KEVIN P. CHEN¹, ¹Department of Electrical and Computer Engineering, University of Pittsburgh, Pittsburgh, PA, USA; ²Corning Incorporated, Corning, NY, USA; ³National Energy Technology Laboratory, Pittsburgh, PA, USA

Additive manufacturing is a bottom-up flexible manufacturing approach that has been a subject of intense research and development efforts. While most of additive manufacturing research have been focused on metal and polymer materials, this research paper studies additive manufacturing for ceramic materials in both amorphous and crystalline states for the fabrications of optics components and opto-mechanic structures that offer superior mechanic and thermal properties for photonic systems. Using power binding and various sintering approach, the present research explores design and optimizations of cellular structures made of metal, metal-diamond composite, and ceramic components that offers unique optical, mechanic and thermal properties, which are useful for compact optical applications at both components and system levels. Using ultrafast laser manufacturing and nanolithography approach, this paper also explores bottom-up fabrication of crystalline structures based on nanostructured templates. Research works presented in this paper discusses potentials and challenges of additive manufacturing for ceramic materials.

 
CL-3:L04  Glass and Glass-ceramic of Silica-calcia System Doped with Eu3+ Ions
A. LUKOWIAK, M. PTAK, A. HOJENSKA, W. STREK, Institute of Low Temperature and Structure Research, PAS, Wroclaw, Poland; J. KRZAK, B. BABIARCZUK, B. BORAK, Department of Mechanics, Materials Science and Engineering, Wroclaw University of Science and Technology, Wroclaw, Poland

Silica–calcia system is a well known basic composition of bioactive glass. This kind of material in biological conditions is capable to form on the surface of the glass a hydroxycarbonate apatite and therefore, has the ability to bind to tissues. The sol–gel processing arrives to the formation of glass samples with high surface area rich in silanol groups that increases the degradation rate and promotes the formation of the apatite layer. The introduction of Eu3+ ions in the bioactive system may allow to obtain new functionalities, for example, to monitor structural changes during glass mineralization or to track drug release. In the presented work, the sol–gel synthesis route resulted in spherical nanosized SiO2–CaO glass particles that were transferred to glass-ceramic system when annealed at temperatures above 800 °C. The changes in the structure were shown by X-ray diffraction analysis and variation of Eu3+ luminescence spectra. The photoluminescent properties of glass and glass-ceramic systems were compared. Other spectroscopy techniques and electron microscopy images were used to determine the morphology, structure, and composition of the obtained biomaterials.
Acknowledgment. Research was supported by the National Science Centre research grant No. 2016/22/E/ST5/00530.