Symposium CL
Inorganic Materials Systems for Advanced Photonics
ABSTRACTS
CL-1:IL01 Research and Perspectives of Transparent Optical Ceramics
YIQUAN WU, K. Inamori, School of Engineering, New York State College of Ceramics at Alfred University, Alfred, NY, USA
Polycrystalline transparent ceramics are emerging as a highly promising alternative to single-crystal materials for potential utilization in a wide range of optics and photonics applications. In active pursuit of successfully processing optical quality materials, crystallographic cubic ceramics have been studied, however, processing anisotropic transparent ceramics presents significant challenges due to their inherent birefringence. In attempt to process transparent non-cubic ceramics to achieve nanostructure grain size, a field-assisted sintering method is studied in which the ceramic samples can be quickly densified without significant grain growth. Meanwhile, transparent ceramics could be made by dry and wet forming techniques. The gel-casting is a near-net shaping process for simple and complex shapes of ceramic fabrication. The process still has some disadvantages associated with toxicity, rigid conditions for reaction and high amount of organic addition. A newly developed gelling system without using toxic organic compounds has been investigated to develop transparent complex-shaped ceramics by casting processing and 3D printing. This novel process is promising to fabricate large-size and complex-shaped transparent ceramics.
CL-1:IL02 Light-driven Multiple Charge Transfers in Metal Oxide Nanocrystals
I. Kriegel, Functional Nanosystems, Italian Institute of Technology, Genova, Italy
Photodoping in doped metal oxide nanocrystals, such as indium tin oxide or doped zinc oxides, has the potential to combine light absorption, charge separation, and accumulation in the same set of materials. The underlying physical process is based on the absorption of photons with light beyond the bandgap. Similar to the photoconversion process, an electron hole pair is created and the charges are separated at the electronic interface with their surroundings. The holes react with sacrificial hole scavengers, such as ethanol, while the extra electrons remain stored within the nanocrystal. Capacitance values, comparable to commercially available supercapacitor materials have ben reported for this light-driven charging process.[1] Within this talk I will give fundamental insight into the mechanism of charge storage within metal oxide nanocrystals. I will further discuss open questions with regards to their implementation as novel light-driven multi-charge accumulation components in the next generation of solar energy devices.[2]
[1]. Brozek, C. K. et al. Nano Lett. 18, 3297–3302 (2018).
[2] Ghini, M. et al. Nanoscale 13, 8773–8783 (2021).
CL-1:IL04 Nonlinear Optics in Whispering Gallery Mode Microresonators
D. Farnesi1, X. Rosello-Mecho2, M. Delgado-Pinar2, M.V. Andrés2, G. Righini1, G. Nunzi Conti1, S. Soria1, 1IFAC-CNR, Institute of Applied Physics “N. Carrara”, Sesto Fiorentino (FI), Italy; 2Dep. of Applied Physics and Electromagnetism-ICMUV, University of Valencia, Burjassot, Spain
Stimulated Brillouin Scattering (SBS) in devices that highly confine light has attracted much attention in the last years Among these devices, whispering gallery mode resonators (WGMR) have shown to be an excellent enhancement platform to study light matter interactions such as stimulated nonlinear optical processes and frequency generation. WGMR can confine light in very small volumes and posses ultra high Q-factors . WGMR have been fabricated in a large variety of geometries and materials. One of the latest geometries, the microbubble (MBR) has attracted much attention lately. Thin walled MBR exhibit strong optomechanical effects like toroids due to their low stiffness and very dense spectral characteristics. Such properties made MBR very attractive for optomechanical and nonlinear interactions, even for larger devices.We will discuss the observation of SBS, cascading SBS in backwards and forward directions, optomechanical parametrical oscillations (OMPO), coexistence of OMPO and nonlinear phenomena, suppression of OMPO, and a detailed modeling of the mechanical oscillations, showing also very dense mechanical mode spectra. We will also discuss the different applications ranging from phonon lasing to ultrasound detection.
CL-2:IL02 Graphene-based Structures and Composites for Biophotonics
A. Lukowiak, Y. Gerasymchuk, K. Halubek-Gluchowska, M. Fandzloch, D. Szymanski, P. Gluchowski, Institute of Low Temperature and Structure Research, PAS, Wroclaw, Poland; L.T.N. TRAN, M. Ferrari, IFN-CNR CSMFO Lab. and FBK Photonics Unit, Trento, Italy
Graphene family materials are widely tested for bio-based applications in tissue engineering and regenerative medicine; imaging of biomolecules, cells, and tissues; biosensing; drug delivery; theranostics, etc. The range of applications became even broader with graphene functionalization and fabrication of composites. Hereby, we present our results obtained in the field of the optically-active graphene-based materials. The synthesis, morphology, and optical properties of selected carbon systems are discussed. First of all, we focus our attention on graphene oxide particles which can be reduced to graphene flakes or combined with other materials (zirconium(IV) phthalocyanine complexes, silver nanoparticles, or bioactive glass particles) to form active nanocomposites. Luminescent carbon dots, which maintain their tunable optical activity in silica-based matrices, are also presented as promising bio-applicable nanoparticles. The studied structures might be used to create new materials not only for nanobiophotonics but also for lighting or catalysis.
Acknowledgments: The research was supported by the National Science Centre grant No. 2016/22/E/ST5/00530.
CL-2:IL05 Impact of the Sintering Pressure on the Thermoluminescence Properties of Persistent Luminescent Ceramics
P. Głuchowski1, 2, R. Tomala1, S. Veltri1, K. Rajfur3, D. KUJAWA1, V. Boiko1, W. Strek1, 1Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw, Poland; 2Nanoceramics Inc., Wroclaw, Poland; 3Wroclaw University of Science and Technology, Wroclaw, Poland
Persistent luminescent materials are an important member of the luminescent material family, whose luminescence can last from minutes to hours after ceasing their excitation. [1]. Persistent luminescent materials that emit in visible range have been widely studied, achieving commercial success and being used as decorations, safety displays, and emergency lighting. The phenomenon of persistent luminescence results from the storage of the excitation energy in traps and its subsequent release induced by the thermal energy available at room temperature. To check energy that is needed to release electrons from the traps thermoluminescence measurements are carried out. Persistent phosphors Gd3Ga3Al2O12:RE (RE:Ce3+,Pr3+,Tb3+) were prepared by sol-gel method. From the powders respective ceramics have been prepared. For all samples glow curves were measured under different conditions. Impact of sintering pressure, vacuum, applied voltage was checked. The analyzed results help to create energy transfer mechanism and correlation between used dopant and co-dopant on the number and depth of the energy traps.
Acknowledgements This work was supported by the National Science Centre, Poland under SONATA 13 project, grant number - 2017/26/D/ST5/00904. [1] J. Hölsä, ECS Interface 18 (2009) 42
CL-2:L07 Enhancing Photoluminescence of Ceramic Phosphors Fabricated by Spark Plasma Sintering
B. RATZKER1, A. Wagner2, S. Kalabukhov2, M. Sokol1, N. Frage2, 1Department of Materials Science and Engineering, Tel Aviv University, Tel Aviv, Israel; 2Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva, Israel
Ceramic phosphors show great promise as high-power color converters for LED and laser-driven solid-state lighting leading to extensive ongoing research on fabrication and optimization of high-quality ceramic phosphors. Moreover, the strive to develop increasingly bright and efficient phosphors stimulates research on scattering effects to enhance photoluminescence. Our work focuses on ceramic YAG phosphors fabricated by spark plasma sintering (SPS), an advanced pressure-assisted sintering technique that enables rapid densification of disc-shaped ceramics. We investigated simple ways to improve the photoluminescence properties by studying the effect of surface roughness and porosity. It was found that luminescence intensity and external quantum efficiency are enhanced by increased light absorption and/or extraction. Since residual porosity was found to be the most effective, we set out to achieve controlled pore growth. This was accomplished by post-sintering heat treatments, utilizing the high-pressured gas trapped within residual pores to induce swelling. Thus, providing a method of microstructure tailoring to enhance photoluminescence and realize more effective ceramic phosphors that can be optimized for different systems and light sources.
CL-3:IL05 Mid-infrared Supercontinuum Generation from Low-phonon Energy Optical Fibers
F. Smektala, R. BIZOT, A. Lemière, A. Maldonado, M. Evrard, F. Désévédavy, B. Kibler, ICB Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-UBFC, Dijon, France
Mid-infrared supercontinuum fibered sources covering 1–20 µm are of great interest for many applications in defense, medical and particularly for sensing. In this spectral region, organic compounds such as biomolecules present fundamental vibrational resonances and an absorption pattern corresponding to their spectroscopic fingerprints. Furthermore, this spectral range covers the strategic atmospheric windows 3-5 µm and 8-12µm. This is particularly interesting for practical applications such as greenhouse gases sensing, chemical sensing, medical therapeutics and food safety monitoring. We present here the fabrication and characterization of infrared nonlinear optical fibers from tellurite glasses or chalcogenide glasses, suitable for the generation of supercontinuum in the mid-IR wavelength range. We discuss the management of the chromatic dispersion in these optical fibers with different profiles (step index or suspended core) which allows for adequate pumping with femtoseconde laser sources. As a result, we obtain different supercontinuum spectra in the mid-IR, and especially a supercontinuum covering the whole 1,7-18 µm range generated in a Ge-Se-Te step index optical fiber pumped in the femtoseconde regime.
CL-4:IL01 The Interplay Between Radiation-induced Attenuation, Photodarkening and Photobleaching at Pump Wavelength in Er- and Yb-doped Silica Optical Fibers
F. MADY, M. BENABDESSELAM, W. BLANC, Université Côte d’Azur, CNRS, INPHYNI UMR 7010, Nice, France
Radiation-induced attenuation (RIA) is the most detrimental effect in erbium- and ytterbium-doped silica fibers (EDF and YDF) operated in radiative environments. In amplifying conditions, RIA develops together with the pump-induced photobleaching (PB) and photodarkening (PD, YDF only) processes. The measured RIA then reflects a complex interplay between RIA, PD and PB. To allow a reliable treatment of RIA issues in fiber amplifier models, this interplay has still to be properly understood and modelled. This is the aim of this work. The RIA was measured at 980 nm in 1-2 cm-long fibers. Such short samples are free from amplification and ASE. They allow achieving well controlled and uniform pump power levels, thus releasing measurements from unwanted dependencies on length or pumping scheme. New remarkable properties are hence revealed, as the existence of local reversible RIA equilibrium levels, only determined by the couple dose rate-pump power. The interplay between RIA, PD and PB is also explicated. Local models are introduced for EDF and YDF that apparently include sufficient physics to reproduce all experimental features, qualitatively and quantitatively. The way these models complement and modify the set of equations used in standard amplifier simulations is presented.
CL-4:IL02 Composite Material Hollow Core Optical Fibres
P.J.A. Sazio, A. Lewis, F. De Lucia, F. Poletti, J.R. Hayes, C.C. Huang, D. Hewak, ORC, University of Southampton, UK; J.V. Badding, Dept. of Chemistry and Materials Research Institute, Pennsylvania State University, State College, PA, USA; W. Belardi, Université de Lille, CNRS, UMR 8523 - PhLAM - Physique des Lasers Atomes et Molécules, Lille, France
Semiconductor-based optical fibre technologies developed by our groups at Penn State and ORC Southampton, have matured over the past decade to the extent that group IV elements such as Si or Ge and even compound II-VI semiconductors such as ZnSe have been grown inside hollow silica glass fibres, allowing the properties of these materials to be exploited for applications such as all-fibre optoelectronics. More recently, hollow core anti-resonant fibres (ARFs) have gained significant interest for state of the art photonic technologies. Mode guidance is largely confined to the air core, thus demonstrating very low optical losses. Furthermore, their internal structure offers a large surface area and is thus ideal as a deposition template for the addition of novel functional materials which would be able to alter their waveguide properties. We have very recently utilised this strong light-matter interaction to externally control the optical properties of our composite material ARF (CM-ARF) waveguides. Here, 2D materials such as the Transition Metal Dichalcogenides MoS2 and WS2 that exhibit many interesting optoelectronic phenomena such as the electro-absorptive effect, were deposited on the inner cladding structure. I will discuss the optical fibres we have fabricated to date.
CL-4:IL03 Chalcogenide Glasses for Advanced Photonics
J.L. Adam, Glasses & Ceramics Research Group, Institut des Sciences Chimiques de Rennes, UMR CNRS 6226, Université de Rennes 1, France
Vitreous materials based on chalcogen elements (S, Se, Te) show large transparency windows that extend from the visible up to 12-15 µm in the infrared, depending on their compositions. This is due to the lower phonon energies of chalcogenides, which are also responsible for enhanced luminescence of rare-earth ions embedded in such matrices. As a result, they possess a high potential for applications as infrared sources, where rare-earth-doped oxide glasses cannot operate. In addition, chalcogenide glasses contain large polarizable atoms and external lone electron pairs, which induce exceptional non-linear properties as compared to oxide glasses. Typically, the non-linear properties of chalcogenide glasses can be 100 or 1000 times as high as the non-linearity of silica. As far as shaping is concerned, specific chalcogenide glass compositions can be obtained in the form of optical fibers, thin films, and planar waveguides. The presentation deals with the latest results in the field of rare-earth-doped sulphide glass optical fibers or micro-waveguides for optical sensing and in the field of chalcogenide glass microstructured optical fibers for the generation of supercontinuum in the infrared.
CL-4:IL04 Novel Hollow Core Optical Fibers: From Design to Applications
W. Belardi1, A. Pastre1, S. Plus1, K. Baudelle1, G. Bouwmans1, L. Bigot1, P. Jaworski2, G. Dudzik2, P. Koziol2, P.J. Sazio3, K. Krzempek2, 1Université de Lille, CNRS, UMR 8523 PhLAM, Villeneuve d'Ascq, France; 3Wroclaw University of Science and Technology, Poland; 3University of Southampton, UK
Hollow Core Optical Fibers (HCs) can allow efficient light guidance in air, in all spectral domains, from UV to mid-IR. Due to the absence of glass material in the fiber core, they have much lower nonlinearity and dispersion than conventional optical fibers, and they could be expected to have also lower attenuation. The research community has been strongly interested in the field of hollow core fibers since the dawn of optical fiber technology, and particularly in the last 20 years, but still their structural design keeps evolving at a fast pace. The large use of numerical or analytical tools, as well as the fabrication and characterisation of novel fiber structures are allowing a better understanding on the link between the geometrical properties of HCs and their optical properties. We discuss here the design evolution and the novel trends in the development of HC fiber structures. In particular, we will show novel HCs for the mid-infrared wavelength range where typical silica based fibers cannot be employed. We will also discuss how novel HCs can, in principle, be used not only as passive components, but also as amplifiers and active devices.
CL-4:IL05 Synthesis and Characterization of Novel Magneto Optical Fibers
M. NALin, Chemistry Institute, São Paulo State University, Araraquara, SP, Brazil; D.F. Franco, Chemistry Institute, São Paulo State University, Araraquara, SP, Brazil
New glass compositions containing high concentrations of Tb3+ ions have been obtained and characterized for production of magneto-optical fibers. In this talk, we report the structural and magneto-optical properties of borogermanates containing up to 18 mol% of Tb4O7. The glasses were characterized by thermal (DSC), XRD, HR-TEM and EDX mapping, UV-Vis and photoluminescence measurements. The magneto-optical properties were investigated by the Faraday rotation experiment and evaluated by the Verdet (VB) constant values at 650, 880, 1050, 1330 and 1550 nm. The maximum VB values obtained at 650 and 1550 nm for the glass (x = 18 mol%) were -128 and -17.6 rad T-1m-1, respectively and are among the best values found in the literature. An optical fiber was manufactured using an intermediary composition containing 8 mol % of Tb4O7. The optical and magneto-optical properties of the fibers are shown and discussed.
CL-5:IL01 Integrated Photonics for Biomedical Spectroscopy
J.S. Wilkinson, Optoelectronics Research Centre, University of Southampton, Southampton, UK
Integrated photonics plays a significant role in applications from long-haul fibre telecommunications to data centres and from novel optical sources to chemical sensing. Silicon photonics in particular has seen enormous growth in recent decades, but there is an increasing need for integrated photonic devices operating at longer wavelengths. Optical techniques are common in providing chemical and biochemical information in a laboratory environment, but the demand for fast, low-cost, automated chemical analysis in applications from food safety and water quality to preventative medicine and point-of-care diagnostics requires low-cost, compact devices and instruments with minimal user intervention for local and low-resource settings. The scale of integration, low cost and robustness of microfabrication which underpins consumer electronics may enable widespread deployment of miniaturised chemical and bioanalytical microsystems. Biosensor and lab-on-chip progress has been hampered by the lack of integrated photonic platforms which can operate over full the mid-infrared (MIR) fingerprint region from about 2μm to 18μm, which would enable new opportunities for sensitive, selective, label-free biochemical analysis. Approaches for waveguide spectroscopies in the NIR & MIR will be discussed.
CL-5:IL02 Manipulation of Light-matter Interaction on the Nanoscale
S. CUNNINGHAM, C. Hrelescu, A.L. Bradley, School of Physics, Trinity College Dublin, College Green, Dublin, Ireland
Plasmonic nanostructures confine light in nanosized volumes, like in the gaps between nanoparticles or at the tips of complex shaped nanoparticles, providing localized and strongly enhanced electromagnetic fields, the so-called hot spots. Furthermore, the presence of nanostructures in the proximity of quantum emitters opens new coupling mechanisms to plasmonic or photonic modes. Here, different strategies to manipulate light with complex shaped nanoparticles, pairs of nanoparticles (nanoresonators), as well as large area hybrid nanostructures will be addressed and discussed. Changes of the local density of optical states by controlling the spectral position of individual modes, the spatial position of the hot spots or the coupling of emission to plasmonic or photonic modes leads to remarkable options for enhanced light trapping, colour generation, spectral and directional modification as well as enhancement of luminescence. Moreover, less favourable light-matter interactions such as Raman scattering and luminescence up-conversion can be enhanced substantially with the aid of nanostructures. Further, new possibilities to tune the plasmon resonances of nanostructures for an optimal spectral overlap with different gain materials will be presented.
CL-5:IL03 Sensing Systems based on Optical Resonators
T. IOPPOLO, College of Engineering and Computing Sciences, New York Institute of Technology, Old Westbury, NY, USA
This talk describes the development of micro-photonic sensors based on optical resonators. The measurement principle is based on the whispering gallery mode (WGM) shifts of dielectric resonators. The term “whispering gallery mode” has been used in recent years to refer to the optical modes of dielectric resonators. The whispering gallery mode (WGM) phenomena was first observed by Lord Rayleigh inside the dome of St Paul Cathedral in London while studying the propagation of sound over curved gallery surface. One of the inherent optical qualities of such devices is the high quality factor one can obtain. It is a measure of how well an optical resonance (or WGM) of the resonator is resolved. The very high quality factor allows for the determination of very small morphology dependent shifts in WGMs of optical resonators, and raises the possibility of development of new micro-photonic devices. The morphological changes (such as size, shape or the optical constants) of the resonator can be caused, for example, by a change in the physical condition of the surrounding. Therefore, by monitoring the WGM shifts, one may determine the change in a physical condition of the environment in which the resonator is embedded.
CL-5:L04 RF - Sputtering Fabrication of Flexible SiO2/HfO2 Glass-based 1D Photonic Crystals and Planar Waveguides
A. Carlotto1, 2, S.M. Pietralunga2, L.T.N. Tran1, 2, 3, O. Sayginer4, E. Iacob5, A. Szczurek1, 6, S. Varas1, J. Krzak6, O.S. Bursi8, 1, D. Zonta7, 1, A. Lukowiak8, G.C. Righini9, M. Ferrari1, A. Chiasera1, 1IFN-CNR CSMFO Lab. and FBK Photonics Unit, Povo, Trento, Italy; 2IFN-CNR, Milano, Italy; 3Dept. of Materials Technology, Fac. of Applied Sciences, Ho Chi Minh City University of Technology and Education, Thu Duc District, Ho Chi Minh City, Vietnam; 4The Technical University of Munich, TranslaTUM, München, Germany; 5Fondazione Bruno Kessler, Centre for Materials and Microsystems, Micro Nano Facility, Povo, Trento, Italy; 6Dept. of Mechanics, Materials and Biomedical Eng., Wroclaw University of Science and Technology, Wroclaw, Poland; 7Dept. of Civil, Environmental and Mechanical Eng., University of Trento, Mesiano, Trento, Italy; 8Institute of Low Temperature and Structure Research, PAS, Wroclaw, Poland; 9MiPLab, IFAC-CNR, Sesto Fiorentino, Italy
While conventional photonic devices are fabricated on rigid substrates, integration of glass systems on deformable substrates has given birth to flexible photonics, a research field which has rapidly emerged in recent years. However, a careful design of the structures, selecting of the materials and the development of a suitable fabrication protocol are required. RF-sputtering deposition protocols are here developed for the fabrication of SiO2/HfO2 glass-based 1D photonic crystals and planar waveguides on flexible polymeric and glass substrates. 1D multilayer structures, made up on SiO2 and HfO2 films, were first modelled by Transfer Matrix Methods and then fabricated by RF-sputtering technique on different substrates. The optical features of the samples were investigated to highlight as the different nature of the substrates and the mechanical deformations of the samples do not influence the transmittance of the samples.
This research is supported by the projects CNR-PAS “Flexible Photonics” (2020-2022); the Polish National Agency for Academic Exchange (NAWA) grant no. PPN/IWA/2018/1/00104, Italian Ministry of Education, University and Research (MIUR) in the frame of the ‘Departments of Excellence’ (grant L 232/2016), ERC-H2020 PAIDEIA GA 816313 and FESR-PON 2014-2020 BEST4U
CL-5:IL05 Tellurite Glass Devices Integrated on Silicon Photonic Chips
J. BRADLEY, Department of Engineering Physics, McMaster University, Hamilton, Ontario, Canada
Tellurite glass is a promising medium for passive, nonlinear and active photonic devices because of its high transparency, high refractive index, high nonlinearity and unique structure allowing for high rare-earth solubility and efficient light emission. Silicon-based photonic platforms, including silicon-on-insulator and silicon nitride, offer high performance devices and systems and leverage the cost-effective high volume production building on established silicon fabrication methods. Hybrid integration of a less mature photonic material such as tellurite glass on these platforms can allow for cost-effective fabrication of advanced devices with high resolution features and high yield. At the same time, silicon platforms can benefit from the new functionalities introduced through such hybrid integration methods, including amplification and light emission. In this talk I present on our recent progress on tellurite glass as a nonlinear and gain medium for hybrid devices on silicon-based photonic platforms, including high-Q resonators, optical amplifiers and lasers. These tellurium oxide integrated nanophotonic devices are promising for passive, active and nonlinear silicon photonic circuits for emerging applications in communications, computing, and sensing.
CL-6:IL01 Correlating the 3D Structure of Nanoparticles with their Optical Properties
W. Albrecht, T. Milagres de Oliveira, S. Bals, Electron Microscopy for Materials Science and NANOlab Center of Excellence, University of Antwerp, Antwerp, Belgium; P. Spaeth, S. Adhikari, M. Orrit, Huygens-Kamerlingh Onnes Laboratory, University of Leiden, Leiden, The Netherlands; X. Zhuo, A. Sánchez-Iglesias, L.M. Liz-Marzán, BioNanoPlasmonics Laboratory, CICbiomaGUNE, Donostia-San Sebastián, Spain; A. Guerrero-Martínez, G. González-Rubio, Departamento de Química Física, Universidad Complutense de Madrid, Madrid, Spain
Understanding the delicate interplay between particle morphology, composition and optical properties is of utmost importance in optimizing particle design for numerous applications. While single-particle optical measurements can reveal insight into the optical properties, electron microscopy (EM) can be utilized to study structural features. With the advances in complex nanoparticles' geometries, however, 2D EM techniques are no longer sufficient and the need for determining the 3D structure arises. In this talk, I will show the correlation of single-particle optical spectroscopy and electron tomography, as well as electron energy loss spectroscopy performed on the same metal nanoparticle. The combination of these techniques give insight into luminescence properties of metal nanoparticle arrangements and how defects influence the plasmonic properties.
CL-6:IL02 XPS Characterization Techniques for Novel Materials and Structures
G. Speranza1,2,3, Lam Thi Ngoc Tran2,4,5, V. Micheli2, A. Chiasera2, A. Chiappini2, M. Ferrari2,6, 1CMM - FBK, Trento, Italy; 2IFN - CNR CSMFO Lab. & FBK CMM, Povo, Trento, Italy; 3Department of Material Engineering, University of Trento, Trento, Italy; 4Department of Civil, Environmental and Mechanical Engineering, University of Trento, Trento, Italy; 5Department of Applied Sciences, Ho Chi Minh City University of Technology and Education, Thu Duc District, Ho Chi Minh City, Vietnam; 6Enrico Fermi Centre, Roma, Italy
High energy excitations such as X-rays generated by electron bombardment of an aluminum anode, can be utilized to excite electrons of the various orbitals in the vacuum. As a consequence of the photoemission process, the photoelectron energy is intimately related to the electronic structure of the material. This makes the X-ray photoelectron spectroscopy (XPS) a powerful technique to probe the sample properties. Referring to materials for photonic applications, the photoluminescence properties depend on the nature of the host material its structure and chemical composition and how it interacts with the dopant. For this reason the emission properties will be affected by the synthesis process and by any kind of treatment which influences the organization and the oxidation state of the hosting and luminescent atoms. XPS provides this information. In a typical analysis, XPS shed light on the composition and on the element concentrations, probes the electronic structure of atoms and their oxidation states. These elements constitute the basis to understand the optical behavior of the materials. In this work we will give some salient examples showing how XPS can be utilized to explain the photoluminescence properties of novel materials developed for photonic applications.
CL-6:IL04 Unraveling the Role of Up-conversion Photonics for Enhancing Photocatalysis: Up-conversion, what else?
J. Méndez-Ramos1, A. Menéndez-Velázquez2, P. Acosta-Mora1, J. del-Castillo1, S. Torres-García1, C. Hernández-Álvarez1, M. Medina-Alayón1, A.C. Yanes1, N.M. Khaidukov3, 1Departamento de Física, Universidad de La Laguna, La Laguna, Tenerife, Spain; 2Centro Tecnológico IDONIAL, Parque Empresarial PEPA, Avilés, Asturias, Spain; 3Russian Academy of Sciences, Moscow, Russian Federation
Spectral conversion of light is an emerging route for enhancing the efficiency of solar energy harvesting schemes. We present evidence of NIR-to-UV-VIS photon conversion for degradation of organic dyes and hydrogen and oxygen evolution via water-splitting. In particular high intense UV-blue up-conversion emissions in rare-earth doped hydrothermal crystals and solvothermal core-shell nanocrystals have been implemented to methylene blue photocatalytic degradation experiments. Up-conversion driven photocatalysis is proved, as a solely photonic effect, converting incident NIR radiation before reaching the contaminated solution. Reported emphasis on control checks is of extreme importance to avoid false narrative, experimental flaws or misinterpretation of up-conversion sensitized photocatalysis. We also explore the implementation of rare-earth doped upconversion materials with the performance of luminescent solar concentrators (LSC), as a not yet fully explored route for enhancing the efficiency of optical devices. In other words, up-conversion emission by itself can boost the photocatalytic reaction efficiency, without other adsorption or possible side effects due to NIR laser radiation, as a univocally photonic effect. Up-conversion, what else?
CL-6:IL05 Residual Stress and Refractive Index Profiles in Silicate Glasses processed by Ion Exchange
G. Macrelli, Isoclima SpA, R&D Department, Este, Italy
Ion exchange in silicate glasses is a non equilibrium mass transfer process performed on a non equilibrium state of matter. Glasses are inherently non equilibrium materials that spontaneusly relax toward the metastable super cooled liquid state. Physical effects resulting from ion exchange are: modifications of ion concentration, residual stress build-up with related stress relaxation phenomena and refractive index modifications. All these effects are interconnected. A discussion is introduced about their physical underpinnings. Characterization methods are critically presented. A focus is mainly addressed to effects related to specific glass chemical compositions and structural configurations. These topics are relevant to technological applications for: glass strengthening, consumer electronics and photonic devices. The discussion here is limited to Ion Exchange processes without the assistance of an external electric field. Nevertheless the discussion introduced and conclusion achieved can be easily extended without loosing generality to different Ion Exchange process configurations.
CL-6:IL06 Terahertz Time-domain Spectroscopy of Amorphous System
TATSUYA Mori, University of Tsukuba, Tsukuba, Japan; Y. Fujii, Ritsumeikan University, Kusatsu, Japan; S. Kitani, Tokyo Institute of Technology, Yokohama, Japan
The boson peak is a universal excitation that appears in the terahertz range in disordered systems. The excitation has long been studied as one of the unresolved problems of glass physics. On the other hand, fractal dynamics, so-called fractons, which was proposed by Alexander and Orbach in 1982, is a universal excitation that appears in fractal objects. We demonstrate that the universal dynamics of both the boson peak and fractons can be detected using terahertz time-domain spectroscopy. We show how these excitations appear in the terahertz spectrum and propose how to evaluate them. The obtained terahertz spectrum is also compared with the results of low-frequency Raman scattering, which is a complementary method for infrared spectroscopy, and low-temperature specific heat.
CL-7:L04 Environmental Infrared Microsensor based on Chalcogenide Materials
V. NAZABAL1, 3, M. Baillieul1, 2, 3, J. Charrier1, C. Boussard-Pledel1, L. Bodiou1, P. Nemec3, K. Boukerma2, E. Rinnert2, K. Michel4, 1University of Rennes 1, France; 2IFREMER, Plouzané, France, 3University of Pardubice, Czech Republic; 4BRGM, Orléans, France
A review of current research on chalcogenide materials contributing to the development of optical microsensors will be presented. The 3-15 μm range is a key region for a large number of optical sensor applications in various fields such as biology and medicine, molecular spectroscopy or environmental monitoring. Infrared spectroscopy is a powerful tool for detecting and determining the composition of complex samples. It is a simple, reliable, fast, economical and non-destructive method. In order to further develop this technique especially for on-site real time monitoring, it is crucial to provide suitable infrared materials covering the mid-infrared spectral range. It is in this context that intensified efforts were performed to develop chalcogenide materials that meet the specific requirements for the development of optical microsensors dedicated to environmental issues [1]. The detection of molecules at low concentrations down to a ppm or ppb level is often necessary and Lab-on-chip based on chalcogenide can provide motivating insights.
[1] Baillieul et al, Toward Chalcogenide Platform Infrared Sensor Dedicated to the In Situ Detection of Aromatic Hydrocarbons in Natural Waters via an Attenuated Total Reflection Spectroscopy Study. Sensors 2021, 21, (7), 2449.
CL-7:IL08 Metal Oxide Nanoparticles for Ultrafast Switching and Energy Applications
F. Scotognella, Dipartimento di Fisica, Politecnico di Milano, Milano, Italy
Metal oxide nanoparticles have intriguing optical and optoelectronic properties. For this reason, they are widely employed for optical filtering, optical sensors, transparent conductive oxides and solar devices. In particular metal oxide nanoparticles the addition of dopant atoms or the nonstoichiometric composition leads to a high level of doping. Such nanostructures are usually called doped semiconductor nanoparticles (DSNPs) and can sustain heavy doping, reaching carrier concentrations of about 10^21 cm^-3, which are intermediate between semiconductors and metals [1]. DSNPs show strong plasmonic resonances in the near infrared and they can be employed for electrodes that are transparent in the visible, ultrafast switches, active components for infrared solar devices. I will discuss the ultrafast switching in DSNP-based structures [2] and I will show promising results towards the employment of DSNPs for infrared photovoltaics [3].
[1] I. Kriegel, F. Scotognella, L. Manna, Plasmonic doped semiconductor nanocrystals: Properties, fabrication, applications and perspectives, Physics Reports. 674 (2017) 1–52. https://doi.org/10.1016/j.physrep.2017.01.003.
[2] G.M. Paternò, C. Iseppon, A. D’Altri, C. Fasanotti, G. Merati, M. Randi, A. Desii, E.A.A. Pogna, D. Viola, G. Cerullo, F. Scotognella, I. Kriegel, Solution processable and optically switchable 1D photonic structures, Sci Rep. 8 (2018) 1–8. https://doi.org/10.1038/s41598-018-21824-w.
[3] F. Marangi, M. Lombardo, A. Villa, F. Scotognella, (INVITED) New Strategies for Solar Cells Beyond the Visible Spectral Range, Optical Materials: X. 11 (2021) 100083. https://doi.org/10.1016/j.omx.2021.100083.