TOMORROW! NSTC/AMPAC/CREOL Distinguished Seminar Series: “The magic of nonlinear laser processing: Nanostructuring inside thin films and shaping multi-functional lab-in-fibre”- Peter Herman 5.1.15/11:00am-12:00pm/CREOL 102/103

NSTC/AMPAC/CREOL Distinguished Seminar Series: “The magic of nonlinear laser processing: Nanostructuring inside thin films and shaping multi-functional lab-in-fibre”- Peter Herman

Friday, May 1, 2015 11:00 AM to 12:00 PM
CREOL Room 102/103

Celebrating the International Year of Light 2015 

Peter R. Herman

Abstract:

The manipulation of femtosecond laser light inside transparent media can be directed on varying interaction pathways of microexplosions, photochemistry, and self-focusing filamentation to open new directions for creating dense memory storage, three-dimensional (3D) optical circuits, 3D microfluidic networks and high-speed scribing tracks. The presentation follows these fundamental interactions towards controlling laser processes in transparent glasses, particularly in optical fibers and thin films that enable highly functional and compact devices to form with the benefits of seamless integration with single mode optical fibers or microelectronic chips.  The concept of forming 3D optical circuits within the fiber cladding is presented together with the means for coupling light efficiently with the fiber core waveguide. Chemical etching of laser-generated nanogratings are used to embed microfluidic channels, micro-optical devices and optical resonator components.  The laser writing overall provides a flexible integration of fiber-cladding photonics and microfluidics on which to build 3D opto-fluidic microsystems in our common base of optical networks through to minimally invasive biomedical probes.  The approach promises to reduce fabrication and packaging costs and to enable highly functional all-fiber microsystems for optical communications, fiber lasers, and sensing.  Examples of integrated approaches in lab-in-a-fiber devices, smart medical catheters, and lab-in-film devices are presented.

Biography:

Peter R. Herman received the B.Eng. degree (1980) in Engineering Physics at McMaster University.  He earned MASc (1982) and PhD (1986) degrees studying lasers and diatomic spectroscopy in the Physics Department at the University of Toronto that followed with a post-doctoral position at the Institute of Laser Engineering in Osaka University, Japan (1987) to the study of laser-plasma physics and x-ray lasers. He joined the Department of Electrical and Computer Engineering at the University of Toronto in 1988 where he holds a full professor position.  Professor Herman directs a large and collaborative research group that develops and applies laser technology and advanced beam delivery systems to control and harvest laser interactions in new frontiers of 3-D nanofabrication.  Our mantra is: “We begin with light and we end with light devices.” To this end we are inventing new methods for processing internally inside optical materials that carve out highly compact and functional lightwave circuits, microfluidics, optofluidic systems, biophotonic sensors, and smart medical catheters. Our end goals are inventing new manufacturing processes and extending optical device and Lab-on-a-chip concepts towards more compact Lab-in-a-fiber and Lab-in-a-film microsystems. Professor Herman is OSA fellow, holds several patents, spun out one company (FiLaser; acquired by Rofin 2014), and has published over 300 papers in journals and conference proceedings. 

For additional information:

Debashis Chanda

LPTH Press Release: LightPath Technologies Announces Fiscal 2015 Third Quarter Financial Results

For Immediate Release: LightPath Technologies Announces Fiscal 2015 Third Quarter Financial Results Financial Results to be announced on May 7th After Close of Market ORLANDO, FL – April 27, 2015 -- LightPath Technologies, Inc. (“LightPath”, the “Company” or “we”) (NASDAQ: LPTH), a leading vertically integrated global manufacturer, distributor and integrator of proprietary optical and infrared components and high-level assemblies, today announced the scheduling of a conference call and simultaneous webcast to discuss the Company’s financial and operational results for the fiscal 2015 third quarter ended March 31, 2015. Conference Call Details: Date: Thursday, May 7, 2015 Time: 4:30 PM (ET) Dial-in Number: 1-800-860-2442   International Dial-in Number: 1-412-858-4600  Webcast: http://services.choruscall.com/links/lpth150507.html Participants are recommended to dial-in or log-on approximately 10 minutes prior to the start of the event. A replay of the call will be available approximately one hour after completion through May 22, 2015. To listen to the replay, dial 1-877-344-7529 (domestic) or 1-412-317-0088 (international), and enter conference ID # 10065010. About LightPath Technologies LightPath Technologies, Inc. (NASDAQ: LPTH) provides optics and photonics solutions for the industrial, defense, telecommunications, testing and measurement, and medical industries. LightPath designs, manufactures, and distributes optical and infrared components including molded glass aspheric lenses and assemblies, infrared lenses and thermal imaging assemblies, fused fiber collimators, and gradient index GRADIUM® lenses. LightPath also offers custom optical assemblies, including full engineering design support.  For more information, visit www.lightpath.com. This news release includes statements that constitute forward-looking statements made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995, including statements regarding our ability to expand our presence in certain markets, future sales growth, continuing reductions in cash usage and implementation of new distribution channels. This information may involve risks and uncertainties that could cause actual results to differ materially from such forward-looking statements. Factors that could cause or contribute to such differences include, but are not limited to, factors detailed by LightPath Technologies, Inc. in its public filings with the Securities and Exchange Commission. Except as required under the federal securities laws and the rules and regulations of the Securities and Exchange Commission, we do not have any intention or obligation to update publicly any forward-looking statements, whether as a result of new information, future events or otherwise. GRADIUM® is a registered trademark of LightPath Technologies. ### Contacts:        Dorothy Cipolla, CFO LightPath Technologies, Inc. Tel: 407-382-4003 x305 Email: dcipolla@lightpath.com Web: www.lightpath.com Jordan Darrow Darrow Associates, Inc. jdarrow@darrowir.com 631-367-1866

NSTC/AMPAC/CREOL Distinguished Seminar Series: “The magic of nonlinear laser processing: Nanostructuring inside thin films and shaping multi-functional lab-in-fibre”- Peter Herman 5.1.15/11:00am-12:00pm/ CREOL RM 102/103

NSTC/AMPAC/CREOL Distinguished Seminar Series: “The magic of nonlinear laser processing: Nanostructuring inside thin films and shaping multi-functional lab-in-fibre”- Peter Herman
Friday, May 1, 2015 11:00 AM to 12:00 PM
CREOL Room 102/103

Celebrating the International Year of Light 2015

Peter R. Herman

Abstract:
The manipulation of femtosecond laser light inside transparent media can be directed on varying interaction pathways of microexplosions, photochemistry, and self-focusing filamentation to open new directions for creating dense memory storage, three-dimensional (3D) optical circuits, 3D microfluidic networks and high-speed scribing tracks. The presentation follows these fundamental interactions towards controlling laser processes in transparent glasses, particularly in optical fibers and thin films that enable highly functional and compact devices to form with the benefits of seamless integration with single mode optical fibers or microelectronic chips.  The concept of forming 3D optical circuits within the fiber cladding is presented together with the means for coupling light efficiently with the fiber core waveguide. Chemical etching of laser-generated nanogratings are used to embed microfluidic channels, micro-optical devices and optical resonator components.  The laser writing overall provides a flexible integration of fiber-cladding photonics and microfluidics on which to build 3D opto-fluidic microsystems in our common base of optical networks through to minimally invasive biomedical probes.  The approach promises to reduce fabrication and packaging costs and to enable highly functional all-fiber microsystems for optical communications, fiber lasers, and sensing.  Examples of integrated approaches in lab-in-a-fiber devices, smart medical catheters, and lab-in-film devices are presented.

Biography:
Peter R. Herman received the B.Eng. degree (1980) in Engineering Physics at McMaster University.  He earned MASc (1982) and PhD (1986) degrees studying lasers and diatomic spectroscopy in the Physics Department at the University of Toronto that followed with a post-doctoral position at the Institute of Laser Engineering in Osaka University, Japan (1987) to the study of laser-plasma physics and x-ray lasers. He joined the Department of Electrical and Computer Engineering at the University of Toronto in 1988 where he holds a full professor position.  Professor Herman directs a large and collaborative research group that develops and applies laser technology and advanced beam delivery systems to control and harvest laser interactions in new frontiers of 3-D nanofabrication.  Our mantra is: “We begin with light and we end with light devices.” To this end we are inventing new methods for processing internally inside optical materials that carve out highly compact and functional lightwave circuits, microfluidics, optofluidic systems, biophotonic sensors, and smart medical catheters. Our end goals are inventing new manufacturing processes and extending optical device and Lab-on-a-chip concepts towards more compact Lab-in-a-fiber and Lab-in-a-film microsystems. Professor Herman is OSA fellow, holds several patents, spun out one company (FiLaser; acquired by Rofin 2014), and has published over 300 papers in journals and conference proceedings.

For additional information:
Debashis Chanda

Manufacturing Joint Faculty Candidate Seminar: "Light-based molecular sensing and imaging for translational biophotonics" by Wei-Chuan Shih 4.20.15/11:00am-12:00pm/ CREOL Rm 103

Seminar: "Light-based molecular sensing and imaging for translational biophotonics" by Wei-Chuan Shih

Monday, April 20, 2015 11:00 AM to 12:00 PM
CREOL Room 103

Celebrating the International Year of Light 2015

Wei-Chuan Shih

Departments of Electrical & Computer Engineering

Department of Biomedical Engineering

Department of Chemistry

University of Houston 

Abstract:

Light-based molecular sensing and imaging techniques are ubiquitous for contactless interrogation of targets of interest. These tools enable the identification and quantification of specific molecules, thereby providing complementary information to structural and morphological imaging. Over the past decade, we have been developing novel instruments, methods, and materials for translational biophotonics. In this talk, I will discuss label-free quantitative Raman spectroscopy and microscopy for biomedical applications such as non-invasive glucose sensing, pathogen identification, and disease diagnosis. I will then discuss surface-enhanced spectroscopies on a unique type of porous plasmonic nanostructure for cancer biomarker detection, label-free multiplexed imaging, and photothermal sterilization and flow control in microfluidics. Lastly, I will discuss laser-based fabrication of micro and nanostructures and its potential in neural applications.

Biography:

Wei-Chuan Shih is an Assistant Professor of Electrical & Computer Engineering, Biomedical Engineering, and Chemistry at University of Houston. He earned a Ph.D from the Massachusetts Institute of Technology under Prof. Michael S Feld. He worked on optical downhole fluid analysis and oil spill sensing at Schlumberger-Doll Research before his current position. He is a recipient of NSF CAREER Award and NASA inaugural Early Career Faculty Award. His research interests are in biophotonics, nano-plasmonics, multi-modal neural stimulation & sensing, point-of-care technology, cancer theranostics, environmental sensing, hyperspectral microscopy & imaging, N/MEMS, and laser-based 3D manufacturing. He has published more than 50 articles in books, journals and conference proceedings, and is the inventor of 6 issued patents. As an independent PI, his research is also supported by NIH, DoI, and GoMRI with a cumulative sum of $3M.

Website: http://nanobiophotonics.ee.uh.edu

For additional information:

Dr. Ranganathan Kumar: 407-823-4389 

Dr. Martin Richardson: 407-823-6819

FW: TODAY ! AT 10:45 AM ! : Physics Colloquium - Physics Faculty Candidate Dr. Luca Argenti, TODAY 4/16, 10:45, PSB 161 & TOMORROW: Teaching Seminar, 4/17, 1:30-2:15, MSB 350

NOTE TIME CHANGE! : Physics Colloquium - Physics Faculty Candidate Dr. Luca Argenti, 4/16, 10:45, PSB 161

Dr. Luca Argenti

Universidad Autónoma de Madrid

How to Win Electrons’ Friendship and Make Them Dance for You

In the realm of electrons, in atoms and molecules, things happen fast. According to Bohr’s planetary model for the hydrogen atom, for example, the “sidereal year’’, i.e., the time it takes to the electron to complete the shortest orbit around the nucleus, has the fantastically small duration of 152 attoseconds (as; 1as = 10^-18 s).  This estimate remains true even when formulated in the language of quantum mechanics. Such ultrafast motion could not be directly confirmed until, at the turn of this century, groundbreaking advancements in laser technology led to the production of flashes of light with sufficiently short duration (the world record is 67 as) to take clear snapshots of it.

In systems bigger than hydrogen, the same Coulomb force that binds an electron to the nucleus also acts repulsively between electrons. The main effect of such repulsion is to screen the nuclear charge, thus reducing the binding energy of each individual electron. To a first approximation, therefore, in several complex systems, electrons can act as if they were independent. As a result, their motion may appear not much more complicated than the one observed in the hydrogen atom. In fact, most of the experiments carried out so far to follow the electronic movement could set in motion only one electron at a time, thus confirming this picture.

Electrostatic repulsion, however, has also a secondary, subtler effect. In the same way as a bus passenger avoids not only to sit next to the other passengers, if she can, but also to bump into them as she walks down the isle, electrons try to avoid each other as they move across an atom or a molecule: the motion of the electrons is correlated. Keeping each other at arm’s length, electrons minimize their mutual repulsion and, as a consequence, they stabilize the ground state of the atom or molecule to which they belong. Such stabilization influences the energy balance of all natural processes, and is key to our understanding and control of matter, from energy transfer in photosynthetic systems, to the inner workings of futuristic quantum computers.  Correlation alters even more dramatically the dynamics in excited states, where pairs of electrons move in unison. Until recently, such concerted motion eluded direct experimental observation. By combining flashes of extreme ultraviolet and visible laser light with a duration of only a few hundred attoseconds and timed very accurately with respect to each other, however, it was eventually shown that monitoring and controlling this motion is in fact possible.

In this colloquium I will illustrate with examples taken from my research on the helium atom, a prototype of poly-electronic systems, how attosecond spectroscopies have opened the road that leads to the direct observation and control of correlated electronic motion in matter.

Teaching Seminar, 4/17, 1:30-2:15, MSB 350

TOMORROW! Manufacturing Joint Faculty Candidate Seminar: "Metallic Laser Additive Manufacturing" by Dr. Jay Choi 4.15.15/ 11:00am-12:00pm/ CREOL RM 103

Seminar: "Metallic Laser Additive Manufacturing" by Dr. Jay Choi

Wednesday, April 15, 2015 11:00 AM to 12:00 PM
CREOL Room 103

Celebrating the International Year of Light 2015

Jay Choi, Ph.D.
Visiting Scholar, Center for Laser Aided Intelligent Manufacturing, University of Michigan, Ann Arbor Director, SenSigma, Ann Arbor, MI

Abstract:

Over the last two decades laser additive manufacturing (LAM) technological communities have made considerable efforts, developing scientific and technological elements necessary for rapid and reliable production of near net shape components with desired properties and capabilities and with minimum cost and lead-time possible. LAM technology has opened up alternative possibilities for the manufacture of end-use components as well as the reuse of legacy components.  Metallic components are directly made from CAD dimension by melting metal powders pixel-by-pixel utilizing a laser, maintaining dimensional accuracy and material integrity utilizing a closed-loop feedback control.  Expanding LAM into high-value safety-stringent applications, next-level of complexities and challenges, such as real-time control of LAM to improve dimensional accuracy to minimize post-processing, real-time minimization of residual stress, in-situ monitoring and control of microstructure to obtain desired properties and performance, methodology to derive desired mechanical properties, and real-time quality control through in-situ inspection, need to be facilitated and addressed in terms of scientific know-how and manufacturing efficiency.  This presentation summarizes and discusses LAM advancements throughout two decades of R&D efforts carried out through lab environments and real-world settings, facilitating those complexities. 

Biography:

Dr. Choi has been overseeing R&D and engineering directives including laser based manufacturing system design, sensor technology, numerical analysis, process quality control, technology management, and so on, regarding government/external R&D contracts, working as R&D expert, faculty, and technical executive throughout academia (UIUC, UMich, and MS&T) and industries: His engineering and R&D experiences/interests are in the fields of advanced manufacturing (e.g. additive / formative / subtractive manufacturing) utilizing laser, surface engineering/tribology, instruments using lasers, rapid production realization, CAE/CAD, transport phenomena in materials processing, and process modeling.  He has over 20 years experiences of mechanical (including opto-mechanical / mechatronics) / materials R&D in the area of materials processing, heat transfer, advanced manufacturing, and laser processing system development.  He has deeply involved in developing advanced laser additive manufacturing techniques for last 20 years.  Dr. Choi has published more than 50 technical publications in the area of laser processing, process modeling, and additive manufacturing through refereed journals and conference proceedings.  He has also participated in several professional societies, such as ASME, LIA, ASTM, TMS, ASEE, and so on.  He got his BSME degree from Seoul National University (Seoul, Korea), and his M.S./Ph.D. degrees from University of Illinois at Urbana-Champaign. 

For additional information:

Dr. Ranganathan Kumar: 407-823-4389 

Dr. Martin Richardson: 407-823-6819

Seminar: "Tailoring crystallization in oxide glasses: Application to transparent polycrystalline ceramics and nanostructured glass-ceramics" by: Mathieu Allix 5.15.15/11:00am-12:00pm/ CREOL RM 103

Seminar: "Tailoring crystallization in oxide glasses: Application to transparent polycrystalline ceramics and nanostructured glass-ceramics" by: Mathieu Allix

Friday, May 15, 2015 11:00 AM to 12:00 PM
CREOL Room 103

Celebrating the International Year of Light 2015

Abstract: 

Crystallization from glass can be a powerful process to elaborate innovating transparent materials for optical and photonic applications if nucleation and crystal growth steps can be precisely controlled. This talk will focus on two main applications: transparent polycrystalline ceramics elaborated by full and congruent crystallization from glass and nanostructured glass-ceramics designed from nanoscale phase separated glasses.

Transparent polycrystalline ceramics elaborated by full crystallization from glass

Transparent polycrystalline ceramics are an emerging class of photonic quality materials competing with single crystal technology for a diverse range of applications including high-energy lasers, scintillating devices, optical lenses, and transparent armor. Polycrystalline ceramics offer several advantages, particularly in the fabrication of complex shapes and large-scale industrial production, and enable greater and more homogenous doping of optically active ions than is possible in single crystals. However, up to date, only a limited number of such materials has been reported. These are either cubic or nanocrystalline transparent polycrystalline ceramics which require complex, time-consuming and so expensive synthetic approaches.

Our recent work shows the possibility to obtain transparent polycrystalline ceramics by full and congruent crystallization from glass. Transparency is observed despite micrometer scale crystals and a non cubic symmetry (no structural isotropy) of the crystalline phase. Interestingly, crystallization from glass can give access to new crystalline phases given the relatively low crystallization temperature compared to classic solid state elaboration temperature. This is demonstrated in the case of a new composition, BaAl₄O₇, showing the existence of two orthorhombic polymorphs both showing high transparency in the visible and infra-red ranges [1,2]. The crystallographic structures of these polymorphs have been determined ab initio from powder diffraction data. From these structural models, the optical birefringence has been obtained by DFT calculations of the dielectric function. These results enable to discuss the transparency property of these materials as a function of the determined crystalline structures and the observed microstructures. Remarkably, these materials show promising scintillation properties when doped by europium [3]. The same elaboration process has been applied to cubic compositions, Sr₃Al₂O₆ and Sr₃Ga₂O₆, allowing very high transparencies to be attained [4]. Lastly, we have focused our work on strontium aluminosilicate compositions, the addition of silica enabling large scale glass samples to be obtained. The full and congruent crystallization of Sr_1+x/2Al_2+xSi_2-xO₈ compositions leads to new transparent polycrystalline ceramics forming a crystalline solid solution exhibiting hexagonal symmetry. These materials show an impressive transmittance higher than 90%, which sets a transparency record for oxide ceramics. A crystallographic study coupled to NMR experiments and DFT calculations of the birefringence allowed us to evidence the role of structural disorder (Al/Si substitution and presence of vacancies on strontium sites) in the origin of the optical isotropy observed in these structurally anisotropic materials. These results propose an innovative concept, the addition of a controlled structural disorder within crystalline structures, in order to lower the birefringence and to elaborate new transparent ceramics [5].

New nanostructured gallogermanate- and gallosilicate-based glass materials exhibiting high transparency in the visible range have been fabricated by conventional melt-quenching. These materials can accommodate wide oxide compositions and present nanoscale phase separation. The size of the nanostructuring can be tailored depending on the nominal composition. A single heat treatment then allows selective crystallization of the phase separated glass, resulting in glass-ceramic materials exhibiting nanostructures and transparency similar to the parent glass.[6,7]

The wide possibilities of designing new nanostructured glass-ceramics with tunable optical properties will be illustrated in the case of a highly transparent ZnGa₂O₄ glass-ceramic exhibiting 50 wt% of nanocrystals with homogeneous and tunable sizes. High resolution scanning transmission electron microscopy analysis coupled with in situ high temperature X-ray diffraction and optical measurements led to a detailed description of the crystallization process. Remarkably, red long-lasting luminescence arising from the entire sample volume is observed in this Cr³⁺ doped material, opening the route to a wider range of performing applications for this famous zinc gallate persistent phosphor.[8,9]

1. M.Allix, S.Alahrache, F.Fayon, M.Suchomel, F.Porcher, T.Cardinal, G.Matzen, Highly Transparent BaAl₄O₇ Polycrystalline Ceramic Obtained by Full Crystallization from Glass, Advanced Materials, 24 5570-5575 (2012)

2. "Transparent aluminate glass, glass-ceramics and ceramics", International patent deposited 1/12/2011, published 6/6/2013, WO2013079707 A1, PCT international extension PCT/EP2012/074171, US20140336032 13/11/2014.

3. G.Patton, F.Moretti, A.Belsky, K.Al Saghir, S.Chenu, G.Matzen, M.Allix, and C.Dujardin, Light yield sensitization by X-ray irradiation in BaAl₄O₇ : Eu²⁺ ceramic scintillator obtained by full crystallization from glass, Physical Chemistry Chemical Physics., 16 24824 (2014)

4. S.Alahraché, K.Al Saghir, S.Chenu, E.Véron, D.De Sousa Meneses, A.I.Becerro, M.Ocaña, F.Moretti, G.Patton, C.Dujardin, F.Cussó, J-P.Guin, M.Nivard, J-C.Sangleboeuf, G.Matzen, M.Allix, Perfectly transparent Sr₃Al₂O₆ polycristalline ceramic elaborated from glass crystallization, Chemistry of Materials, 25 4017-4024 (2013)

5. K.Al Saghir, S.Chenu, E.Veron, F.Fayon*, M.Suchomel, C.Genevois, F.Porcher, G.Matzen, D.Massiot and M.Allix*, Transparency through Structural Disorder: A New Concept for Innovative Transparent Ceramics, Chemistry of Materials, 27 508-514 (2015)

6. "Nanostructured glass and glass-ceramics transparent in the visible and infrared ranges", International patent deposited 28/02/2014, published 4/9/2014, WO2014131881 A1, PCT in progress, PCT/EP2014/053932.

7. S.Chenu, E.Véron, C.Genevois, G.Matzen, T.Cardinal, A.Etienne, D.Massiot, M.Allix, Tuneable Nanostructuring of Highly Transparent Zinc Gallogermanate Glasses and Glass-Ceramics, Advanced Optical Materials, 2 364 (2014)

8. S. Chenu, E. Veron, C. Genevois, A. Garcia, G. Matzen, M. Allix, Long-lasting luminescent ZnGa₂O₄:Cr³⁺ transparent glass-ceramics,Journal of Materials Chemistry C, 2 10002-10010 (2014)

9. M.Allix, S.Chenu, E.Véron, T.Poumeyrol, E.A.Kouadri-Boudjelthia, S.Alahraché, F.Porcher, D.Massiot, F.Fayon, Considerable improvement of long-persistent luminescence in germanium and tin substituted ZnGa₂O₄, Chemistry of Materials, 25 1600–1606 (2013)

Keywords: Glass crystallization, transparent polycrystalline ceramics, transparent glass-ceramics, phase separation, structure determination from powder diffraction, long lasting luminescence, scintillation, Transmission electron

Biography:

Dr. Mathieu Allix is a CNRS researcher in material chemistry in Orléans, France. He received his PhD from the University of Caen in 2004 and eventually moved to a 3 years postdoctoral position in Liverpool, UK under the supervision of Matt Rosseinsky. His research focuses on crystallization in oxide glasses with an application to transparent polycrystalline ceramics elaborated by full and congruent crystallization from glass and nanostructured glass-ceramics designed from nanoscale phase separated glasses. He is author of over 70 publications and recently received the CNRS bronze medal award.

For additional information:

Dr. Kathleen Richardson

TOMORROW! Nanophotonics Joint Faculty Candidate Seminar: "Opto-Excitonic Circuits: Processing Light with Matter" by Parag Deotare 4.9.15/ 11:00am-12:00pm/ CREOL Rm A214

Opto-Excitonic Circuits: Processing Light with Matter by Parag Deotare

Thursday, April 9, 2015 11:00 AM to 12:00 PM
CREOL Room A214

Celebrating the International Year of Light 2015

Parag Deotare

Postdoctoral associate at the Organic and Nanostructured Electronics Laboratory (ONELab) at Massachusetts Institute of Technology.

Abstract

Progress of the current hybridized photon-electron communication technology has been slowed down by the limited efficiency of electrical interconnects. While optical interconnects is a viable solution, it falls short to offer an efficient long term solution, since logic operations will be performed using electrons. Optical interconnects in conjunction with excitonic circuits offer a plausible solution since it not only overcomes the losses and delays experienced by electrons but also benefits from seamless transformation between an exciton and a photon.

In my talk, I will discuss the importance of reconfigurable optical nanocavities for on-chip optical interconnects. In particular, I will talk on photonic crystal nanobeam cavities and discuss an all-optical reconfiguration technique based on optical gradient force. I will introduce the benefits of excitonic circuits and discuss a technique to visualize exciton diffusion, an important parameter for designing excitonic devices. I will also discuss an excitonic modulator based on charged excitons (trions) in tungsten diselenide (WSe₂) monolayer. Such opto-excitonic circuits open a new way to process information reaping the benefits of unprecedented energy efficiency offered by a photon as an information carrier.

Biography 

Parag is a postdoctoral associate at the Organic and Nanostructured Electronics Laboratory (ONELab) at Massachusetts Institute of Technology. His research interest lies in understanding light - matter interaction in nanostructured materials for applications in data communications and life sciences. His work spans the area of optical nanocavities, cavity quantum electrodynamics, optomechanics, nanofabrication and optical interconnects. Parag received his BE degree in Electrical Engineering from University of Pune, India in 2004, MS degree from Texas A&M University in 2007 and PhD from Harvard University in 2012. 

For additional information:

Dr. Ayman Abouraddy

Associate Professor of Optics

407-823-6809

Seminar: "Structure, Optical Properties, and Crystallization in Multicomponent Chalcogenide Glasses" by John McCloy 5.15.15/3:00-4:00pm/ CREOL Rm 103

Seminar: "Structure, Optical Properties, and Crystallization in Multicomponent Chalcogenide Glasses" by John McCloy

Friday, May 15, 2015 3:00 PM to 4:00 PM
CREOL Room 103

Celebrating the International Year of Light 2015

John McCloy

Abstract: 

The search for producible materials with simultaneous occurrence of superior thermo-mechanical properties and long-wave infrared (LWIR) transmission has been a longstanding problem in infrared ceramics engineering.  Recent research has suggested the possibility of using chalcogenide glass processing as a means to achieve breakthroughs in this area.  This talk will focus on three aspects of this problem.  1) vision and scoping experiments for fully ceramized LWIR glass ceramics based on sulfide glasses; 2) prediction methods of optical properties of multicomponent IR glasses; and 3) comparative topological effects on structural and optical properties of ternary Ge-based chalcogenide glasses. 

Long-wave Infrared Transmitting Glass-Ceramics

Three sulfide systems were explored including two with La2S3 in hopes of imparting strong bonds from this refractory sulfide, and two containing GeS2 in hopes of widening the glass-forming region. Attempts were made to produce glasses in the Ga2S3-La2S3-(ZnS,CaS) system, the GeS2-La2S3 system, and the GeS2-Ga2S3-CdS system. Microstructural and thermal analyses were used to explore nucleation and growth in these systems and infrared transmission and mechanical hardness showed potential for LWIR window use. The GeS2-Ga2S3-CdS system showed good LWIR transmission and pre-crystallized hardness superior to chemical vapor deposited ZnS. The Ga2S3-La2S3 glasses did not appear to be viable candidates at this time due to strong tendency for phase separation, a small temperature window between crystallization and glass transition temperatures, and problems with oxygen contamination in the La2S3 source. Glass formation in these materials is shown to be a strong function of quenching method and raw materials.  Suggestions are made for alternative methods for producing fully ceramized LWIR-transmitting glass ceramics. 

Optical Property Prediction in Infrared Glasses

It is often useful to obtain custom glasses that meet particular requirements of refractive index and dispersion for high-end optical design and applications.  In the case of infrared glasses, limited experimental data are available due to difficulties in processing of these glasses and also measuring refractive indices accurately.  Methods for estimating refractive index and dispersion as a function of composition for selected infrared-transmitting glasses are reviewed and evaluated, including Gladstone-Dale, Wemple-DiDomenico single oscillator, Optical basicity, and Lorentz-Lorenz total polarizability.  Various estimates for a set of PbO-Bi2O3-Ga2O3 (heavy metal oxide) and As-S (chalcogenide) glasses are compared with measured values of index and dispersion.  Problems associated with known glass topology changes and index prediction are discussed.      

Topological Effects on Properties of Ge-based Ternary Chalcogenide Glasses

Germanium based ternary chalcogenide glasses have been explored for over 50 years.  However, glass scientists are still discovering the complexities of these systems, particularly in relation to the continuum between random covalent network (RCN) and chemical ordered covalent network (COCN) structures. Recent understanding of crystal precipitation in these glass systems has aided in understanding of the medium range ordering.  In this final part of the talk, a comparison is made between the behavior of glass transition versus average coordination number for known compositions in Ge-Ga-Se, Ge-Ga-S, Ge-Sb-Se, and Ge-As-Se systems.

Biography:

John McCloy, PhD, is an Associate Professor of Materials Science and Engineering at Washington State University (WSU) in the School of Mechanical and Materials Engineering
(MME). He hold degrees in Materials Science & Engineering from the Massachusetts Institute of Technology and the University of Arizona. From 2008-2013 he was a senior scientist at the Pacific Northwest National Laboratory (PNNL), for the last several years as Team Lead of Glass and Materials Science. From 2000-2008 he was with Raytheon Missile Systems working on infrared systems and materials. Dr. McCloy has held roles in line management, technology management, research and development, engineering, and manufacturing. He has worked in operations, test, and engineering organizations, and led multi-disciplinary project teams of >20 in both manufacturing and engineering research & development. His current research and teaching at WSU involves Nuclear, Optical, Magnetic, and Electronic materials, with particular focus on the effect of disordering on structure and functional properties.

For additional information:

Dr. Kathleen Richardson

407-823-6815