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Seminars 2018

2018-08-07: Kista Science Seminar
Title: Semiconductor Nanowires for Optoelectronics Applications
Speaker: Chennupati Jagadish, Australian National University, Canberra, Australia
Location: Faculty Lounge, Electrum, KTH-Kista
Time: 10.30am
Abstrat: Semiconductor Nanowires are considered as building blocks for next generation electronics and photonics. In this talk, I will discuss about growth of Semiconductor Nanowires using Vapor-Lqiuid-Solid (VLS) and Selective Area Epitaxy (SAE) methods and discuss about materials issues related to nanowires. I will present results on GaAs nanowire lasers, multi-quantum well nanowire lasers, zinc doped GaAs and InP nanowire lasers and nanopositioning of these lasers for flexible electronics applications. I will also discuss about use of these nanowires for THz detectors, Solar Cells and Neuroscience Applications.

2018-06-15: Licentiat seminar
Title: Generation and detection of non-classical photon states
Candidate: Katarina Stensson
Time: 1:00 PM
Location: Lecture hall FB53, Albanova KTH
External reviewer: Guilherme Xavier, Linköpings Universitet, Sweden
Supervisor: Gunnar Björk

2018-06-15: PhD defence
Title: Silicon Nanopore Arrays: Fabrication and Applications for DNA Sensing
Candidate: Miao Zhang
Time: 10:00 AM
Location: Lecture Hall C, Electrum KTH, Kistagången 16
Opponent: Associate Professor Meni Wanunu, Dept of Physics, Northeastern University, Boston, USA
Supervisors: Jan Linnros, Ilya Sychugov, Niclas Roxhed
Abstract: Available on KTH-DiVA

2018-06-14: PhD defence
Title: Energy scaling of infrared nanosecond optical parametric oscillators and amplifiers based on Rb:KTiOPO4
Candidate: Riaan Stuart Coetzee
Time: 10:00 AM
Location: Lecture hall FD42, Albanova, Roslagstullsbacken 21, KTH, Stockholm
Opponent: Dr. Gunnar Rustad, FFI, Norway
Supervisors: Valdas Pasiskevicius
Abstract: Available on KTH-DiVA

2018-06-13: PhD defence
Title: Optical properties of GaN and InGaN studied by time- and spatially-resolved spectroscopy
Candidate: Tomas Kristijonas Uzdavinys
Time: 10:00 AM
Location: Lecture Hall C (Sven-Olof Öhrvik), Electrum, Kistagången 16, Kista
Opponent: Dr. Audrius Alkauskas, Center for Physical Sciences and Technology, Vilnius, Lithuania
Supervisors: Prof. Saulius Marcinkevicius, Department of Applied Physics, SCI School, KTH
Abstract: Time-resolved and near-field optical spectroscopy has been applied to establish several fundamental material parameters of gallium nitride (GaN) and study spatial variations in recombination parameters in indium gallium nitride (InGaN) layers and quantum wells. The main results include: i) determining the energy value between the two lowest conduction band minima of GaN and intervalley electron scattering times; ii) determining recombination parameters and revealing the crucial role of Fe-ion excited states in carrier recombination in GaN:Fe; iii) establishing a relation between the surface morphology and the alloy composition in InGaN epitaxial layers; iv) revealing the spatial nonuniformity of radiative and nonradiative recombination times in nonpolar InGaN quantum wells and v) determining the primary cause of the spectral broadening of InGaN quantum well emission spectra. These results are important for future development of high power electronic devices as well as light emitting and laser diodes operating in the visible spectral range.

2018-06-07: Applied Physics Seminar
Title: Room temperature upconversion imaging and detection in the mid-infrared with single photon detection capability
Speaker: Professor Christian Pedersen, DTU Technical University of Denmark
Location: Lecture room FA32, AlbaNova
Time: 9.15-10.00 am
Abstract: The mid-infrared (2-12 µm) wavelength range is an emerging new topic for frontier research. Its general importance relates to a multitude of mid-IR industrial and biomedical sensor applications. In particular, the chemical fingerprints of most complex molecules such as those found in food, tissue or catalytic compounds all have vibrational spectra in the mid-IR, thus identifiable through mid-IR spectroscopy. The main obstacle for the exploitation of the mid-IR optical window has been a historical lack of efficient mid-IR excitation light sources and sensitive mid-IR detectors/imaging devices. At DTU Fotonik, the Optical Sensor Technology Group has developed a new concept for IR light detection, where mid-IR light, rather than detected directly, are translated to near visible light for sensitive detection using CCD cameras, thus resulting in very low systems noise, even at room temperature. Here both theory and different applications will be presented.

2018-05-31: Lise Meitner Distinguished Lecture
Title: The art of taming light: What we can learn from a bacterium… and beyond
Speaker: Lene Vestergaard Hau, Harvard University
Location: Oskar Klein auditorium FR4
Time: 15:15-16:00 (Cofee and tea from 15:00)
Abstract: We love to manipulate light and have realized that we have a kindred soul in the form of a small bacterium - the cyanobacterium - whose light manipulations result in photosynthesis. This bacterium is in some ways amazing at manipulating light and in some ways…well not so much. But the system is modular and remarkably, the workings of the ‘best’ part of the system were discovered only in recent years but are still not not fully understood. Involved is an enzyme with the capability to perform light driven electrolysis and production of the oxygen in the atmosphere. Our interest in this system has led us to develop a new platform for studies of biomolecules at the single molecule level. I will discuss this platform and its potential for studies of photosynthetic enzymes and of proteins more generally.

2018-05-30: OQS seminar
Title: Polarization pulse dynamics in ultrafast thulium fiber lasers and nonlinear mid-infrared photothermal imaging
Speaker: Assistant Professor Michelle Sander
Location: FD41, AlbaNova
Time: 11.00am-12:00pm
Abstract: Thulium fiber lasers operating in the eye-safe wavelength region from 1.7 µm to 2.2 µm are attractive for applications in gas/environmental sensing, biomedical diagnosis and surgery and nonlinear conversion. Dual-output ultrafast lasers pave a promising pathway towards compact single sources for high precision metrology and dual comb spectroscopy. Based on vector soliton dynamics, a compact fiber laser with co-generated, orthogonally polarized interlaced pulses and coherent energy exchange will be discussed. Further, self-organized multiple pulsing operation and the generation of extreme events and chaotic transient states is demonstrated in turn-key, compact thulium fiber lasers. The second part of this talk will focus on mid-infrared vibrational photothermal spectroscopy in the fingerprint region (at wavelengths of ~5μm and longer), which can reveal characteristic details about molecular compounds with high sensitivity and specificity. A novel nonlinear photothermal operating regime with characteristic spectral narrowing, bifurcation and strong enhancements will be presented as a new pathway for material characterization. This technique can offer sub-diffraction limited imaging resolution and can be applied to analyze phase transitions or secondary protein conformations in biomedical tissue.

2018-02-15: Applied Physics Seminar
Title: Topological lasers
Speaker: Prof. Claudio Conti, Director of the CNR Institute for Complex Systems, Rome
Location: Seminar room FA31, KTH-AlbaNova
Time: 09:00-10:00
Abstract: Following the Nobel prize in 2016, topological ideas are progressively enriching various research directions in condensed matter physics, from graphene to photonics. The recent years witnessed an exploding number of top-level publications with practical applications and fundamental physics. Topological photonics is attracting growing interest from classical and quantum perspectives. Authors reported many ground-breaking results, as topologically protected modes in photonic crystals and quantum simulations of the 4D Hall effect. Here we introduce the leading ideas in the most accessible way, and review topics like the topological classification of photonic band structures, synthetic magnetic fields, and artificial dimensions. We discuss some recent results on topological lasers and possible developments like frequency-comb emitters, PT-symmetric devices, and the application of machine learning to design topological photonic devices.

2018-01-17: ADOPT-OQS seminar
Title: Extension of tests on basic principles of Quantum Mechanics using Quantum Communications to an orbiting terminal in Space
Speaker: Prof. Paolo Villoresi from the University of Padova
Location: Seminar room FA32, KTH-AlbaNova
Time: 11:00-12:00
Abstract: See the attached. (pdf 117 kB)

2018-01-17: ADOPT-OQS seminar
Title: Droplet-etched GaAs/AlGaAs quantum dots for quantum photonics applications
Speaker: Prof. Armando Rastelli, JKU Linz
Location: Seminar room FA32, KTH-AlbaNova
Time: 10:00-11:00
Abstract: -

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Last changed: Aug 21, 2018