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Seminars 2017

2017-12-20: ADOPT seminar
Title: Nanowires for tandem junction solar cells
Speaker: Prof. Magnus Borgström
Location: Seminar room FB54, KTH-AlbaNova
Time: 15:00-16:00
Abstract: Abstract_Magnus_Borgstrom.pdf (pdf 473 kB)

2017-12-08: PhD defence
Title: Studies on domain wall properties and dynamics in KTiOPO4 and Rb-doped KTiOPO4
Candidate: Gustav Lindgren
Time: 10:00 AM
Location: Lecture hall FA31, Albanova, Roslagstullsbacken 21, KTH, Stockholm
Opponent: Professor Pam Thomas, Warwick University, UK
Supervisors: Assoc Prof. Carlota Canalias, Prof. Fredrik Laurell
Abstract: KTiOPO4 (KTP) and Rb-doped KTP (RKTP) are two of the most attractive nonlinear optical materials for engineering of periodically poled domain structures, commonly used as frequency-conversion devices for laser radiation via the quasi-phase matching (QPM) technique. These materials have excellent non-linearity, wide transparency windows and high resistance to optical damage. Furthermore their large domain-velocity anisotropy allows the fabrication of high aspect-ratio domain structures, needed for many QPM applications. To create highly efficient devices, precise control over the structure uniformity and duty-cycle is required. Constant improvement of the domain engineering techniques has allowed pushing the limits of the achievable domain aspect-ratio. For this development to continue, a deeper understanding of the formation dynamics and stability of the domain gratings is of utmost importance. As the domain-size in nanostructured devices decreases, the density of the domains walls (DWs) increases and their properties are ever more important for device performance. Indeed, more knowledge on the domain wall properties, and the means to engineer them, could enable new applications exploiting these properties.
This thesis presents studies on domain wall properties and dynamics in KTP and RKTP. The sub-millisecond dynamics of grating formation in RKTP under an applied electric field has been studied in the high-field regime using online second harmonic generation. The effects of different pulse shapes were compared and single triangular pulses were found to be superior in terms of the resulting grating quality.
The high-temperature stability of domain gratings was investigated. The domain wall motion induced by annealing was shown to be highly anisotropic along the a- and b­-crystal axes, and dependent on the period of the grating period.
The local charge transportation at the domains and domain walls in KTP was characterized using atomic force microscopy, demonstrating a fourfold increase of conductivity at the walls. Voltage-cycling measurements revealed memristive-like characteristics, attributed to the effect of ionic motion and local charge accumulation. The enhanced conductivity of charged domain walls was used as an imaging tool, to study domain wall dynamics while inducing motion through the application of an external field.
Finally, the interplay between ionic motion, spontaneous polarization and polarization reversal was investigated, showing direct evidence of elastic modulus modification during local polarization switching.

2017-12-05: ADOPT seminar
Title: Nanophotonics materials and devices
Speaker: Prof. Mattias Hammar, Department of Electronics, KTH
Location: Seminar room FA32, KTH-AlbaNova
Time: 15:00-16:00
Abstract: The increasing request for internet and advanced networking services as well as other high-end photonics applications put enormous requirements on versatile and high-performance optical components, in turn calling for new materials combinations, processing schemes and nanophotonic concepts. Here we review capabilities and developments at the KTH Electrum Laboratory with some examples related to telecommunication wavelength vertical-cavity surface-emitting lasers (VCSELs) and transistor-VCSELs, silicon-integrated photonic crystal nanomembrane and photonic bandedge VCSELs, and interband type-II quantum-dot long-wavelength infrared detectors for thermal imaging.

2017-11-29: ADOPT seminar
Title: Optical spectroscopy of single molecules and gold nanoparticles
Speaker: Prof. Michel Orrit, University Leiden, Netherlands
Location: Seminar room FA31, KTH-AlbaNova
Time: 11:00-12:00
Abstract: Fluorescence remains the workhorse method in single-molecule optics. Nonetheless, new techniques generalizing single-molecule optical observations have appeared recently. Photothermal microscopy opens the study of non-fluorescent absorbers, down to single-molecule sensitivity. Combining this contrast with photoluminescence, we can measure the luminescence quantum yield on a single-particle basis. The high signal-to-noise ratio of this technique enables uses of individual gold nanoparticles for local plasmonic and chemical probing.
Gold nanorods generate strong field enhancements near their tips. Matching the rods' plasmon to a dye's spectra, we observe enhancements in excess of thousand-fold for the fluorescence of single molecules of Crystal Violet and other weak emitters. This method generalizes single-molecule fluorescence to a broad range of weak emitters.
We recently studied the dynamics of vapor nanobubbles created in the liquid surrounding a single immobilized gold nanosphere. We found that these nanobubbles form in an instable, explosive process before collapsing. Nanobubbles can react to reflected sound waves such as those released in the explosion.

2017-11-27: KSS seminar
Title: Si nanocrystals and nanowires for photonic and energy device applications
Speaker: Jun Xu, Nanjing University
Location: Darlington seminar room (Materials Physics), Electrum B4, Kista
Time: 10:00-11:00

2017-11-24: PhD defence by Aleksandrs Marinis
Title: Polymer components for photonic integrated circuits
Candidate: Aleksandrs Marinis
Time: 2:00 PM
Location: Lecture Hall C, Electrum, KTH-Kista
Opponent: Prof. Leif Katsuo Oxenlowe, Denmark University of Technology
Main supervisor: Prof. Sergei Popov, Department of Applied Physics, KTH
Abstract: Optical polymers are a subject of intense research and industry implementation for several decades. Nowadays, organic materials are widely utilized in microelectronic and optoelectronic businesses. Comparing to inorganic materials, optical polymers are inexpensive, easy to process and flexible enough to meet a broad range of application-specific requirements. These advantages allow a development of cost-efficient polymer photonic integrated circuits for on-chip optical communications, signal processing, sensing, etc. However, polymer platform suffers from some drawbacks, for example, low refractive index contrast between core and cladding. This limits light confinement in a core and, consequently, integrated polymer device miniaturization. Also, polymers lack active functionality like light emission, amplification, modulation, etc. In this work, we developed methods to improve a performance of integrated passive polymer waveguides and demonstrated active devices based on polymer waveguides doped with silicon quantum dots. Also, we present novel silicon nanocrystal/polymer hybrid optical materials for active applications.

In the integrated device part of this work, we demonstrate optical waveguides with enhanced performance. We report uniform high refractive index contrast of 57.5% in air-suspended SU-8 waveguides. After SiO2 lower cladding removal, optical mode is well-confined and substrate leakage losses are eliminated. More of it, decreased radiation losses in curved waveguides allow low-loss bending with radii as small as 15 µm, which is far better than >100 µm for typical polymer waveguides. This approach provides high integration density and simplified photonic integrated circuit design. Another study shows a positive effect of thermal treatment on pedestal-standing acrylate waveguides. By heating slightly higher than polymer glass transition temperature, the viscosity decreases and reflows cracks and other surface roughness, minimizing scattering losses. Further heating reshapes initially rectangular waveguides into cylindrical ones yielding nearly negligible polarization dependent losses of <0.1 dB/cm, which is highly desirable for a proper circuit operation. When applied to polymer microring resonators, this treatment method enhances cavity Q factor more than 2 times. Considering polymers’ high compatibility with different dopants, we fabricated and evaluated all-optical intensity modulator based on PMMA waveguides with silicon quantum dots encapsulated. Demonstrated active device shows a potential to become a low-cost kHz range switch in all-optical circuits.

We also developed and characterized novel hybrid optical materials. Here, photoluminescent Si nanocrystals are encapsulated into PMMA and OSTE polymers. Obtained nanocomposites show stable photoluminescence in visible and near-infrared region with high quantum efficiency. We achieved the highest up to date ~65% quantum yield for solid-state Si nanocrystal composites. Demonstrated materials are a step towards Si-based on-chip light sources and nonlinearity driven active devices.

Integrated devices and materials presented in this work enhance the performance and expand functionality of polymer PICs. The components described here can serve not only as elements of optical communication circuits, but also as building blocks for on-chip sensing applications, microfluidics, optical memory, etc.

2017-11-24: PhD defence by Gleb Lobov
Title: Electro-optical properties of one-dimensional organic crystals
Candidate: Gleb Lobov
Time: 10:00 AM
Location: Lecture Hall C, Electrum, KTH-Kista
Opponent: Prof. Malgosia Kaczmarek, University of Southampton, UK
Main supervisor: Prof. Sergei Popov, Department of Applied Physics, KTH
Abstract: The recent development of photonics and applications puts new challenges for systems using emission, transmission and modulation of light. For these reasons, novel optical materials attract a special interest for their enabling properties for novel technologies.

In this work, we performed the research on fundamental properties and the possibility of implementation of electro-optical response of Poly-3-hexylthiophene-2,5-diyl (P3HT) nanofibers, which belong to the class of organic semiconductor crystalline materials. Our research demonstrated that an external electric field allows controlling the orientation of nanofibers dispersed in a solution by changing the electrical properties of P3HT crystals. This method was used to introduce a collective alignment of P3HT nanofibers and to impact the optical properties of the colloid.

The spectroscopic and polarization measurements show that P3HT nanofibers possess optical anisotropy in a wide range of visible spectrum. This property combined with the ability to manipulate the orientation of nanofibers dynamically, was used for direct phase and intensity modulation of transmitted light. Along with these investigations, several engineering and technology tasks were solved. We have designed the transverse electro-optical cell using all-optical-fiber approach, as well as the longitudinal electro-optical cell was fabricated using a novel polymer molding technique.

The obtained research results demonstrate the potential of P3HT crystalline nanofibers as a material class of large niche of applications, not only limited to photovoltaics but also being implemented in electro-optical systems to control light polarization and propagation.

2017-11-21: ADOPT seminar
Title: Mid-IR Femtosecond Fiber-based Lasers for science and beyond
Speaker: Irina T. Sorokina, Department of Physics, NTNU - Norwegian University of Science and Technology, Trondheim Norway
Location: Seminar room FA31, KTH-AlbaNova
Time: 15:00-16:00
Abstract: The presentation will review recent progress at the Laser Physics Group of NTNU in ultrafast fiber laser technology in general and in novel laser materials in particular in the mid-IR wavelength range ³2 μm. I will focus and discuss in more detail the two novel laser systems built around passively mode-locked Tm:fiber lasers and fiber-based Cr:ZnS lasers, generating sub-100 femtosecond pulses and frequency combs with several Watt average output powers, hundreds of kilowatts peak powers and tens of nanojoule pulse energies. Broad tunability between 2 and 2.5 μm as well as a simple all-silica-fiber design makes the Tm-fiber laser and Cr:ZnS truly unique light sources. They are particularly relevant for ultrasensitive laser spectroscopy and stand-off trace gas detection, especially in oil and gas industry. Beyond purely scientific applications they are the lasers of choice for fine material processing of semiconductors, glasses and plastics. The talk will also provide an insight into future trends and developments in the area of novel micro- and nano-crystalline based materials for compact integrated wave-guide based laser systems in the mid-IR as well as for integrated Si-photonics and solar cells.

2017-11-16: KSS seminar
Title: Thin film solar cells based on Cu2ZnSnS4
Speaker: Charlotte Platzer Björkman, Uppsala University
Location: Darlington seminar room (Materials Physics), Electrum B4, Kista
Time: 15:00-16:00
Abstract: Thin film solar cells have the advantage of very high light absorption due to a direct band gap, giving potential for light weight and flexible solar modules and lower production costs as compared to dominating silicon solar cells. The two commercial thin film technologies, CdTe and Cu(In,Ga)Se2, "CIGS", both contain elements that are relatively expensive. An alternative thin film material from only abundant elements is Cu2ZnSnS4, "CZTS". In this talk I will describe the research at Uppsala University on CZTS solar cells and make comparisons to the commercial CIGS technology.

2017-11-13: ADOPT seminar
Title: Semiconductor-Superconductor Hybrid Devices
Speaker: Alex Hayat, Technion
Location: Seminar room FA31, KTH-AlbaNova
Time: 15:00-16:00
Abstract: Various applications in the rapidly growing field of quantum information science require reliable and efficient quantum light sources. We observed superconducting proximity in semiconductor light-emitting diodes. These hybrid structures were proposed by us as an efficient approach for generation of entangled photons, based on Cooper-pair luminescence in semiconductors, which does not require isolated emitters. Semiconductor quantum wells, remove the light-heavy-hole degeneracy, allowing efficient photon entanglement generation in simple electrically-driven structures, taking advantage of the superconducting macroscopic coherence. Based on the developed theory we analyzed a new effect of enhanced light amplification in electrically-driven semiconductor-superconductor structures, including Cooper-pair based two-photon gain. Moreover, we proposed a compact and highly-efficient scheme for a complete Bell-state analysis using two-photon absorption in a superconducting proximity region of a semiconductor avalanche photodiode. This Cooper-pair based two-photon absorption results in a strong detection preference of a specified entangled state.
Realizing high-Tc superconductors-based quantum light sources paves the way widespread use of quantum technologies. In our experimental studies we investigated hybrid high-Tc superconductor-semiconductor tunnel junctions. These devices were fabricated by the newly-developed mechanical bonding technique, resulting in high-Tc semiconductor planar junctions acting as superconducting tunnel diodes. Tunneling-spectra characterization of the hybrid junctions of BSCCO combined with bulk GaAs, or a GaAs/AlGaAs quantum well, exhibits excess voltage and nonlinearity. A nanoscale thin film YBCO/GaN device was also demonstrated based on PLD growth. We produced high-temperature superconductivity in topological insulators Bi2Se3 and Bi2Te3 via proximity to BSCCO, persisting up to at least 80K – a temperature an order of magnitude higher than any previous observations.

2017-10-30: ADOPT seminar
Title: Ichtyosaurs (and other pets) in the quantum laboratory
Speaker: Klaus Mølmer, University of Aarhus, Denmark
Location: Seminar room FA32, KTH-AlbaNova
Time: 11:00-12:00
Abstract: Erwin Schrödinger was always frustrated by the apparent quantum jumps and collapses in quantum systems subject to measurement, and as late as in 1952, he declared the mere idea of doing experiments with single quantum particles “as absurd as the one of raising Ichtyosauria in the Zoo”. On this subject Schrödinger was wrong, and a variety of single quantum systems are now available for experimental investigation. Schrödinger may have been terrified to know that these systems are now candidates for applications in crucial technologies such as quantum information and quantum metrology. In this talk, I shall review methods to describe, control and understand the behavior of the Ichtyosauria in the quantum laboratory and show examples of how we can benefit from their random quantum jump behavior.

2017-10-26: APHYS seminar
Title: Relativistic attosecond physics
Speaker: László Veisz, Department of Physics, Umeå University
Location: Seminar room FB52, KTH-AlbaNova
Time: 09:00-10:00
Abstract: Generation of laser light with relativistic intensities, in which free electrons quiver with almost the speed of light, is routine nowadays. Similarly, the production of low-energy, field-controlled, quasi-single-cycle laser pulses is performed in various laboratories. However, the combination of these two properties in a unique light source -an optical parametric synthesizer- is only available in the relativistic attosecond physics laboratories (REAL). This system and its application to generate the shortest energetic extreme ultraviolet flashes and electron pulses with duration in the attosecond regime (1 as = 10-18 s) will be introduced. These flashes form the basis of filming electron dynamics as they freeze the motion of electrons in matter.

2017-10-25: ADOPT seminar
Title: III-V semiconductor nanowire/graphene structures and photonic devices
Speaker: Prof. Helge Weman, Norwegian University of Science and Technology (NTUU)
Location: Seminar room FB41, KTH-AlbaNova
Time: 4:00-5:00 PM
Abstract: See the attached (pdf 24 kB)

2017-10-18: ADOPT seminar
Title: Controling the emission properties of nanowires quantum dot with strain engineering and photonic structures
Speaker: Dr. Gilles Nogues, CNRS
Location: Seminar room FA32, KTH-AlbaNova
Time: 11.00-12.00PM
Abstract: In this talk I will review different experiment performed in Grenoble which are aimed at controlling the emission properties of a single quantum dot embedded in a II-VI nanowire. Growth condition allow to apply a well defined strain on the dot and hence to control its hole ground state (heavy or light-hole). I will also present two strategies to couple the nanowire QD to a photonic structure in order to optimize its light collection efficiency.

2017-10-11: ADOPT seminar
Title: Generating and detecting single microwave photons and phonons
Speaker: Göran Johansson, Chalmers University of Technology
Location: Seminar room FA32, KTH-AlbaNova
Time: 9.00-10.00AM
Abstract: ADOPT_Seminar_20171011.pdf (pdf 21 kB)

2017-10-04: ADOPT seminar
Title: Coupling artificial atoms to light and sound
Speaker: Per Delsing, Chalmers University of Technology
Location: Seminar room FA32, KTH-AlbaNova
Time: 11AM-12PM
Abstract: Abstract Per Delsing KTH 4 October 2017.pdf (pdf 412 kB)

2017-09-29: PhD defence by Ruslan Ivanov
Title: Impact of carrier localization on recombination in InGaN quantum wells with nonbasal crystallographic orientations
Candidate: Ruslan Ivanov
Time: 1:00 PM
Location: Lecture Hall B, Electrum, KTH-Kista
Opponent: Prof. Nicolas Grandjean, EPFL
Supervisor: Prof. Saulius Marcinkevicius, Department of Applied Physics KTH

2017-09-20: ADOPT seminar
Title: Thermal Scanning Probe Lithography and its Applications
Speaker: Tero Kulmala, SwissLitho, Zurich
Location: Seminar room FA32, KTH-AlbaNova
Time: 11AM-12PM
Abstract: see the attached (pdf 431 kB)

2017-09-14: APHYS seminar
Title: First x-ray nanoimaging experiments at NanoMAX
Speaker: Ulrich Vogt, BioX, KTH
Location: Seminar room FB42, KTH-AlbaNova
Time: 09:15-10:00
Abstract: NanoMAX is a hard x-ray nanoprobe beamline at the new Swedish synchrotron radiation source MAX IV that became operational in 2016. We were selected as the first external user of the MAX IV facility in Dec 2016 and we will present our results obtained at the NanoMAX. We will also show some results from other groups obtained during the first user period in spring 2017 in order to highlight the possibilities of the beamline for potential future users.

2017-08-29: ADOPT seminar
Title: Understanding Carrier Dynamics and Energetics in Controlled Nanowire Heterostructures
Speaker: Leigh Morris Smith, Department Physics, University of Cincinnati
Location: Seminar room FA32, KTH-AlbaNova
Time: 11:00-12:00
Abstract: Nanowire heterostructures can now be fabricated with ever higher precision and quality. With this control, it is now possible to design and fabricate heterostructures to enable particular physical properties which do not occur naturally. In this talk, I will discuss a variety of optical spectroscopies with high spatial, temporal and energy resolution which allow the measurement of physical properties of single nanowires. Through comparison of these measurements with structural images using electron microscopy of similar wires, we begin to understand how the nanostructure of single wires impacts their properties. The talk ends with a discussion of preliminary measurements of single nanowires in the mid-infrared which we hope will lead to similar understanding of small-gap nanostructures which have large spin-orbit interactions.

2017-08-23: ADOPT seminar
Title: Intrinsic nanostructures–semiconducting asymmetric nano-channel diodes
Speaker: Roman Sobolewski, University of Rochester
Location: Seminar room FB41, KTH AlbaNova
Time: 11:00-12:00
Abstract and biography: See the attached (doc 35 kB)

2017-06-15: PhD defence by Charlotte Liljestrand
Title: Advanced nano- and microdomain engineering of Rb-doped KTiOPO4 for nonlinear optical applications
Candidate: Charlotte Liljestrand
Time: 9:15 AM
Location: Seminar room FA32, AlbaNova University Center
Opponent: Prof. Sunao Kurimura, National Institute for Materials Science, Japan
Supervisor: Assoc Prof. Carlota Canalias, Department of Applied Physics KTH, Stockholm
Fine-pitch ferroelectric domain gratings with periods of a few µm are extensively used for generation of light in the visible and near-infrared spectral regions though quasi-phase matched (QPM) frequency conversion. Sub-µm QPM enables demonstration of nonlinear optics with counterpropagating waves, a field of nonlinear optics which remains sparsely explored due to the difficulty of fabricating high quality gratings.
In recent years, bulk Rb-doped KTiOPO4 (RKTP) has emerged as a highly promising nonlinear materials for fabrication of fine-pitch QPM devices through periodic electric field poling. RKTP possess large optical nonlinearity and high resistance to optical damage, while demonstrating improved material homogeneity and lower ionic conductivity than its isomorphs which are important features for poling. Although very fine-pitch QPM gratings, as well as large aperture QPM devices, have been demonstrated, fabrication of sub-µm high quality QPM devices remains a challenge.
The primary aim of this thesis was to develop a reliable method to fabricate high quality sub-µm periodically poled RKTP crystals (PPRKTP) and exploit them in novel optical applications. First a UV laser interference lithographic technique was developed to pattern the samples below the conventional lithography limit, and secondly a novel poling method was developed. It is based on periodic modulation of the coercive field through ion exchange, where K+ ions are exchanged with Rb+ in the crystal, to modulate the coercive field and the ionic conductivity. This enables periodic poling of higher quality and with shorter period than ever before. With the fabricated QPM devices I could demonstrate several novel optical devices and evaluate some of the physical properties of this new material.
High quality PPRKTP with a period of 755 nm was fabricated and used to demonstrate the first cascaded mirrorless optical parametric oscillator (MOPO), as well as the first MOPO pumped by a Q-switched laser. PPRKTP samples for blue light second harmonic generation was developed and investigated with a high power 946 nm fiber laser. Up to 2 W of power was demonstrated for bulk samples, where the output power was limited by blue light induced absorption, leading to thermal dephasing of the device. Laser-written waveguides were fabricated in PPRKTP for the first time, and a record high second harmonic power of 76 mW was obtained.
Finally, the long term stability of ferroelectric domain gratings was investigated. It is an important device issue, particularly for shorter grating periods, which theoretically should be more unstable than those with longer pitch. To shed light on this, we studied domain formation and domain stability at elevated temperatures and could correlate the stability with the grating period, as expected. Moreover, it was found that in the unstable state domain wall motion was highly anisotropic with rapid movement in y-direction while only small movements were observed in the x-direction of the crystal.

2019-06-09: PhD defence by Aditya Kakkar
Title: Frequency Noise in Coherent Optical Systems: Impact and Mitigation Methods
Candidate: Aditya Kakkar
Time: Friday June 9, 14.00
Room: Sal C, Electrum, Kista
Opponent: Prof. Magnus Karlsson, Chalmers Tekniska Högskola
Main Supervisor: Doc. Richard Schatz, KTH
Abstract and thesis: available on KTH DiVA

2019-06-09: PhD defence by Jaime Rodrigo Navarro
Title: Phase Noise Tolerant Modulation Formats and DSP Algorithms for Coherent Optical Systems
Candidate: Jaime Rodrigo Navarro
Time: Friday June 9, 10.00
Room: Sal C (Sal Sven-Olof Öhrvik), Electrum, Kista
Opponent: Prof. Gabriella Bosco, Politecnico di Torino
Main Supervisor: Prof. Sergei Popov, KTH
Abstract and thesis: Available on KTH DiVA

2017-05-24: Quantum Materials and Photonics seminar
Title: Towards scalable sources of entangled photons based on strain-engineered quantum dots
Speaker: Asst. Prof. Rinaldo Trotta, Institute of Semiconductor and Solid State Physics, Johannes Kepler University in Linz, Austria.
Location: Seminar room FA32, KTH AlbaNova
Time: 11:00-12:00
Abstract: See the attached. (pdf 74 kB)

2017-05-22: Seminar on Silicon Photonics
Title: Strained Silicon Photonics
Speaker: Dr Laurent Vivien, CNRS director, Centre for Nanoscience and Nanotechnology, University of Paris Sud, Orsay, France
Location: Room Darlington, Electrum, KTH Kista
Time: 2:30-3:30pm
Abstract: Silicon photonics is being considered as the future photonic platform, mainly for the reduction of photonic system costs and the increase of the number of functionalities on the same integrated chip by combining photonics and electronics. However, silicon is a centrosymmetric crystal, which inhibits Pockels effect: a second order nonlinear effect, which allows for light modulation at speeds that are not limited by carriers and driven at very low power consumption. Nevertheless, this limitation can be overcome by straining the crystal lattice and breaking the crystal symmetry of silicon. This crystal modification is achieved by depositing a SiN high-stress overlayer.
Over the last few years, several researches have been performed exploring Pockels effect in strained silicon. In this work, we present recent developments on the subject taking into account parasitic effects including plasma dispersion effect and fixed charge effect under an electric field. We experimentally demonstrate Pockels effect in silicon waveguides strained by a SiN overlayer deposited by PECVD as a function of waveguide geometry. Recent results on high-speed measurements have been performed to well dissociate Pockels effect and plasma dispersion effect. An overview of the recent advances in strained silicon photonics will be given during the seminar.

2017-05-22: PhD defence by Xu Sun
Title: Hybrid Plasmonic Devices for Optical Communication and Sensing
Candidate: Xu Sun
Time: 10:00 AM
Location: Lecture Hall C, Electrum, KTH Kista
Opponent: Dr Laurent Vivien, CNRS director, Centre for Nanoscience and Nanotechnology, University of Paris Sud, Orsay, France
Supervisor: Doc Lech Wosinski, Department of Applied Physics, KTH
Abstract and thesis: Available on KTH diva

2017-05-17: Quantum Materials and Photonics seminar
Title: Quantum structures and photonics with III-V nanowires
Speaker: Prof. Anna Fontcuberta i Morral, Laboratory of Semiconductor Materials, EPFL in Lausanne, Switzerland
Location: Room FA31, KTH AlbaNova
Time: 11:00-12:00
Abstract: Semiconductor nanowires have increasingly attracted attention because of their special properties derived of their filamentary nature and high crystalline quality. In this presentation we will review some of the possibilities that nanowires give in terms of fabrication of quantum structures as well as their photonic properties associated with their shape. We will also explain how these can be applied to improve and created new concepts in optoelectronic applications and solar energy conversion.

2017-05-12: PhD defence by Saroosh Shabbir
Title: Majorana Representation in Quantum Optics - SU(2) Interfermometry and Uncertainty Relations
Candidate: Saroosh Shabbir
Time: 13:00
Location: Seminar room FA31, AlbaNova University Center
Opponent: Prof. Maria Checkova, Max-Planck Institute for the Science of Light, Erlangen, Germany
Supervisor: Prof. Gunnar Björk, Department of Applied Physics KTH, Stockholm
Abstract and thesis: Available on KTH diva

2017-05-11: Applied Physics seminar on TeraHertz
Title: THz technology - a reality?
Speaker: Prof. Ulf Österberg, Department of Electronic Systems, Norwegian University of Science and Technology, Trondheim, Norway
Location: Room FA31, KTH AlbaNova
Time: 9:15-10:00 (coffee to be served at 9)
Abstract: This talk will give an overview of THz technology from the 1980's and forward. The emphasis will be on free space communications, fundamental spectroscopy and THz nano antennas.

2017-05-10: Quantum Materials and Photonics seminar
Title: Quantum photonics with semiconductor nanostructures
Speaker: Prof. Peter Michler, head of the Institute for Semiconductor Optics and Functional Interfaces at the University of Stuttgart
Location: Room FA31, KTH AlbaNova
Time: 11:00-12:00
Abstract: See attachment (pdf 57 kB)

2017-04-19: Quantum Materials and Photonics seminar
Title: New silicon photonic components enabled by MEMS technology
Speaker: Asst Prof. Kristinn B. Gylfason, MST, KTH
Location: Room FA31, KTH AlbaNova
Time: 11:00-12:00
Abstract: Silicon photonics is the study and application of integrated optical systems which use silicon as an optical medium, usually by confining light in optical waveguides etched into the surface of silicon-on-insulator (SOI) wafers. Microelectromechanical systems (MEMS) refers to the technology of mechanics on the microscale actuated by electrostatic actuators. Due to the low power requirements of electrostatic actuation, MEMS components are very power efficient, making them well suited for dense integration and mobile operation. MEMS components are conventionally also implemented in silicon, and due to the success of the silicon MEMS platform, MEMS sensors such as accelerometers, gyros, and microphones are now standard in every smartphone. By combining these two successful technologies in a single SOI wafer, new active photonic components with extremely low power consumption can be made. We discuss our recent experimental work on tunable filters, tunable fiber-to-chip couplers, and thermal emitters and detectors enabled by the marriage of silicon MEMS and silicon photonics.

2017-04-19: Applied Physics Seminar
Title: Quantum technology and the control of coherence in quantum networks
Speaker: Prof. Giorgos Tsironis, Center for Quantum Complexity and Nanotechnology, Department of Physics, University of Crete
Location: Room FB42, KTH AlbaNova
Time: 09:15-10:00
Abstract: Macroscopic quantum devices are becoming reality not only for computational purposes but also as sensors and for other general applications. A quantum superconducting chip with reasonable number of qubits -of order 20- is close to being build with decoherence times in the order of milliseconds. In this talk we will focus on superconducting technology and analyze the emergence of coherence in coupled networks of meta-atoms made of units such as SQUIDS and Josephson junctions. These networks may operate classically in a negative permeability regime, induce intrinsic nonlinear localized modes, tame disorder through hysteretic loops or transmit through nonlinear frequency bands. In the quantum regime, on the other hand, meta-atoms may interact through injected electromagnetic fields and form propagating “quantum breathers”, i.e. compound semiclassical propagating modes induced by the nonlinearity of the qubit-field interaction. These coherent modes generate self-induced transparency in the medium and in certain cases may also induce superradiance.

2017-04-18: Seminar by PRL Editor
Title: Successful Letters in Physical Review Letters: An Editor’s perspective
Speaker: Dr. Serena Dalena, Associate Editor of PRL
Location: Room FA32, KTH AlbaNova
Time: 15:00-16:00, April 18, 2017.
Abstract: Physical Review Letters publishes over 20,000 pages of scientific content per year while maintaining its presence as the premier physics journal. The purpose of this talk is to shed light into PRL editorial process and policy and address the many questions frequently raised by the thousands of active authors, referees and readers. How do the editors determine which papers to publish in PRL? What how-tos should you know as an author and a referee? Why should you submit your work to us? How are journals in general and PRL in particular reorienting amid increasing competition and other challenges? I plan to address these and related issues during my presentation and the subsequent discussion.

2017-04-07: PhD defence by Miguel Iglesias Olmedo
Title: Impairment Mitigation in High Capacity and Cost-efficient Optical Data Links
Candidate: Miguel Iglesias Olmedo
Time: 10 AM
Location: Hall B, Electrum, KTH Kista
Opponent: Prof. Marco Santagustina, University of Padova, Italy
Supervisor: Prof. Sergei Popov, Adj. Prof. Gunnar Jocobsen

2017-04-06: Seminar by Marco Santagiustina
Title: Research activities at the Photonic and Electromagnetics Group (PEG) of the University of Padova
Speaker: Prof. Marco Santagiustina
Time: April 6, 14:30
Place: Darlington, B4, Electrum, KTH Kista
Abstract: A survey of the ongoing research activities of PEG will be given. In the field of fiber optics the group has contributed
to the modelling and characterization of linear and nonlinear effects and the mastering of back-scattering techniques has opened
a new research area in the field of fiber optics sensors. Modelling complex photonic waveguides has been also an active research topic that will be briefly described.

2017-04-06: KTH-IEEE seminar on "Cultural Competence"
Title: Cultural Competence - A Key Skill to Work Successfully in International Teams
Speaker: Ekaterina von Gertten, Aperian Global
Organizer: Elena Vasilieva, KTH, IEEE WIE, IEEE Sweden
Time: 6 Apr 2017, 17:00 – 19:00
Location: KTH, Electrum, sal B
Abstract: In collaboration with Royal Institute of Technology, IEEE and Aperian Global, we invite you to join us for an evening of insights & discussion. In such a fast developing globalized world, the majority of us are members of an international team. This means that one has to create relationships and get work done through communicating across cultural boundaries. Cultural competence is now considered one of the key skills to succeed with an international career and the lack of it is viewed as one of the biggest obstacles for achieving efficiency in diverse teams. During the presentation, participants will: (1) Learn how our cultural background shapes our personalities & behaviors in the workplace; (2) Explore cultural dimensions & GlobeSmart, the industry-leading cultural inventory; (3) Gain tools & strategies for developing cultural agility
More info: CulturalCompetenceKeynote Flyer.pdf (pdf 476 kB)

2017-03-29: Quantum Materials and Photonics seminar
Title: Quantum dots in nanowires, a novel solid-state platform for quantum optics and hybrid nanomechanics
Speaker: Dr. Julien Claudon, CEA in Grenoble, France
Time: 29 March, 1-2pm
Location: FA31, KTH AlbaNova
Abstract: Abstract in PDF (pdf 159 kB)

2017-03-22: Quantum Materials and Photonics seminar
Filamentation of ultrashort laser pulses in air
Speaker: Andre Mysyrowicz, from Laboratoire d'Optique Appliquée, France
Time: 22 March, 1-2 pm
Location: Room FA31, KTH AlbaNova
Abstract: Abstract_QMP_20170322 (pdf 131 kB)

2017-03-15: Quantum Materials and Photonics seminar
Qubiz: Tunnelling the Barrier – Bringing Quantum Technologies to Market
Speaker: Cathal Mahon from Qubiz, Quantum Innovation Center, Copenhagen
Time: 11-12 noon
Location: FB42, KTH AlbaNova
Abstract: Qubiz: Quantum Innovation Center is a National Center dedicated to leveraging the very strong and unique research position within Quantum Physics in Denmark with a view to Commercializing Quantum Technologies. It represents Innovation Fund Denmark’s biggest single investment (potentially up to 22M€) with almost an additional 30 M€ from University and Industrial Partners over the planned 5-year period.

2017-02-22: Quantum Materials and Photonics seminar
Title: Rare earth ion doped crystals for quantum technology
Speaker: Stefan Kröll, Lund University
Time: 11-12 noon
Location: KTH AlbaNova
Abstract: Rare earth ions doped into inorganic crystals can remain in quantum superposition states during several hours and it is possible to entangle ions in spatially remote crystals with each other. This talk will review how rare earth ion doped crystals can be used in quantum tasks and in particular as quantum memories. If time permits the talk may also touch on slow light effects in these materials. The talk will be aimed to a general physics audience with interest in coherent interactions between light and matter.

2017-02-22: Quantum Materials and Photonics seminar
Title: The latest (monolayer WSe2) and greatest (InGaAs quantum dots) in solid-state quantum emitters
Speaker: Brian Gerardot, Quantum Photonics Laboratory, Heriot-Watt Universit y
Time: 11-12 noon
Location: FA31, KTH AlbaNova
Abstract: Motivated by potential technologies that exploit quantum mechanical superposition and entanglement, I will present our recent progress in the application of quantum optical techniques to coherently probe and manipulate solid-state quantum emitters. I will first discuss resonance fluorescence from single self-assembled InGaAs quantum dots, focusing particularly on the generation of ultra-coherent, indistinguishable photons in spite of the presence of environmental noise induced by nearby fluctuating nuclear spins or electronic charges. I will then present recent work on a “new” quantum emitter: a localised exciton in a WSe2 monolayer. Such a two-dimensional transition metal dichalcogenide semiconductor is an intriguing host for a quantum emitter due its unique optical, electronic, and structural properties. I will show how such emitters can be both spatially and spectrally localised via strain gradients and probe their magneto- and quantum-optical properties. These results raise the prospect to deterministically strain-engineer arrays of quantum emitters in two-dimensional semiconductors.

2017-02-21: Seminar by Val Zwiller
Title: Communicating with light
Speaker: Val Zwiller, QNP and ADOPT, KTH
Time: 5-6:30 PM
Location: Dome of Visions, Valhallavägen 79
Abstract: The seminar describes how light as an electromagnetic wave can be used in optical communications (fiber optics) and imaging.

2017-02-14: Quantum Materials and Photonics seminar
Title: Nanophotonic circuits for unconventional computing
Speaker: Prof. Wolfram Pernice, University of Muenster, Germany
Time: 11am-12noon
Location: FA32, KTH AlbaNova
Abstract: Nanophotonic circuits employ waveguiding devices to route light across quasi-planar integrated optical chips in analogy to electrical wires in integrated electrical circuits. Using materials with high refractive index allows for confining light into sub-wavelength dimensions as efficient optical wires. This way complex systems can be assembled from individual photonic building blocks using reliable nanofabrication routines. Besides applications in classical information processing and sensing, nanophotonic circuits provide interesting options for optical computing when combined with functional materials. Here I will give an overview of two recent efforts to realize the constituents for non-traditional computing architectures. Both approaches employ near-field coupling to nanophotonic waveguides as a resource to tailor light-matter interactions within an on-chip circuit architecture. I will introduce phase-change nanophotonic circuits as a platform for arithmetic processing, where calculation and storage of results are carried out in the same physical location. This approach allows for performing basic arithmetic on chip in an all-optical fashion. As an alternative, I will describe how nanophotonic circuits provide a rich toolbox for non-classical computations when operated at the single photon level. In this case, nanoscale fabrication enables the scalable realization of the building blocks required for linear optical quantum computing. I will present recent results on establishing such a platform with pure electronic control and nanoscale footprint.

2017-02-10: Quantum Materials and Photonics seminar
Title: Atomistic Modeling of Excitonic States in Semiconducting Nanostructures
Speaker: Prof. Michał Zieliński, Nicolaus Copernicus University
Time: 11am-12noon
Location: FA31, KTH AlbaNova
Abstract: See the attachment (pdf 201 kB)

2017-02-08: Quantum Materials and Photonics seminar
Title: Quantum optics with new toys
Speaker: Prof. Radek Łapkiewicz, University of Warsaw
Time: 11am-12noon
Location: FA32, KTH AlbaNova
I will discuss a few experiments with photons, trying to convince you that:
1. It is possible to image objects without detecting the light scattered by them.
2. Correlations between two particles can be witnessed by detecting only one particle.
3. Spatial phase of a single photon can be measured.
The experiments share the idea of replacing single pixel detectors with cameras in the classic setups of Leonard Mandel.

Page responsible:Max Yan
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Last changed: Dec 18, 2017