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Seminars 2015

2015-12-14: PhD defence by Miu Yoong Leong
Title: Coherent Optical Transmission Systems: Performance and Coding Aspects
Candidate: Miu Yoong Leong
Supervisors: Assoc. prof. Sergei Popov, Prof. Gunnar Jacobsen
Opponent: Prof. Enrico Forestieri, Scuola Superiore Sant’Anna, Istituto TeCIP, Italy 
Time: 14 December 2015, 10.00 am
Location: Sal C, Electrum, Kista
Abstract: Available from KTH Diva

2015-10-23: PhD defence by Fatemeh (Mahtab) Sangghaleh
Title: Carrier Dynamics in Single Silicon Quantum Dots
Candidate: Fatemeh Sangghaleh
Time: 2015-10-23, 10:00AM
Location:  Hall C, KTH-Electrum
Opponent: Dr. Leigh Canham, pSiMedica Ltd & University of Birmingham, UK
Supervisors: Jan Linnros and Ilya Sytjugov
Abstract and thesis: Available from KTH Diva

2015-10-22: KSS seminar by Leigh Canham
Title: Broadening the functionality of semiconductor silicon technology via materials science
Speaker: Leigh Canham, PhD, Adj Prof, pSiMedica Ltd, Malvern, UK, School of Physics and Astronomy, University of Birmingham, UK
Time: 2015-10-22, 3:00PM
Location: Darlington seminar room, Electrum B4, KTH-Kista
The semiconductor silicon, at the heart of our electronics and solar cell industries, has often been referred to as the most studied and influential material made by mankind. Nanostructuring it however has yielded some very surprising properties and phenomena, many of which are surveyed in this lecture. Focus is given to two distinct areas:
- the physics behind and exploitation of quantum confinement effects in generating efficient visible light emission for silicon-based optoelectronics
- the biochemistry and exploitation of biodegradability and biocompatibility in medical therapy, nutrition and consumer care applications.

For widespread industrial use, nanoscale silicon will be required in a variety of physical forms and at widely varying purity and cost. Solid silicon is commercially available in wafer form at electronics grade 99.99999% purity down to metallurgical grade powders at 97-99% purity for the construction industry. For optoelectronics, sensing and high-value medical uses, “top-down”wafer and powder electrochemical etching techniques have been developed to generate nanostructured chips, membranes and particles at the kilogramme level. An exciting “bottom up” manufacturing opportunity will also be discussed to scale-up biogenic silicon production to the ton level by utilizing what botanists refer to as “silicon accumulator plants” that take silicic acid molecules from the soil. It will be shown that earth abundant plants like bamboo, rice, ferns, grasses and sugarcane contain and sometimes even secrete silica nanostructures. These can be chemically converted to solid silicon or silicon nanostructures of moderate purity, for specific uses. Nanoscale silicon looks destined to become a very “green” and multifunctional nanomaterial in the future.

2015-10-14: PhD defence by Patrik Holmberg
Title: Laser processing of silica based glass
Candidate: Patrik Holmberg
Time: 2015-10-14, 1:00PM
Location: FB 52, AlbaNova Universitetscentrum, Roslagstullsbacken 21, Stockholm
Opponent: Professor Dr. Valerio Pruneri, ICFO - The Institute of Photonic Sciences, Barcelona, Spain
Supervisors: Michael Fokine
Abstract and thesis:  available from KTH DiVa

2015-10-13: KSS & ADOPT seminar
Title: New Nonlinear Optical Materials for the Mid-Infrared
Speaker: Peter G. Schunemann, BAE Systems Inc
Time: Tuesday 2015-10-13, 2:30PM
Location: Faculty Lounge, Electrum, KTH-Kista
AbstractPeterSchunemann_KSS_Adopt.pdf (pdf 409 kB)

2015-10-12: PhD defence by Staffan Tjörnhammar
Title: Properties of Volume Bragg Gratings and Nonlinear Crystals for Laser Engineering
Candidate: Staffan Tjörnhammar
Time: Monday october 12, 2015, at 10.00
Location:  Room FB42, Albanova, Roslagstullsbacken 21, KTH, Stockholm
Opponent: Takunori Taira, National Institutes of Natural Sciences, Japan
Supervisors: Fredrik Laurell, Valdas Pasiskevicius

This thesis focuses on two topics: thermal limitations of volume Bragg gratings (VBGs) employed as laser-cavity mirrors and formation of color centers in KTiOPO4 and its isomorphs.

To explore the mechanisms of the thermal limitations of VBGs in high power lasers, I designed and constructed a diode-pumped, solid‑state laser with a VBG as cavity mirror that had a significantly higher absorption than what is typical. Thereby I could study the limiting thermal effects by using only moderate intra-cavity power. Additionally, I designed a computer model to numerically investigate the thermal effects in VBGs. Both the experiments and the simulations showed that the laser became successively more unstable when the power was increased. Absorption of the reflected laser beam causes broadening of the grating spectrum accompanied by decreasing diffraction efficiency. The reduced reflectivity leads to a leakage of the radiation through the grating. Moreover, the simulations showed that this increased instability was due to a reshaping of the intensity distribution profile inside the grating, which, in turn, leads to a sharp reduction of the diffraction efficiency.

High-intensity visible radiation induces color centers in KTiOPO4, which can lead to severe decrease in the performance of the crystal and can cause catastrophic breakdown. The formation of color centers was investigated by measuring picosecond, blue-light induced infrared absorption (BLIIRA) in periodically-poled KTiOPO4, Rb:KTiOPO4, RbTiOPO4, KTiOAsO4 and RbTiOAsO4 through thermal lens spectroscopy using a common-path interferometer. This setup is capable of measuring absorption as low as 10-5 cm-1. The dependence of the BLIIRA signal on blue light average power and intensity as well as on the crystal temperature was studied. The results show the presence of at least two different types of color centers. A higher level of remnant absorption was observed in the phosphates compared to that of the arsenates. The largest portion of the induced absorption is attributed to photo-generated electrons and holes being self-trapped in the proximity to the Ti4+ and O2- ions, respectively, forming polaron color centers. Stabilization of these centers is aided by the presence of mobile alkali metal vacancies in the crystal.

2015-09-24: Lecture by Sir Michael Berry
Title: Nature’s optics and our understanding of light
Speaker: Sir Michael Berry
Location: Oskar Klein lecture hall, KTH AlbaNova
Time: Thursday, 2015-09-24, 3:15PM

2015-09-25: PhD defence by Peter Zeil
Title: Tailored fiber lasers and their use in nonlinear optics
Candidate: Peter Zeil, Laser Physics, Dep. of Applied Physics, KTH
Time: Friday 2015-09-25, 10:00am
Location: Room FB52, AlbaNova Universitscenter, Roslagstullsbacken 21, Stockholm
Opponent: Professor Andy Clarkson, University of Southampton, Southampton, England
Supervisors: Professor Fredrik Laurell
Abstract and thesis: available from DiVA

2015-06-05: PhD defence by Johan Ahrens
Title: Non-contextual inequalities and dimensionality
Candidate: Johan Ahrens
Time: 02:00PM, 2015-06-05
Location: Room FB42, AlbaNova Universitscenter, Roslagstullsbacken 21, Stockholm
Opponent: Otfried Gühne, Department Physik, Universitaet Siegen, Germany
Supervisors: Prof. Mohamed Bourennane
Abstract and thesis: Available from DiVA portal

2015-06-03: Seminar on quantum cascade laser by Federico Capasso
Title: Novel high performance widely tunable quantum cascade lasers for spectroscopy, sensors and the Internet of everything
Speaker: Prof. Federico Capasso, Harvard University, USA
Place: Hall A, Electrum, KTH-Kista, Isafjordsgatan 22
Time: 2015-06-03, 2PM
Quantum cascade (QC) lasers have opened up in the last 15 years an underutilized portion of the spectrum (mid-infrared)  to a wide range of high volume applications. I will describe recent advances in my group including QC lasers with aperiodic gratings designed to target selectively the fingerprints of complex molecules (fingerprint gratings), broadly tunable lasers with sampled gratings and recent advances of our company EOS photonics in compact spectrometer and sensors for a wide range of applications in spectroscopy, pharmacy, medical ,environmental and security including in-network uses.

2015-06-02: PhD defence by Reyhaneh Soltanmoradi
Title: Structured Metallic Films for Enhanced Light Transmission and Absorption
Candidate: Reyhaneh Soltanmoradi
Time: 10:00AM, 2015-06-02
Location: Room C, Electrum, KTH Kista, Isafjordsgatan 22
Opponent: Assoc. Prof. Sanshui Xiao, Technical University of Denmark, Denmark
Supervisors: Doc. Min Yan, Dr. Qin Wang, Prof. Min Qiu, Assoc. Prof. Sergei Popov
Abstract and thesis: online on DiVA

2015-04-15: PhD defence by Michele Manzo
Title: Engineering ferroelectric domains and charge transport by proton exchange in lithium niobate
Candidate: Michele Manzo
Time: 10:00AM, 2015-04-15
Location: Room FD5, AlbaNova Universitscenter, Roslagstullsbacken 21, Stockholm
Opponent: Marin Alexe, University of Warwick, Dept of Physics, Coventry, England
Supervisors: Assoc. Prof. Katia Gallo
Abstract and thesis:   online on DiVA

Cover image of Michele's thesis

2015-04-08: "Year of Light" lecture at KVA
Title: Light and laser - Applications in environmental, ecological, and medical areas
Speaker: Sune Svanberg
Time: Wednesday 8 april 2015, 6-7pm
Location: Kungl. Vetenskapsakademien, Lilla Frescativägen 4A, Stockholm
More info: Brochure (pdf 709 kB)

Page responsible:Max Yan
Belongs to: School of Engineering Sciences (SCI)
Last changed: Dec 14, 2015