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  • 1.
    Abd Alrahman, Chadi
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Khodabakhsh, Amir
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Schmidt, Florian M.
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Qu, Zhechao
    Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics.
    Foltynowicz, Aleksandra
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Cavity-enhanced optical frequency comb spectroscopy of high-temperature H2O in a flame2014In: Optics Express, E-ISSN 1094-4087, Vol. 22, no 11, p. 13889-13895Article in journal (Refereed)
    Abstract [en]

    We demonstrate near-infrared cavity-enhanced optical frequency comb spectroscopy of water in a premixed methane/air flat flame. The detection system is based on an Er:fiber femtosecond laser, a high finesse optical cavity containing the flame, and a fast-scanning Fourier transform spectrometer (FTS). High absorption sensitivity is obtained by the combination of a high-bandwidth two-point comb-cavity lock and auto-balanced detection in the FTS. The system allows recording high-temperature water absorption spectra with a resolution of 1 GHz and a bandwidth of 50 nm in an acquisition time of 0.4 s, with absorption sensitivity of 4.2 x 10 (9) cm(-1) Hz(-1/2) per spectral element.

  • 2.
    Ako, Thomas
    et al.
    Laboratory of Photonic and Microwave Engineering, School of Information and Communication Technology, Royal Insitute of Technology, Electrum 229, Kista, Sweden.
    Yan, Min
    Laboratory of Photonic and Microwave Engineering, School of Information and Communication Technology, Royal Insitute of Technology, Electrum 229, Kista, Sweden.
    Qiu, Min
    Laboratory of Photonic and Microwave Engineering, School of Information and Communication Technology, Royal Insitute of Technology, Electrum 229, Kista, Sweden.
    Design of invisibility cloaks with an open tunnel2010In: Optics Express, E-ISSN 1094-4087, Vol. 18, no 26, p. 27060-27066Article in journal (Refereed)
    Abstract [en]

    In this paper we apply the methodology of transformation optics for design of a novel invisibility cloak which can possess an open tunnel. Such a cloak facilitates the insertion (retrieval) of matter into (from) the cloak’s interior without significantly affecting the cloak’s performance, overcoming the matter exchange bottleneck inherent to most previously proposed cloak designs. We achieve this by applying a transformation which expands a point at the origin in electromagnetic space to a finite area in physical space in a highly anisotropic manner. The invisibility performance of the proposed cloak is verified by using full-wave finite-element simulations.

  • 3.
    Ako, Thomas
    et al.
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Yan, Min
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Qiu, Min
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics, Photonics.
    Design of invisibility cloaks with an open tunnel2010In: Optics Express, E-ISSN 1094-4087, Vol. 18, no 26, p. 27060-27066Article in journal (Refereed)
    Abstract [en]

    In this paper we apply the methodology of transformation optics for design of a novel invisibility cloak which can possess an open tunnel. Such a cloak facilitates the insertion (retrieval) of matter into (from) the cloak's interior without significantly affecting the cloak's performance, overcoming the matter exchange bottleneck inherent to most previously proposed cloak designs. We achieve this by applying a transformation which expands a point at the origin in electromagnetic space to a finite area in physical space in a highly anisotropic manner. The invisibility performance of the proposed cloak is verified by using full-wave finite-element simulations. (C) 2010 Optical Society of America

  • 4. Akram, Muhammad Nadeem
    et al.
    Xiang, Yu
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Yu, Xingang
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Zabel, Thomas
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Hammar, Mattias
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Influence of base-region thickness on the performance of Pnp transistor-VCSEL2014In: Optics Express, E-ISSN 1094-4087, Vol. 22, no 22, p. 27398-27414Article in journal (Refereed)
    Abstract [en]

    We have recently reported a 980nm GaAs-based three terminal Pnp transistor-vertical-cavity surface-emitting laser (TVCSEL) operating at room temperature with optical power up to 1.8mW. However, the current gain beta = Delta I-c/Delta I-b was near zero just before lasing and became negative after the lasing threshold. The main cause of the negative current gain was found to be a gradual and position-dependent forward-biasing (saturation) of the base-collector junction with increasing bias even before lasing threshold. In this article, detailed multi-physics device simulations are performed to better understand the device physics, and find ways to avoid the premature saturation of the base-collector junction. We have optimized the thickness of the base region as well as its doping concentration and the location of the quantum wells to ensure that the T-VCSEL is in the active mode throughout its range of operation. That is, the emitter-base junction is forward biased and base-collector junction is reversed biased for sweeping the excess charges out of the base region.

  • 5.
    Alarcon, Alvaro
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Argillander, Joakim
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Spegel-Lexne, Daniel
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Xavier, Guilherme B
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Dynamic generation of photonic spatial quantum states with an all-fiber platform2023In: Optics Express, E-ISSN 1094-4087, Vol. 31, no 6, p. 10673-10683Article in journal (Refereed)
    Abstract [en]

    Photonic spatial quantum states are a subject of great interest for applications in quantum communication. One important challenge has been how to dynamically generate these states using only fiber-optical components. Here we propose and experimentally demonstrate an all-fiber system that can dynamically switch between any general transverse spatial qubit state based on linearly polarized modes. Our platform is based on a fast optical switch based on a Sagnac interferometer combined with a photonic lantern and few-mode optical fibers. We show switching times between spatial modes on the order of 5 ns and demonstrate the applicability of our scheme for quantum technologies by demonstrating a measurement-device-independent (MDI) quantum random number generator based on our platform. We run the generator continuously over 15 hours, acquiring over 13.46 Gbits of random numbers, of which we ensure that at least 60.52% are private, following the MDI protocol. Our results show the use of photonic lanterns to dynamically create spatial modes using only fiber components, which due to their robustness and integration capabilities, have important consequences for photonic classical and quantum information processing.(c) 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

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  • 6.
    Alarcon, Alvaro
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering. Univ Concepcion, Chile.
    Gonzalez, P.
    Univ Concepcion, Chile.
    Carine, J.
    Univ Concepcion, Chile; Univ Catolica Santisima, Chile.
    Lima, G.
    Univ Concepcion, Chile.
    Xavier, Guilherme B
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Polarization-independent single-photon switch based on a fiber-optical Sagnac interferometer for quantum communication networks2020In: Optics Express, E-ISSN 1094-4087, Vol. 28, no 22, p. 33731-33738Article in journal (Refereed)
    Abstract [en]

    An essential component of future quantum networks is an optical switch capable of dynamically routing single photons. Here we implement such a switch, based on a fiber-optical Sagnac interferometer design. The routing is implemented with a pair of fast electro-optical telecom phase modulators placed inside the Sagnac loop, such that each modulator acts on an orthogonal polarization component of the single photons, in order to yield polarization-independent capability that is crucial for several applications. We obtain an average extinction ratio of more than 19 dB between both outputs of the switch. Our experiment is built exclusively with commercial off-the-shelf components, thus allowing direct compatibility with current optical communication systems. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

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  • 7. Alcusa-Saez, E. P.
    et al.
    Diez, A.
    Rivera-Perez, E.
    Margulis, Walter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Norin, Lars
    ACREO.
    Andres, M. V.
    Acousto-optic interaction in polyimide coated optical fibers with flexural waves2017In: Optics Express, E-ISSN 1094-4087, Vol. 25, no 15, p. 17167-17173Article in journal (Refereed)
    Abstract [en]

    Acousto-optic coupling in polyimide-coated single-mode optical fibers using flexural elastic waves is demonstrated. The effect of the polyimide coating on the acoustooptic interaction process is analyzed in detailed. Theoretical and experimental results are in good agreement. Although the elastic attenuation is significant, we show that acousto-optic coupling can be produced with a reasonably good efficiency. To our knowledge, it is the first experimental demonstration of acousto-optic coupling in optical fibers with robust protective coating.

  • 8.
    Alcusa-Sáez, E. P.
    et al.
    ICMUV Departamento de Física Aplicada y Electromagnetismo, Spain.
    Díez, Antonio
    ICMUV Departamento de Física Aplicada y Electromagnetismo, Spain.
    Rivera-Pérez, E.
    ICMUV Departamento de Física Aplicada y Electromagnetismo, Spain.
    Margulis, Walter
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo. KTH Royal Institute of Technology, Sweden.
    Norin, L.
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo. KTH Royal Institute of Technology, Sweden.
    Andrés, M. V.
    ICMUV Departamento de Física Aplicada y Electromagnetismo, Spain.
    Acousto-optic interaction in polyimide coated optical fibers with flexural waves2017In: Optics Express, E-ISSN 1094-4087, Vol. 25, no 15, p. 17167-17173Article in journal (Refereed)
    Abstract [en]

    Acousto-optic coupling in polyimide-coated single-mode optical fibers using flexural elastic waves is demonstrated. The effect of the polyimide coating on the acousto-optic interaction process is analyzed in detailed. Theoretical and experimental results are in good agreement. Although the elastic attenuation is significant, we show that acousto-optic coupling can be produced with a reasonably good efficiency. To our knowledge, it is the first experimental demonstration of acousto-optic coupling in optical fibers with robust protective coating.

  • 9.
    Amer, Eynas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Gren, Per
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Edenharder, Stefan
    Institut für Technische Optik, Universität Stuttgart.
    Sjödahl, Mikael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Stimulated Raman scattering detection for chemically specific time-resolved imaging of gases2016In: Optics Express, E-ISSN 1094-4087, Vol. 24, no 9, p. 9984-9993Article in journal (Refereed)
    Abstract [en]

    stimulated Raman scattering (SRS) imaging technique based on spatial modulation of the pump beam has been used to study gases. The SRS gain signal was separated from the Stokes beam background in the spatial frequency domain. The SRS signal shows linear behaviour with the gas pressure at a range from 1.0 to 8.0 bars. The signal is linearly proportional to the pump beam intensity while it is enhanced with increasing the Stokes beam intensity to a certain limit than it saturates. Further, the chemical specificity of the technique has been investigated. Two sharp peaks with line width at half maximum of about 0.30 nm have been obtained at Stokes beam wavelengths of 629.93 nm and 634.05 nm corresponding to the methane and ethylene gases, respectively. The results show that SRS imaging is a promising technique to provide chemical specificity as well as spatial and temporal information of gaseous species

  • 10.
    Amer, Eynas
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Gren, Per
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    Sjödahl, Mikael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
    UV laser interaction with a fluorescent dye solution studied using pulsed digital holography2013In: Optics Express, E-ISSN 1094-4087, Vol. 21, no 21, p. 25316-25323Article in journal (Refereed)
    Abstract [en]

    A frequency tripled Q-switched Nd-YAG laser (wavelength 355 nm, pulse duration 12 ns) has been used to pump Coumarin 153 dye solved in ethanol. Simultaneously, a frequency doubled pulse (532 nm) from the same laser is used to probe the solvent perpendicularly resulting in a gain through stimulated laser induced fluorescence (LIF) emission. The resulting gain of the probe beam is recorded using digital holography by blending it with a reference beam on the detector. Two digital holograms without and with the pump beam were recorded. Intensity maps were calculated from the recorded digital holograms and used to calculate the gain of the probe beam due to the stimulated LIF. In addition numerical data of the local temperature rise was calculated from the corresponding phase maps using Radon inversion. It was concluded that about 15% of the pump beam energy is transferred to the dye solution as heat while the rest is consumed in the radiative process. The results show that pulsed digital holography is a promising technique for quantitative study of fluorescent species

  • 11. Amotchkina, Tatiana
    et al.
    Trubetskov, Michael K.
    Pervak, Yurij
    Veisz, Laszlo
    Max-Planck-Institut für Quantenoptik, D-85748 Garching, Germany.
    Pervak, Vladimir
    Stress compensation with antireflection coatings for ultrafast laser applications: from theory to practice2014In: Optics Express, E-ISSN 1094-4087, Vol. 22, no 24, p. 30387-30393Article in journal (Refereed)
    Abstract [en]

    Each complicated coating, in particular, a dispersive mirror consists of dozens of layers. Thin films layers have mechanical stresses. After summing up stresses from all layers, the resulting stress is high enough to bend even a relatively thick substrate. To avoid this effect we suggest depositing an antireflection coating (AR) at the back-side of the substrate which together with suppression of unwanted reflections from the back side will also compensate this stress. We demonstrate unique, extremely thick and sophisticated AR coating consisting of 71 layers with the total physical thickness of 7.5 µm. This AR coating completely compensates stress from the dispersive mirror coated on the front side and minimizes unwanted reflections.

  • 12.
    Andreasson, Jakob
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Martin, Andrew V.
    Liang, Meng
    Timneanu, Nicusor
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Aquila, Andrew
    Wang, Fenglin
    Iwan, Bianca
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Svenda, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Ekeberg, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Hantke, Max
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Bielecki, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Rolles, Daniel
    Rudenko, Artem
    Foucar, Lutz
    Hartmann, Robert
    Erk, Benjamin
    Rudek, Benedikt
    Chapman, Henry N.
    Hajdu, Janos
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Barty, Anton
    Automated identification and classification of single particle serial femtosecond X-ray diffraction data2014In: Optics Express, E-ISSN 1094-4087, Vol. 22, no 3, p. 2497-2510Article in journal (Refereed)
    Abstract [en]

    The first hard X-ray laser, the Linac Coherent Light Source (LCLS), produces 120 shots per second. Particles injected into the X-ray beam are hit randomly and in unknown orientations by the extremely intense X-ray pulses, where the femtosecond-duration X-ray pulses diffract from the sample before the particle structure is significantly changed even though the sample is ultimately destroyed by the deposited X-ray energy. Single particle X-ray diffraction experiments generate data at the FEL repetition rate, resulting in more than 400,000 detector readouts in an hour, the data stream during an experiment contains blank frames mixed with hits on single particles, clusters and contaminants. The diffraction signal is generally weak and it is superimposed on a low but continually fluctuating background signal, originating from photon noise in the beam line and electronic noise from the detector. Meanwhile, explosion of the sample creates fragments with a characteristic signature. Here, we describe methods based on rapid image analysis combined with ion Time-of-Flight (ToF) spectroscopy of the fragments to achieve an efficient, automated and unsupervised sorting of diffraction data. The studies described here form a basis for the development of real-time frame rejection methods, e. g. for the European XFEL, which is expected to produce 100 million pulses per hour. (C)2014 Optical Society of America

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  • 13.
    Antelius, Mikael
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Gylfason, Kristinn B.
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Sohlström, Hans
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    An apodized SOI waveguide-to-fiber surface grating coupler for single lithography silicon photonics2011In: Optics Express, E-ISSN 1094-4087, Vol. 19, no 4, p. 3592-3598Article in journal (Refereed)
    Abstract [en]

    We present the design, fabrication, and characterization of a grating for coupling between a single mode silica fiber and the TE mode in a silicon photonic waveguide on a silicon on insulator (SOI) substrate. The grating is etched completely through the silicon device layer, thus permitting the fabrication of through-etched surface coupled silicon nanophotonic circuits in a single lithography step. Furthermore, the grating is apodized to match the diffracted wave to the mode profile of the fiber. We experimentally demonstrate a coupling efficiency of 35% with a 1 dB bandwidth of 47 nm at 1536 nm on a standard SOI substrate. Furthermore, we show by simulation that with an optimized buried oxide thickness, a coupling efficiency of 72% and a 1 dB bandwidth of 38 nm at 1550 nm is achievable. This is, to our knowledge, the highest simulated coupling efficiency for single-etch TE-mode grating couplers. In particular, simulations show that apodizing a conventional periodic through-etched grating decreases the back-reflection into the waveguide from 21% to 0.1%.

  • 14.
    Ao, Xianyu
    et al.
    KTH.
    He, Sailing
    KTH, Superseded Departments (pre-2005), Electromagnetic Theory.
    Two-stage design method for realization of photonic bandgap structures with desired symmetries by interference lithography2004In: Optics Express, E-ISSN 1094-4087, Vol. 12, no 6, p. 978-983Article in journal (Refereed)
    Abstract [en]

    Interference lithography for the fabrication of photonic crystals is considered. A two-stage design method for realization of photonic bandgap structures with desired symmetries is developed. An optimal photonic crystal with a large bandgap is searched by adjusting some parameters while keeping some basic symmetry of the unit cell unchanged. A nonlinear programming method is then used to find the optimal electric field vectors of the laser beams and realize the desired interference pattern. The present method is useful for a rational and systematical design of new photonic bandgap structures.

  • 15. Aquila, Andrew
    et al.
    Hunter, Mark S.
    Doak, R. Bruce
    Kirian, Richard A.
    Fromme, Petra
    White, Thomas A.
    Andreasson, Jakob
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Arnlund, David
    Bajt, Saša
    Barends, Thomas R. M.
    Barthelmess, Miriam
    Bogan, Michael J.
    Bostedt, Christoph
    Bottin, Hervé
    Bozek, John D.
    Caleman, Carl
    Coppola, Nicola
    Davidsson, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    DePonte, Daniel P.
    Elser, Veit
    Epp, Sascha W.
    Erk, Benjamin
    Fleckenstein, Holger
    Foucar, Lutz
    Frank, Matthias
    Fromme, Raimund
    Graafsma, Heinz
    Grotjohann, Ingo
    Gumprecht, Lars
    Hajdu, Janos
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Hampton, Christina Y.
    Hartmann, Andreas
    Hartmann, Robert
    Hau-Riege, Stefan
    Hauser, Günter
    Hirsemann, Helmut
    Holl, Peter
    Holton, James M.
    Hömke, André
    Johansson, Linda
    Kimmel, Nils
    Kassemeyer, Stephan
    Krasniqi, Faton
    Kühnel, Kai-Uwe
    Liang, Mengning
    Lomb, Lukas
    Malmerberg, Erik
    Marchesini, Stefano
    Martin, Andrew V.
    Maia, Filipe R.N.C.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Messerschmidt, Marc
    Nass, Karol
    Reich, Christian
    Neutze, Richard
    Rolles, Daniel
    Rudek, Benedikt
    Rudenko, Artem
    Schlichting, Ilme
    Schmidt, Carlo
    Schmidt, Kevin E.
    Schulz, Joachim
    Seibert, M. Marvin
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Soltau, Heike
    Shoeman, Robert L.
    Sierra, Raymond
    Starodub, Dmitri
    Stellato, Francesco
    Stern, Stephan
    Strüder, Lothar
    Timneanu, Nicusor
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Ullrich, Joachim
    Wang, Xiaoyu
    Williams, Garth J.
    Weidenspointner, Georg
    Weierstall, Uwe
    Wunderer, Cornelia
    Barty, Anton
    Spence, John C. H.
    Chapman, Henry N.
    Time-resolved protein nanocrystallography using an X-ray free-electron laser2012In: Optics Express, E-ISSN 1094-4087, Vol. 20, no 3, p. 2706-2716Article in journal (Refereed)
    Abstract [en]

    We demonstrate the use of an X-ray free electron laser synchronized with an optical pump laser to obtain X-ray diffraction snapshots from the photoactivated states of large membrane protein complexes in the form of nanocrystals flowing in a liquid jet. Light-induced changes of Photosystem I-Ferredoxin co-crystals were observed at time delays of 5 to 10 µs after excitation. The result correlates with the microsecond kinetics of electron transfer from Photosystem I to ferredoxin. The undocking process that follows the electron transfer leads to large rearrangements in the crystals that will terminally lead to the disintegration of the crystals. We describe the experimental setup and obtain the first time-resolved femtosecond serial X-ray crystallography results from an irreversible photo-chemical reaction at the Linac Coherent Light Source. This technique opens the door to time-resolved structural studies of reaction dynamics in biological systems.

  • 16. Arias, Augusto
    et al.
    Etcheverry, Sebastian
    Solano, Pablo
    Staforelli, Juan
    Gallardo, Maria Jose
    Rubinsztein-Dunlop, Helina
    Saavedra, Carlos
    Simultaneous rotation, orientation and displacement control of birefringent microparticles in holographic optical tweezers2013In: Optics Express, E-ISSN 1094-4087, Vol. 21, no 1, p. 102-111Article in journal (Refereed)
    Abstract [en]

    We report the experimental implementation of a new method for generating multiple dynamical optical tweezers, where each one of them is generated with an independent linear polarization state with arbitrary orientation. This also allows an independent simultaneous polarization-rotation control. The laser beam, both for generating multiple traps and polarization control, has been modulated using a single reflective nematic liquid crystal with parallel alignment. We present experimental results of controlled displacement, orientation and rotation of birefringent particles. In addition, a simple method for estimating and canceling out the primary astigmatism present in the system is presented.

  • 17.
    Arwin, Hans
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Berlind, Torun
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Johs, Blaine
    JA Woollam Co Inc, NE USA .
    Järrendahl, Kenneth
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Cuticle structure of the scarab beetle Cetonia aurata analyzed by regression analysis of Mueller-matrix ellipsometric data2013In: Optics Express, E-ISSN 1094-4087, Vol. 21, no 19, p. 22645-22656Article in journal (Refereed)
    Abstract [en]

    Since one hundred years it is known that some scarab beetles reflect elliptically and near-circular polarized light as demonstrated by Michelson for the beetle Chrysina resplendens. The handedness of the polarization is in a majority of cases left-handed but also right-handed polarization has been found. In addition, brilliant colors with metallic shine are observed. The polarization and color effects are generated in the beetle exoskeleton, the so-called cuticle. The objective of this work is to demonstrate that structural parameters and materials optical functions of these photonic structures can be extracted by advanced modeling of spectral multi-angle Mueller-matrix data recorded from beetle cuticles. A dual-rotating compensator ellipsometer is used to record normalized Mueller-matrix data in the spectral range 400 – 800 nm at angles of incidence in the range 25–75°. Analysis of data measured on the scarab beetle Cetonia aurata are presented in detail. The model used in the analysis mimics a chiral nanostructure and is based on a twisted layered structure. Given the complexity of the nanostructure, an excellent fit between experimental and model data is achieved. The obtained model parameters are the spectral variation of the refractive indices of the cuticle layers and structural parameters of the chiral structure.

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  • 18.
    Arwin, Hans
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Magnusson, Roger
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, Faculty of Science & Engineering.
    Garcia-Caurel, Enric
    Laboratoire des Physique des Interfaces et Couches Minces, Ecole Polytechnique, CNRS, France.
    Fallet, C.
    Bioaxial SAS, 40 rue de Paradis, France.
    Järrendahl, Kenneth
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Foldyna, M.
    Laboratoire des Physique des Interfaces et Couches Minces, Ecole Polytechnique, CNRS, France.
    De Martino, A.
    Laboratoire des Physique des Interfaces et Couches Minces, Ecole Polytechnique, CNRS, France.
    Ossikovski, R.
    Laboratoire des Physique des Interfaces et Couches Minces, Ecole Polytechnique, CNRS, France.
    Sum decomposition of Mueller-matrix images and spectra of beetle cuticles2015In: Optics Express, E-ISSN 1094-4087, Vol. 23, no 3, p. 1951-1966Article in journal (Refereed)
    Abstract [en]

    Spectral Mueller matrices measured at multiple angles of incidence as well as Mueller matrix images are recorded on the exoskeletons (cuticles) of the scarab beetles Cetonia aurata and Chrysina argenteola. Cetonia aurata is green whereas Chrysina argenteola is gold-colored. When illuminated with natural (unpolarized) light, both species reflect left-handed and near-circularly polarized light originating from helicoidal structures in their cuticles. These structures are referred to as circular Bragg reflectors. For both species the Mueller matrices are found to be nondiagonal depolarizers. The matrices are Cloude decomposed to a sum of non-depolarizing matrices and it is found that the cuticle optical response, in a first approximation can be described as a sum of Mueller matrices from an ideal mirror and an ideal circular polarizer with relative weights determined by the eigenvalues of the covariance matrices of the measured Mueller matrices. The spectral and image decompositions are consistent with each other. A regression-based decomposition of the spectral and image Mueller matrices is also presented whereby the basic optical components are assumed to be a mirror and a circular polarizer as suggested by the Cloude decomposition. The advantage with a regression decomposition compared to a Cloude decomposition is its better stability as the matrices in the decomposition are determined a priori. The origin of the depolarizing features are discussed but from present data it is not possible to conclude whether the two major components, the mirror and the circular polarizer are laterally separated in domains in the cuticle or if the depolarization originates from the intrinsic properties of the helicoidal structure.

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  • 19. Atlasov, K.A.
    et al.
    Karlsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Rudra, A.
    Dwir, B.
    Kapon, E.
    Wavelength and loss splitting in directly coupled photonic-crystal defect microcavities2008In: Optics Express, E-ISSN 1094-4087, Vol. 16, no 20, p. 16255-16264Article in journal (Refereed)
    Abstract [en]

    Coupling between photonic-crystal defect microcavities is observed to result in a splitting not only of the mode wavelength but also of the modal loss. It is discussed that the characteristics of the loss splitting may have an important impact on the optical energy transfer between the coupled resonators. The loss splitting - given by the imaginary part of the coupling strength - is found to arise from the difference in diffractive outof-plane radiation losses of the symmetric and the antisymmetric modes of the coupled system. An approach to control the splitting via coupling barrier engineering is presented. © 2008 Optical Society of America.

  • 20.
    Atlasow, Kirill A.
    et al.
    Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratory of Physics of Nanostructures, CH-1015 Lausanne, Switzerland.
    Calic, Milan
    Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratory of Physics of Nanostructures, CH-1015 Lausanne, Switzerland.
    Karlsson, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology. Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratory of Physics of Nanostructures, CH-1015 Lausanne, Switzerland.
    Gallo, Pascal
    Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratory of Physics of Nanostructures, CH-1015 Lausanne, Switzerland.
    Rudra, Alok
    n/Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratory of Physics of Nanostructures, CH-1015 Lausanne, Switzerland.
    Dwir, Benjamin
    Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratory of Physics of Nanostructures, CH-1015 Lausanne, Switzerland.
    Kapon, Eli
    Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratory of Physics of Nanostructures, CH-1015 Lausanne, Switzerland.
    Photonic-crystal microcavity laser with site-controlled quantum-wire active medium2009In: Optics Express, E-ISSN 1094-4087, Vol. 17, no 20, p. 18178-18183Article in journal (Refereed)
    Abstract [en]

    Site-controlled quantum-wire photonic-crystal microcavity laser is experimentally demonstrated using optical pumping. The single-mode lasing and threshold are established based on the transient laser response, linewidth narrowing, and the details of the non-linear power input-output charateristics. Average-power threshold as low as ~240 nW (absorbed power) and spontaneous emission coupling coefficient β~0.3 are derived.

  • 21.
    Awel, Salah
    et al.
    Deutsch Elektronen Synchrotron DESY, Ctr Free Electron Laser Sci CFEL, Notkestr 85, D-22607 Hamburg, Germany..
    Bohne, Sven
    Hamburg Univ Technol, Eissendorfer Str 42, D-21073 Hamburg, Germany..
    Ebrahimifard, Reza
    Deutsch Elektronen Synchrotron DESY, Notkestr 85, D-22607 Hamburg, Germany..
    Trieu, Hoc Khiem
    Bajt, Sasa
    Deutsch Elektronen Synchrotron DESY, Notkestr 85, D-22607 Hamburg, Germany.;Hamburg Ctr Ultrafast Imaging, Luruper Chaussee 149, D-22761 Hamburg, Germany..
    Chapman, Henry
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics. Deutsch Elektronen Synchrotron DESY, Ctr Free Electron Laser Sci CFEL, Notkestr 85, D-22607 Hamburg, Germany.;Hamburg Ctr Ultrafast Imaging, Luruper Chaussee 149, D-22761 Hamburg, Germany.;Univ Hamburg, Dept Phys, Luruper Chaussee 149, D-22761 Hamburg, Germany.;Uppsala Univ, Dept Phys & Astron, Mol & Condensed Matter Phys, Uppsala, Sweden..
    Optical bunching of particles in a liquid flow2021In: Optics Express, E-ISSN 1094-4087, Vol. 29, no 21, p. 34394-34410Article in journal (Refereed)
    Abstract [en]

    High-speed liquid micro-jets are used to rapidly and repeatedly deliver protein microcrystals to focused and pulsed X-ray beams in the method of serial femtosecond crystallography. However, the current continuous flow of crystals is mismatched to the arrival of X-ray pulses, wasting vast amounts of an often rare and precious sample. Here, we introduce a method to address this problem by periodically trapping and releasing crystals in the liquid flow, creating locally concentrated crystal bunches, using an optical trap integrated in the microfluidic supply line. We experimentally demonstrate a 30-fold increase of particle concentration into 10 Hz bunches of 6.4 tm diameter polystyrene particles. Furthermore, using particle trajectory simulations, a comprehensive description of the optical bunching process and parameter space is presented. Adding this compact optofluidics device to existing injection systems would thereby dramatically reduce sample consumption and extend the application of serial crystallography to a greater range of protein crystal systems that cannot be produced in high abundance. Our approach is suitable for other microfluidic systems that require synchronous measurements of flowing objects. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

  • 22. Baek, In Hyung
    et al.
    Choi, Sun Young
    Lee, Hwang Woon
    Cho, Won Bae
    Petrov, Valentin
    Agnesi, Antonio
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Yeom, Dong-Il
    Kim, Kihong
    Rotermund, Fabian
    Single-walled carbon nanotube saturable absorber assisted high-power mode-locking of a Ti:sapphire laser2011In: Optics Express, E-ISSN 1094-4087, Vol. 19, no 8, p. 7833-7838Article in journal (Refereed)
    Abstract [en]

    We report on passive mode-locking of a Ti:sapphire laser employing a single-walled carbon nanotube saturable absorber (SWCNT-SA) specially designed and fabricated for wavelengths near 800 nm. Mode-locked pulses as short as 62 fs were generated at a repetition rate of 99.4 MHz. We achieved output powers from the SWCNT-SA mode-locked laser as high as 600 mW with a slope efficiency of 26%. The characteristics of SWCNT-SA-assisted mode-locking were compared with those of Kerr-lens mode-locking without SWCNT-SA.

  • 23.
    Baghban, Mohammad Amin
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Schollhammer, Jean
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Errando-Herranz, Carlos
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Gylfason, Kristinn B
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Bragg gratings in thin-film LiNbO3 waveguides2017In: Optics Express, E-ISSN 1094-4087, Optics Express, ISSN 1094-4087, Vol. 25, no 26, p. 32323-32332Article in journal (Refereed)
    Abstract [en]

    We design, fabricate and characterize sidewall corrugated Bragg gratings in a high confinement integrated optics lithium niobate platform, comprising submicrometric photonic wires, tapers and grating couplers to interface off-chip standard telecom optical fibers. We analyze the grating performance as band-rejection filter for TE-polarized signals in the telecom C-band, considering both rectangular and sinusoidal sidewall profiles, and demonstrate record extinction ratios as high as 27 dB and rejection bandwidths as narrow as 3 nm. The results show the potential for an efficient integration of novel photonic functionalities into low-footprint LiNbO3 nonlinear and electro-optical waveguide devices.

  • 24. Bagschik, K.
    et al.
    Frömter, R.
    Müller, L.
    Roseker, W.
    Bach, J.
    Staeck, P.
    Thönnißen, C.
    Schleitzer, S.
    Hårdensson Berntsen, Magnus
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Weier, C.
    Adam, R.
    Viefhaus, J.
    Schneider, C. M.
    Grübel, G.
    Oepen, H. P.
    Spatial coherence determination from the Fourier analysis of a resonant soft X-ray magnetic speckle pattern2016In: Optics Express, E-ISSN 1094-4087, Vol. 24, no 20, p. 23162-23176Article in journal (Refereed)
    Abstract [en]

    We present a method to determine the two-dimensional spatial coherence of synchrotron radiation in the soft X-ray regime by analyzing the Fourier transform of the magnetic speckle pattern from a ferromagnetic film in a multidomain state. To corroborate the results, a Young's double-pinhole experiment has been performed. The transverse coherence lengths in vertical and horizontal direction of both approaches are in a good agreement. The method presented here is simple and gives a direct access to the coherence properties of synchrotron radiation without nanostructured test objects.

  • 25. Barrios, Carlos Angulo
    et al.
    Sanchez, Benito
    Gylfason, Kristinn Björgvin
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Griol, Amadeu
    Sohlström, Hans
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Holgado, Miquel
    Casquel, Raphael
    Demonstration of slot-waveguide structures on silicon nitride / silicon oxide platform2007In: Optics Express, E-ISSN 1094-4087, Vol. 15, no 11, p. 6846-6856Article in journal (Refereed)
    Abstract [en]

    We report on the first demonstration of guiding light in vertical slot-waveguides on silicon nitride/silicon oxide material system. Integrated ring resonators and Fabry-Perot cavities have been fabricated and characterized in order to determine optical features of the slot-waveguides. Group index behavior evidences guiding and confinement in the low-index slot region at O-band (1260-1370nm) telecommunication wavelengths. Propagation losses of < 20 dB/cm have been measured for the transverse-electric mode of the slot-waveguides.

  • 26.
    Belonovski, Alexey V
    et al.
    St Petersburg Acad Univ, Russia.
    Levitskii, Iaroslav V
    ITMO Univ, Russia; Ioffe Inst, Russia.
    Morozov, Konstantin M.
    ITMO Univ, Russia.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Kaliteevski, Mikhail A.
    St Petersburg Acad Univ, Russia; ITMO Univ, Russia; Ioffe Inst, Russia.
    Weak and strong coupling of photons and excitons in planar meso-cavities2020In: Optics Express, E-ISSN 1094-4087, Vol. 28, no 9, p. 12688-12698Article in journal (Refereed)
    Abstract [en]

    The interaction of an exciton and cavity modes is considered in planar meso-cavities, which have lateral sizes corresponding to few wavelengths. In meso-cavities, the frequency interval between the optical modes is comparable or smaller than the value of the Rabi splitting between the exciton and the optical modes. The Hamiltonian of the interaction between the exciton and the cavity modes is constructed, and it is shown that such an interaction between the cavity modes and the exciton can occur both in weak and in strong coupling regimes. The latter case can be accompanied by a pronounced splitting of the emission peaks as shown for modelled meso-cavities of triangular, square and hexagonal shapes, where it is demonstrated that Q-factors for the adjacent cavity modes as well as the strength of interaction with excitons can differ by few orders of magnitude. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

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  • 27.
    Belonovski, Alexey V
    et al.
    St Petersburg Acad Univ, Russia; ITMO Univ, Russia.
    Morozov, Konstantin M.
    ITMO Univ, Russia.
    Girshova, Elizaveta I
    St Petersburg Acad Univ, Russia; ITMO Univ, Russia.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Kaliteevski, Mikhail A.
    St Petersburg Acad Univ, Russia; ITMO Univ, Russia.
    Quantum analysis of luminescence of an exciton in a meso-cavity2021In: Optics Express, E-ISSN 1094-4087, Vol. 29, no 13, p. 20724-20734Article in journal (Refereed)
    Abstract [en]

    Interaction of cavity modes with an exciton in a meso-cavity (the structure supporting several cavity modes separated by an energy interval comparable to Rabi-splitting of an exciton and cavity modes) has been analyzed using a quantum-mechanical approach. Simultaneous interaction of an exciton and several cavity modes results in few novel effects such as ladder-like increase of the exciton population in the system, quantum beating and non-monotonic dependence of the ground polariton state in the system on the pumping. Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License.

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  • 28.
    Bergstrand, Jan
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Experimental Biomolecular Physics.
    Rönnlund, Daniel
    KTH, School of Engineering Sciences (SCI), Applied Physics, Experimental Biomolecular Physics.
    Widengren, Jerker
    KTH, School of Engineering Sciences (SCI), Applied Physics, Experimental Biomolecular Physics.
    Wennmalm, Stefan
    KTH, School of Engineering Sciences (SCI), Applied Physics, Experimental Biomolecular Physics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Scanning inverse fluorescence correlation spectroscopy2014In: Optics Express, E-ISSN 1094-4087, Vol. 22, no 11, p. 13073-13090Article in journal (Refereed)
    Abstract [en]

    Scanning Inverse Fluorescence Correlation Spectroscopy (siFCS) is introduced to determine the absolute size of nanodomains on surfaces. We describe here equations for obtaining the domain size from cross-and auto-correlation functions, measurement simulations which enabled testing of these equations, and measurements on model surfaces mimicking membranes containing nanodomains. Using a confocal microscope of 270 nm resolution the size of 250 nm domains were estimated by siFCS to 257 +/- 12 nm diameter, and 40 nm domains were estimated to 65 +/- 26 nm diameter. Applications of siFCS for sizing of nanodomains and protein clusters in cell membranes are discussed.

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    Bergstrand et al Opt Expr 2014
  • 29. Bertani, Stefano
    et al.
    Jacobsson, Bjorn
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Stjernström, Mårten
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Analytical Chemistry.
    Stretching-tunable external-cavity laser locked by an elastic silicone grating2006In: Optics Express, E-ISSN 1094-4087, Vol. 14, no 25, p. 11982-11986Article in journal (Refereed)
    Abstract [en]

    We demonstrate wavelength locking of a diode laser at 760 nm with feedback from an elastic transmission grating in the Littrow configuration. The laser was in a single longitudinal mode with a side-mode suppression of 20 dB. By stretching the grating the laser could be tuned over a few nm. The grating was fabricated in a silicone elastomer ( polydimethylsiloxane) by a moulding technique, and coated by a thin layer of Ti and Au to achieve an increased diffraction efficiency needed for efficient locking.

  • 30.
    Bertilson, Michael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    von Hofsten, Olof
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Experimental Biomolecular Physics.
    Holmberg, Anders
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    High-resolution computed tomography with a compact soft x-ray microscope2009In: Optics Express, E-ISSN 1094-4087, Vol. 17, no 13, p. 11057-11065Article in journal (Refereed)
    Abstract [en]

    Computed tomography based on high-resolution soft x-ray microscopy utilizes the natural contrast for biological specimens provided by the water window (lambda = 2.4 - 4.4 nm) and the high resolving power of zone plate objectives. It is capable of revealing the 3D structure of biological specimens at sub-visible-microscopic resolution. To date, the technique has only been available at synchrotron-based microscopes, which limits the researchers access. In the present paper we demonstrate high-resolution soft x-ray tomography with a laboratory zone-plate-based soft x-ray microscope. The specimen, a diatom mounted on a glass capillary, was reconstructed from a tilt series of 53 images covering 180 using a filtered back projection algorithm. The resolution of the tomogram was estimated to a half period of 140 nm using a differential-phase-residual method. Cryo-fixation, increased source brightness and extended-depth-of-focus objectives are important for pushing the resolution of compact systems for biological samples.

  • 31.
    Bertilson, Michael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    von Hofsten, Olov
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Numerical model for tomographic image formation in transmission x-ray microscopy2011In: Optics Express, E-ISSN 1094-4087, Vol. 19, no 12, p. 11578-11583Article in journal (Refereed)
    Abstract [en]

    We present a numerical image-formation model for investigating the influence of partial coherence, sample thickness and depth-of-focus on the accuracy of tomographic reconstructions in transmission x-ray microscopes. The model combines wave propagation through the object by finite difference techniques with Fourier methods. We include a ray-tracing model to analyse the origin of detrimental stray light in zone plate-based x-ray microscopes. These models allow optimization of x-ray microscopy systems for quantitative tomographic imaging of thick objects. Results show that both the depth-of-focus and the reconstructed local absorption coefficient are highly dependent on the degree of coherence of the optical system.

  • 32.
    Berzins, Andris
    et al.
    Univ Latvia, Latvia; Univ New Mexico, NM 87131 USA.
    Smits, Janis
    Univ Latvia, Latvia; Univ New Mexico, NM 87131 USA.
    Petruhins, Andrejs
    Linköping University, Department of Physics, Chemistry and Biology, Materials design. Linköping University, Faculty of Science & Engineering.
    Rimsa, Roberts
    Univ Latvia, Latvia.
    Mozolevskis, Gatis
    Univ Latvia, Latvia.
    Zubkins, Martins
    Univ Latvia, Latvia.
    Fescenko, Ilja
    Univ Latvia, Latvia.
    NV microscopy of thermally controlled stresses caused by thin Cr2O3 films2023In: Optics Express, E-ISSN 1094-4087, Vol. 31, no 11, p. 17950-17963Article in journal (Refereed)
    Abstract [en]

    Many modern applications, including quantum computing and quantum sensing, use substrate-film interfaces. Particularly, thin films of chromium or titanium and their oxides are commonly used to bind various structures, such as resonators, masks, or microwave antennas, to a diamond surface. Due to different thermal expansions of involved materials, such films and structures could produce significant stresses, which need to be measured or predicted. In this paper, we demonstrate imaging of stresses in the top layer of diamond with deposited structures of Cr2O3 at temperatures 19 & DEG;C and 37 & DEG;C by using stress-sensitive optically detected magnetic resonances (ODMR) in NV centers. We also calculated stresses in the diamond-film interface by using finite-element analysis and correlated them to measured ODMR frequency shifts. As predicted by the simulation, the measured high-contrast frequency-shift patterns are only due to thermal stresses, whose spin-stress coupling constant along the NV axis is 21 & PLUSMN;1 MHz/GPa, that is in agreement with constants previously obtained from single NV centers in diamond cantilever. We demonstrate that NV microscopy is a convenient platform for optically detecting and quantifying spatial distributions of stresses in diamond-based photonic devices with micrometer precision and propose thin films as a means for local application of temperature-controlled stresses. Our results also show that thin-film structures produce significant stresses in diamond substrates, which should be accounted for in NV-based applications.

  • 33.
    Bjorling, Alexander
    et al.
    Lund Univ, Max IV Lab, S-22100 Lund, Sweden..
    Kalbfleisch, Sebastian
    Lund Univ, Max IV Lab, S-22100 Lund, Sweden..
    Kahnt, Maik
    Lund Univ, Max IV Lab, S-22100 Lund, Sweden..
    Sala, Simone
    Lund Univ, Max IV Lab, S-22100 Lund, Sweden..
    Parfeniukas, Karolis
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Vogt, Ulrich
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Carbone, Gerardina
    Lund Univ, Max IV Lab, S-22100 Lund, Sweden..
    Johansson, Ulf
    Lund Univ, Max IV Lab, S-22100 Lund, Sweden..
    Ptychographic characterization of a coherent nanofocused X-ray beam2020In: Optics Express, E-ISSN 1094-4087, Vol. 28, no 4, p. 5069-5076Article in journal (Refereed)
    Abstract [en]

    The NanoMAX hard X-ray nanoprobe is the first beamline to take full advantage of the diffraction-limited storage ring at the MAX IV synchrotron and delivers a high coherent photon flux for applications in diffraction and imaging. Here, we characterize its coherent and focused beam using ptychographic analysis. We derive beam profiles in the energy range 6-22 keV and estimate the coherent flux based on a probe mode decomposition approach.

  • 34.
    Bogdanowicz, Janusz
    et al.
    IMEC, Kapeldreef 75, B-3000 Leuven, Belgium.
    Gilbert, Matthieu
    IMEC, Kapeldreef 75, B-3000 Leuven, Belgium.
    Innocenti, Nicolas
    KTH, School of Computer Science and Communication (CSC), Computational Biology, CB. KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.
    Koelling, Sebastian
    IMEC, Kapeldreef 75, B-3000 Leuven, Belgium.
    Vanderheyden, Benoit
    4 Institut Montefiore, Sart-Tilman B28, B-4000 Liege, Belgium.
    Vandervorst, Wilfried
    IMEC, Kapeldreef 75, B-3000 Leuven, Belgium.
    Light absorption in conical silicon particles2013In: Optics Express, E-ISSN 1094-4087, Vol. 21, no 3, p. 3891-3896Article in journal (Refereed)
    Abstract [en]

    The problem of the absorption of light by a nanoscale dielectric cone is discussed. A simplified solution based on the analytical Mie theory of scattering and absorption by cylindrical objects is proposed and supported by the experimental observation of sharply localized holes in conical silicon tips after high-fluence irradiation. This study reveals that light couples with tapered objects dominantly at specific locations, where the local radius corresponds to one of the resonant radii of a cylindrical object, as predicted by Mie theory.

  • 35.
    Bogdanski, Jan
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Ahrens, Johan
    Bourennane, Mohamed
    Stockholm University, Faculty of Science, Department of Physics.
    Sagnac secret sharing over telecom fiber networks2009In: Optics Express, E-ISSN 1094-4087, Vol. 17, no 2, p. 1055-1063Article in journal (Refereed)
    Abstract [en]

    We report the first Sagnac quantum secret sharing (in threeand four-party implementations) over 1550 nm single mode fiber (SMF) networks, using a single qubit protocol with phase encoding. Our secret sharing experiment has been based on a single qubit protocol, which has opened the door to practical secret sharing implementation over fiber telecom channels and in free-space. The previous quantum secret sharing proposals were based on multiparticle entangled states, difficult in the practical implementation and not scalable. Our experimental data in the three-party implementation show stable (in regards to birefringence drift) quantum secret sharing transmissions at the total Sagnac transmission loop distances of 55-75 km with the quantum bit error rates (QBER) of 2.3-2.4% for the mean photon number μ = 0.1 and 1.7-2.1% for μ = 0.3. In the four-party case we have achieved quantum secret sharing transmissions at the total Sagnac transmission loop distances of 45-55 km with the quantum bit error rates (QBER) of 3.0-3.7% for the mean photon number μ = 0.1 and 1.8-3.0% for μ = 0.3. The stability of quantum transmission has been achieved thanks to our new concept for compensation of SMF birefringence effects in Sagnac, based on a polarization control system and a polarization insensitive phase modulator. The measurement results have showed feasibility of quantum secret sharing over telecom fiber networks in Sagnac configuration, using standard fiber telecom components.

  • 36.
    Bogdanski, Jan
    et al.
    Stockholm University, Faculty of Science, Department of Physics.
    Ahrens, Johan
    Bourennane, Mohamed
    Stockholm University, Faculty of Science, Department of Physics.
    Single mode fiber birefringence compensation in Sagnac and "plug & play" interferometric setups2009In: Optics Express, E-ISSN 1094-4087, Vol. 17, no 6, p. 4485-4494Article in journal (Refereed)
    Abstract [en]

    Single mode fiber (SMF) birefringence effects have been a limiting factor for a variety of Sagnac applications over longer distance SMF links. In this report, we present a new concept of the SMF birefringence compensation in a Sagnac interferometric setup, based on a novel polarization control system. For the destructive interference, our control system guarantees a perfect compensation of both the SMF birefringence and imperfect propagation times matching of the setup’s components. For the stabilization of the constructive interference, we have applied a fiber stretcher and a simple proportional−integral−derivative (PID) controller. The enclosed experimental data of the setup’s visibility confirm validity of our polarization control system. We have also showed that the SMF birefringence model used in a “plug & play” interferometric setup [19], widely cited in the papers on quantum key distribution [11, 12, 13], cannot be applied in SMF Sagnac interferometric setup. However, the SMF birefringence model based on the Kapron equivalence well describes SMF Sagnac.

  • 37.
    Bowers, Mark S.
    et al.
    Lockheed Martin Rotary & Mission Syst, 22121 20th Ave SE, Bothell, WA 98021 USA..
    Canalias, Carlota
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Mirov, Sergey
    AdValue Photon Inc, 3440 E Britannia Dr,Suite 190, Tucson, AZ 85706 USA.;IPG Photon Southeast Technol Ctr, 100 Lucerne Lane, Birmingham, AL 35211 USA.;Univ Alabama Birmingham, 1530 3rd Ave S, Birmingham, AL 35294 USA..
    Nilsson, Johan
    Univ Southampton, Optoelect Res Ctr, Southampton SO17 1BJ, Hants, England..
    Saraceno, Clara J.
    Ruhr Univ Bochum, Photon & Ultrafast Laser Sci, Univ Str 150, D-44801 Bochum, Germany..
    Schunemann, Peter G.
    BAE Syst, MER15-1813,POB 868, Nashua, NH 03061 USA..
    Feature issue introduction: advanced solid-state lasers2022In: Optics Express, E-ISSN 1094-4087, Vol. 30, no 12, p. 20762-20766Article in journal (Refereed)
    Abstract [en]

    This joint issue of Optics Express and Optical Materials Express features 36 state-of-the art articles written by authors who participated in the international conference advanced solid state lasers held online from October 3-7, 2021. This review provides a summary of these articles covering a wide spectrum of topics around solid-state lasers from materials research to sources and from design innovation to applications.

  • 38. Boyko, Andrey A.
    et al.
    Marchev, Georgi M.
    Petrov, Valentin
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Kolker, Dmitry B.
    Zukauskas, Andrius
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Kostyukova, Nadezhda Y.
    Intracavity-pumped, cascaded AgGaSe2 optical parametric oscillator tunable from 5.8 to 18 mu m2015In: Optics Express, E-ISSN 1094-4087, Vol. 23, no 26, p. 33460-33465Article in journal (Refereed)
    Abstract [en]

    A AgGaSe2 nonlinear crystal placed in a coupled cavity is intracavity pumped by the similar to 1.85-mu m signal pulses of a 1.064-mu m pumped Rb: PPKTP doubly-resonant optical parametric oscillator (OPO) operating at a repetition rate of 100 Hz. Using two samples cut for type-I and II phase-matching, the overall idler tunability of the singly-resonant AgGeSe2 OPO covers an unprecedented spectral range from 5.8 to similar to 18 mu m in the mid-IR.

  • 39. Brizuela, Fernando
    et al.
    Carbajo, Sergio
    Sakdinawat, Anne
    Alessi, David
    Martz, Dale H.
    Electrical and Computer Engineering, Colorado State University.
    Wang, Yong
    Luther, Bradley
    Goldberg, Kenneth A.
    Mochi, Iacopo
    Attwood, David T.
    La Fontaine, Bruno
    Rocca, Jorge J.
    Menoni, Carmen S.
    Extreme ultraviolet laser-based table-top aerial image metrology of lithographic masks2010In: Optics Express, E-ISSN 1094-4087, Vol. 18, no 14, p. 14467-14473Article in journal (Refereed)
    Abstract [en]

    We have realized the first demonstration of a table-top aerial imaging microscope capable of characterizing pattern and defect printability in extreme ultraviolet lithography masks. The microscope combines the output of a 13.2 nm wavelength, table-top, plasma-based, EUV laser with zone plate optics to mimic the imaging conditions of an EUV lithographic stepper. We have characterized the illumination of the system and performed line-edge roughness measurements on an EUVL mask. The results open a path for the development of a compact aerial imaging microscope for high-volume manufacturing.

  • 40.
    Brunetti, Anna Chiara
    et al.
    DTU Technical University of Denmark, Denmark.
    Margulis, Walter
    RISE, Swedish ICT, Acreo.
    Rottwitt, Karsten
    DTU Technical University of Denmark, Denmark.
    Raman probes based on optically-poled double-clad fiber and coupler2012In: Optics Express, E-ISSN 1094-4087, Vol. 20, no 27, p. 28563-28572Article in journal (Refereed)
    Abstract [en]

    Two fiber Raman probes are presented, one based on an optically-poled double-clad fiber and the second based on an opticallypoled double-clad fiber coupler respectively. Optical poling of the core of the fiber allows for the generation of enough 532nm light to perform Raman spectroscopy of a sample of dimethyl sulfoxide (DMSO), when illuminating the waveguide with 1064nm laser light. The Raman signal is collected in the inner cladding, from which it is retrieved with either a bulk dichroic mirror or a double-clad fiber coupler. The coupler allows for a substantial reduction of the fiber spectral background signal conveyed to the spectrometer.

  • 41.
    Burvall, Anna
    et al.
    National university of Ireland, Galway.
    Barrett, Harrison H.
    University of Arizona.
    Dainty, Christopher
    National University of Ireland, Galway.
    Myers, Kyle J.
    U.S. Food and Drug Administration Laboratory for the Assessment of Medical Imaging Systems.
    Singular-value decomposition for through-focus imaging systems2006In: Optics Express, E-ISSN 1094-4087, Vol. 23, no 10, p. 2440-2448Article in journal (Refereed)
    Abstract [en]

    Singular-value decomposition (SVD) of a linear imaging system gives information on the null and measurement components of object and image and provides a method for object reconstruction from image data. We apply SVD to through-focus imaging systems that produce several two-dimensional images of a three-dimensional object. Analytical expressions for the singular functions are derived in the geometrical approximation for a telecentric, laterally shift-invariant system linear in intensity. The modes are evaluated numerically, and their accuracy confirmed. Similarly, the modes are derived and evaluated for a continuous image representing the limit of a large number of image planes.

  • 42.
    Burvall, Anna
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Barrett, Harrison H.
    Myers, Kyle J.
    Dainty, Christopher
    Singular-value decomposition of a tomosynthesis system2010In: Optics Express, E-ISSN 1094-4087, Vol. 18, no 20, p. 20699-20711Article in journal (Refereed)
    Abstract [en]

    Tomosynthesis is an emerging technique with potential to replace mammography, since it gives 3D information at a relatively small increase in dose and cost. We present an analytical singular-value decomposition of a tomosynthesis system, which provides the measurement component of any given object. The method is demonstrated on an example object. The measurement component can be used as a reconstruction of the object, and can also be utilized in future observer studies of tomosynthesis image quality.

  • 43.
    Burvall, Anna
    et al.
    National University of Ireland, Galway.
    Daly, Elisabeth
    National University of Ireland, Galway.
    Chamot, Stephane R.
    Swiss Federal Polytechnic School of Lausanne.
    Dainty, Chris
    National University of Ireland, Galway.
    Linearity of the pyramid wavefront sensor2006In: Optics Express, E-ISSN 1094-4087, Vol. 14, no 25, p. 11925-11934Article in journal (Refereed)
    Abstract [en]

    The pyramid wavefront sensor is very similar to the Fourier knife-edge test, but employs dynamic modulation to quantify the phase derivative. For circular modulation, we compare approximate geometrical optics calculations, more exact diffraction calculations, and experimental results. We show that both the sinusoidal and the approximate linear relationship between wavefront derivative and wavefront sensor response can be derived rigorously from diffraction theory. We also show that geometrical, diffraction and experimental results are very similar, and conclude that the approximate geometrical predictions can be used in place of the more complex diffraction results.

  • 44.
    Burvall, Anna
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Lundstrom, Ulf
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Takman, Per A. C.
    Larsson, Daniel H.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Hertz, Hans M.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.
    Phase retrieval in X-ray phase-contrast imaging suitable for tomography2011In: Optics Express, E-ISSN 1094-4087, Vol. 19, no 11, p. 10359-10376Article in journal (Refereed)
    Abstract [en]

    In-line phase-contrast X-ray imaging provides images where both absorption and refraction contribute. For quantitative analysis of these images, the phase needs to be retrieved numerically. There are many phase-retrieval methods available. Those suitable for phase-contrast tomography, i.e., non-iterative phase-retrieval methods that use only one image at each projection angle, all follow the same pattern though derived in different ways. We outline this pattern and use it to compare the methods to each other, considering only phase-retrieval performance and not the additional effects of tomographic reconstruction. We also outline derivations, approximations and assumptions, and show which methods are similar or identical and how they relate to each other. A simple scheme for choosing reconstruction method is presented, and numerical phase-retrieval performed for all methods.

  • 45.
    Burvall, Anna
    et al.
    KTH, Superseded Departments (pre-2005), Microelectronics and Information Technology, IMIT.
    Martinsson, Per
    KTH, Superseded Departments (pre-2005), Microelectronics and Information Technology, IMIT.
    Friberg, Ari
    KTH, Superseded Departments (pre-2005), Microelectronics and Information Technology, IMIT.
    Communication modes applied to axicons2004In: Optics Express, E-ISSN 1094-4087, Vol. 12, no 3, p. 377-383Article in journal (Refereed)
    Abstract [en]

    The communication modes, which constitute a convenient method for the propagation and information analysis of optical fields, are formulated in the generalized axicon geometry. The transmitting region is the axicon’s annular aperture, and the observation domain is the optical axis containing the focal line segment. We show that in rotational symmetry one may employ the prolate spheroidal wave functions to represent the communication modes. Further, in usual circumstances the modes can be approximated by quadratic waves in the aperture domain and by sinc functions in the image domain. Both the exact communication modes and the approximate technique are confirmed numerically, with linear axicons as examples.

  • 46.
    Cai, Yangjian
    et al.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    He, Sailing
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Propagation of various dark hollow beams in a turbulent atmosphere2006In: Optics Express, E-ISSN 1094-4087, Vol. 14, no 4, p. 1353-1367Article in journal (Refereed)
    Abstract [en]

    Propagation of a dark hollow beam (DHB) of circular, elliptical or rectangular symmetry in a turbulent atmosphere is investigated. Analytical formulas for the average intensity of various DHBs propagating in a turbulent atmosphere are derived in a tensor form based on the extended Huygens-Fresnel integral. The intensity and spreading properties of the DHBs in a turbulent atmosphere are studied numerically. It is found that after a long propagation distance a dark hollow beam of circular or non-circular eventually becomes a circular Gaussian beam (without dark hollow) in a turbulent atmosphere, which is much different from its propagation properties in free space. The conversion from a DHB to a circular Gaussian beam becomes quicker and the beam spot in the far field spreads more rapidly for a larger structure constant, a shorter wavelength, a lower beam order and a smaller waist size of the initial beam.

  • 47.
    Caleman, Carl
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Timneanu, Nicusor
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics.
    Martin, Andrew V.
    Jönsson, H. Olof
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Aquila, Andrew
    Barty, Anton
    Scott, Howard A.
    White, Thomas A.
    Chapman, Henry N.
    Ultrafast self-gating Bragg diffraction of exploding nanocrystals in an X-ray laser2015In: Optics Express, E-ISSN 1094-4087, Vol. 23, no 2, p. 1213-1231Article in journal (Refereed)
    Abstract [en]

    In structural determination of crystalline proteins using intense femtosecond X-ray lasers, damage processes lead to loss of structural coherence during the exposure. We use a nonthermal description for the damage dynamics to calculate the ultrafast ionization and the subsequent atomic displacement. These effects degrade the Bragg diffraction on femtosecond time scales and gate the ultrafast imaging. This process is intensity and resolution dependent. At high intensities the signal is gated by the ionization affecting low resolution information first. At lower intensities, atomic displacement dominates the loss of coherence affecting high-resolution information. We find that pulse length is not a limiting factor as long as there is a high enough X-ray flux to measure a diffracted signal.

  • 48.
    Calil Kores, Cristine
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics. Department of Applied Physics, School of Engineering Sciences, Roslagstullsbacken 21, 10691 Stockholm, Sweden .
    Ismail, Nur
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Geskus, Dimitri
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Dijkstra, Meindert
    Bernhardi, Edward
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics. Visiting scientist .
    Pollnau, Markus
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics. Advanced Technology Institute, Department of Electrical and Electronic Engineering, University of Surrey, Guildford GU2 7XH, UK.
    Temperature dependence of the spectral characteristics of distributed-feedback resonators2018In: Optics Express, E-ISSN 1094-4087, Vol. 26, no 4, p. 4892-4905Article in journal (Refereed)
    Abstract [en]

    We characterize the spectral response of a distributed-feedback resonator when subject to a thermal chirp. An Al2O3 rib waveguide with a corrugated surface Bragg grating inscribed into its SiO2 top cladding is experimentally investigated. We induce a near-to-linear temperature gradient along the resonator, leading to a similar variation of the grating period, and characterize its spectral response in terms of wavelength and linewidth of the resonance peak. Simulations are carried out, showing good agreement with the experimental results and indicating that the wavelength of the resonance peak is a result only of the total accumulated phase shift. For any chirp profile we are able to calculate the reflectivities at the resonance wavelength, and this information largely explains how the linewidth of the resonance changes. This result shows that the increase in linewidth is governed by the increase of the resonator outcoupling losses. 

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  • 49.
    Camara, A.
    et al.
    RISE - Research Institutes of Sweden (2017-2019), ICT, Acreo. Pontifícia Universidade Católica do Rio de Janeiro,Brazil.
    Tarasenko, O.
    RISE, Swedish ICT, Acreo.
    Margulis, W.
    RISE, Swedish ICT, Acreo. KTH Royal Institute of Technology, Sweden.
    Study of thermally poled fibers with a two-dimensional model2014In: Optics Express, E-ISSN 1094-4087, Vol. 22, p. 17700-15Article in journal (Refereed)
    Abstract [en]

    A two-dimensional (2D) numerical model is implemented to describe the movement of ions under thermal poling for the specific case of optical fibers. Three types of cations are considered (representing Na+, Li + and H3O+) of different mobility values. A cross-sectional map of the carrier concentration is obtained as a function of time. The role of the various cations is investigated. The assumptions of the model are validated by comparing the predictions to experimental data of the time evolution of the nonlinearity induced. A variational analysis of poling parameters including temperature, poling voltage, sign of the bias potential and initial ionic concentrations is performed for a particular fiber geometry. The analysis allows identifying the impact of these parameters on the induced secondorder nonlinearity in poled fibers.

  • 50. Camara, Alexandre R.
    et al.
    Pereira, Joao M. B.
    Tarasenko, Oleksandr
    Margulis, Walter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics. Fiber Optic Department, Acreo Swedish ICT, Electrum 236, 164 40 Kista, Sweden.
    Carvalho, Isabel C. S.
    Departamento de Física, Pontifícia Universidade Católica Do Rio de Janeiro, Rua Marquês de São Vicente 225, Gávea, 22451-900, Rio de Janeiro, Brazil.
    Optical creation and erasure of the linear electrooptical effect in silica fiber2015In: Optics Express, E-ISSN 1094-4087, Vol. 23, no 14, p. 18060-18069Article in journal (Refereed)
    Abstract [en]

    We study the creation and erasure of the linear electrooptical effect in silicate fibers by optical poling. Carriers are released by exposure to green light and displaced with simultaneous application of an internal dc field. The second order nonlinear coefficient induced grows with poling bias. The field recorded (similar to 10(8) V/m) is comparable to that obtained through classical thermal poling of fibers. In the regime studied here, the second-order nonlinearity induced (similar to 0.06 pm/V) is limited by the field applied during poling (1.2 x 10(8) V/m). Optical erasure with high-power green light alone is very efficient. The dynamics of the writing and erasing process is discussed, and the two dimensional (2D) field distribution across the fiber is simulated. (C) 2015 Optical Society of America

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