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  • 1.
    Berg, Frenk van den
    et al.
    Tata Steel.
    Aarnts, Maxim
    Yang, Haibing
    Fintelman, F
    Ennis, Bernard
    Gillgren, Lars
    SSAB.
    Jorge-Badiola, Denis
    Martinez-de-Guerenu, Ane
    Davis, Claire
    West, Graeme
    Zhou, Lei
    Jolfaei, Mohsen
    Peyton, Anthony J
    Wilson, John W.
    Volker, Arno
    Marina, Q
    Duijster, Arno
    Malmström, Mikael
    Swerim AB.
    Jansson, Anton
    Swerim AB.
    Hutchinson, Bevis
    Swerim AB.
    Mocci, Claudio
    Vannucci, M.
    Colla, Valentina
    Reboud, Christophe
    Skarlatos, Anastassios
    Miorelli, Roberto
    Lombard, Patrick
    Hubert, Olivier
    Taurines, Julien
    Lobanova, I
    Despréaux, S
    Labbé, Stéphane
    Celada-Casero, Carola
    How the EU project “Online Microstructure Analytics” advances inline sensing of microstructure during steel manufacturing2023In: Research and Review Journal of Nondestructive Testing (ReJNDT), ISSN 2941-4989, Vol. 1, no 1Article in journal (Refereed)
    Abstract [en]

    Weight savings in mobility and transport are mandatory in order to reduce CO2 emissions and energy consumption. The steel industry offers weight saving solutions by a growing portfolio of Advanced High Strength Steel (AHSS) products. AHSS owe their strength to their largely refined and complex microstructures, containing multiple metallurgical phases. Optimal control of the thermo-mechanical processing of AHSS requires inline sensors for real-time monitoring of evolution and consistency of microstructure and material properties.

  • 2.
    Berg, Frenk van den
    et al.
    Tata Steel, IJmuiden, Netherlands.
    Kok, P. J. J.
    Tata Steel, IJmuiden, Netherlands.
    Yang, H.
    Tata Steel, IJmuiden, Netherlands.
    Aarnts, M.
    Tata Steel, IJmuiden, Netherlands.
    Meilland, P.
    Arcelor Research, Maizières les Metz, France.
    Kebe, T.
    ThyssenKrupp Steel, Duisburg, Germany.
    Stolzenberg, M.
    Salzgitter Mannesmann Forschung GmbH, Duisburg, Germany.
    Krix, D.
    Salzgitter Mannesmann Forschung GmbH, Duisburg, Germany.
    Zhu, W.
    University of Manchester, Manchester, United Kingdom.
    Peyton, A. J.
    University of Manchester, Manchester, United Kingdom.
    Martinez-de-Guerenu, A.
    CEIT - Centre of Studies & Technical Research of Gipuzkoa, San Sebastián, Spain.
    Gutierrez, I.
    CEIT - Centre of Studies & Technical Research of Gipuzkoa, San Sebastián, Spain.
    Jorge-Badiola, D.
    CEIT - Centre of Studies & Technical Research of Gipuzkoa, San Sebastián, Spain.
    Malmström, Mikael
    Swerea KIMAB AB, Stockholm, Sweden.
    Volker, A.
    TNO Science & Industry, Delft, Netherlands.
    Duijster, A.
    TNO Science & Industry, Delft, Netherlands.
    Wirdelius, Håkan
    Chalmers University of Technology, Gothenburg, Sweden.
    Boström, A.
    Chalmers University of Technology, Gothenburg, Sweden.
    Mocci, C.
    Scuola Superiore Sant'Anna, Ghezzano, Pisa, Italy.
    Vannucci, M.
    Scuola Superiore Sant'Anna7, Ghezzano, Pisa, Italy.
    Colla, V.
    Scuola Superiore Sant'Anna7, Ghezzano, Pisa, Italy.
    Davis, C.
    University of Warwick, Coventry, United Kingdom.
    Zhou, L.
    University of Warwick, Coventry, United Kingdom.
    Schmidt, R.
    Arcelor Mittal Eisenhüttenstadt (AMEH), Eisenhüttenstadt, Germany.
    Labbé, S.
    University of Grenoble (UJF)-Alpes, Grenoble cedex, France.
    Reboud, C.
    Commissariat Energie Atomique (CEA), Gif-Sur-Yvette, France.
    Skarlatos, A.
    Commissariat Energie Atomique (CEA), Gif-Sur-Yvette, France.
    Leconte, V.
    Altair France, Antony cedex, France.
    Lombard, P.
    Altair France, Antony cedex, France.
    Results of the European collaborative project "Product Uniformity Control" to improve the inline sensing of mechanical properties and microstructure of automotive steels2018In: e-Journal of Nondestructive Testing (eJNDT), ISSN 1435-4934, Vol. 23, no 8Article in journal (Refereed)
    Abstract [en]

    A European consortium consisting of four major steel manufacturers and ten academic technology institutes has conducted a research and development project, called “Product Uniformity Control“ (PUC) in the period 2013 to 2017. This project aimed to develop and improve non-destructive (inline) measurement techniques to characterise the (uniformity of the) microstructure of steel strip products. In this project, a multitude of strip steel samples from various stages of production have been collected from the four participating steel manufacturers. The samples have been characterised in various ways, namely on their (1) non-destructive measurement parameters using different techniques suited for inline evaluation, (2) fundamental ultrasonic and electromagnetic properties (wave speed, ultrasonic attenuation, magnetisation loops, coercive field), (3) tensile properties (stress-strain curves) and (4) microstructure (by optical micrographs and EBSD images). The correlations between these different characterisations will be addressed. Besides the experimental characterisation, a strong accent has been on modelling activities: during the project, fundamental models have been developed to describe, starting from 2D and 3D microstructures, the ultrasonic and magnetic properties, which are next used as input to sensor models that predict the output of the inline measurement systems. This contribution presents the recent results of experimental work, which underlines the importance of associated modelling studies for the interpretation of the measurement data for the benefit of inline characterisation of the mechanical properties complementary to traditional destructive tensile testing.

  • 3. Berg, Frenk van den
    et al.
    Kok, Piet
    Yang, Haibing
    Aarnts, Maxim
    Beugeling, Willem
    Meilland, Philip
    Kebe, Thomas
    Stolzenberg, Mathias
    Krix, David
    Peyton, Anthony
    Zhu, Wenqian
    Martinez-de-Guerenu, Ane
    Gutierrez, Isabel
    Jorge-Badiola, Denis
    Malmström, Mikael
    Swerea KIMAB.
    Lindh-Ulmgren, Eva
    Swerea KIMAB.
    Volker, Arno
    Duijster, Arno
    Wirdelius, Håkan
    Chalmers.
    Boström, Anders
    Mocci, Claudio
    Vannucci, Marco
    Colla, Valentina
    Davis, Claire
    Zhou, Lei
    Schmidt, Rene
    Labbe, Stephane
    Reboud, Christophe
    Skarlatos, Anastasios
    Leconte, Vincent
    Lombard, Patrick
    Product Uniformity Control (PUC): How 15 European research institutes contribute to improve the in-line characterisation of microstructure and mechanical properties in the manufacturing of steel strip2017Conference paper (Other academic)
  • 4. F.D, Van Den Berg
    et al.
    P.J.J, Kok
    H, Yang
    M.P, Aarnts
    P, Meilland
    T, Kebe
    M, Stolzenberg
    D, Krix
    W, Zhu
    A.J, Peyton
    A, Martinez-De-Guerenu
    I, Gutierrez
    D, Jorge-Badiola
    Malmström, Mikael
    Swerim AB.
    A, Volker
    A, Duijster
    H, Wirdelius
    A, Boström
    C, Mocci
    M, Vannucci
    V, Colla
    C, Davis
    L, Zhou
    R, Schmidt
    S, Labbé
    C, Reboud
    A, Skarlatos
    V, Leconte
    P, Lombard
    Product Uniformity Control - A Research Collaboration of European Steel Industries to Non-Destructive Evaluation of Microstructure and Mechanical Properties2018In: Volume 43: Electromagnetic Non-Destructive Evaluation (XXI), IOS Press, 2018, p. 120-129Chapter in book (Refereed)
    Abstract [en]

    In steel manufacturing, the conventional method to determine the mechanical properties and microstructure is by offline, destructive (lab-)characterisation of sample material that is typically taken from the head or the tail of the coil. Since coils can be up to 7 km long, the samples are not always representative for the main coil body. Also, the time delay (typically a few days) between the actual production and the availability of the characterisation results implies that these results cannot be exploited for real-time adaptation of the process settings.

  • 5. Forsberg, Pontus
    et al.
    Malmström, Mikael
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics. Uppsala Univ, Sweden.
    Catalan, Ernesto Vargas
    Karlsson, Mikael
    Diamond grating waveplates2016In: Optical Materials Express, ISSN 2159-3930, E-ISSN 2159-3930, Vol. 6, no 6, p. 2024-2030Article in journal (Refereed)
    Abstract [en]

    Two designs of diamond quarter-wave plates for CO2 lasers, based on the birefringence of sub-wavelength gratings, were manufactured and tested. In one design the grating was etched on the surface of a 300 mu m thick polycrystalline diamond substrate. The other consisted of a diamond grating hanging freely in air, suspended at the edges from a silicon frame. The free-hanging design, while more fragile, had several advantages both in terms of fabrication and performance such as a larger grating period, higher transmission, and no need for an antireflective treatment of the backside.

  • 6.
    Hutchinson, Bevis
    et al.
    Swerea KIMAB.
    Malmström, Mikael
    Swerea KIMAB.
    Bate, Pete
    Lindh-Ulmgren, Eva
    Swerea KIMAB.
    Evaluation of texture using laser-ultrasonics (LUS) applied to steel processing2017Conference paper (Other academic)
  • 7.
    Hutchinson, Bevis
    et al.
    Swerim AB.
    Malmström, Mikael
    Swerim AB.
    Jansson, Anton
    Swerim AB.
    Lundin, Peter
    Swerim AB.
    High precision measurement of elastic anisotropy in metals2022In: 5th International Workshop on Laser-Ultrasound for Metals, 2022Conference paper (Refereed)
    Abstract [en]

    Anisotropy of elastic wave propagation in metals is controlled by texture together with crystalline anisotropy, so laser-ultrasonic measurements can provide valuable information about a material’s underlying elastic phenomena. Evidently, anisotropy cannot be deduced from a single measurement and various approaches have been used to detect and quantify this which are reviewed briefly in the introduction. These include:

    • Measurements of velocity by rotating the material with respect to the instrument. This is seldom feasible in an industrial environment but we demonstrate how high precision can be achieved this way in laboratory experiments.

    • Changing the wave path using a masked axicon lens or by deflecting the generating laser using galvano-mirror optics. This latter approach is well suited to industrial application such as in steel processing. Examples of this method will be presented. • Combining different wave types having the same direction of propagation such as S0 and SH0 or S0, SH0 and P waves.

    • Using P-waves arrivals measured after different numbers of reflections through the thickness of the plate. Although the same fixed positions are used for generation and detection, the successive pulses pass along different directions in the material.

    The largest uncertainty in LUS generally comes from the measurement of distance between the two laser points. By machining the material into a cylinder using a lathe, the diameter is extremely constant as the specimen is rotated. This has allowed velocities to be measured with a precision of better than 1 part in 10,000. Results on stainless steels show excellent agreement between measured wave velocities and values calculated from the texture. Another application to quenched and tempered martensite is shown below. Tempering between 20°C and 650°C causes reduction in hardness and leads to increases in stiffness and wave velocity but the anisotropy is almost unchanged. The Galvano mirror technique is demonstrated in application to hot rolled steels where many path directions in the material can be rapidly scanned. Finally, we discuss some limitations of texture measurements from ultrasonic measurements.

    Download full text (pdf)
    Abstract
  • 8.
    Hutchinson, Bevis
    et al.
    Swerea KIMAB.
    Malmström, Mikael
    Swerea KIMAB.
    Lönnqvist, Johan
    Bate, Pete
    Ehteshami, Hossein
    KTH.
    Korzhavyi, Pavel A.
    KTH, School of Industrial Engineering and Management (ITM).
    Elasticity and wave velocity in fcc iron (austenite) at elevated temperatures – Experimental verification of ab-initio calculations2018In: Ultrasonics, ISSN 0041-624X, E-ISSN 1874-9968, Vol. 87, p. 44-47Article in journal (Refereed)
    Abstract [en]

    High temperature crystal elasticity constants for face centred cubic austenite are important for interpreting the ultrasonic properties of iron and steels but cannot be determined by normal single crystal methods. Values of these constants have recently been calculated using an ab-initio approach and the present work was carried out to test their applicability using laser-ultrasonic measurements. Steel samples having a known texture were examined at temperatures between 800 °C and 1100 °C to measure the velocity of longitudinal P-waves which were found to be in good agreement with modelled values.

  • 9.
    Jansson, Anton
    et al.
    Swerim AB.
    Malmström, Mikael
    Swerim AB.
    Lundin, Peter
    Swerim AB.
    Laser utrasonics for quality control of resistance spot welding2022In: 5th International Workshop on Laser-Ultrasound for Metals, May 5-6, 2022, Gif-sur-Yvette, France, 2022Conference paper (Refereed)
  • 10.
    Lindberg, Robert
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Zeil, Peter
    KTH, School of Engineering Sciences (SCI).
    Malmström, Mikael
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Modelling and Optimizationof High Repetition Rate Fiber Ampliers2015Conference paper (Refereed)
  • 11.
    Lindberg, Robert
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Zeil, Peter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Malmström, Mikael
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Accurate modeling of high-repetition rate ultrashort pulse amplification in optical fibers2016In: Scientific Reports, E-ISSN 2045-2322, Vol. 6Article in journal (Refereed)
    Abstract [en]

    A numerical model for amplification of ultrashort pulses with high repetition rates in fiber amplifiers is presented. The pulse propagation is modeled by jointly solving the steady-state rate equations and the generalized nonlinear Schrödinger equation, which allows accurate treatment of nonlinear and dispersive effects whilst considering arbitrary spatial and spectral gain dependencies. Comparison of data acquired by using the developed model and experimental results prove to be in good agreement.

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    fulltext
  • 12.
    Lindberg, Robert
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Zeil, Peter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Malmström, Mikael
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Modelling and optimization of high repetition rate fiber amplifiers2015In: Proceedings 2015 European Conference on Lasers and Electro-Optics - European Quantum Electronics Conference, CLEO/Europe-EQEC 2015, Optical Society of America , 2015Conference paper (Refereed)
  • 13.
    Lindberg, Robert
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Zeil, Peter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Malmström, Mikael
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Numerical Study and Validation of Ultra-short Pulse Amplification in Fiber Amplifiers at High Repetition Rates2016In: CLEO: Science and Innovations, SI 2016, Optica Publishing Group , 2016, article id SM1Q.6Conference paper (Refereed)
    Abstract [en]

    We present a numerical method for studying fiber-based ultra-short pulse amplification at high repetition rates. Validation of the simulations, by comparison with experimental results, are also presented.

  • 14.
    Lindberg, Robert
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Zeil, Peter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Malmström, Mikael
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Numerical Study and Validation of Ultra-short Pulse Amplification in Fiber Amplifiers at High Repetition Rates2016Conference paper (Refereed)
    Abstract [en]

    We present a numerical method for studying fiber-based ultra-short pulse amplification at high repetition rates. Validation of the simulations, by comparison with experimental results, are also presented.

    Download full text (pdf)
    fulltext
  • 15.
    Lindgren, Erik
    et al.
    Högskolan Väst.
    Malmström, Mikael
    Swerim AB.
    Annika, Strondl
    Swerim AB.
    Anton, Jansson
    Swerim AB.
    Nondestructive Evaluation with Laser Ultrasound of Powder Bed Fusion Printed Metal2019Conference paper (Refereed)
    Abstract [en]

    Many of the main advantages of 3D printing metal components, for example the possibility to manufacture parts of high geometric complexity in small series, typically make the nondestructive quality control difficult and resource intense. A number of published studies have proposed in-process nondestructive evaluation of the printed material, as it is built layer by layer, as a possible general approach solution to this difficulty. Previous studies have also indicated that the non-contact nondestructive testing method laser ultrasound might be an applicable method to conduct such an in-process nondestructive evaluation of 3D printed parts. Potential pros of such an ultrasonic based evaluation, as compared to more process monitoring like approaches (e.g. acoustic emission from the printing process) would for example be increased defect characterization capabilities.In this work laser ultrasonic nondestructive evaluation of both electron beam and laser beam powder bed fusion printed metal is demonstrated. Nickel-base and Stainless Steel samples are evaluated both from a machined surface and, in order to simulate the in-process setup, from the as-printed top surface.The laser ultrasonic evaluation results are then compared to results from other material characterization methods, such as light optical microscopy and X-ray inspection. Designed artificial defects as well as process material anomalies could be detected with the proposed laser ultrasonic evaluation. In some cases material defects could be detected also when the laser ultrasonic evaluation was performed from the as-printed top surface.Our results are similar to other studies that have been reported on the subject: laser ultrasound can be utilized to detect material anomalies of interest in powder bed fusion printed metal material. Further research is required in order to better understand and improve the capability and reliability of the nondestructive evaluation method.

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    Submitted Abstract
    Download (pdf)
    Presentation
  • 16.
    Lindgren, Erik
    et al.
    Högskolan Väst.
    Malmström, Mikael
    Swerim AB.
    Ålgårdh, Joakim
    Swerim AB.
    Strondl, Annika
    Swerim AB.
    Nondestructive Evaluation with Laser Ultrasound of Powder Bed Fusion Printed Metal Parts2019Conference paper (Refereed)
    Abstract [en]

    Introduction/Purpose

    Many of the main advantages of 3D printing metal components, for example the possibility to manufacture components of high geometriccomplexity in small series, typically make the nondestructive quality control difficult and resource intense. A number of published studies haveproposed in-process quality control of the component, as it is built layer by layer, as a possible general approach solution to this difficulty. Previousstudies have also indicated that the non-contact nondestructive testing method laser ultrasound might be an applicable method to conduct such anin-process nondestructive evaluation of 3D printed components.

    Methods

    In this work laser ultrasonic nondestructive evaluation of both electron beam and laser beam powder bed fusion printed metal parts isdemonstrated. Nickel-base and Stainless Steel samples are evaluated both from a machined surface and, in order to simulate the in-process setup,from the as-printed top surface.

    Results

    The laser ultrasonic evaluation results are compared to results from other material characterization methods. Designed artificial defects as well asprocess material anomalies could be detected with the proposed laser ultrasonic evaluation, both when the evaluation was performed from the asprintedtop surface as well as from the machined surface.

    Conclusions

    We conclude that laser ultrasound can be utilized to detect material anomalies of interest in powder bed fusion printed metal parts. Furtherresearch is required in order to better understand and improve the capability and reliability of the nondestructive evaluation method.

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  • 17.
    Malmstrom, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Karlsson, Mikael
    Forsberg, Pontus
    Cai, Yixiao
    Nikolajeff, Fredrik
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Waveguides in polycrystalline diamond for mid-IR sensing2016In: Optical Materials Express, ISSN 2159-3930, E-ISSN 2159-3930, Vol. 6, no 4, p. 1286-1295Article in journal (Refereed)
    Abstract [en]

    8 mm long channel waveguides were manufactured in polycrystalline diamond with inductively coupled plasma etching and characterized in terms of mode-profile and propagation loss in the 1.5 - 3.4 mu m spectral region. As proof of principle, the waveguides were evaluated in an evanescent field sensing setup targeting the CH absorption peak of isopropanol at similar to 3.4 mu m, showing good agreement with numerical finite element simulations. (C) 2016 Optical Society of America

  • 18.
    Malmström, Mikael
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    All-fiber modulators for laser applications2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The objective of this thesis was to explore the usefulness of all-fiber modulators for laser applications. The modulators were all based on refractive index change achieved in the core of the studied fiber- components, exploiting either the elasto-optic effect or the electro-optic effect. This was realized with the aid of electrodes inside the fiber cladding close to the core that provided either thermal stress in the core, or an electric field across the core. The electrodes consisted of low melting-point alloys, such as BiSn and AuSn, which were pushed into the hole-fiber, in the liquid state, which then solidified to form solid electrodes filling the entire hole.

    Together with an analyzer such as a polarizer or an interferometer the achieved refractive index modulation in the core could then be translated into an amplitude modulation of the guided light, which was subsequently utilized for switching fiber-lasers to generate cavity dumped, Q-switched, or mode-locked pulses. The fast rise/fall-time of a few nanoseconds for the elasto-optic devices was due to the fast thermal expansion of the electrodes. The maximum repetition rate, however, was limited to a few tens of kHz, due to the slow thermal processes for dissipation of the applied energy. The electro-optic fiber components, which displayed similar rise/fall-times on the other hand, showed a much higher cut-off frequency of 16 MHz.

    The electro-optic, all-fiber switch was also employed to select single pulses at 1 MHz repetition rate out of a 7 MHz train of pulses. Additionally, simulations using the finite element method were performed in order to gain insight and to explain the underlying processes of the observed response of a long-period grating written in a 2-hole fiber with electrodes, when applying HV-pulses to one of these.

    The thesis shows that the studied fiber-components show great potential of becoming complementary devices with high damage threshold for all-fiber laser applications in the future. 

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  • 19.
    Malmström, Mikael
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Multi-angle Oblique Optical Coherence Tomography2008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Optical Coherence Tomography (OCT) is a non-invasive high-resolutionmethod for measuring the reectance of scattering media in 1/2/3D, e.g.skin. The method has been used in a number of dierent medical elds andfor measurement of tissue optical properties.The software developed in this thesis is able to display features hidden ina shadowed volume by adding multiple OCT measurements taken at obliqueangles, a technique here called Multiple-Angle Oblique Optical CoherenceTomography (MAO-OCT).Three dierent objects with were measured at 5 to 9 angles. The measurementswere automatically and manually aligned in the software. They werealso tested with 6 dierent high pass intensity lters (HPIF) and reduced insize using 4 dierent methods to speed up calculations.The software's automatic alignment was tested with one tilted computergenerated test at 9 angles and with 5 dierent shadow strengths.With MAO-OCT it is possible to remove some eects of shadows in OCT,though it comes with a cost of reduced sharpness. The errors depend muchon the dierences in index of refraction in the sample.The software managed to automatically align 90% of the articial measurements,and 60% of the OCT measurements. The shadow strength andthe resize method had no noticeable eect on the automatic alignment of themeasurements.

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  • 20.
    Malmström, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Boivinet, S.
    Tarasenko, O.
    Lecourt, J. -B
    Hernandez, Y.
    Margulis, W.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    All-fiber polarization-maintaining electrooptic pulse-picker2015In: Conference on Lasers and Electro-Optics Europe - Technical Digest, Institute of Electrical and Electronics Engineers Inc. , 2015Conference paper (Refereed)
    Abstract [en]

    An alignment free all-fiber pulse-picker running at variable repetition-rate for selecting pulses from an 86 MHz mode-locked Yb-fiber laser at 0-0.6 MHz with better than 35 dB extinction ratio is presented. 

  • 21.
    Malmström, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics. Department of Engineering Sciences, Applied Materials Science, Uppsala University, Ångströmlaboratoriet, Uppsala, Sweden.
    Boivinet, S.
    Tarasenko, O.e
    Lecourt, J.-B.
    Hernandez, Y.
    Margulis, W.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    All-fiber polarization-maintaining electrooptic pulse-picker2015In: CLEO: Science and Innovations, CLEO-SI 2015, Optical Society of America, 2015Conference paper (Refereed)
    Abstract [en]

    An alignment free all-fiber pulse-picker running at variable repetition-rate for selecting pulses from an 86 MHz mode-locked Yb-fiber laser at 0-0.6 MHz with better than 35 dB extinction ratio is presented.

  • 22.
    Malmström, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Cai, Yixiao
    Uppsala Universitet, Sweden.
    Karlsson, Mikael
    Uppsala Universitet, Sweden.
    Forsberg, Pontus
    Uppsala Universitet, Sweden.
    Nikolajeff, Fredrik
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Diamond waveguides for mid-IR sensing2014In: Optics & Photonics in Sweden, 2014, p. 1-1Conference paper (Other academic)
    Download full text (pdf)
    fulltext
  • 23.
    Malmström, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Engholm, M.
    Jelger, Pär
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Photodarkening resistant Yb/Ce/Al silica 980 nm fiberlaser2010In: Optics InfoBase Conference Papers, OSA Publishing , 2010Conference paper (Refereed)
    Abstract [en]

    A linearly polarized fiber laser emitting at 979 nm with an output power of 2 W is presented. By using a photodarkening-resistant Yb/Ce/Al-codoped silica fiber, degradation-free operation is achieved over several hours.

  • 24.
    Malmström, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Engholm, Magnus
    Jelger, Pär
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Photodarkening resistant Yb/Ce/Al silica 980 nm fiberlaser2010In: Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference: 2010 Laser Science to Photonic Applications, CLEO/QELS 2010, IEEE , 2010, p. 5500412-Conference paper (Refereed)
    Abstract [en]

    A linearly polarized fiber laser emitting at 979 nm with an output power of 2 W is presented. By using a photodarkening-resistant Yb/Ce/Al-codoped silica fiber, degradation-free operation is achieved over several hours.

  • 25.
    Malmström, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics. Uppsala University, Sweden.
    Forsberg, P.
    Cai, Y.
    Karlsson, M.
    Nikolajeff, F.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Diamond waveguides for mid-IR chemical sensing2015In: Proceedings 2015 European Conference on Lasers and Electro-Optics - European Quantum Electronics Conference, CLEO/Europe-EQEC 2015, Optical Society of America, 2015, article id CL_4_1Conference paper (Refereed)
    Abstract [en]

    Mid-infrared (MIR) spectroscopy is an extremely powerful method to study biomolecules, since it combines chemical specificity and sensitivity with almost non-destructive probing. MIR vibrational spectroscopy (500 to 3500 cm−1; 3–20 µm) is based on the excitation of fundamental molecular vibrations, which are characteristic for each species, as well as its molecular structure. Recently nanocrystaline diamond (NCD) has been compared with traditional bioanalytical test formats (polystyrene microtiter plates) using an antibody based ELISA targeting C-reactive protein, and showed superior signal-to-noise ratios for NCD surfaces [1]. The detection of an organic substance with evanescent field absorption has been demonstrated in slab diamond waveguide (DWG) with significant sensitivity improvement compared to conventional MIR slab/strip waveguides [2]. We aim to combine these two findings into a miniaturized MIR-spectroscopic measurement technique based on diamond waveguides with a NCD surface that enable super sensitive, label-free detection of chemicals and biomolecular interactions. Here, the characterization of an 8 mm long multimode diamond strip waveguide is presented.

  • 26.
    Malmström, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Forsberg, P.
    Cai, Y.
    Karlsson, M.
    Nikolajeff, F.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Diamond waveguides for mid-IR chemical sensing2014In: Optics InfoBase Conference Papers, OSA - The Optical Society , 2014Conference paper (Refereed)
  • 27.
    Malmström, Mikael
    et al.
    Swerim AB.
    Jansson, Anton
    Swerim AB.
    Hutchinson, Bevis
    Swerim AB.
    Application of Laser-Ultrasonics for Evaluating Textures and Anisotropy2022In: Applied Sciences, ISSN 2076-3417, Vol. 12, no 20Article in journal (Refereed)
    Abstract [en]

    Various approaches are reviewed for determining elastic anisotropy and its coupling to crystallographic texture, with special reference to ultrasonic measurements. Two new methods are described for measuring the anisotropy of P-wave velocity using laser-ultrasonics. Making measurements across the diameter of a cylindrical specimen as it is rotated makes it possible to maintain a very constant known path length. This permits extremely accurate measurements with a precision of better than 0.01%. Results on 316 stainless steel in different conditions are compared with calculated values obtained from EBSD textures together with measured densities and crystalline coefficients from the literature. Excellent agreement is obtained when applying the Hill geometrical average procedure. A similar approach is adopted to measure the variation of wave velocity in a martensitic steel, after tempering at a range of temperatures. Changes in the anisotropy associated with thermal softening are discussed. The second method uses Galvano mirrors to steer the generating laser to different positions over a sheet surface, allowing wave velocities to be determined along different directions in the anisotropic material.

  • 28.
    Malmström, Mikael
    et al.
    Swerim AB.
    Jansson, Anton
    Swerim AB.
    Hutchinson, Bevis
    Swerim AB.
    Lindell, David
    Swerim AB.
    Comparative study of structures in cold rolled 316 stainless steel using laser ultrasonics and electron backscatter diffraction measurements2021In: 5th ESTAD (European Steel Technology and Application Days), Stockholm: Jernkontoret – the Swedish Steel Producers’ Association , 2021Conference paper (Refereed)
    Abstract [en]

    This work aims to develop an online texture sensor for the steelworks environment in order to estimatethe recrystallized fraction [1]. The material investigated was AISI 316 stainless steel of which 4 samples had been cold rolled with either 70% or 50% reduction to a final thickness of ~12 mm. Prior to the rollingtwo of samples were annealed at 1200 °C for 1.5 hours resulting in a grain size growth from ~25 to ~60μm. All measurements were made at room temperature. The influence of texture on the anisotropy ofwave velocities were measured for various polar- and azimuthal-angles, ρ and θ respectively. Additionally, the grain sizes were measured by LUS using the b-parameter analysis of attenuation data. Thus, both grain size and texture were measured on the specimen. In addition, the microstructures andthe textures were determined using electron back-scattering diffraction (EBSD) at the through thicknesscenter of the 4 samples after which the stiffness matrix was calculated using the Hill approximation withtabulated single crystal stiffness coefficients and sample density. The phase velocity was then calculatedusing the MTEX toolbox [2] for the same angles as the LUS measurements. The resulting velocity forthe TD scan of the high temperature annealed sample with 50 % reduction is plotted in Fig. 1 below. There is a significant difference between the EBSD and LUS data especially for large anglesmostly due to the in-house lab rolling which introduced several bends in the RD direction and had a~2 % thickness variation over the TD direction. The LUS measurements were performed in a positionwith the least curvature but the geometrical effects are not compensated for in the velocity calculation. Nevertheless, in a future industrial application such compensation will not be necessary since theproduct uniformity is expected to be very high.

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    Abstract
    Download (mp4)
    Recorded presentation
  • 29.
    Malmström, Mikael
    et al.
    KTH. Swerim AB.
    Jansson, Anton
    Swerim AB.
    Hutchinson, Bevis
    Swerim AB.
    Lundin, Peter
    Swerim AB.
    Gillgren, Lars
    SSAB.
    Bäcke, Linda
    SSAB.
    Sollander, Hans
    SSAB.
    Bärwald, Mattias
    EMG Automation GmbH.
    Berg, Frenk van den
    Tata Steel.
    Laser ultrasonics for online monitoring of microstructures in the hot strip mill2023Conference paper (Refereed)
    Download full text (pdf)
    Presentation
  • 30.
    Malmström, Mikael
    et al.
    Swerim AB, Stockholm, Sweden.
    Jansson, Anton
    Swerim AB.
    Hutchinson, Bevis
    Swerim AB.
    Lundin, Peter
    Swerim AB.
    Gillgren, Lars
    SSAB.
    Sollander, Hans
    SSAB.
    Bärwald, Matthias
    EMG Automation GmbH.
    On-line grain size gauge for the hot strip mill based on laser ultrasonics2022In: 5th International Workshop on Laser-Ultrasound for Metals, 2022Conference paper (Refereed)
  • 31.
    Malmström, Mikael
    et al.
    Swerim AB.
    Jansson, Anton
    Swerim AB.
    Hutchinson, Bevis
    Swerim AB.
    Lönnqvist, Johan
    Swerim AB.
    Gillgren, Lars
    SSAB.
    Bäcke, Linda
    SSAB.
    Sollander, Hans
    SSAB.
    Bärwald, Matthias
    EMG Automation GmbH.
    Hochhard, Sascha
    EMG Automation GmbH.
    Lundin, Peter
    Swerim AB.
    Laser-Ultrasound-Based Grain Size Gauge for the Hot Strip Mill2022In: Applied Sciences, ISSN 2076-3417, Vol. 12, no 19Article in journal (Refereed)
    Abstract [en]

    The paper summarizes the creation of a robust online grain size gauge for a hot strip mill. A method and algorithm for calculating the grain size from the measured ultrasonic attenuation is presented. This new method is self-calibrating, does not rely on a geometrical reference sample and can cope with the effects of diffraction on the attenuation. The model is based on 52 quenched samples measured with more than 23,000 laser ultrasonics shots and has a correlation coefficient R2 of 0.8. Typical online laser ultrasonic measurements from the hot strip mill and the calculated grain size versus length are presented for a couple of steel strips.

  • 32.
    Malmström, Mikael
    et al.
    Swerim AB, Stockholm, Sweden.
    Jansson, Anton
    Swerim AB.
    Lundin, Peter
    Swerim AB.
    Bäcke, Linda
    SSAB.
    Recrystallization kinetics of Fe-30Ni model alloy with 0.08-0.83‰ Nb2022In: 5th International Workshop on Laser-Ultrasound for Metals, 2022Conference paper (Refereed)
  • 33.
    Malmström, Mikael
    et al.
    Swerim AB.
    Jansson, Jansson
    Swerim AB.
    Lindell, David
    Swerim AB.
    Brask, Johannes
    Swerim AB.
    Hutchinson, Bevis
    Swerim AB.
    Comparative study of structures in annealed 304 stainless steel using laser-ultrasonics (LUS) in combination with EBSD and XRD2019Conference paper (Refereed)
    Abstract [en]

    The material investigated was 304 (18/8) stainless steel that had been rolled with 70% at 700°C reduction to a final thickness of 2.9 mm. This warm rolling was chosen to avoid complications due to the formation of deformation martensite at room temperature. A 2.9x30x170 mm strip of the steel was then annealed in a controlled temperature gradient ranging from room temperature up to 1100°C so that all possible microstructural stages were represented, comprising recovery, recrystallisation and grain growth as well as their related texture changes. All measurements were made after cooling the specimen down to room temperature.Grain sizes were measured by LUS using the b-parameter analysis of attenuation data. In addition, the newly developed method for scanning the generating laser was applied to show the influence of texture on the anisotropy of wave velocities. Thus, both grain size and texture were continuously monitored along the length of the gradient annealed specimen.X-ray diffraction (XRD) was applied at various positions such that recovery and recrystallisation could be quantified using peak breadth measurements. In addition, microstructures and textures were determined using electron back-scattering diffraction (EBSD) at several locations corresponding to different annealing temperatures.All the observations were congruent in defining the location where primary recrystallisation had taken place over a relatively short distance on the specimen. The XRD line breadths dropped sharply and then remained constant after higher temperatures. However, the LUS grain sizes which also showed a sharp decrease then increased continuously as grain growth progressed, in good agreement with the EBSD observations. The anisotropic wave velocity results confirmed a significant change in the texture corresponding to recrystallisation despite the fact that EBSD showed that there was, in fact, only a modest weakening. A sensitive parameter defining recrystallisation was found to be the Poisson’s ratio which fell sharply and then increased very gradually up to the highest temperatures. This is interpreted as being due to the textural change during recrystallisation, followed by some sharpening of the annealing texture during subsequent grain growth.

    Download full text (pdf)
    Submitted abstract
    Download (pdf)
    Presentation
  • 34.
    Malmström, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Lecourt, J-B
    Multitel Applied Photonics Department, Belgium.
    Hernandez, Y
    Multitel Applied Photonics Department, Belgium.
    Giannone, D
    Multitel Applied Photonics Department, Belgium.
    Tarasenko, Oleksandr
    Acreo AB, Electrum, Kista.
    Margulis, Walter
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Q-switched all-fiber Ytterbium laser with an integrated polarization switch2010In: 4th EPS-QEOD Europhoton Conference, 2010Conference paper (Refereed)
    Abstract [en]

    An all-fiber nanosecond risetime polarizationswitch is employed in an Ytterbium cavity. Thepulsed laser operation is polarized and in the1 μm wavelength range. The main optical outputcharacteristics are: repetition rate of 2 kHz,pulse energy of 13 uJ, and peak powers close to 90Watts.

    Download full text (pdf)
    fulltext
  • 35.
    Malmström, Mikael
    et al.
    Swerim AB.
    Lindh-Ulmgren, Eva
    Swerim AB.
    Martin, David
    Swerim AB.
    Hutchinson, Bevis
    Swerim AB.
    Åslund, Mattias
    Mauritzson, Lena
    Sollander, Hans
    SSAB.
    Mousavi, Saed
    SSAB.
    Moosavi, Ebrahim
    Sandvik.
    Sandström, Mattias
    Sandvik.
    Siriki, Raveendra
    Sandvik.
    Bergman, Anders
    Sandvik.
    Laser ultrasonics for real-time monitoring of microstructures for efficient development and manufacturing of high performance steel2018Conference paper (Refereed)
  • 36.
    Malmström, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Margulis, Walter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Tarasenko, Oleksandr
    Acreo AB.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Mode locking of Er fiber laser with electro optical fiber modulator2011In: 2nd EOS Topical Meeting on Lasers (ETML'11): 4th EOS Topical Meeting on Optical Microsystems (OμS’11), 2011Conference paper (Refereed)
    Abstract [en]

    This paper demonstrates a self-starting mode-locked fiber laser that incorporates anelectrooptical fiber modulator and exploits soliton compression for picosecond pulsegeneration. The ring laser runs at 1.3 MHz, the pulse duration is ~2 ps and thebandwidth ~1 nm. The laser cavity is all fiber-based and the fiber modulator stabilizespulse formation.

    Download full text (pdf)
    fulltext
  • 37.
    Malmström, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Margulis, Walter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Tarasenko, Oleksandr
    Acreo.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Soliton generation from an actively mode-locked fiber laser incorporating an electro-optic fiber modulator2012In: Optics Express, E-ISSN 1094-4087, Vol. 20, no 3, p. 2905-2910Article in journal (Refereed)
    Abstract [en]

    This work demonstrates an actively mode-locked fiber laser operating in soliton regime and employing an all-fiber electro-optic modulator. Nonlinear polarization rotation is utilized for femtosecond pulse generation. Stable operation of the all-fiber ring laser is readily achieved at a fundamental repetition rate of 2.6 MHz and produces 460 fs pulses with a spectral bandwidth of 5.3 nm.

  • 38.
    Malmström, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Margulis, Walter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Yu, Zhangwei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Tarasenko, Oleksandr
    Acreo AB.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    All-Fiber Q-Switched and Cavity Dumped Laser Using an Electrically Addressed Microstructured Fiber2010In: Advanced Solid-State Photonics, 2010Conference paper (Refereed)
    Abstract [en]

    We report on a pulsed fiber laser with two regimes of operation, one where cavity-roundtrip pulse durations are produced (85 ns long, 40 Wpp) and one with high power pulses (2 ns long, 148 Wpp).

  • 39.
    Malmström, Mikael
    et al.
    Swerim AB.
    Martin, David
    Swerim AB.
    Lindh-Ulmgren, Eva
    Swerim AB.
    Hutchinson, Bevis
    Swerim AB.
    Raveendra, Siriki
    Sandvik Materials Technology.
    Microstructural studies of hot deformed austenite using GLEEBLE stress relaxation tests combined with laser ultrasonics and metallography2019Conference paper (Refereed)
    Download full text (pdf)
    fulltext
    Download full text (pdf)
    Presentation
  • 40.
    Malmström, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Tarasenko, Oleksandr
    Margulis, Walter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Pulse selection at 1 MHz with electrooptic fiber switch2012In: Optics Express, E-ISSN 1094-4087, Vol. 20, no 9, p. 9465-9470Article in journal (Refereed)
    Abstract [en]

    Two 78-cm long electrooptic fibers with nonlinear coefficient. chi((2)) similar to 0.26 pm/V are used in a Sagnac loop for pulse selection at up to 1 MHz repetition rate. Laser pulses of 1.5 mu m wavelength arriving at every 140 ns are selected with an extinction ratio as high as -30 dB. The arrangement is entirely based on silica fiber.

  • 41.
    Malmström, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics. Uppsala University, Sweden.
    Tarasenko, Oleksandr
    Margulis, Walter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics. Acreo Swedish ICT AB, Dept Fiber Photon, Stockholm, Sweden.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    All-Fiber Nanosecond Gating for Time-Resolved Spectral Analysis2016In: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 28, no 8, p. 829-832Article in journal (Refereed)
    Abstract [en]

    We demonstrate the addition of time gating to a standard optical spectrum analyzer (OSA) operating in the spectral region similar to 1.06 mu m. This is accomplished by opening for 7 ns the optical input to the OSA with an electrically driven poled fiber in a Sagnac loop. The sequential interrogation with nanosecond resolution of the reflection from three fiber Bragg gratings along a piece of fiber allows distinguishing the spectral peaks created with a minimum separation of 85 cm. The passive extinction ratio of this device is >40 dB and returns to >40 dB from >23 dB on a 35-ns time scale directly after time gating.

  • 42.
    Malmström, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Tarasenko, Oleksandr
    Margulis, Walter
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Pulse selection at 1 MHz with electro-optic fiber switch2012Conference paper (Other academic)
  • 43.
    Malmström, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Tarasenko, Oleksandr
    Acreo AB.
    Margulis, Walter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Ytterbium-doped fiber laser mode-locked with electrooptical fiber2012In: Europhoton: 5th EPS-QEOD Europhoton 2012, 2012Conference paper (Refereed)
    Abstract [en]

    An actively mode-locked Yb-doped fiber laser is demonstrated, incorporating an electrooptical fiber phase modulator, driven with 40 Vpp. The all-spliced linear cavity generates subnanosec- ond pulses at 1065 nm wavelength with a fundamental repetition rate of 15.6 MHz. It produces comparable output pulses up to the 7th harmonic at 109 MHz.

  • 44.
    Malmström, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Yu, Zhangwei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Margulis, Walter
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Tarasenko, O.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    All-fiber cavity dumping2009In: Optics Express, E-ISSN 1094-4087, Vol. 17, no 20, p. 17596-17602Article in journal (Refereed)
    Abstract [en]

    Cavity dumping of an all-fiber laser system is demonstrated. The active element is a pulse-picker with nanosecond rise time consisting of a microstructured fiber with electrically driven internal electrodes. The device is used for intracavity polarization rotation and dumping through a polarization splitter. The optical flux is removed from the cavity within one roundtrip and most of the amplified spontaneous emission, spiking and relaxation oscillation that follow during the gain recovery phase of the laser are blocked from the output signal.

  • 45.
    Malmström, Mikael
    et al.
    Swerea KIMAB.
    Åslund, Mattias
    Swerea KIMAB.
    Lindh-Ulmgren, Eva
    Hutchinson, Bevis
    Martin, David
    Pyykkönen, Juha
    Swerea KIMAB.
    Recent experience of LUS in hot deformation of steels using Gleeble and rolling experiments2017Conference paper (Other academic)
  • 46.
    Margulis, Walter
    et al.
    Acreo AB, Sweden.
    Malmström, Mikael
    Acreo AB, Sweden.
    Rugeland, Patrik
    Acreo AB, Sweden.
    Tarasenko, Oleksandr
    Second-order Nonlinearity in Fibers and Applications2012Conference paper (Refereed)
    Abstract [en]

    Fiber modulators with strong field recorded exhibit the linear electrooptic effect. Interferometry transforms phase- into intensity modulation. Vπ 100-V is obtained, with an electrical bandwidth of tens of MHz. Applications and limitations are discussed.

  • 47.
    Margulis, Walter
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Malmström, Mikael
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Tarasenko, Oleksandr
    Acreo.
    Yu, Zhangwei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Rugeland, Patrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Electrical fiber components and applications [invited]2012Conference paper (Other academic)
  • 48.
    Margulis, Walter
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Tarasenko, O.
    Malmström, Mikael
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Rugeland, Patrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Yu, Zhangwei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Electrically controlled fibers2012In: Technical Digest - 2012 17th Opto-Electronics and Communications Conference, OECC 2012, IEEE , 2012, p. 803-804Conference paper (Refereed)
    Abstract [en]

    Fibers with internal electrodes are driven electrically. They allow for the control of polarization, wavelength tuning, nanosecond light gating, Q-switching and mode-locking of lasers. These are some of the applications discussed in this paper.

  • 49.
    Margulis, Walter
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Tarasenko, Oleksandr
    Acreo AB.
    Malmström, Mikael
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Myrén, Niklas
    Yu, Zhangwei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Electrically controlled fibers: what next2011In: 7th International Workshop on Fibre Optics and Passive Components, 2011Conference paper (Refereed)
    Abstract [en]

    The ability of providing a fiber with internal electrodes opens the doors for electricalcontrol of light in fibers. Refractive index change through poling and acoustic pulses arising fromheated electrodes are exploited to this end. We discuss main achievements and limitations, andlook ahead to what needs to be done for making these components more widely usable.

  • 50.
    Margulis, Walter
    et al.
    Acreo AB.
    Tarasenko, Oleksandr
    Acreo AB.
    Malmström, Mikael
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Rugeland, Patrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Yu, Zhangwei
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    High-Speed Switching in Optical Fibers2010Conference paper (Refereed)
12 1 - 50 of 65
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