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  • 2601.
    Zhou, Tunhe
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Zanette, Irene
    Zdora, Marie-Christine
    Lundström, Ulf
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik. Stanford Univ, Dept Biol Struct, Stanford, CA 94305 USA.
    Larsson, Daniel H.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hertz, Hans M.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Pfeiffer, Franz
    Burvall, Anna
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Speckle-based x-ray phase-contrast imaging with a laboratory source and the scanning technique2015Inngår i: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 40, nr 12, s. 2822-2825Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The speckle-based scanning method for x-ray phase-contrast imaging is implemented with a liquid-metal-jet source. Using the two-dimensional scanning technique, the phase shift introduced by the object is retrieved in both transverse orientations, and the limitations on spatial resolution inherent to the speckle-tracking technique are avoided. This method opens up possibilities of new high-resolution multimodal applications for lab-based phasecontrast x-ray imaging.

  • 2602.
    Zhou, Tunhe
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Zdora, Marie-Christine
    Zanette, Irene
    Romell, Jenny
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Hertz, Hans M.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Burvall, Anna
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Noise analysis of speckle-based x-ray phase-contrast imaging2016Inngår i: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 41, nr 23, s. 5490-5493Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Speckle-based x-ray phase-contrast imaging has drawn increasing interest in recent years as a simple, multimodal, cost-efficient, and laboratory-source adaptable method. We investigate its noise properties to help further optimization on the method and further comparison with other phase-contrast methods. An analytical model for assessing noise in a differential phase signal is adapted from studies on the digital image correlation technique in experimental mechanics and is supported by simulations and experiments. The model indicates that the noise of the differential phase signal from speckle-based imaging has a behavior similar to that of the grating-based method.

  • 2603.
    Zhou, Tunhe
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Zdora, M.-C.
    Zanette, I.
    Romell, J.
    Hertz, H. M.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Burvall, Anna
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Biomedicinsk fysik och röntgenfysik.
    Noise analysis of speckle-based x-ray phase-contrast imagingManuskript (preprint) (Annet vitenskapelig)
  • 2604.
    Zichi, Julien
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvant- och biofotonik.
    NbTiN for improved superconducting detectors2019Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The physics of single photons is fascinating, by manipulating them we can observe and probe quantum effects. Doing so requires the fabrication and utilization of single photon sources, of which many types have been developed including quantum dots, trapped atoms and ions, and color centers. On the other end of the experiments, single photon detectors play a role of utmost importance, and while several types of detectors exist, superconducting nanowire single photon detectors are now the state-of-the-art technology. By offering near unity detection efficiency from the ultra-violet to the mid-infrared light spectrum, with negligible noise and excellent time resolution, they made possible many experiments that were previously technologically unfeasible. The same appealing characteristics have found a use in applications outside of the quantum optics framework, with notably light detection and ranging, biomedical imaging or CMOS circuits testing.In this thesis a controlled growth method for tailoring the characteristics of niobium titanium nitride in the framework of superconducting nanowire single photon detectors was developed. Reactive co-sputter deposition of niobium titanium nitride was shown to be a versatile method, both in terms of the degree of control over the material composition, and in the choice of substrates that it allows. Unity internal detection efficiency of detectors at telecom wavelengths was achieved by optimizing the niobium content in the material. The influence of lattice matching on the critical temperatures of films deposited at room temperature was investigated. The fabrication of superconducting nanowire single photon detectors on aluminum nitride-on-sapphire, on lithium niobate nano-waveguides, on gallium arsenide, and the integration on SiN waveguides was achieved. The material was used to fabricate detectors with optimized response for any linear polarization of the incoming photons by using a fractal architecture. Another method was proposed to achieve the same results by encapsulating meandering detectors in a high index dielectric material, resulting in a decrease of the permittivity mismatch between the nanowire material and its surrounding and therefore optimizing the efficiency for both orthogonal linear polarizations.Finally, detectors were fabricated from films developed in this work, and were operated to enable the implementation of polarization-based entanglement distribution in optical fibers in a real-conditions scenario, over a record distance of 96 km. This paves the way for the development of quantum communication networks using existing optical fiber links.

  • 2605.
    Zichi, Julien
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvant- och biofotonik.
    Chang, Chang
    Steinhauer, Stephan
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvant- och biofotonik.
    von Fieandt, Kristina
    Los, Johannes W. N.
    Visser, Gijs
    Kalhor, Nima
    Lettner, Thomas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvant- och biofotonik.
    Elshaari, Ali W.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvant- och biofotonik.
    Esmaeil Zadeh, Iman
    Zwiller, Val
    NbxTi1-xN low timing jitter single-photon detectors with unity internal detection efficiency at 1550 nmManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The requirements in quantum optics experiments for high single photon detectionefficiency, low timing jitter, low dark count rate and short dead time have been fulfilled withthe development of superconducting nanowire single photon detectors. Although they offer adetection efficiency above 90%, achieving a high time resolution in devices made ofamorphous materials is a challenge, particularly at temperatures above 0.8 K. Devices madefrom niobium nitride and niobium titanium nitride allow to reach the best timing jitter, but inturn have stronger requirements in terms of film quality to achieve a high efficiency. Here wetake advantage of the flexibility of reactive co-sputter deposition to tailor the composition ofNbxTi1-xN superconducting films, and show that a Nb fraction of x = 0.62 allows for thefabrication of detectors from films as thick as 9 nm and covering an active area of 20 μm,with a wide detection saturation plateau at telecom wavelengths and in particular at 1550 nm.This is a signature of an internal detection efficiency saturation, achieved while maintainingthe high time resolution associated with NbTiN and operation at 2.5K. With our optimizedrecipe, we reliably fabricated detectors with high critical current densities reaching asaturation plateau at 1550 nm with 80% system detection efficiency, and with a FWHMtiming jitter as low as 19.47 ps.

  • 2606.
    Zichi, Julien
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvant- och biofotonik.
    Chang, Jin
    Delft Univ Technol, Fac Appl Sci, ImPhys Dept, Opt Res Grp, Lorentzweg 1, NL-2628 CJ Delft, Netherlands..
    Steinhauer, Stephan
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvant- och biofotonik.
    Von Fieandt, Kristina
    Uppsala Univ, Angstrom Lab, Dept Chem, Inorgan Chem Res Programme, Box 538, SE-75121 Uppsala, Sweden..
    Los, Johannes W. N.
    Single Quantum BV, NL-2628 CH Delft, Netherlands..
    Visser, Gus
    Single Quantum BV, NL-2628 CH Delft, Netherlands..
    Kalhor, Nima
    Single Quantum BV, NL-2628 CH Delft, Netherlands..
    Lettner, Thomas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvant- och biofotonik.
    Elshaari, Ali W.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvant- och biofotonik.
    Zadeh, Iman Esmaeil
    Delft Univ Technol, Fac Appl Sci, ImPhys Dept, Opt Res Grp, Lorentzweg 1, NL-2628 CJ Delft, Netherlands..
    Zwiller, Val
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvant- och biofotonik. Single Quantum BV, NL-2628 CH Delft, Netherlands..
    Optimizing the stoichiometry of ultrathin NbTiN films for high-performance superconducting nanowire single-photon detectors2019Inngår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 27, nr 19, s. 26579-26587Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The requirements in quantum optics experiments for high single-photon detection efficiency. low timing jitter, low dark count rate and short dead time have been fulfilled with the development of superconducting nanowire single-photon detectors. Although they offer a detection efficiency above 90%, achieving a high time resolution in devices made of amorphous materials is a challenge, particularly at temperatures above 0.8 K. Devices made from niobium nitride and niobium titanium nitride allow us to reach the best timing jitter but. in turn, have stronger requirements in terms of film quality to achieve a high efficiency. Here we take advantage of the flexibility of reactive co-sputter deposition to tailor the composition of NbxTi1-xN superconducting films and show that a Nb fraction of x = 0.62 allows for the fabrication of detectors from films as thick as 9 nm and covering an active area of 20 mu m. with a wide detection saturation plateau at telecom wavelengths and in particular at 1550 nm. This is a signature of an internal detection efficiency saturation, achieved while maintaining the high time resolution associated with NbTiN and operation at 2.5K. With our optimized recipe, we reliably fabricated detectors with high critical current densities reaching a saturation plateau at 1550 nm with 80% system detection efficiency and with a FWHM timing jitter as low as 19.5 ps. Open Access Publishing Agreement

  • 2607.
    Zichi, Julien
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvant- och biofotonik.
    Gyger, Samuel
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvant- och biofotonik.
    Baghban, Mohammad Amin
    Elshaari, Ali W.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvant- och biofotonik.
    Gallo, Katia
    Zwiller, Val
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvant- och biofotonik.
    An NbTiN superconducting single photon detector implemented on a LiNbO3 nano-waveguide at telecom wavelength2019Inngår i: Poster session T.Po2, 2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Fiber-coupled superconducting nanowire single photon detectors are a ubiquitous tool for quantum optics experiments as they offer near unity detection efficiency over a broad wavelength range, low dark count rate, excellent time resolution and high saturation rate. Nevertheless, advancing quantum optics experiments and applications beyond the few-photon limit requires large scale integrated systems of quantum sources and detectors. In recent years there has been a tremendous progress with integrating single photon detectors with a variety of photonic platforms. This includes attempts on ion-diffused waveguides in LiNbO3, a non-linear and electro-optic material with widespread use for signal processing, frequency conversion, and quantum optics devices. However the realization of superconducting detectors on single mode waveguides remains elusive. Here we present an NbTiN superconducting single photon detector integrated directly on a LiNbO3 single mode nanophotonic waveguide at telecom wavelength, with a high critical current density and a dark count rate of 3 mHz at 99% of its critical current.

  • 2608.
    Zichi, Julien
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvant- och biofotonik.
    Yang, Lily
    Gyger, Samuel
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvant- och biofotonik.
    Lettner, Thomas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvant- och biofotonik.
    Errando-Herranz, Carlos
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Mikro- och nanosystemteknik.
    Jöns, Klaus D.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvant- och biofotonik.
    Baghban, Mohammad Amin
    Gallo, Katia
    Steinhauer, Stephan
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvant- och biofotonik.
    Zwiller, Val
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvant- och biofotonik.
    Heterogeneous integration of NbTiN by universal room temperature depositionManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Being the Nb-based compound with the highest known critical temperature, NbTiN is of particular interest for many applications. It is used in Josephson junctions for single flux quantum logic gates, as a superconducting electrode to contact semiconductor devices, and one important use is in superconducting nanowire single photon detectors. These detectors are the ideal candidate for on-chip integration in photonic circuits, offering near-unity detection efficiency, low noise and excellent time resolution, therefore it is desirable to implement them on a wide variety of platforms. However, it remains a challenge to deposit the superconducting material with a process suitable for heterogeneous integration, as the most widespread material, NbN, is associated with a deposition at a high temperature. Taking advantage of the possibility to deposit superconducting NbTiN with various stoichiometries by co-sputter deposition at room temperature, we demonstrate growth on six different substrates – silicon dioxide, silicon nitride, gallium arsenide, lithium niobate, [Pb(Mg1/3Nb2/3)O3]-x[PbTiO3] or PMN-PT, and aluminum nitride – in the same deposition run, and show that all the films exhibit superconducting properties with similar critical temperatures. We fabricated waveguide-compatible superconducting nanowire single photon detectors on five substrates, report short dead times for all devices with a narrow spread of performances, and discuss their different photon detection saturation behavior. Our method simplifies the fabrication of superconducting devices on a wide range of materials.

  • 2609. Zielińska, J. A.
    et al.
    Zukauskas, A.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Noyan, M. A.
    Mitchell, M. W.
    Fully-resonant, tunable, monolithic frequency conversion as a coherent UVA source2017Inngår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 25, nr 2, s. 1142-1150Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We demonstrate a monolithic frequency converter incorporating up to four tuning degrees of freedom, three temperature and one strain, allowing resonance of pump and generated wavelengths simultaneous with optimal phase-matching. With a Rb-doped periodically-poled potassium titanyl phosphate (KTP) implementation, we demonstrate efficient continuous-wave second harmonic generation from 795 to 397, with low-power efficiency of 72% and high-power slope efficiency of 4.5%. The measured performance shows good agreement with theoretical modeling of the device. We measure optical bistability effects, and show how they can be used to improve the stability of the output against pump frequency and amplitude variations. 

  • 2610. Zisis, G.
    et al.
    Manzo, Michele
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Gallo, Katia
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvantelektronik och -optik, QEO.
    Soergel, E.
    Mailis, S.
    UV laser-induced poling inhibition in proton exchanged LiNbO3 crystals2017Inngår i: Applied physics. B, Lasers and optics (Print), ISSN 0946-2171, E-ISSN 1432-0649, Vol. 123, nr 4, artikkel-id 158Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The applicability of the UV laser-induced poling inhibition method for ferroelectric domain engineering in proton exchanged lithium niobate planar waveguides is investigated. Our results indicate that intense UV irradiation of proton exchanged lithium niobate samples can, indeed, produce poling inhibited domains in this material under certain irradiation conditions. However, there is strong indication that the temperature gradient that is formed during UV irradiation modifies the local proton concentration leading to changes in the refractive index profile of the original planar waveguide.

  • 2611. Ziss, Dorian
    et al.
    Martin-Sanchez, Javier
    Lettner, Thomas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvantnanofotonik.
    Halilovic, Alma
    Trevisi, Giovanna
    Trotta, Rinaldo
    Rastelli, Armando
    Stangl, Julian
    Comparison of different bonding techniques for efficient strain transfer using piezoelectric actuators2017Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 121, nr 13, artikkel-id 135303Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, strain transfer efficiencies from a single crystalline piezoelectric lead magnesium niobatelead titanate substrate to a GaAs semiconductor membrane bonded on top are investigated using state-of-the-art x-ray diffraction (XRD) techniques and finite-element-method (FEM) simulations. Two different bonding techniques are studied, namely, gold-thermo-compression and polymer-based SU8 bonding. Our results show a much higher strain-transfer for the "soft" SU8 bonding in comparison to the "hard" bonding via gold-thermo-compression. A comparison between the XRD results and FEM simulations allows us to explain this unexpected result with the presence of complex interface structures between the different layers.

  • 2612.
    Zivanov, Jasenko
    et al.
    MRC, Lab Mol Biol, Cambridge, England..
    Nakane, Takanori
    MRC, Lab Mol Biol, Cambridge, England..
    Forsberg, Björn O.
    Stockholm Univ, Dept Biochem & Biophys, Sci Life Lab, Stockholm, Sweden..
    Kimanius, Dari
    Stockholm Univ, Dept Biochem & Biophys, Sci Life Lab, Stockholm, Sweden..
    Hagen, Wim J. H.
    European Mol Biol Lab, Struct & Computat Biol Unit, Heidelberg, Germany.;European Mol Biol Lab, Cryoelectron Microscopy Serv Platform, Heidelberg, Germany..
    Lindahl, Erik
    KTH, Centra, SeRC - Swedish e-Science Research Centre. KTH, Centra, Science for Life Laboratory, SciLifeLab. KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik. Stockholm Univ, Dept Biochem & Biophys, Sci Life Lab, Stockholm, Sweden..
    Scheres, Sjors H. W.
    MRC, Lab Mol Biol, Cambridge, England..
    New tools for automated high-resolution cryo-EM structure determination in RELION-32018Inngår i: eLIFE, E-ISSN 2050-084X, Vol. 7, artikkel-id e42166Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Here, we describe the third major release of RELION. CPU-based vector acceleration has been added in addition to GPU support, which provides flexibility in use of resources and avoids memory limitations. Reference-free autopicking with Laplacian-of-Gaussian filtering and execution of jobs from python allows non-interactive processing during acquisition, including 2D-classification, de novo model generation and 3D-classification. Per-particle refinement of CTF parameters and correction of estimated beam tilt provides higher resolution reconstructions when particles are at different heights in the ice, and/or coma-free alignment has not been optimal. Ewald sphere curvature correction improves resolution for large particles. We illustrate these developments with publicly available data sets: together with a Bayesian approach to beam-induced motion correction it leads to resolution improvements of 0.2-0.7 angstrom compared to previous RELION versions.

  • 2613.
    Zohdi, Zeynab
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik. Karolinska Inst, Dept Clin Neurosci, Ctr Psychiat Res, SE-17176 Solna, Sweden ; Univ Bu Ali Sina, Dept Chem, Hamadan 65174, Iran.
    Hashemi, Mahdi
    Univ Bu Ali Sina, Dept Chem, Hamadan 65174, Iran..
    Uheida, Abdusalam
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Moein, Mohammad Mahdi
    Karolinska Inst, Dept Clin Neurosci, Ctr Psychiat Res, SE-17176 Solna, Sweden..
    Abdel-Rehim, Mohamed
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik. Karolinska Inst, Dept Clin Neurosci, Ctr Psychiat Res, SE-17176 Solna, Sweden Dept Appl Phys, SE-16440 Stockholm, Sweden..
    Graphene Oxide Tablets for Sample Preparation of Drugs in Biological Fluids: Determination of Omeprazole in Human Saliva for Liquid Chromatography Tandem Mass Spectrometry2019Inngår i: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 24, nr 7, artikkel-id 1191Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, a novel sort of sample preparation sorbent was developed, by preparing thin layer graphene oxide tablets (GO-Tabs) utilizing a mixture of graphene oxide and polyethylene glycol on a polyethylene substrate. The GO-Tabs were used for extraction and concentration of omeprazole (OME) in human saliva samples. The determination of OME was carried out using liquid chromatography-tandem mass spectrometry (LC-MS/MS) under gradient LC conditions and in the positive ion mode (ESI+) with mass transitions of m/z 346.3 -> 198.0 for OME and m/z 369.98 -> 252.0 for the internal standard. Standard calibration for the saliva samples was in the range of 2.0-2000 nmol L-1. Limits of detection and quantification were 0.05 and 2.0 nmol L-1, respectively. Method validation showed good method accuracy and precision; the inter-day precision values ranged from 5.7 to 8.3 (%RSD), and the accuracy of determinations varied from -11.8% to 13.3% (% deviation from nominal values). The extraction recovery was 60%, and GO-Tabs could be re-used for more than ten extractions without deterioration in recovery. In this study, the determination of OME in real human saliva samples using GO-Tab extraction was validated.

  • 2614.
    Zukauskas, Andrius
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    QPM Devices in KTA and RKTP2014Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Even though KTiOPO4 (KTP) is considered to be one of the best nonlinear materials for quasi phase matched (QPM) frequency conversion in the visible and the near-infrared spectral regions, its use is often limited by poor material homogeneity, high ionic conductivity, a considerable linear absorption and photochromatic damage. On the other hand, the improved material homogeneity and the lower ionic conductivity of bulk Rb-doped KTP (RKTP) make this material an ideal alternative for fabrication of fine-pitch QPM gratings, while the arsenate isomorph KTiOAsO4 (KTA) promises a better performance in the green spectral region and adds the advantage of a wider transparency window in the infrared. Unfortunately, the available studies on these materials are limited and unable to answer the question whether RKTP and KTA are feasible alternatives to KTP in terms of periodic poling and optical performance. The optical performance of the QPM devices depends on the periodic poling quality, therefore, a detailed comprehension of domain-grating formation in the KTP isomorphs is highly desired. The goals of this thesis were to gain a better understanding of the periodic poling process in the KTP isomorphs, in order to study the specifics of ferroelectric domain engineering in KTA and RKTP, and to evaluate the optical performance of these isomorphs. Fine-pitch periodically poled structures were engineered both in KTA and RKTP crystals. It was demonstrated that QPM gratings with excellent quality and with periods as short as 8.49 μm can be fabricated in KTA crystals. Comparative transmission studies have shown that periodically poled KTA (PPKTA) crystals can be superior to KTP for QPM second harmonic generation in the visible spectral region due to lower linear absorption. It was also demonstrated that RKTP is a superior alternative to KTP for high-quality QPM grating fabrication. A consistent room-temperature periodic poling of 5 mm thick RKTP crystals with a period of 38.86 μm has been achieved. The obtained large aperture periodically poled RKTP (PPRKTP) crystals showed an outstanding QPM grating uniformity and excellent optical performance in optical parametric oscillator (OPO) applications. Moreover, it was shown that RKTP is less susceptible to blue-induced infrared absorption than KTP. Finally, a novel and a relatively simple method for self-assembling quasi-periodic sub-μm scale ferroelectric domain structure in RKTP crystals has been presented. It was shown that, after treatment in aqueous KOH/KNO3 solution, periodic poling of RKTP with planar electrodes resulted in one-dimensional ferroelectric domain structure with an average periodicity of 650±200 nm, extending over the whole 1 mm thick crystal. Such self-assembled structures in RKTP were used to demonstrate 5th order non-collinear QPM backward second harmonic generation.

  • 2615.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Coetzee, Riaan Stuart
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Highly-efficient sub-µm periodically poled RKTP for mirrorless OPO: Fabrication, characterization and performance2018Inngår i: Optics InfoBase Conference Papers, OSA - The Optical Society , 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We present a highly-reliable fabrication technique for sub-µm PPRKTP demonstrating periodicities as short as 500 nm. The crystals are used for counter-propagating three-wave mixing interactions with a conversion efficiency exceeding 50% and mJ-level output energy.

  • 2616.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Liljestrand, Charlotte
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Fabrication of sub-μm ferroelectric domain gratings for counter-propagating nonlinear interactions2016Konferansepaper (Fagfellevurdert)
  • 2617.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Liljestrand, Charlotte
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Progress in Fabrication of sub-µm QPM Devices in Bulk Rb-doped KTP2012Konferansepaper (Fagfellevurdert)
  • 2618.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Liljestrand, Charlotte
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Viotti, Anne-Lise
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Highly-Efficient Cascaded Mirrorless OPO in Sub-mu m Periodically Poled RKTP Crystals2017Inngår i: 2017 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), IEEE , 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We demonstrate low threshold mirrorless optical parametric oscillation in sub-mu m periodically poled RKTP crystals reaching an efficiency of 43%. The generated signal serves as a pump in a cascaded MOPO process in the same crystal.

  • 2619.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Liljestrand, Charlotte
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Viotti, Anne-Lise
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Highly-efficient cascaded mirrorless OPO in sub-µm periodically poled RKTP crystals2017Konferansepaper (Fagfellevurdert)
  • 2620.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Liljestrand, Charlotte
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Viotti, Anne-Lise
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Highly-efficient cascaded mirrorless OPO in sub-μm periodically poled RKTP crystals2017Inngår i: Optics InfoBase Conference Papers, Optical Society of America, 2017, Vol. Part F41Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We demonstrate low threshold mirrorless optical parametric oscillation in sub-μm periodically poled RKTP crystals reaching an efficiency of 43%. The generated signal serves as a pump in a cascaded MOPO process in the same crystal.

  • 2621.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Bulk Self-assembled Ferroelectric Domain Structures in RKTP2016Konferansepaper (Fagfellevurdert)
  • 2622.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Quasi-periodic self-assembled sub-micrometer ferroelectric bulk domain gratings in Rb-doped KTiOPO42013Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 103, nr 25, s. 252905-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a simple technique for fabricating quasi-periodic bulk sub-μm ferroelectric domain gratings in Rb-doped KTiOPO4 (RKTP) based on self-organized ferroelectric domain formation. One-dimensional ferroelectric domain structures, with an average periodicity of 650 ± 200 nm and extending throughout 1 mm thick crystals, are obtained by etching and subsequent electric field poling using planar electrodes. The sub-μm structures in RKTP were used to demonstrate 5th order non-collinear quasi-phase matched backward second harmonic generation.

  • 2623.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Second-harmonic generation in periodically poled bulk Rb-doped KTiOPO4 below 400 nm at high peak-intensities2013Inngår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 21, nr 2, s. 1395-1403Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We demonstrate that bulk Rb-doped KTiOPO4 (RKTP) shows improved susceptibility to gray-tracking compared to flux-grown KTiOPO4. We show high-fidelity periodic poling of 1 mm thick RKTP with a period of 3.18 mu m for second harmonic generation at 398 nm with a normalized conversion efficiency of 1.79%/Wcm. The crystal is used to frequency-double 138 fs-long pulses with an efficiency of 20% and a peak intensity of 560 MW/cm(2) without visible gray-tracking signs. We demonstrate that two-photon absorption is the predominant mechanism limiting the SHG efficiency in this spectral range at high peak powers and high repetition rates.

  • 2624.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Fan-out periodically poled structures in Rb-doped KTiOPO4 for continuously tunable QPM devices2019Inngår i: NONLINEAR FREQUENCY GENERATION AND CONVERSION: MATERIALS AND DEVICES XVIII / [ed] Schunemann, PG Schepler, KL, SPIE-INT SOC OPTICAL ENGINEERING , 2019, artikkel-id UNSP 109020NKonferansepaper (Fagfellevurdert)
    Abstract [en]

    Since the first demonstration of electric field poling in 1993, the use of quasi-phase matching (QPM) technique has gained wide adoption in a multitude of applications. The QPM field today is dominated mainly by the ferroelectric oxide materials from LiNbO3 (LN) and KTiOPO4 (KTP) families, where QPM structures are implemented by the electric field poling technique. While typical QPM devices have a fixed-period, one-dimensional domain grating design, which is the most straightforward to implement, numerous applications require the ability to continuously tune the wavelength over a wider spectral range. For applications where temperature tuning is not desired, a fan-out QPM grating design may be advantageous. The tuning here is performed by transverse translation of the structure in respect to the pump beam, while keeping the crystal temperature constant. While the implementation of fan-out gratings is reasonably well researched in LN, there is a lack of reliable data for KTP isomorphs. Taking into account the high domain growth anisotropy in KTP, an important factor becomes the angle between the domain walls and the b-axis of the crystal. This angle directly affects the quality and dimensions of the QPM device. However, its upper boundary has not been determined to date. In this work we discuss the prospects and limitations of PPKTP devices with fan-out grating designs. We present a fan-out PPRKTP device, where the transverse fan-out rate is 0.5 mu m/mm. In an OPO configuration pumped by 532 nm such PPRKTP crystal is able to provide continuously tunable radiation between 0.7 -2.2 mu m.

  • 2625.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Grey-Track Resistant Periodically Poled Rb-doped KTiOPO4 For Blue-Light Generation2010Inngår i: Optics InfoBase Conference Papers, 2010, s. 5500148-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We present periodic poling of Rb-doped KTiOPO4. The crystal is used to obtain blue radiation at 398 nm with an efficiency of 30% and a peak intensity of 2 MW/cm2 without grey-tracking.

  • 2626.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik. Royal Inst Technol, Dept Appl Phys, S-10691 Stockholm, Sweden..
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Grey-Track Resistant Periodically Poled Rb-doped KTiOPO(4) For Blue-Light Generation2010Inngår i: 2010 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) AND QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (QELS), IEEE , 2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We present periodic poling of Rb-doped KTiOPO(4). The crystal is used to obtain blue radiation at 398 nm with an efficiency of 30% and a peak intensity of 2 MW/cm(2) without grey-tracking.

  • 2627.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    High-fidelity periodic domain structures in KTiOAsO4 for the visible spectral range2013Inngår i: Optical Materials Express, ISSN 2159-3930, E-ISSN 2159-3930, Vol. 3, nr 9, s. 1444-1449Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We demonstrate room temperature periodic poling of KTiOAsO4 crystals with a period of 8.49 mu m for second harmonic generation of 1066 nm wavelength. The crystals are tested in a continuous wave SHG setup at 533 nm and show high quality periodic ferroelectric domain structure across the whole 1 mm crystal thickness, exhibiting d(eff) = 10.5 pm/V and normalized conversion efficiency of 1.2%/Wcm.

  • 2628.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Periodically poled KTiOAsO4 for second harmonic generation in the green region2013Inngår i: 2013 Conference on Lasers and Electro-Optics, CLEO 2013, IEEE Computer Society, 2013, s. 6833702-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We present high-quality room temperature periodic poling of KTiOAsO4 with a period of 8.49 μm. The crystals are evaluated for SHG at 533 nm, and show deff = 10.5 pm/V and ηnorm = 1.19%/Wcm. OCIS codes: 190.4400 (Nonlinear optics, materials); 160.2260 (Ferroelectrics).

  • 2629.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Self-assembled ferroelectric nano-domain gratings in bulk RKTP2012Inngår i: 2012 Conference on Lasers and Electro-Optics, CLEO 2012, IEEE , 2012, s. 6325938-Konferansepaper (Fagfellevurdert)
    Abstract [en]

     We present the fabrication of self-assembled bulk domain gratings of sub-μm periodicity in Rb-doped KTiOPO4 crystals. The structures are used to demonstrate QPM backwards propagating non-collinear second harmonic generation.

  • 2630.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Safinas, Maratas
    Ekspla Ltd..
    Michailovas, Andrejus
    Ekspla Ltd..
    High-Performance Periodically Poled Rb-doped KTP For Frequency Conversion In Blue/Green Region2010Inngår i: Conference digest, 2010Konferansepaper (Fagfellevurdert)
  • 2631.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Strömqvist, Gustav
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Fokine, Michael
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Fabrication of submicrometer quasi-phase-matched devices in KTP and RKTP [Invited]2011Inngår i: Optical Materials Express, ISSN 2159-3930, Vol. 1, nr 7, s. 1319-1325Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We review the techniques used for fabrication of bulk submicrometer ferroelectric domain gratings in KTiOPO4 (KTP) and demonstrate that bulk Rb-doped KTiOPO4 (RKTP) is an excellent candidate for implementation of dense domain gratings. Compared to KTP, RKTP presents predominant domain propagation along the polar c-direction, substantially reduced lateral domain broadening, and higher poling yield. As a result we obtain homogeneous sub-μm periodic poling of RKTP with a period of 690 nm in 1 mm thick samples.

  • 2632.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Thilmann, Nicky
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    5 mm thick periodically poled Rb-doped KTP for high energy optical parametric frequency conversion2011Inngår i: Optical Materials Express, ISSN 2159-3930, Vol. 1, nr 2, s. 201-206Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A 5 mm thick periodically poled bulk Rb-doped KTiOPO4 (KTP) crystal with a period of 38.86 μm was fabricated by electric field poling. Chemical etching and optical evaluation show a high quality of the periodic ferroelectric domain structure through the whole crystal aperture. The fabricated quasi-phase matching (QPM) device was used in an optical parametric oscillator pumped at 1064 nm with 12 ns pulses at 100 Hz repetition rate to generate 60 mJ parametric radiation with a conversion efficiency of 50%.

  • 2633.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Thilmann, Nicky
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    5 mm Thick Periodically Poled Rb:KTiOPO4 for High Power Optical Frequency Conversion2011Inngår i: Advanced Solid State Photonics 2011, 2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A periodically poled bulk Rb-doped KTiOPO 4crystal with 5 mm aperture was fabricated at room temperature. The ferroelectric domain structure is shown to be homogeneous across the whole aperture with a deffof 11 pm/V.

  • 2634.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Thilmann, Nicky
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    High Fidelity Large Aperture Periodically Poled Rb:KTiOPO(4) for High Energy Frequency Conversion2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We demonstrate periodic poling of 5 mm thick Rb-doped KTiOPO(4) crystals at room temperature. The ferroelectric domain grating is shown to be uniform and homogeneous across the whole crystal aperture.

  • 2635.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Thilmann, Nicky
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Periodically poled KTiOAsO4 for highly efficient midinfrared optical parametric devices2009Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 95, nr 19Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We demonstrate high pattern-fidelity periodic poling of KTiOAsO4 at room temperature. The periodically poled crystal shows a d(eff) of 10.1 pm/V and is used in an optical parametric oscillator pumped at 1064 nm to generate parametric radiation at 1538 and 3452 nm with a conversion efficiency of 45%.

  • 2636.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Thilmann, Nicky
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Periodically Poled KTiOAsO4 For Mid-Infrared Light Generation2010Inngår i: Advanced Solid-State Photonics 2010, 2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A periodically poled KTiOAsO4crystal was fabricated at room temperature. The poled crystal shows a deffof 10.1 pm/V and gives a parametric conversion efficiency of 45%.

  • 2637.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Viotti, Anne-Lise
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Coetzee, Riaan Stuart
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Liljestrand, Charlotte
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Recent advances in sub-mu m PPKTP for non-linear interactions with counter-propagating photons2019Inngår i: NONLINEAR FREQUENCY GENERATION AND CONVERSION: MATERIALS AND DEVICES XVIII / [ed] Schunemann, PG Schepler, KL, SPIE-INT SOC OPTICAL ENGINEERING , 2019, artikkel-id UNSP 109020GKonferansepaper (Fagfellevurdert)
    Abstract [en]

    Mirrorless optical parametric oscillators (MOPO) represent a special class of parametric devices based on three-wave nonlinear interaction in which the generated photons counter-propagate. Owing to the phase-matching condition of the counter-propagating waves, MOPOs can sustain oscillation without mirrors and present unique and useful tuning and spectral properties. In this paper, we will review our recent advances in structuring technology to achieve quasi-phase matching periodicities as short as 500 nm in Rb-doped KTiOPO4, which are necessary to compensate for the large phase mismatch. We will also review the performance of MOPOs both in the ps- and ns- pumping regime. In the latter, our crystals reach single-pass conversion efficiencies exceeding 50%, with mJ-level output energies.

  • 2638.
    Zukauskas, Andrius
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Viotti, Anne-Lise
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Liljestrand, Charlotte
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik. KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Pasiskevicius, Valdas
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik. KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Canalias, Carlota
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik. KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Cascaded counter-propagating nonlinear interactions inhighly-efficient sub-μm periodically poled crystals2017Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, artikkel-id 8037Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Mirrorless optical parametric oscillators (MOPOs) are very attractive parametric devices that rely on the nonlinear interaction of counter-propagating photons to inherently establish distributed feedback, without the use of external mirrors or surface coatings. These devices offer unique spectral and coherence properties that will benefit a large variety of applications ranging from spectroscopy to quantum communications. The major obstacle in exploiting their full potential is ascribed to the difficulty in engineering a nonlinear material in which the generation of counter-propagating waves can be phase matched. Here we present a reliable and consistent technique for fabrication of highly-efficient sub-micrometer periodically poled Rb-doped KTiOPO4. We experimentally demonstrate the first cascaded counter-propagating interactions in which the generated forward signal serves as a pump for a secondary MOPO process, reaching pump depletion larger than 60%. The cascaded process exemplifies the high efficiency of our nonlinear photonic structures. Our domain-engineering technique paves the way to realize counter-propagating schemes and devices that have been deemed unfeasible until now.

  • 2639.
    Zwiller, Val
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik. KTH, Skolan för elektro- och systemteknik (EES).
    Quantum optics with nanowires (Conference Presentation)2017Inngår i: QUANTUM DOTS AND NANOSTRUCTURES: GROWTH, CHARACTERIZATION, AND MODELING XIV / [ed] Huffaker, DL Eisele, H, SPIE-INT SOC OPTICAL ENGINEERING , 2017, artikkel-id UNSP 101140IKonferansepaper (Fagfellevurdert)
  • 2640.
    Zwiller, Val
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Kvantnanofotonik.
    Zadeh, I. E.
    Los, J. W. N.
    Gourgues, R. B. M.
    Steinmetz, V.
    Dobrovolskiy, S. M.
    Dorenbos, S. N.
    Single-photon detection with near unity efficiency, ultrahigh detection-rates, and ultra-high time resolution2017Inngår i: CLEO: Science and Innovations part of CLEO: 2017 : 4-19 May 2017, San Jose, California, United States, Optical Society of America, 2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Single-photon detectors with high efficiency, high time resolution, low dark counts and high photon detection-rates are vital for most demanding quantum optics experiments. Combining all performances in a single device has been challenging. Here, we demonstrate a broadband detector with efficiency higher than 92%, over 150 MHz photon detection-rate and dark counts below 130 Hz operated in a conventional Gifford-McMahon cryostat. Furthermore, using our custom made cryogenic amplifiers and optimized detector, we reach a record low jitter of 14.80 ps while maintaining high efficiency.

  • 2641.
    Åhlfeldt, Henrik
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Laurell, Fredrik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik.
    Time-dependent change of the phase-matching wavelength due to refractive-index instabilities in proton-exchanged LiTaO3 waveguides1994Konferansepaper (Fagfellevurdert)
  • 2642.
    Önfelt, Björn
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik. Karolinska Inst, Dept Microbiol Tumor & Cell Biol, Stockholm, Sweden.
    NATURAL KILLER CELL IMMUNE SURVEILLANCE AT THE SINGLE CELL LEVEL2011Inngår i: PROGRESS ON POST-GENOME TECHNOLOGIES AND MODERN NATURAL PRODUCTS, 2011 / [ed] Zhou, G Huang, C Li, ZP Takeyama, H Lu, Z, SOUTHEAST UNIV PRESS , 2011, s. 55-55Konferansepaper (Fagfellevurdert)
  • 2643.
    Östman, Erik
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Spectral and dynamical measurements using the magneto-optical Kerr efects2011Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The Magneto-Optical Kerr Eect (MOKE) is a powerful tool for studying the magnetic properties of various materials such as thin lm multilayers or magnetic nanostructures. This paper presents the construction of two systems for dierent MOKE measurements. The MOKE spectrometer is capable of measuring the magneto-optical Kerr rotation as function of photon energy between 1.55 eV to 3.1 eV (400 nm to 800 nm). Permalloy, Ni, Co and Ni antidot samples have been measured to calibrate the system. A large magneto-optical enhancement is observed for the antidot lm in the expected energy range. The time-resolved MOKE (tr-MOKE) measurements are performed by exciting the samples with magnetic eld pulses. The change in magnetization as a function of time is measured using continuous-wave light. When ready the system will be able to measure the magnetization in the time domain at a sub-nano second scale.

50515253 2601 - 2643 of 2643
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