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  • 1.
    Adshead, Mason
    et al.
    Photon Science Institute, Department of Electrical and Electronic Engineering, University of Manchester, Manchester, M13 9PL, UK.
    Sanaee, Maryam
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Blight, Daniel
    Photon Science Institute, Department of Electrical and Electronic Engineering, University of Manchester, Manchester, M13 9PL, UK.
    Prencipe, Alessandro
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Curry, Richard J.
    Photon Science Institute, Department of Electrical and Electronic Engineering, University of Manchester, Manchester, M13 9PL, UK.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Erbium implantation in thin film Lithium Niobate2023In: 2023 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023, Institute of Electrical and Electronics Engineers (IEEE) , 2023Conference paper (Refereed)
    Abstract [en]

    Lithium niobate on insulator (LNOI), thanks to its electro-optic properties and second order nonlinearity, is one of the most promising photonic materials for on-chip implementation of a complex photonic integrated circuit (PIC) [1]. Integration of rare earth ion emitters (RIE), characterized by high coherent transitions in both optical and microwave domains, into LNOI is a very attractive perspective to fully exploit the potential of this material in quantum optics applications and for on chip light generation and amplification. By choosing Erbium ions these functionalities can be implemented at telecom wavelengths (~1550 nm). Erbium integration in LNOI can be achieved using the smart cut technique [2]. However, this approach implies heating the material up to ~1100 ºC, approaching the Curie temperature of lithium niobate (~1200 ºC). Ion implantation also permits the incorporation of RIE into the lithium niobate (LN) crystal structure, operating at lower temperature with high spatial precision of the doped region in a complex PIC.

  • 2.
    Al-attar, Nebras
    et al.
    School of biosystems and food Engineering, University of Technology, Baghdad, 10066, Iraq; Laser and Optoelectronics Engineering Department, University of Technology, Baghdad, 10066, Iraq.
    Al-Shammari, Rusul M.
    School of Physics, University College Dublin Belfield, 7 Dublin, D04 N2E5, Ireland; Conway Institute of Biomolecular and Biomedical Research, University College Dublin Belfield, 7 Dublin, D04 N2E5, Ireland.
    Manzo, Michele
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Rodriguez, Brian J.
    School of Physics, University College Dublin Belfield, 7 Dublin, D04 N2E5, Ireland; Conway Institute of Biomolecular and Biomedical Research, University College Dublin Belfield, 7 Dublin, D04 N2E5, Ireland.
    Rice, James H.
    School of Physics, University College Dublin Belfield, 7 Dublin, D04 N2E5, Ireland.
    Wide-field surface-enhanced Raman scattering from ferroelectrically defined Au nanoparticle microarrays for optical sensing2018In: Proceedings CLEO: Applications and Technology 2018, Optica Publishing Group , 2018Conference paper (Refereed)
    Abstract [en]

    The acquisition-time in optical sensors using SERS is vital value. Wide-field SERS is used to perform high-density of hot-spots of GNPs photodeposition on a periodically-protonexchanged- LiNbO3 which, leads to increase the sensitivity at ultralow probe concentrations.

  • 3. Al-Shammari, R. M.
    et al.
    Alattar, N.
    Manzo, Michele
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Rodriguez, B. J.
    Rice, J. H.
    Label-free cell membrane detection by Raman spectroscopy using biocompatible gold nanostructure microscale arrays on a ferroelectric template2017In: Optics InfoBase Conference Papers, OSA - The Optical Society , 2017Conference paper (Refereed)
  • 4.
    Al-Shammari, Rusul M.
    et al.
    Univ Coll Dublin, Sch Phys, Dublin D04 N2E5, Ireland.;Univ Coll Dublin, Conway Inst Biomol & Biomed Res, Dublin D04 N2E5, Ireland..
    Al-Attar, Nebras
    Univ Coll Dublin, Sch Phys, Dublin D04 N2E5, Ireland.;Univ Technol Baghdad, Laser & Optoelect Engn Dept, Baghdad 10066, Iraq..
    Manzo, Michele
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Rodriguez, Brian J.
    Univ Coll Dublin, Sch Phys, Dublin D04 N2E5, Ireland.;Univ Coll Dublin, Conway Inst Biomol & Biomed Res, Dublin D04 N2E5, Ireland..
    Rice, James H.
    Univ Coll Dublin, Sch Phys, Dublin D04 N2E5, Ireland..
    Single-Molecule Nonresonant Wide-Field Surface-Enhanced Raman Scattering from Ferroelectrically Defined Au Nanoparticle Microarrays2018In: ACS Omega, E-ISSN 2470-1343, Vol. 3, no 3, p. 3165-3172Article in journal (Refereed)
    Abstract [en]

    Single-molecule detection by surface-enhanced Raman scattering (SERS) is a powerful spectroscopic technique that is of interest for the sensor development field. An important aspect of optimizing the materials used in SERS-based sensors is the ability to have a high density of "hot spots" that enhance the SERS sensitivity to the single-molecule level. Photodeposition of gold (Au) nanoparticles through electric-field-directed self-assembly on a periodically proton-exchanged lithium niobate (PPELN) substrate provides conditions to form well-ordered microscale features consisting of closely packed Au nanoparticles. The resulting Au nanoparticle microstructure arrays (microarrays) are plasmon-active and support nonresonant single-molecule SERS at ultralow concentrations (<10(-9)-10(-13) M) with excitation power densities <1 x 10(-3) W cm(-2) using wide-field imaging. The microarrays offer excellent SERS reproducibility, with an intensity variation of <7.5% across the substrate. As most biomarkers and molecules do not support resonance enhancement, this work demonstrates that PPELN is a suitable template for high-sensitivity, nonresonant sensing applications.

  • 5. Al-Shammari, Rusul M.
    et al.
    Baghban, Mohammad Amin
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Al-attar, Nebras
    Gowen, Aoife
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Rice, James H.
    Rodriguez, Brian J.
    Photoinduced Enhanced Raman from Lithium Niobate on Insulator Template2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 36, p. 30871-30878Article in journal (Refereed)
    Abstract [en]

    Photoinduced enhanced Raman spectroscopy from a lithium niobate on insulator (LNOI)−silver nanoparticle template is demonstrated both by irradiating the template with 254 nm ultraviolet (UV) light before adding an analyte and before placing the substrate in the Raman system (substrate irradiation) and by irradiating the sample in the Raman system after adding the molecule (sample irradiation). The photoinduced enhancement enables up to an ∼sevenfold increase of the surface-enhanced Raman scattering signal strength of an analyte following substrate irradiation, whereas an ∼threefold enhancement above the surface-enhanced signal is obtained for sample irradiation. The photoinduced enhancement relaxes over the course of ∼10 h for a substrate irradiation duration of 150 min before returning to initial signal levels. The increase in Raman scattering intensity following UV irradiation is attributed to photoinduced charge transfer from the LNOI template to the analyte. New Raman bands are observed following UV irradiation, the appearance of which is suggestive of a photocatalytic reaction and highlight the potential of LNOI as a photoactive surface-enhanced Raman spectroscopy substrate.

  • 6.
    Al-Shammari, Rusul M.
    et al.
    School of Physics, University College Dublin, Belfield, Dublin, 4, Ireland, Belfield; Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin, 4, Ireland, Belfield.
    Kassem, Ahmed
    School of Veterinary Medicine, University College Dublin, Belfield, Dublin, 4, Ireland, Belfield; School of Veterinary Medicine, University of Kufa, Iraq.
    Al-attar, Nebras
    Laser and Optoelectronic Engineering Department, University of Technology -Iraq, Baghdad, Iraq; School of Chemistry, Trinity College Dublin, The University of Dublin, Dublin, 4, Ireland.
    Manzo, Michele
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Whyte, Paul
    School of Veterinary Medicine, University College Dublin, Belfield, Dublin, 4, Ireland, Belfield.
    Rice, James H.
    School of Physics, University College Dublin, Belfield, Dublin, 4, Ireland, Belfield.
    Rodriguez, Brian J.
    School of Physics, University College Dublin, Belfield, Dublin, 4, Ireland, Belfield; Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin, 4, Ireland, Belfield.
    Antibacterial properties of lithium niobate crystal substrates2023In: International Journal of Optomechatronics, ISSN 1559-9612, Vol. 17, no 1, article id 2250400Article in journal (Refereed)
    Abstract [en]

    The bactericidal properties of chemically patterned lithium niobate substrates under a super-bandgap UV light source is established. UV irradiation of lithium niobate surfaces inoculated with bacteria leads to antimicrobial activity compared to a glass substrate under similar conditions, as determined by surface enhanced Raman spectroscopy and corroborated with a fluorescence-based live/dead assay. This finding may expand the possible biomedical applications of lithium niobate.

  • 7. Al-Shammari, Rusul M.
    et al.
    Manzo, Michele
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Rice, James H.
    Rodriguez, Brian J.
    Tunable Wettability of Ferroelectric Lithium Niobate Surfaces: The Role of Engineered Microstructure and Tailored Metallic Nanostructures2017In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 12, p. 6643-6649Article in journal (Refereed)
    Abstract [en]

    An important aspect of optimizing micro- and optofluidic devices for lab on -a-chip systems is the ability to engineer materials properties including surface structure and charge to control wettability. Biocompatible ferroelectric lithium niobate (LN), which is well-known for acoustic and nonlinear optical applications, has recently found potential micro- and optofluidic applications. However, the tunable wettability of such substrates has yet to be explored in detail. Here, we show that the contact angle of LN substrates can be reproducibly tailored between similar to 7 degrees and similar to 421 degrees by controlling the surface topography and chemistry at the nano- and micrometer scale via ferroelectric domain and polarization engineering and polarization-directed photoassisted deposition of metallic nanostructures.

  • 8. Assanto, Gaetano
    et al.
    Gallo, Katia
    Optoelectronics Reserach Centre, University of Southampton.
    Spatial simultons in two-dimensional purely nonlinear lattices2008Conference paper (Refereed)
  • 9. Assanto, Gaetano
    et al.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Pasquazi, Alessia
    Stivala, Salvatore
    Spatial Solitons in 2D Lattices of a Nonlinear Nature2008In: Optics and photonics news (Print), ISSN 1047-6938, E-ISSN 1541-3721, Vol. 19, no 6, p. 29-32Article in journal (Refereed)
    Abstract [en]

    Researchers have observed two-color optical solitons in a 2D parametric photonic lattices (PPLs) with hexagonal symmetry in lithium niobate. PPLs behave as uniform and homogenous dielectrics under weak excitation whereas, at high powers, they allow for the simultaneous quasi-phase-matching of several susceptibility processes. It has been observed that 2D PPLs support novel simulation space dynamics through twin-beam second-harmonic generation. In the symmetric configuration, solitons can form in an enhanced spectral range for confinement, while in the asymmetric cases, they can be steered by varying the input power and wave-length. Quadratic spatial solitons in planar nonlinear lattices unveils new opportunities for physics and also enable applications of self-trapped light beams, including the engineering of solitons states for analog signal processing and all-optical switching/routing in aperiodic lattices and quasi-crystals.

  • 10.
    Baghban, Mohammad Amin
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Impact of longitudinal fields on second harmonic generation in lithium niobate nanopillars2016In: APL Photonics, ISSN 2378-0967, Vol. 1, no 6, article id 061302Article in journal (Refereed)
    Abstract [en]

    An optimized focused ion beam process is used to fabricate micrometer-long LiNbO3 nanopillars with diameters varying between 150 and 325 nm. Polarimetric mappings of second harmonic generation from a wavelength of 850 nm demonstrate the ability to modify the polarization features of the nonlinearresponse through a fine adjustment of the pillar size. The effect is ascribed to the non-negligible contribution of the longitudinal fields associated with sub-wavelength light confinement in the LiNbO3nanopillars. The results also highlight the importance of a fine control over the nanopillar size in order to effectively engineer their nonlinear response.

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  • 11.
    Baghban, Mohammad Amin
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Phase-Shifted Bragg Grating Resonators in Thin-Film Lithium Niobate Waveguides2019In: 2019 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO), 2019Conference paper (Refereed)
    Abstract [en]

    We demonstrate narrowband integrated filters with 0.23 mm-long phase-shifted Bragg gratings in corrugated single-mode thin-film LiNbO3 photonic wires, achieving quality factors of 1.24x10(4) and extinction ratios up to 24 dB at telecom wavelengths.

  • 12.
    Baghban, Mohammad Amin
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Mahato, Sunil Kumar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Low-loss ridge waveguides in thin film lithium niobate-oninsulator (LNOI) fabricated by reactive ion etching2014In: Optics InfoBase Conference Papers, OSA - The Optical Society , 2014Conference paper (Refereed)
    Abstract [en]

    We report on the fabrication of waveguides in 300 nm-thick Y-cut lithium niobate on silicon through optimized reactive ion etching, yielding sidewall roughness of 22.9 nm and propagation losses of 8.62 dB/cm at 1550 nm.

  • 13.
    Baghban, Mohammad Amin
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Schollhammer, Jean
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Errando-Herranz, Carlos
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Gylfason, Kristinn B
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Bragg gratings in thin-film LiNbO3 waveguides2017In: Optics Express, E-ISSN 1094-4087, Optics Express, ISSN 1094-4087, Vol. 25, no 26, p. 32323-32332Article in journal (Refereed)
    Abstract [en]

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

  • 14.
    Baghban, Mohammad Amin
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Schollhammer, Jean
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Errando-Herranz, Carlos
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Gylfason, Kristinn B.
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Waveguide Gratings in Thin-Film Lithium Niobate on Insulator2017In: CLEO: 2017, OSA Technical Digest, Optical Society of America, 2017Conference paper (Refereed)
  • 15.
    Baghban, Mohammad Amin
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Schollhammer, Jean
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Errando-Herranz, Carlos
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Gylfason, Kristinn B.
    KTH, School of Electrical Engineering and Computer Science (EECS), Intelligent systems, Micro and Nanosystems.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Waveguide Gratings in Thin-Film Lithium Niobate on Insulator2017In: 2017 CONFERENCE ON LASERS AND ELECTRO-OPTICS EUROPE & EUROPEAN QUANTUM ELECTRONICS CONFERENCE (CLEO/EUROPE-EQEC), IEEE , 2017Conference paper (Refereed)
  • 16.
    Baghban, Mohammad Amin
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Swillo, Marcin
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Second-Harmonic generation engineering in lithium niobate nanopillars2019In: Proceedings 2015 European Conference on Lasers and Electro-Optics - European Quantum Electronics Conference, CLEO/Europe-EQEC 2015, Optical Society of America (OSA) , 2019Conference paper (Refereed)
  • 17.
    Baghban, Mohammad Amin
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Swillo, Marcin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Second-harmonic generation engineering in lithium niobate nanopillars2015In: Optics InfoBase Conference Papers, OSA - The Optical Society , 2015Conference paper (Refereed)
  • 18. Balobaid, Laila
    et al.
    Carville, N. Craig
    Manzo, Michele
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Collins, Liam
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Rodriguez, Brian J.
    Photoreduction of metal nanostructures on periodically proton exchanged MgO-doped lithium niobate crystals2013In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 103, no 18, p. 182904-Article in journal (Refereed)
    Abstract [en]

    Local reactivity on periodically proton exchanged lithium niobate (PPE: LN) surfaces is a promising route for the fabrication of regularly spaced nanostructures. Here, using MgO-doped PPE: LN templates, we investigate the influence of the doping on the nanostructure formation as a function of the proton exchange (PE) depth. The deposition is found to occur preferentially along the boundary between MgO-doped LN and the PE region when the PE depth is at least 1.73 mu m, however, for shallower depths, deposition occurs across the entire PE region. The results are found to be consistent with an increased photoconductivity of the MgO-doped LN.

  • 19. Balobaid, Laila
    et al.
    Carville, N. Craig
    Manzo, Michele
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Rodriguez, Brian J.
    Direct shape control of photoreduced nanostructures on proton exchanged ferroelectric templates2013In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 102, no 4, p. 042908-Article in journal (Refereed)
    Abstract [en]

    Photoreduction on a periodically proton exchanged ferroelectric crystal leads to the formation of periodic metallic nanostructures on the surface. By varying the depth of the proton exchange (PE) from 0.59 to 3.10 mu m in congruent lithium niobate crystals, the width of the lateral diffusion region formed by protons diffusing under the mask layer can be controlled. The resulting deposition occurs in the PE region with the shallowest PE depth and preferentially in the lateral diffusion region for greater PE depths. PE depth-control provides a route for the fabrication of complex metallic nanostructures with controlled dimensions on chemically patterned ferroelectric templates.

  • 20.
    Brambilla, E.
    et al.
    Univ Insubria, Dept Sci & High Technol, Via Valleggio 11, I-22100 Como, Italy..
    Jedrkiewicz, O.
    CNR, Ist Foton & Nanotecnol, Udr Como, Via Valleggio 11, I-22100 Como, Italy..
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Tamosauskas, G.
    Vilnius Univ, Dept Quantum Elect, Sauletekio 10, LT-10223 Vilnius, Lithuania..
    Gatti, A.
    CNR, Ist Foton & Nanotecnol, Udr Como, Via Valleggio 11, I-22100 Como, Italy..
    Three and Four-Modes Parametric Processes in Hexagonally Poled Nonlinear Photonic Crystals2018In: OPTICS, PHOTONICS AND LASERS / [ed] Yurish, S Y, INT FREQUENCY SENSOR ASSOC-IFSA , 2018, p. 176-178Conference paper (Refereed)
    Abstract [en]

    We investigate the properties of the field emitted through parametric down-conversion (PDC) in a nonlinear photonics crystal (NPC) with a hexagonal poling pattern, both from a theoretical point of view and with an experiment performed at the University of Insubria. Considering the high gain regime of PDC, we demonstrate the existence of concurrent PDC processes mediated by two noncollinear poling vectors which are coherently coupled and reciprocally stimulated. We find that these non-standard 3-mode and 4-mode interaction processes undergo a substantial enhancement of the parametric gain with respect to the usual 2-mode PDC, and give rise to hot spots order of magnitudes brighter than standard 2-mode fluorescence which have been observed in the source far field. We performed a complete characterization of the source spectral-angular emission, finding a very good agreement between the experiment and the theoretical predictions.

  • 21. Bratfalean, Radu
    et al.
    Gallo, Katia
    Optoelectronics Research Centre, University of Southampton (UK).
    Broderick, Neil
    Peacock, Anna
    Frequency conversion in a nonlinear photonic quasi-crystal2004Conference paper (Refereed)
  • 22. Bratfalean, Radu
    et al.
    Peacock, Anna
    Broderick, Neil
    Gallo, Katia
    Optoelectronics Research Centre, University of Southampton (UK).
    Lewen, Ruth
    Harmonic generation in a two-dimensional nonlinear quasi-crystal2005In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 30, no 4, p. 424-426Article in journal (Refereed)
    Abstract [en]

    Second-harmonic generation in a two-dimensional nonlinear quasi-crystal is demonstrated for the first time to our knowledge. Temperature and wavelength tuning of the crystal reveal the uniformity of the pattern while angle tuning reveals the dense nature of the crystal's Fourier spectrum. These results compare well with theoretical predictions showing the excellent uniformity of the crystal and suggest that more-complicated nonlinear holograms should be possible.

  • 23. Canagasabey, Albert
    et al.
    Ibsen, Morten
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Gladyshev, Alexey V.
    Dianov, Evgeny M.
    Corbari, Costantino
    Kazansky, Peter G.
    Aperiodically poled silica fibers for bandwidth control of quasi-phase-matched second-harmonic generation2010In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 35, no 5, p. 724-726Article in journal (Refereed)
    Abstract [en]

    Precise control of the bandwidth of quasi-phase-matched second-harmonic generation in silica fibers is realized through chirped-period poling. The bandwidth is expanded by a factor of 33 over a uniform-period poled fiber of the same interaction length.

  • 24. Carville, N. C.
    et al.
    Manzo, Michele
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Denning, D.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Rodriguez, B. J.
    Growth mechanism of photoreduced silver nanostructures on periodically proton exchanged lithium niobate: Time and concentration dependence2013In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 113, no 18, p. 187212-1-187212-7Article in journal (Refereed)
    Abstract [en]

    Photodeposition of metallic nanostructures onto ferroelectric surfaces, which have been chemically patterned using a proton exchange process, has recently been demonstrated. By varying the molar concentration of the AgNO 3 solution and the illumination time, one can determine the initial nucleation sites, control the rate of nucleation and the height of silver nanostructures formed, and study the mechanisms by which these processes occurs. The nanoparticles are found to deposit preferentially in the boundary between ferroelectric and proton exchanged regions, in an area proton exchanged via lateral diffusion under the masking layer used for chemical patterning, consistent with our previous results. Using a short illumination time (3 min), we are able to determine that the initial nucleation of the silver nanostructure, having a width of 0.17 ± 0.02 μm and a height of 1.61 ± 0.98 nm, occurs near the edge of the reactive ion etched area within this lateral diffusion region. Over longer illumination times (15 min), we find that the silver deposition has spread to a width of 1.29 ± 0.06 μm, extending across the entire lateral diffusion region. We report that at a high molar concentration of AgNO3 (10-2 M), the amount of silver deposition for 5 min UV illumination is greater (2.88 ± 0.58 nm) compared to that at low (10-4 M) concentrations (0.78 ± 0.35 nm), however, this is not the case for longer time periods. With increasing illumination time (15 min), experiments at 10-4 M had greater overall deposition, 6.90 ± 1.52 nm, compared to 4.50 ± 0.76 nm at 10 -2 M. For longer exposure times (30 min) at 10-2 M, the nanostructure height is 4.72 ± 0.59 nm, suggesting a saturation in the nanostructure height. The results are discussed in terms of the electric double layer that forms at the crystal surface. There is an order of magnitude difference between the Debye lengths for 10-2 and 10-4 M solutions, i.e., 3.04 vs. 30.40 nm, which suggests the Debye length plays a role in the availability of Ag ions at the surface.

  • 25. Carville, N. Craig
    et al.
    Collins, Liam
    Manzo, Michele
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Lukasz, Bart I.
    McKayed, Katey K.
    Simpson, Jeremy C.
    Rodriguez, Brian J.
    Biocompatibility of ferroelectric lithium niobate and the influence of polarization charge on osteoblast proliferation and function2015In: Journal of Biomedical Materials Research. Part A, ISSN 1549-3296, E-ISSN 1552-4965, Vol. 103, no 8, p. 2540-2548Article in journal (Refereed)
    Abstract [en]

    In this work, the influence of substrate surface charge on in vitro osteoblast cell proliferation on ferroelectric lithium niobate (LN) crystal surfaces is investigated. LN has a spontaneous polarization along the z-axis and is thus characterized by positive and negative bound polarization charge at the +z and -z surfaces. Biocompatibility of LN was demonstrated via culturing and fluorescence imaging of MC3T3 osteoblast cells for up to 11 days. The cells showed enhanced proliferation rates and improved osteoblast function through mineral formation on the positively and negatively charged LN surfaces compared to electrostatically neutral x-cut LN and a glass cover slip control. These results highlight the potential of LN as a template for investigating the role of charge on cellular processes.

  • 26. Carville, N. Craig
    et al.
    Manzo, Michele
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Damm, Signe
    Castiella, Marion
    Collins, Liam
    Denning, Denise
    Weber, Stefan
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Rice, James
    Rodriguez, Brian
    Photoreduction of SERS-Active Metallic Nanostructures on Chemically Patterned Ferroelectric Crystals2012In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 6, no 8, p. 7373-7380Article in journal (Refereed)
    Abstract [en]

    Photodeposition of metallic nanostructures onto ferroelectric surfaces is typically based on patterning local surface reactivity via electric field poling. Here, we demonstrate metal deposition onto substrates which have been chemically patterned via proton exchange (i.e., without polarization reversal). The chemical patterning provides the ability to tailor the electrostatic fields near the surface of lithium niobate crystals, and these engineered fields are used to fabricate metallic nanostructures. The effect of the proton exchange process on the piezoelectric and electrostatic properties of the surface is characterized using voltage-modulated atomic force microscopy techniques, which, combined with modeling of the electric fields at the surface of the crystal, reveal that the deposition occurs preferentially along the boundary between ferroelectric and proton-exchanged regions. The metallic nanostructures have been further functionalized with a target probe molecule, 4-aminothiophenol, from which surface-enhanced Raman scattering (SERS) signal is detected, demonstrating the suitability of chemically patterned ferroelectrics as SERS-active templates.

  • 27. Carville, N. Craig
    et al.
    Neumayer, Sabine M.
    Manzo, Michele
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Baghban, Mohammad-Amin
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Ivanov, Ilia N.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Rodriguez, Brian J.
    Influence of annealing on the photodeposition of silver on periodically poled lithium niobate2016In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 119, no 5, article id 054102Article in journal (Refereed)
    Abstract [en]

    The preferential deposition of metal nanoparticles onto periodically poled lithium niobate surfaces, whereby photogenerated electrons accumulate in accordance with local electric fields and reduce metal ions from solution, is known to depend on the intensity and wavelength of the illumination and the concentration of the solution used. Here, it is shown that for identical deposition conditions (wavelength, intensity, concentration), post-poling annealing for 10 h at 200 degrees C modifies the surface reactivity through the reorientation of internal defect fields. Whereas silver nanoparticles deposit preferentially on the +z domains on unannealed crystals, the deposition occurs preferentially along 180 degrees domain walls for annealed crystals. In neither case is the deposition selective; limited deposition occurs also on the unannealed -z domain surface and on both annealed domain surfaces. The observed behavior is attributed to a relaxation of the poling-induced defect frustration mediated by Li+ ion mobility during annealing, which affects the accumulation of electrons, thereby changing the surface reactivity. The evolution of the defect field with temperature is corroborated using Raman spectroscopy.

  • 28. Carville, N. Craig
    et al.
    Neumayer, Sabine M.
    Manzo, Michele
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Rodriguez, Brian J.
    Biocompatible Gold Nanoparticle Arrays Photodeposited on Periodically Proton Exchanged Lithium Niobate2016In: ACS Biomaterials Science & Engineering, E-ISSN 2373-9878, Vol. 2, no 8, p. 1351-1356Article in journal (Refereed)
    Abstract [en]

    Photodeposition of silver nanoparticles onto chemically patterned lithium niobate having alternating lithium niobate and proton exchanged regions has been previously investigated. Here, the spatially defined photodeposition of gold nanoparticles onto periodically proton exchanged lithium niobate is demonstrated. It is shown that the location where the gold nanoparticles form can be tailored by altering the concentration of HAuCl4. This enables the possibility to sequentially deposit gold and silver in different locations to create bimetallic arrays. The cytocompatibility of photodeposited gold, silver, and bimetallic ferroelectric templates to osteoblast-like cells is also investigated. Gold samples provide significantly greater cell biocompatibility than silver samples. These results highlight a potential route for using photodeposited gold on lithium niobate as a template for applications in cellular biosensing.

  • 29. Cherifi-Hertel, S.
    et al.
    Bulou, H.
    Hertel, R.
    Taupier, G.
    Dorkenoo, K. D. H.
    Andreas, C.
    Guyonnet, J.
    Gaponenko, I.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Paruch, P.
    Non-Ising and chiral ferroelectric domain walls revealed by nonlinear optical microscopy2017In: Nature Communications, E-ISSN 2041-1723, Vol. 8, article id 15768Article in journal (Refereed)
    Abstract [en]

    The properties of ferroelectric domain walls can significantly differ from those of their parent material. Elucidating their internal structure is essential for the design of advanced devices exploiting nanoscale ferroicity and such localized functional properties. Here, we probe the internal structure of 180° ferroelectric domain walls in lead zirconate titanate (PZT) thin films and lithium tantalate bulk crystals by means of second-harmonic generation microscopy. In both systems, we detect a pronounced second-harmonic signal at the walls. Local polarimetry analysis of this signal combined with numerical modelling reveals the existence of a planar polarization within the walls, with Néel and Bloch-like configurations in PZT and lithium tantalate, respectively. Moreover, we find domain wall chirality reversal at line defects crossing lithium tantalate crystals. Our results demonstrate a clear deviation from the ideal Ising configuration that is traditionally expected in uniaxial ferroelectrics, corroborating recent theoretical predictions of a more complex, often chiral structure.

  • 30. Conforti, Matteo
    et al.
    Baronio, Fabio
    Levenius, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Broadband parametric processes in chi((2)) nonlinear photonic crystals2014In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 39, no 12, p. 3457-3460Article in journal (Refereed)
    Abstract [en]

    We develop a general model, based on a (2 + 1)D unidirectional pulse propagation equation, for describing broadband noncollinear parametric interactions in 2D quadratic lattices. We apply it to the analysis of twin-beam optical parametric generation in hexagonally poled LiTaO3, gaining further insights into experimental observations.

  • 31.
    Conforti, Matteo
    et al.
    PhLAM/IRCICA, CNRS-Université Lille 1, UMR 8523/USR 3380, F-59655 Villeneuve d’Ascq, France.
    Baronio, Fabio
    2Dipartimento di Ingegneria dell’Informazione, Università di Brescia, Via Branze 38, 25123 Brescia, Italy .
    Levenius, Martin
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics. KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum and Biophotonics.
    Broadband parametric processes in quadratic nonlinear photonic crystals2014In: Bragg Gratings, Photosensitivity, and Poling in Glass Waveguides, BGPP 2014, The Optical Society , 2014Conference paper (Refereed)
    Abstract [en]

    We develop a general model, based on a (2+1)D unidirectional pulse propagation equation, for describing broadband noncollinear parametric interactions in two-dimensional quadratic lattices. We apply it to the analysis of twin-beam optical parametric generation in hexagonally poled LiTaO&#60;inf>3&#60;/inf>, gaining further insights into experimental observations.

  • 32. Damm, S.
    et al.
    Carville, N. C.
    Manzo, Michele
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Lopez, S.
    Keyes, T. E.
    Forster, R. J.
    Rodriguez, B. J.
    Rice, J. H.
    Formation of ferroelectrically defined Ag nanoarray patterns2014In: Proceedings of SPIE - The International Society for Optical Engineering, SPIE - International Society for Optical Engineering, 2014Conference paper (Refereed)
    Abstract [en]

    In order to produce the most effective Ag nanoarrays for plasmon enhanced fluorescence and Raman scattering made using ferroelectric substrates, the optimum conditions for the creation of arrays must be identified. We study here Ag nanopattern arrays formed using ferroelectric lithography based on periodically proton exchanged (PPE) template methods. We examine different conditions in regard to deposition of Ag nanoparticles and analyze the plasmon enhanced signal from the resulting nanoarray. We apply FLIM (fluorescence lifetime imaging) to assess different Ag nanoarray preparation conditions on fluorescence emission from selected fluorphores. In addition, we apply Raman and luminescence spectroscopy with AFM (atomic force microscopy) to study the plasmon enhancement of luminescence and Raman from the Ag nanoarrays.

  • 33. Damm, S.
    et al.
    Carville, N. C.
    Manzo, Michele
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Rodriguez, B. J.
    Rice, J.
    SERS from Ag and Au nanoarrays made using photochemical patterning2013In: 2013 Conference on Lasers and Electro-Optics Europe and International Quantum Electronics Conference, CLEO/Europe-IQEC 2013, IEEE Computer Society, 2013, p. 6801468-Conference paper (Refereed)
    Abstract [en]

    Metallic nanostructures made from 'coinage' metals such as silver or gold, yield plasmons when light creates a collective oscillation of the conduction electrons on the surface of the metal, creating a greatly enhanced electromagnetic field [1-3]. The specific properties of the plasmonic structures have been found to be greatly dependent on factors such as size, shape, and dielectric environment [1-3]. These properties have been exploited in a variety of plasmonic applications ranging from sensing to enhanced fluorescence [4].

  • 34.
    Damm, Signe
    et al.
    Natl Univ Ireland Univ Coll Dublin, Sch Phys, Dublin 4, Ireland..
    Carville, N. Craig
    Natl Univ Ireland Univ Coll Dublin, Sch Phys, Dublin 4, Ireland..
    Manzo, Michele
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Lopez, Sergio G.
    Dublin City Univ, Sch Chem Sci, Dublin 9, Ireland..
    Keyes, Tia E.
    Dublin City Univ, Sch Chem Sci, Dublin 9, Ireland..
    Forster, Robert J.
    Dublin City Univ, Sch Chem Sci, Dublin 9, Ireland..
    Rodriguez, Brian J.
    Natl Univ Ireland Univ Coll Dublin, Sch Phys, Dublin 4, Ireland..
    Rice, James H.
    Natl Univ Ireland Univ Coll Dublin, Sch Phys, Dublin 4, Ireland..
    Erratum to: Surface enhanced luminescence and Raman scattering from ferroelectrically defined Ag nanopatterned arrays2013In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 103, no 10, article id 109902Article in journal (Refereed)
  • 35. Damm, Signe
    et al.
    Carville, N. Craig
    Manzo, Michele
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Lopez, Sergio G.
    Keyes, Tia E.
    Forster, Robert J.
    Rodriguez, Brian J.
    Rice, James H.
    Surface enhanced luminescence and Raman scattering from ferroelectrically defined Ag nanopatterned arrays2013In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 103, no 8, p. 083105-Article in journal (Refereed)
    Abstract [en]

    Ag nanopatterned arrays prepared using periodically proton exchanged templates have been demonstrated to support surface enhanced luminescence. Fluorescence lifetime imaging reveals that luminescence intensity is greatest on Ag and that the lifetime of the molecular probe is reduced, in line with a surface enhanced luminescence mechanism. Studies establish that the substrate simultaneously supports surface enhanced luminescence and Raman scattering. Spatial dependence along the nanopatterned arrays shows <7% variation in Raman scattering signal intensity, offering high reproducibility for practical applications. Fluorophores emitting near the plasmon absorption maxima are enhanced 4-fold.

  • 36. Damm, Signe
    et al.
    Carville, N. Craig
    Manzo, Michele
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Rodriguez, Brian J.
    Rice, James H.
    Protein assemblies on ferroelectrically patterned microarrays of Ag nanoparticles2017In: Ferroelectrics (Print), ISSN 0015-0193, E-ISSN 1563-5112, Vol. 515, no 1, p. 141-148Article in journal (Refereed)
    Abstract [en]

    Nano-bio interfaces play a significant role in assay device design and performance, here we study the use of a combined plasmonic and ferroelectric active substrate design for protein assemblies on a plasmon active array. We demonstrate that biotinylation and protein assemblies can bemade onmetal nanoparticles patterned on ferroelectric substrates. These results inturndemonstratethat ferroelectric substrates combined with active plasmonics is potentially applicable as substrates for biological assays.

  • 37. Damm, Signe
    et al.
    Carville, Nigel
    Rodriguez, Brian
    Manzo, Michele
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    James, Rice
    Plasmon enhanced Raman from Ag nanopatterns made using periodically poled lithium niobate and periodically proton exchanged template methods2012In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 116, no 50, p. 26543-26550Article in journal (Refereed)
    Abstract [en]

    We study Ag nanopattern arrays formed using ferroelectric lithography based on two separate approaches, i.e., periodically poled lithium niobate (PPLN) and periodically proton exchanged (PPE) template methods. We demonstrate that such nanoarrays are plasmon active. Raman spectroscopy was applied to study molecular probe 4-aminothiophenol (4-ABT) absorbed onto a silver nanostructured array. The observed Raman spectra show peaks arising from b2 modes, which occur for plasmon enhanced Raman from 4-ABT in place of a1 modes, which occur in normal Raman scattering. We demonstrate that the PPLN and PPE substrates possess different plasmonic properties with PPE creating a stronger SERS signal relative to PPLN substrates.

  • 38.
    El Hassan, Ashraf
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Van Qui, Henri Vo
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Coherent difference frequency generation in nonlinear photonic crystals2023In: 2023 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023, Institute of Electrical and Electronics Engineers (IEEE) , 2023Conference paper (Refereed)
    Abstract [en]

    Two-dimensional lattices of the optical nonlinearity implemented by periodic poling in X(2) materials afford additional degrees of freedom for enhanced gains in optical parametric generation [1-2] and the generation of multipartite photon entanglement in compact device formats [3]. So far all investigations have considered single-frequency excitation of the crystals in classical or quantum parametric downconversion regimes. However, the effects underpinned by the coherent coupling of multiple nonlinear resonances unique to 2D lattices, may be expected to further enlarge the spectrum of possibilities also in suitably seeded coherent parametric amplification and difference frequency generation (DFG) processes.

  • 39.
    Fergestad, Halvor
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Hänsel, Wolfgang
    Menlo Systems GmbH, 82152 Martinsried, Germany.
    Kordts, Arne
    Menlo Systems GmbH, 82152 Martinsried, Germany.
    Prencipe, Alessandro
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Holzwarth, Ronald
    Menlo Systems GmbH, 82152 Martinsried, Germany.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Engineered dispersion measurements in LiNbO3 nanophotonic wires2023In: 2023 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023, Institute of Electrical and Electronics Engineers (IEEE) , 2023Conference paper (Refereed)
    Abstract [en]

    Dispersion engineering of waveguides in photonic integrated circuits (PIC) is a crucial design tool for tailoring nonlinear functionalities in the rapidly emerging thin film LiNbO3 (TFLN) platform, exemplified by frequency comb generation, soliton formation and broadband frequency conversion [1]. Experimentally, the dispersion of PIC structures is typically measured in terms of free-spectral range (FSR) variation in ring cavity configurations or propagation time delays in long waveguides under short pulse excitation [2], methods with their own limitations when it comes to measurements in straight and relatively short (< cm) waveguides, such as TFLN ones.

  • 40. Folli, V.
    et al.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Conti, C.
    Purely nonlinear disorder-induced localizations and their parametric amplification2013In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 38, no 24, p. 5276-5279Article in journal (Refereed)
    Abstract [en]

    We investigate spatial localization in a quadratic nonlinear medium in the presence of randomness. By means of numerical simulations and theoretical analyses we show that, in the down conversion regime, the transverse random modulation of the nonlinear susceptibility generates localizations of the fundamental wave that grow exponentially in propagation. The localization length is optically controlled by the pump intensity that determines the amplification rate. The results also apply to cubic nonlinearities.

  • 41.
    Fu, Daiheng
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Fergestad, Halvor
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Prencipe, Alessandro
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Li, Tiantong
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Polarization coupling in thin film lithium niobate waveguide2023In: 2023 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023, Institute of Electrical and Electronics Engineers (IEEE) , 2023Conference paper (Refereed)
    Abstract [en]

    Polarization control in photonic integrated circuit (PIC) waveguides is receiving broad attention for application in quantum systems and telecommunication [1]. Thin film lithium niobate (TFLN) is an ideal platform for polarization control applications due to its birefringence and electro-optic properties [2]. We observe polarization coupling between fundamental TE and TM modes in TFLN waveguides.

  • 42.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Nonlinear wave dynamics in 2D periodically poled waveguides2009In: 2009 IEEE/LEOS WINTER TOPICALS MEETING SERIES (WTM 2009), NEW YORK: IEEE , 2009, p. 162-163Conference paper (Refereed)
    Abstract [en]

    An overview of recent results on spatial solitons in purely nonlinear 2D lattices is presented. Theory and experiments highlight new possibilities for multicolour soliton excitation and control via planar nonlinear structures in periodically poled materials.

  • 43.
    Gallo, Katia
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics. KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Spatial Wave Dynamics in 2-D Periodically Poled LiNbO3 Waveguides2009In: IEEE Journal of Quantum Electronics, ISSN 0018-9197, E-ISSN 1558-1713, Vol. 45, no 11, p. 1415-1420Article in journal (Refereed)
    Abstract [en]

    Recent results on parametric spatial solitary waves arising from multiple resonances in purely nonlinear 2-D lattices are presented. Theory and experiments highlight new possibilities for light self-confinement and steering via engineered planar nonlinear structures in periodically poled materials.

  • 44.
    Gallo, Katia
    et al.
    Optoelectronics Research Centre, University of Southampton.
    Assanto, Gaetano
    Spatial solitons in chi(2) planar photonic crystals2007In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 32, no 21, p. 3149-3151Article in journal (Refereed)
    Abstract [en]

    We analyze light self-confinement induced by multiple nonlinear resonances in a two-dimensional 2 photoniccrystal. With reference to second-harmonic generation in a hexagonal lattice, we show that the systemcan not only support two-color (1+1)D solitary waves with enhanced confinement and steering capabilitiesbut also enable novel features such as wavelength-dependent soliton routing.

  • 45.
    Gallo, Katia
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Baghban, Mohammad Amin
    KTH, School of Engineering Sciences (SCI), Applied Physics, Quantum Electronics and Quantum Optics, QEO.
    Recent Developments on the Lithium Niobate Material Platform: The Silicon of Nonlinear Optics?2015Conference paper (Refereed)
    Abstract [en]

    The talk addresses current challenges and future prospects in combining nanotechnology, ferroelectric domain structuring and integrated optics in LiNbO3 materials to develop small-footprint devices for telecom and quantum optics, and potentially also life-science, applications.

  • 46.
    Gallo, Katia
    et al.
    Optoelectronics Research Centre, University of Southampton.
    Codemard, Christophe
    Gawith, Corin
    Broderick, Neil
    Smith, Peter
    Nilsson, Johan
    Richardson, David
    Guided-Wave Second Harmonic Generation in Hexagonally Poled RPE:LiNbO32005In: Conference on Lasers and Electro-Optics Europe - Technical Digest, 2005, p. 1568014-Conference paper (Refereed)
  • 47.
    Gallo, Katia
    et al.
    Optoelectronics Research Centre, University of Southampton.
    Codemard, Christophe
    Gawith, Corin
    Nilsson, Johan
    Smith, Peter
    Broderick, Neil
    Richardson, David
    Guided-wave second-harmonic generation in a LiNbO3 nonlinear photonic crystal2006In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 31, no 9, p. 1232-1234Article in journal (Refereed)
    Abstract [en]

    We demonstrate twin-beam second-harmonic generation from telecommunications wavelengths in an optimized buried reverse proton exchanged planar waveguide made in 2D hexagonally poled LiNbO3. Experiments carried out with a nanosecond narrow-bandwidth, high-power fiber source thoroughly explored the response of the nonlinear photonic crystal device in terms of its power, wavelength, and angle tunability.

  • 48.
    Gallo, Katia
    et al.
    Optoelectronics Research Centre, University of Southampton.
    Codemard, Christophe
    Gawith, Corin
    Smith, Peter
    Nilsson, Johan
    Broderick, Neil
    Richardson, David
    Buried slab waveguides in LiNbO3 nonlinear photonic crystals2005In: Proceedings of WFOPC 2005: 4th IEEE/LEOS Workshop on Fibres and Optical Passive Components / [ed] RivaSanseverino, S; Artiglia, M, 2005, p. 36-40Conference paper (Refereed)
    Abstract [en]

    We present an efficient integrated device for SHG at telecom wavelengths in Hexagonally Poled LiNbO3, based on the reverse proton exchange waveguide technology. We discuss its nonlinear response in terms of power, wavelength and angle tunability and use the experimental SHG data to infer also information on the linear properties of the waveguide.

  • 49.
    Gallo, Katia
    et al.
    Optoelectronics Research Centre, University of Southampton.
    Gawith, C.B.E.
    Wellington, I.T.
    Mailis, Sakellaris
    Eason, Robert
    Smith, Peter
    Richardson, David
    Kostritskii, Sergey
    Ultraviolet writing of channel waveguides in proton-exchanged LiNbO32007In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 101, no 1, p. 014110-Article in journal (Refereed)
    Abstract [en]

    We report on a direct ultraviolet (UV) writing method for the fabrication of channel waveguides at 1.55 mu m in LiNbO3 through UV irradiation of surface and buried planar waveguides made by annealed proton exchange and reverse proton exchange. A systematic study of the guidance properties as a function of the UV writing conditions is presented.

  • 50.
    Gallo, Katia
    et al.
    Optoelectronics Research Centre, University of Southampton.
    Gawith, Corin
    Prawiharjo, Jerry
    Broderick, Neil
    Smith, Peter
    Mailis, Sakellaris
    Eason, Robert
    Richardson, David
    UV-written channel waveguides in proton-exchanged Lithium Niobate2004In: Conference on Lasers and Electro-Optics, CLEO, 2004, p. 557-559Conference paper (Refereed)
    Abstract [en]

    We report on the direct UV-writing of channel waveguides in annealed proton-exchanged (APE) and reverse proton-exchanged (RPE) layers in LiNbO 3 and demonstrate efficient guiding within single mode channels at telecom wavelengths.

1234 1 - 50 of 153
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