TY - JOUR A1 - Schiek, Roland T1 - Excitation of nonlinear beams: from the linear Talbot effect through modulation instability to Akhmediev breathers JF - Optics express N2 - The smooth transition between stable, Talbot-effect-dominated and modulationally unstable nonlinear optical beam propagation is described as the superposition of oscillating, growing and decaying eigenmodes of the common linearized theory of modulation instability. The saturation of the instability in form of breather maxima is embedded between eigenmode growth and decay. This explains well the changes of beam characteristics when the input intensity increases in experiments on modulation instability and breather excitation in spatial-spatial experimental platforms. An increased accuracy of instability gain measurements, a variety of interesting nonlinear beam scenarios and a more selective and well-directed breather excitation are demonstrated experimentally. KW - DYNAMICS KW - FIBER KW - GENERATION KW - PEREGRINE SOLITON KW - SPATIAL SOLITONS KW - WAVE-GUIDE Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-26049 N1 - Corresponding author: Roland Schiek VL - 29 IS - 10 SP - 15830 EP - 15851 PB - Optica Publishing Group CY - Washington, DC, USA ER - TY - JOUR A1 - Schiek, Roland T1 - Nonlinear refractive index in silica glass JF - Optical Materials Expres N2 - The third-order nonlinear susceptibility of silica glass is measured via self-phase modulation in standard single mode fibers at a wavelength of 1550 nm. To minimize the influence of polarization state changes along the propagation only meter-long fibers were investigated. With pulse durations of picoseconds a quasi-instantaneous nonlinearity with ultrafast electronic and fast nuclear-vibration contributions produces under conditions of negligible dispersion a classic and clean nonlinear phase shift following exactly the shape of the pulse power. The complex pulse envelope was retrieved from frequency optical gating spectrograms. The nonlinear fiber parameter γ could be determined with an accuracy of 3.7 percent. Considering the mode field structure and the doping influence the nonlinear refractive index of silica glass as the fiber base material was found to be n 2 =2.22⋅10 −16 cm 2 W±6.0% for picosecond-long pulses. Comparing nonlinear phase shifts from linear and circular polarized light a nuclear-vibration contribution to the cubic fiber nonlinearity of 25 percent was estimated. Y1 - 2023 U6 - https://doi.org/10.1364/ome.489520 N1 - Corresponding author: Roland Schiek VL - 13 IS - 6 SP - 1727 EP - 1740 PB - Optica ER - TY - JOUR A1 - Schiek, Roland A1 - Baronio, Fabio T1 - Spatial Akhmediev breathers and modulation instability growth-decay cycles in a quadratic optical medium JF - Physical Review Research N2 - We investigate the spatial nonlinear localization of light on a quasi-plane-wave background with a harmonic perturbation induced by modulation instability in a quadratic nonlinear optical medium. In particular, we demonstrate experimentally the excitation of deterministic Akhmediev breathers and thus the growth-decay dynamics of modulation instability in a LiNbO3 slab waveguide. The results should stimulate new interest in modulation instability, extreme events, turbulence, recurrence, and supercontinuum generation in quadratic nonlinear optics. Y1 - 2019 U6 - https://doi.org/10.1103/PhysRevResearch.1.032036 VL - 1 IS - 3 SP - 1 EP - 5 PB - American Physical Society ER - TY - CHAP A1 - Schiek, Roland A1 - Baronio, Fabio T1 - Spatial Akhmediev Breathers in Slab Waveguides T2 - 2019 Conference on Lasers and Electro-Optics Europe European Quantum Electronics Conference (CLEO/Europe-EQEC), 23-27 June 2019, Munich, Germany N2 - Summary form only given. The analytical breather-solutions of the Nonlinear Schrödinger Equation (NLS) [1] have been intensively studied and verified experimentally in the time-space system of optical pulse propagation in fibers [2]. In space-space systems, i.e. in optical beam propagation breathers in ultra-fast nonlinear media have not been observed due to the breather’s infinite background and a resulting extremely large power. In a lithium niobate slab waveguide with two second-harmonic (SH) resonances the resulting quasi-cubic cascaded quadratic nonlinearity provided together with the intrinsic cubic susceptibility enough nonlinearity for breather excitation at experimentally reachable powers. We could characterize the fi rst ultra -fast spatial -spatial optical breathers in a 5 -cm -long titanium indiffused lithium niobate slab waveguide at power levels down to tens of kW. The guided fundamental wave (FW) TM° fi lm mode at A = 1.32μm is phase -matched for type -I SH generation to TE 0 and TEi SH modes at temperatures near 295 and 344C. With temperature tuning the phase -mismatch and the two effective cascaded nonlinearities were adjusted. For breather observation, we aimed for a large phase -mismatch with low SH levels such that the cascaded nonlinearity is quasi -cubic and the propagation is well approximated by the NLS and its breather solutions. A frequency -doubled Nd:YAG-pumped OPA with CW-seeding delivered 5-ps long pulses with up to 200kW peak power in the waveguide. With a cylindrical telescope the beam was transformed into a very wide elliptical beam to approximate the breather background. The beam was end -fire coupled into the FW TM () mode. A variable few % of the beam were separated and coupled with a tilt and good overlap to the main beam into the waveguide to produce a spatial modulation of the input with adjustable period and modulation depth. A beam width of 1.5mm was large enough in the compromise between available beam power and infinite beam width. A beam with a transverse modulation with periods between 130 to 300μm approximates a constant background with modulation well enough to trigger modulation instability that develops eventually into the breather. KW - Frequency conversion KW - lithium niobate KW - Modulation KW - Optical beams KW - Optical pulses KW - Optical waveguides KW - Slabs Y1 - 2019 U6 - https://doi.org/10.1109/CLEOE-EQEC.2019.8872896 ER - TY - JOUR A1 - Setzpfandt, Frank A1 - Solntsev, Alexander S. A1 - Titchener, James A1 - Wu, Che Wen A1 - Xiong, Chunle A1 - Schiek, Roland A1 - Pertsch, Thomas A1 - Neshev, Dragomir N. A1 - Sukhorukov, Andrey A. T1 - Tunable generation of entangled photons in a nonlinear directional coupler JF - Laser & Photonics Reviews N2 - The on-chip integration of quantum light sources has enabled the realization of complex quantum photonic circuits. However, for the practical implementation of such circuits in quantum information applications, it is crucial to develop sources delivering entangled quantum photon states with on-demand tunability. Here we propose and experimentally demonstrate the concept of a widely tunable quantum light source based on spontaneous parametric down-conversion in a simple nonlinear directional coupler. We show that spatial photon-pair correlations and entanglement can be reconfigured on-demand by tuning the phase difference between the pump beams and the phase mismatch inside the structure. We experimentally demonstrate the generation of split states, robust N00N states, various intermediate regimes and biphoton steering on a single chip. Furthermore we theoretically investigate other regimes allowing all-optically tunable generation of all Bell states and flexible control of path-energy entanglement. Such wide-range capabilities of a structure comprised of just two coupled nonlinear waveguides are attributed to the intricate interplay between linear coupling and nonlinear phase matching. This scheme provides an important advance towards the realization of reconfigurable quantum circuitry. KW - ARRAYS KW - directional coupler KW - entanglement KW - GATES KW - nonlinearity KW - PAIR GENERATION KW - photon pairs KW - WAVE KW - waveguides Y1 - 2016 U6 - https://doi.org/10.1002/lpor.201500216 VL - 10 IS - 1 SP - 131 EP - 136 PB - WILEY-VCH ER - TY - CHAP A1 - Schiek, Roland T1 - Self-phase modulation in lithium niobate waveguides T2 - 2014 International Conference Laser Optics, title=Self-phase modulation in lithium niobate waveguides, 30 June-4 July 2014, St. Petersburg, Russia N2 - Self-phase modulation in lithium niobate wave-guides with cascaded quadratic and cubic nonlinearities is characterized by comparison of amplitude and phase of input and output pulse envelopes and spectra. Cubic nonlinear susceptibility coefficients of lithium niobate were determined from the measured nonlinear phase shifts. KW - Frequency measurement KW - Frequency modulation KW - lithium niobate KW - nonlinear susceptibility KW - self-phase modulation KW - Wavelength measurement Y1 - 2014 U6 - https://doi.org/10.1109/LO.2014.6886403 PB - IEEE ER - TY - CHAP A1 - Schiek, Roland A1 - Setzpfandt, Frank A1 - Baronio, Fabio T1 - Akhmediev Breathers and Modulation Instability’s Growth-Decay Cycle in Slab Waveguides T2 - Nonlinear Optics : 15-19 July 2019, Waikoloa Beach, Hawaii, United States N2 - Optical film waveguides served as new platform for investigating Akhmediev Breathers. Using the interplay between third-order and cascaded second-order optical nonlinearities breathers and modulation instability cycles in a wide nonlinear regime were characterized. Y1 - 2019 SN - 978-1-943580-62-0 U6 - https://doi.org/10.1364/nlo.2019.ntu2a.2 PB - OSA CY - Washington, D.C. ER - TY - GEN A1 - Schiek, Roland T1 - On the experimental ex citation of modulation instability and Akhmediev breathers T2 - CHAOS 2020, Proceedings, 13th Chaotic Modeling and Simulation, International Conference, 9 - 12 June, 2020, Florence, Italy, Y1 - 2020 ER - TY - CHAP A1 - Schiek, Roland T1 - Parameter Scans for Characterization of Nonlinear Beam Propagation T2 - Proceedings OSA Nonlinear Optics 2021: 9-13 August 2021, Washington, DC, United States N2 - Intensity-dependent beam propagation inside nonlinear media is difficult to characterize without cutting back — and destroying — the sample. Observing the output dependent on system parameters can provide information on the beam dynamics along the path. Y1 - 2021 SN - 978-1-943580-97-2 U6 - https://doi.org/10.1364/nlo.2021.ntu1b.5 PB - Optica Publishing Group, OSA CY - Washington, D.C. ER - TY - JOUR A1 - Setzpfandt, Frank A1 - Sohler, Wolfgang A1 - Schiek, Roland A1 - Pertsch, Thomas T1 - Nonlinear coupling in discrete optical waveguide arrays with quadratic nonlinearity JF - Physical Review A N2 - We demonstrate nonlinear coupling in a discrete optical system. This is achieved in waveguide arrays with quadratic nonlinearity, where the symmetries of the nonlinearly interacting waveguide modes are used to suppress the usually dominating nonlinear effects within individual waveguides. We derive a mathematical model to describe the nonlinear coupling in such waveguide arrays and show experimentally the profound effects of this nonlinear coupling mechanism on second-harmonic generation. KW - BLOCH OSCILLATIONS KW - DYNAMICS KW - LIQUID-CRYSTALS KW - PHOTONIC LATTICES KW - PROPAGATION KW - SOLITONS Y1 - 2015 U6 - https://doi.org/10.1103/PhysRevA.92.043832 VL - 92 IS - 4 PB - American Physical Society ER - TY - CHAP A1 - Setzpfandt, Frank A1 - Solntsev, Alexander S. A1 - Titchener, James A1 - Wu, Che Wen A1 - Xiong, Chunle A1 - Pertsch, Thomas A1 - Schiek, Roland A1 - Neshev, Dragomir N. A1 - Sukhorukov, Andrey A. T1 - Optically Tunable Entangled Photon State Generation in a Nonlinear Directional Coupler T2 - Nonlinear Optics [Kauai, Hawaii 26-31 July 2015] N2 - We propose and experimentally demonstrate an all-optically tunable biphoton quantum light source using a nonlinear directional coupler. The source can generate high-fidelity N00N states, completely split states, and states with variable degrees of entanglement. Y1 - 2015 SN - 978-1-55752-001-2 U6 - https://doi.org/10.1364/nlo.2015.nw2a.4 IS - paper NW2A.4 PB - OSA CY - Washington, D.C. ER -