检索结果-内蒙古大学图书馆

Degenerate squeezing in waveguides: a unified theoretical approach

学校读者我要写书评

暂无评论

JOURNAL OF PHYSICS-PHOTONICS 2020年第3期2卷

作者： Helt, L. G. Quesada, N. Xanadu Toronto ON Canada

We consider pulsed-pump spontaneous parametric downconversion (SPDC) as well as pulsed single- and dual-pump spontaneous four-wave mixing processes in waveguides within a unified Hamiltonian theoretical framework. Working with linear operator equations ink-space, our approach allows inclusion of linear losses, self- and cross-phase modulation, and dispersion to any order. We describe state evolution in terms of second-order moments, for which we develop explicit expressions. We use our approach to calculate the joint spectral amplitude of degenerate squeezing using SPDC analytically in the perturbative limit, benchmark our theory against well-known results in the limit of negligible group velocity dispersion, and study the suitability of recently proposed sources for quantum sampling experiments.

关键词： quantum optics squeezing waveguides

Propagating transverse electric and transverse magnetic modes in liquid crystal-clad planar waveguides

学校读者我要写书评

暂无评论

LIQUID CRYSTALS 2020年第4期47卷 531-539页

作者： Kolacz, Jakub Gotjen, Henry G. Bekele, Robel Y. Myers, Jason D. Frantz, Jesse A. Ziemkiewicz, Michael Spilimann, Christopher M. US Naval Res Lab Ctr Bio Mol Sci & Engn Washington DC 20375 USA Univ Res Fdn Greenbelt MD USA US Naval Res Lab Div Opt Sci Washington DC USA Analog Devices Inc Golden CO USA

In a planar dielectric waveguide, weak confinement of a propagating mode in a high index core leads to a measurable evanescent interaction with the cladding. In this work, we study the effect of a reorientable anisotropic cladding on the behaviour of Transverse Electric (TE) and Transverse Magnetic (TM) mode polarisations using a liquid crystal (LC)-clad waveguide architecture. The polarised evanescent field of a guided mode interacts with a voltage-tunable birefringent LC cladding to deflect an out-coupled beam. Experimental measurements are coupled with a theoretical framework and show good consistency with simulation results. We isolate the effect of mode confinement by changing the thickness of the high index core. Interactions between the LC index ellipsoid and the mode polarisation are probed by changing the initial alignment of the LC. Finally, we examine the difference in deflection between TE and TM modes, which incorporates both a change in mode confinement and a difference in LC index components.

关键词： Liquid crystal liquid crystal devices waveguides planar waveguides polarization

Bound modes in the continuum based phononic waveguides

学校读者我要写书评

暂无评论

arXiv 2022年

作者： Rahman, Adib Pal, Raj Kumar Department of Mechanical and Nuclear Engineering Kansas State University ManhattanKS66506 United States

We analytically predict and numerically demonstrate the existence of a family of bound modes in the continuum (BICs) in bi-layered spring mass chains. A coupled array of such chains is then used to illustrate transversely bound waves propagating along a channel in a lattice. We start by considering the compact region formed by coupling two spring mass chains with defects and predict bound modes arising due to reflection symmetries in this region. Dispersion analysis of a waveguide consisting of an array of appropriately coupled bi-layered chains reveals the presence of a branch having bound modes in the passband. Finally, detailed numerical analyses verify the existence of a BIC and its propagation through the waveguide at passband frequencies without energy leakage. The framework allows to achieve BICs and their propagation, for any arbitrary size and location of the compact region. Such BICs open avenues for novel classes of resonators with extremely high Q factors due to zero energy leakage and allow for guiding confined waves in structures without requiring bandgaps. Copyright © 2022, The Authors. All rights reserved.

关键词： waveguides

Reconstruction of smooth shape defects in waveguides using locally resonant frequencies

学校读者我要写书评

暂无评论

arXiv 2022年

作者： Niclas, Angèle Seppecher, Laurent Institut Camille Jordan École Centrale Lyon France

This article aims to present a new method to reconstruct slowly varying width defects in 2D waveguides using locally resonant frequencies. At these frequencies, locally resonant modes propagate in the waveguide under the form of Airy functions depending on a parameter called the locally resonant point. In this particular point, the local width of the waveguide is known and its location can be recovered from boundary measurements of the wavefield. Using the same process for different frequencies, we produce a good approximation of the width in all the waveguide. Given multi-frequency measurements taken at the surface of the waveguide, we provide a L∞-stable explicit method to reconstruct the width of the waveguide. We finally validate our method on numerical data, and we discuss its applications and limits. © 2022, CC BY-SA.

关键词： waveguides

SINGLE MODE MULTI-FREQUENCY FACTORIZATION METHOD FOR THE INVERSE SOURCE PROBLEM IN ACOUSTIC waveguides

学校读者我要写书评

暂无评论

arXiv 2022年

作者： Meng, Shixu Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing100190 China

This paper investigates the inverse source problem with a single propagating mode at multiple frequencies in an acoustic waveguide. The goal is to provide both theoretical justifications and efficient algorithms for imaging extended sources using the sampling methods. In contrast to the existing far/near field operator based on the integral over the space variable in the sampling methods, a multi-frequency far-field operator is introduced based on the integral over the frequency variable. This far-field operator is defined in a way to incorporate the possibly non-linear dispersion relation, a unique feature in waveguides. The factorization method is deployed to establish a rigorous characterization of the range support which is the support of source in the direction of wave propagation. A related factorization-based sampling method is also discussed. These sampling methods are shown to be capable of imaging the range support of the source. Numerical examples are provided to illustrate the performance of the sampling methods, including an example to image a complete sound-soft block. Copyright © 2022, The Authors. All rights reserved.

关键词： waveguides

Engineering symmetry-selective couplings of a superconducting artificial molecule to microwave waveguides

学校读者我要写书评

暂无评论

arXiv 2022年

作者： Aamir, Mohammed Ali Moreno, Claudia Castillo Sundelin, Simon Biznárová, Janka Scigliuzzo, Marco Patel, Kowshik Erappaji Osman, Amr Lozano, D.P. Gasparinetti, Simone Department of Microtechnology and Nanoscience Chalmers University of Technology Gothenburg412 96 Sweden

Tailoring the decay rate of structured quantum emitters into their environment opens new avenues for nonlinear quantum optics, collective phenomena, and quantum communications. Here we demonstrate a novel coupling scheme between an artificial molecule comprising two identical, strongly coupled transmon qubits, and two microwave waveguides. In our scheme, the coupling is engineered so that transitions between states of the same (opposite) symmetry, with respect to the permutation operator, are predominantly coupled to one (the other) waveguide. The symmetry-based coupling selectivity, as quantified by the ratio of the coupling strengths, exceeds a factor of 30 for both the waveguides in our device. In addition, we implement a two-photon Raman process activated by simultaneously driving both waveguides, and show that it can be used to coherently couple states of different symmetry in the single-excitation manifold of the molecule. Using that process, we implement frequency conversion across the waveguides, mediated by the molecule, with efficiency of about 95%. Finally, we show that this coupling arrangement makes it possible to straightforwardly generate spatially-separated Bell states propagating across the waveguides. We envisage further applications to quantum thermodynamics, microwave photodetection, and photon-photon gates. Copyright © 2022, The Authors. All rights reserved.

关键词： waveguides

Two-color pulse compounds in waveguides with a zero-nonlinearity point

学校读者我要写书评

暂无评论

arXiv 2022年

作者： Melchert, O. Bose, S. Willms, S. Babushkin, I. Morgner, U. Demircan, A. Welfengarten 1 Hannover30167 Germany Welfengarten 1A Hannover30167 Germany Nienburger Str. 17 Hannover30167 Germany

We study incoherently coupled two-frequency pulse compounds in waveguides with single zero-dispersion and zero-nonlinearity points. In such waveguides, supported by a negative nonlinearity, soliton dynamics can be obtained even in domains of normal dispersion. We demonstrate trapping of weak pulses by solitary-wave wells, forming nonlinear-photonics meta-atoms, and molecule-like bound-states of pulses. We study the impact of Raman effect on these pulse compounds, finding that, depending on the precise subpulse configuration, they decelerate, accelerate, or are completely unaffected. Our results extend the range of systems in which two-frequency pulse compounds can be expected to exist and demonstrate further unique and unexpected behavior. © 2022, CC BY.

关键词： waveguides

Symmetry-induced quasicrystalline waveguides

学校读者我要写书评

暂无评论

arXiv 2022年

作者： Davies, Bryn Craster, Richard V. Department of Mathematics Imperial College London South Kensington Campus LondonSW7 2AZ United Kingdom

Introducing an axis of reflectional symmetry in a quasicrystal leads to the creation of localised edge modes that can be used to build waveguides. We develop theory that characterises reflection-induced localised modes in materials that are formed by recursive tiling rules. This general theory treats a one-dimensional continuous differential model and describes a broad class of both quasicrystalline and periodic materials. We present an analysis of a material based on the Fibonacci sequence, which has previously been shown to have exotic, Cantor-like spectra with very wide spectral gaps. Our approach provides a way to create localised edge modes at frequencies within these spectral gaps, giving strong and stable wave localisation. We also use our general framework to make a comparison with reflection-induced modes in periodic materials. These comparisons show that while quasicrystalline waveguides enjoy enhanced robustness over periodic materials in certain settings, the benefits are less clear if the decay rates are matched. This shows the need to carefully consider equivalent structures when making robustness comparisons and to draw conclusions on a case-by-case basis, depending on the specific application. © 2022, CC BY.

关键词： waveguides

Generating Optic Terahertz Pulses in waveguides with Quadratic Nonlinearity

学校读者我要写书评

暂无评论

Bulletin of the Russian Academy of Sciences: Physics 2020年第2期84卷 177-179页

作者： Sazonov, S.V. Zakharova, I.G. Kalinovich, A.A. Moscow State University Moscow119991 Russia National Research Center Kurchatov Institute Moscow123098 Russia

Abstract: The formation of optic terahertz bullets upon optical rectification in a planar waveguide with quadratic nonlinearity has been studied via numerical simulation. The input optical pulses composed of tens of vibrations, as well as pulses with several vibrations, have been considered. For the latter case, a steady optical terahertz bullet propagation has been shown. © 2020, Allerton Press, Inc.

关键词： waveguides