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Petr Hlubina - One of the best experts on this subject based on the ideXlab platform.

  • Theoretical and experimental analysis of waveguiding in a two-mode birefringent holey fiber
    Photonic Crystal Fibers, 2007
    Co-Authors: Petr Hlubina, Tadeusz Martynkien, Marcin Szpulak, Dalibor Ciprian, Jana Trojková, G. Statkiewicz, Waclaw Urbanczyk
    Abstract:

    We present the results of theoretical and experimental analysis of waveguiding in a two-mode birefringent holey fiber in which the birefringence is induced by two large holes adjacent to the fiber core. First, using a full-vector finite-element method we modeled the wavelength dependence of the phase and group effective indices for the fundamental and higher-order linearly polarized (LP) modes in two orthogonal polarizations. Then we evaluated the wavelength dependence of the phase and group modal birefringences for both LP modes and the Intermodal Dispersion in two orthogonal polarizations as well. Second, we used different interferometric techniques, including time-domain and spectral-domain ones and a lateral force method, to measure in a broad spectral range the wavelength dependence of the phase and group modal birefringences for the fundamental and higher-order LP modes. Employing a white-light spectral interferometric method, we also measured the wavelength dependence of the Intermodal Dispersion for two orthogonal polarizations of the two LP modes. Furthermore, using an unbalanced Mach-Zehnder interferometer we measured the wavelength dependence of the relative group effective index for the fundamental mode.

  • Measurement and modelling of Dispersion characteristics of a two-mode birefringent holey fibre
    Measurement Science and Technology, 2006
    Co-Authors: Petr Hlubina, Tadeusz Martynkien, Marcin Szpulak, Dalibor Ciprian, G. Statkiewicz, Lenka Knyblová, Waclaw Urbanczyk
    Abstract:

    Employing several interferometric methods, we measured in a broad spectral range the wavelength dependences of the phase modal birefringence and the polarization mode Dispersion for the LP01 and even LP11 spatial modes supported by a birefringent holey fibre. We also determined the wavelength dependence of the Intermodal Dispersion between the X- and Y-polarized LP01 and even LP11 spatial modes. Furthermore, using a full-vector finite-element method, we modelled all the measured Dispersion characteristics and demonstrated good agreement between experimental and theoretical results.

  • Measurement of optical fibers by interferometric methods
    Optical Fibers: Applications, 2005
    Co-Authors: Petr Hlubina
    Abstract:

    An overview of some important results is presented in measurement of optical fibers by interferometric methods in two domains. Both time-domain and spectral-domain measurements are analyzed theoretically including the effect of the first-order and second-order Intermodal Dispersion. In the time-domain measurements, a tandem configuration of a Michelson interferometer and a few-mode optical fiber is used and the spatial interference fringes are resolved to measure the Intermodal group optical path difference. In the spectral-domain measurements, the Intermodal interference at the output of an optical fiber alone shows up as a periodic modulation of the source spectrum when a high-resolution spectrometer is used. Utilizing a white-light spectral interferometric method employing a low-resolution spectrometer and a tandem configuration of a Michelson interferometer and an optical fiber under test, the equalization wavelengths are resolved and the Intermodal Dispersion in the optical fiber can be measured over a wide spectral range. We have used the method for measuring either Intermodal Dispersion in circular-core, elliptical-core and bow-tie fibers or Dispersion of birefringence in elliptical-core fibers.

  • Spectral-domain Intermodal interference and the effect of a low-resolution spectrometer
    Optik, 2005
    Co-Authors: Petr Hlubina
    Abstract:

    Spectral-domain Intermodal interference is analysed theoretically at the output of a few-mode optical fibre alone and at the output of the optical fibre in a tandem configuration with a Michelson interferometer. The theoretical analysis is performed under general measurement conditions when a broadband source and a low-resolution spectrometer of a Gaussian response function are considered and when the first- and second-order Intermodal Dispersion effects in the optical fibre are taken into account. The theoretical analysis is performed for two different examples of Dispersion curves of a two-mode optical fibre and the effect of the limiting factors is specified.

  • White-light spectral interferometry and its applications in fiber optics
    2005
    Co-Authors: Petr Hlubina
    Abstract:

    In this contribution, an overview of applications of white-light spectral interferometry in Dispersion characteriza- tion of optical fibers is presented. First, spectral-domain Intermodal interference is analyzed theoretically at the output of a few-mode optical fiber alone and at the output of the optical fiber in a tandem configuration with a Michelson interferometer. The theoretical analysis is performed under general measurement conditions when a broadband source and a spectrometer of a Gaussian response function are considered and when the first-order and second-order Intermodal Dispersion effects in the optical fiber are taken into account. Second, the theoretical analysis is performed for three different examples of Dispersion curves of two-mode optical fibers and the effect of the limiting factors is specified. Finally, the theory is accompanied by the corresponding experiments for mea- suring either the Intermodal Dispersion in circular-core and elliptical-core fibers or the Dispersion of birefringence in the elliptical-core fiber.

Kin Seng Chiang - One of the best experts on this subject based on the ideXlab platform.

  • Two-core photonic crystal fiber with zero Intermodal Dispersion
    Optics Communications, 2013
    Co-Authors: Min Liu, Kin Seng Chiang
    Abstract:

    Abstract Intermodal Dispersion (IMD) in a two-core fiber can distort or even breakup pulses propagating in the fiber, and thus limit the usefulness of the fiber for applications that involve the transmission of ultrashort pulses. In this paper, we analyze a two-core photonic crystal fiber (PCF) for the elimination of IMD. The refractive index of the two cores required is slightly lower than the surrounding index and can serve as an effective parameter for the control of the wavelength at which the IMD disappears. The fiber has a conventional PCF structure and is compatible with the existing PCF fabrication technology.

  • Design of two-core photonic crystal fiber to eliminate Intermodal Dispersion
    Asia Communications and Photonics Conference, 2012
    Co-Authors: Min Liu, Kin Seng Chiang
    Abstract:

    A two-core photonic crystal fiber is proposed to eliminate Intermodal Dispersion. The fiber can be fabricated readily with the existing technology and is suitable for applications that involve ultrashort pulses.

  • Effects of intrapulse stimulated Raman scattering on short pulse propagation in a nonlinear two-core fiber
    Applied Physics B, 2006
    Co-Authors: Min Liu, Kin Seng Chiang
    Abstract:

    The switching dynamics of short pulses propagating in a two-core optical fiber under the effects of intrapulse stimulated Raman scattering (ISRS) and Intermodal Dispersion is investigated theoretically. We find that, when the input pulses are short and intense enough, ISRS in general reduces the width of the pulses propagating in the launching core of the fiber and, at the same time, slows down the pulses. However, if the two-core fiber contains sufficient Intermodal Dispersion, the pulse-narrowing effect of ISRS can be weakened. Using typical fiber parameters, we demonstrate with numerical examples how the interaction of ISRS and Intermodal Dispersion affects the pulse shape.

  • THEORY OF PULSE PROPAGATION IN OPTICAL DIRECTIONAL COUPLERS
    Journal of Nonlinear Optical Physics & Materials, 2005
    Co-Authors: Kin Seng Chiang
    Abstract:

    Since the existence of Intermodal Dispersion or coupling coefficient Dispersion in an optical directional coupler was highlighted ten years ago, a number of theoretical studies for the understanding of the significance of this Dispersion effect on pulse propagation in a directional coupler under various situations have been reported. This paper provides a review of these studies. Both the normal-mode theory and the coupled-mode theory of the coupler are described. The application of the more popular coupled-mode theory to the study of nonlinear pulse switching, soliton interaction, soliton formation, and active couplers is discussed. Experimental works are also described briefly.

  • Soliton states in a nonlinear directional coupler with Intermodal Dispersion
    Physics Letters A, 2002
    Co-Authors: Vipul Rastogi, Kin Seng Chiang, Nail Akhmediev
    Abstract:

    We study numerically the propagation of short optical pulses in a nonlinear directional coupler that possesses significant Intermodal Dispersion. Using the split-step method with fast Fourier transform, we calculate the soliton solutions of such a coupler and highlight the effect of Intermodal Dispersion on the propagation dynamics of the pulses. We find that the Intermodal Dispersion has only a small effect on the shape of the soliton states, in spite of the fact that it can distort and break up low-energy pulses launched into one arm of the coupler. The Intermodal Dispersion, however, can cause a drift in the velocity of the soliton pulses.

Meng Liu - One of the best experts on this subject based on the ideXlab platform.

Roberto Llorente Sáez - One of the best experts on this subject based on the ideXlab platform.

  • Ultra-short pulse propagation model for multi-core fibers based on local modes
    Scientific Reports, 2017
    Co-Authors: Andrés Macho Ortiz, Carlos García-meca, Francisco Javier Fraile-peláez, Frederic Cortés-juan, Roberto Llorente Sáez
    Abstract:

    Multi-core fibers (MCFs) have sparked a new paradigm in optical communications and open new possibilities and applications in experimental physics and other fields of science, such as biological and medical imaging. In many of these cases, ultra-short pulse propagation is revealed as a key factor that enables us to exploit the full potential of this technology. Unfortunately, the propagation of such pulses in real MCFs has not yet been modelled considering polarization effects or typical random medium perturbations, which usually give rise to both longitudinal and temporal birefringent effects. Using the concept of local modes, we develop here an accurate ultra-short pulse propagation model that rigorously accounts for these phenomena in single-mode MCFs. Based on this theory, we demonstrate analytically and numerically the Intermodal Dispersion between different LP_01 polarized core modes induced by these random perturbations when propagating femtosecond pulses in the linear and nonlinear fiber regimes. The ever-decreasing core-to-core distance significantly enhances the Intermodal Dispersion induced by these birefringent effects, which can become the major physical impairment in the single-mode regime. To demonstrate the power of our model, we give explicit strategies to reduce the impact of this optical impairment by increasing the MCF perturbations.

Amarendra K. Sarma - One of the best experts on this subject based on the ideXlab platform.

  • A comparative study of soliton switching in a two-and three-core coupler with TOD and IMD
    Optik, 2009
    Co-Authors: Amarendra K. Sarma
    Abstract:

    A numerical study of soliton switching in a two- and three-core coupler is carried out taking into account the effect of Intermodal Dispersion and third-order Dispersion. A two and three-core coupler with linear and triangular configuration is considered. It is found that the three-core coupler with linear configuration shows the best switching characteristics.

  • Dark soliton switching in an NLDC in the presence of higher-order perturbative effects
    Optics and Laser Technology, 2009
    Co-Authors: Amarendra K. Sarma
    Abstract:

    Dark soliton switching in a nonlinear directional coupler in the presence of Intermodal Dispersion, cross-phase modulation (CPM), third-order Dispersion, Raman effect, and self-steepening effect is reported for the first time. It is shown that, with the exception of CPM, all of the other perturbative effects have almost no effect on the switching characteristics of the dark soliton switch, which is an improvement over the corresponding bright soliton switch. Although the CPM increases the critical power of dark soliton switching, the soliton pulse remains stable inside the coupler during its propagation.

  • Phase-induced soliton switching in fiber nonlinear directional couplers
    Optical Engineering, 2007
    Co-Authors: Amarendra K. Sarma, Ajit Kumar
    Abstract:

    A numerical study of femtosecond soliton switching by the relative phase change of a weak control pulse is carried out for a Kerr coupler with the simultaneous presence of Intermodal Dispersion, cross-phase modulation, third-order Dispersion, self-steepening, and intrapulse Raman scattering. It is shown (numerically) that cross-phase modulation, though it appears as a very tiny parameter, plays a positive role in this mode of soliton switching and that these perturbative effects may lead to useful soliton switching if the relative phase of the control pulse is monitored judiciously.

  • Perturbative effects on ultra-short soliton self-switching
    Pramana, 2007
    Co-Authors: Amarendra K. Sarma, Ajit Kumar
    Abstract:

    A numerical study of ultra-short self-soliton switching along with the corresponding analysis of coupler parameters is carried out for a Kerr coupler with Intermodal Dispersion. The influence of perturbations like third-order Dispersion, self-steepening and intrapulse Raman scattering, on switching characteristics is also studied.

  • Femtosecond-Soliton Switching in a Three-Core Coupler
    Japanese Journal of Applied Physics, 2005
    Co-Authors: Ajit Kumar, Amarendra K. Sarma
    Abstract:

    Soliton switching in a three-core Kerr-coupler is studied numerically by taking into account Intermodal Dispersion (IMD), third-order Dispersion and higher-order nonlinear effects, like the Raman and self-steepening effects. It is shown that the weak coupling regime is the most suitable for the purpose. Also, it is shown that IMD has negligible influence on switching, while, out of the higher-order nonlinear effects, Raman intrapulse scattering has the dominant effect.