The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
Aalto

Applications of Microstructured Fibers: Supercontinua and Novel Components

Mikko Lehtonen

Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Electrical and Communications Engineering for public examination and debate in Micronova at Helsinki University of Technology (Espoo, Finland) on the 2nd of December, 2005, at 12 noon.

Overview in PDF format (ISBN 951-22-7914-2)   [1025 KB]
Dissertation is also available in print (ISBN 951-22-7913-4)

Abstract

Microstructured fibers are a special class of pure-silica optical fibers. They consist of a silica core, surrounded by a periodic array of air-holes running along the entire length of the fiber. These air-holes permit guidance of light through total-internal reflection. Diameter and spacing of the air-holes determines the optical properties of the fiber, therefore allowing for tailoring of the fiber according to the intended application.

This thesis contains novel results on supercontinuum generation in microstructured fibers. Several critical advances have been made in tailoring of the fiber properties in order to further reduce power requirements hindering miniaturization of supercontinuum sources. In particular, the influence of a second zero-dispersion wavelength of the fiber and the input polarization of highly-birefringent fibers have been studied. Furthermore, a novel two-pump scheme allows for efficient generation of broadband blue-light. The generated supercontinua are applied to characterization of absorption and transmission spectra of novel optical components. The high spectral power density of supercontinuum allows for observation of several new excited-state absorption lines of Erbium-doped fibers and characterization of optical components with strong variations in the transmission spectrum.

The second part of the thesis deals with applications developed for microstructured fibers. A tapered microstructured fiber is designed for coupling between standard fibers and photonic-crystal waveguides. An elliptical-core microstructured fiber is proposed as an efficient adapter between standard fibers and highly asymmetric waveguides. In addition, a microstructured fiber based optically bistable fiber cavity is applied to all-optical switching. In particular, an optical flip-flop is numerically studied.

This thesis consists of an overview and of the following 7 publications:

  1. G. Genty, M. Lehtonen, and H. Ludvigsen, Effect of cross-phase modulation on supercontinuum generated in microstructured fibers with sub-30 fs pulses, Optics Express 12, 4614-4624 (2004). © 2004 Optical Society of America (OSA). By permission.
  2. G. Genty, M. Lehtonen, H. Ludvigsen, and M. Kaivola, Enhanced bandwidth of supercontinuum generated in microstructured fibers, Optics Express 12, 3471-3480 (2004). © 2004 Optical Society of America (OSA). By permission.
  3. M. Lehtonen, G. Genty, M. Kaivola, and H. Ludvigsen, Supercontinuum generation in a highly birefringent microstructured fiber, Applied Physics Letters 82, 2197-2199 (2003). © 2003 American Institute of Physics. By permission.
  4. G. Genty, M. Lehtonen, and H. Ludvigsen, Route to broadband blue-light generation in microstructured fibers, Optics Letters 30, 756-758 (2005). © 2005 Optical Society of America (OSA). By permission.
  5. M. Lehtonen, G. Genty, and H. Ludvigsen, Absorption and transmission spectral measurement of fiber-optic components using supercontinuum radiation, Applied Physics B 81, 231-234 (2005).
  6. M. Lehtonen, G. Genty, and H. Ludvigsen, Tapered microstructured fibers for efficient coupling to optical waveguides: a numerical study, Applied Physics B 81, 295-300 (2005).
  7. G. Genty, M. Lehtonen, and H. Ludvigsen, Optical bistability and signal processing in a microstructured fiber ring resonator, Applied Physics B 81, 357-362 (2005).

Errata of publication 3

Keywords: microstructured fibers, supercontinuum, nonlinear optics, photonic crystals

This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited.

© 2005 Helsinki University of Technology

Last update 2011-05-26