Modal analysis of layer-structured optical fibers

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Doctoral thesis (article-based)
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Verkkokirja (657 KB, 44,[2] s.)
TKK dissertations, 143
Numerical modeling techniques play a key role in the development of new fiber optics, e.g., for telecommunications or sensing applications. In particular, the refractive-index profiles of various specialty optical fibers are increasingly designed with numerical tools. In this thesis, analytical and numerical mode-analysis techniques are applied to layer-structured specialty fibers as well as to partially coherent optical fields. The work is divided into three parts. In the first part, hollow-core and annular-core optical fibers are considered. The accuracy of the weak-guidance approximation for the low-order modes of such fibers is first assessed. Then, the approximation is employed to investigate the use of hollow-core multimode fibers in evanescent-wave guiding of laser-cooled atoms. Two schemes for creating the required evanescent-wave field on the inner surface of the fiber are analyzed. These are based on the selective excitation of tubular fiber modes with Laguerre-Gaussian input beams and on the dithering of a Gaussian beam at the fiber input to average out the speckles due to multimode interference. The first part of the thesis is concluded with a full-vector analysis of the self-imaging properties of annular-core fibers. In the second part, microstructured optical fibers with coated inclusions are studied. The effect of high-refractive-index dielectric inclusions on the photonic bandgap of a photonic-crystal fiber is characterized. Also, a novel design for a fiber-integrated surface-plasmon-resonance sensor based on a three-hole microstructured fiber with metal inclusions is proposed. The sensor makes use of an aqueous analyte infiltrated into the fiber pores. In the third part, the coherent-mode analysis of partially coherent light is applied to a random, stationary optical field which rotates with respect to an observer. The spectral changes due to the rotation are exemplified for a field with Gaussian Schell-model space correlations.
modal analysis, hollow optical fiber, self-imaging, fiber-optical sensor, optical coherence
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  • [Publication 1]: Markus Hautakorpi and Matti Kaivola. 2005. Modal analysis of M-type-dielectric-profile optical fibers in the weakly guiding approximation. Journal of the Optical Society of America A, volume 22, number 6, pages 1163-1169. © 2005 Optical Society of America (OSA). By permission.
  • [Publication 2]: M. Hautakorpi, A. Shevchenko, and M. Kaivola. 2004. Spatially smooth evanescent-wave profiles in a multimode hollow optical fiber for atom guiding. Optics Communications, volume 237, numbers 1-3, pages 103-110. © 2004 Elsevier Science. By permission.
  • [Publication 3]: Markus Hautakorpi and Matti Kaivola. 2006. Modal analysis of the self-imaging phenomenon in optical fibers with an annular core. Applied Optics, volume 45, number 25, pages 6388-6392. © 2006 Optical Society of America (OSA). By permission.
  • [Publication 4]: Markus Hautakorpi, Maija Mattinen, and Hanne Ludvigsen. 2008. Surface-plasmon-resonance sensor based on three-hole microstructured optical fiber. Optics Express, volume 16, number 12, pages 8427-8432. © 2008 Optical Society of America (OSA). By permission.
  • [Publication 5]: M. Hautakorpi, J. Lindberg, T. Setälä, and M. Kaivola. 2006. Rotational frequency shifts in partially coherent optical fields. Journal of the Optical Society of America A, volume 23, number 5, pages 1159-1163. © 2006 Optical Society of America (OSA). By permission.
  • [Errata file]: Errata of publication 1