Personne :
Chang, Junho

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Chang
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Junho
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Département de génie électrique et de génie informatique, Faculté des sciences et de génie, Université Laval
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ncf11921682
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Résultats de recherche

Voici les éléments 1 - 3 sur 3
  • Publication
    Accès libre
    Highly-elliptical-core fiber with stress-induced birefringence for mode multiplexing
    (Optical Society of America, 2020-05-13) Chang, Junho; Corsi, Alessandro; LaRochelle, Sophie; Wang, Lixian; Wang, Ruohui; Rusch, Leslie
    We report the polarization–maintaining properties of a highly–elliptical–core fiber surrounded by a trench that was designed to optimize the modal effective indices and bending loss for a total of five spatial modes with twofold polarization degeneracy (ten channels). In addition to the asymmetric core structure, the birefringence of the fiber is increased by the thermal stress introduced during the fabrication. We examine this effect and compare the calculated modal effective index differences to experimentally measured values. The results show a modal birefringence larger than 10-4 for all guided spatial modes. The fiber has a propagation loss, averaged over all mode groups, of 0.45 dB/km. The mode stability to bending is evaluated by selectively exciting/detecting each spatial mode while perturbing the fiber. This few–mode polarization–maintaining fiber is of interest for MIMO–free mode division multiplexing transmission systems.
  • Publication
    Accès libre
    Design of highly-elliptical-core ten-mode fiber for space division multiplexing with 2x2 MIM
    (IEEE Photonics Society, 2019-02-18) Chang, Junho; Corsi, Alessandro; LaRochelle, Sophie; Rusch, Leslie
    We propose a weakly-coupled few-mode fiber requiring only 2×2 MIMO equalizer blocks, which makes it compatible with standard coherent receivers with polarization diversity. The fiber has a highly-elliptical core, surrounded by a depressed index trench in the cladding, and supports five spatial modes with twofold polarization degeneracy (ten channels). The fiber is designed to mitigate inter-modal crosstalk since the effective index difference between spatial modes is larger than ∼1×10−3 over the C-band. Through numerical simulations, we report on bending loss and other modal characteristics such as effective area and chromatic dispersion. Finally, we briefly discuss the scalability of the design.
  • Publication
    Accès libre
    Design analysis of OAM fibers using particle swarm optimization algorithm
    (Institute of Electrical and Electronics Engineers, 2019-10-07) Chang, Junho; Corsi, Alessandro; LaRochelle, Sophie; Rusch, Leslie
    We study the design of ring core fibers (RCFs) supporting orbital angular momentum (OAM) modes for mode division multiplexing (MDM) transmission systems. We develop target criteria to optimize fiber designs using a particle swarm optimization (PSO) algorithm under fabrication constraints. Effective index separation, Δneff, and polarization purity of each OAM mode are known to determine modal crosstalk levels. To reduce the complexity of multiple-input multiple-output (MIMO) processing required to compensate for modal crosstalk, we define an objective function based on these quantities. Our design analysis focuses on four different concepts of step-index RCF leading to different modal and structural characteristics. The optimum design for each concept is derived using the PSO algorithm. We investigate the impact of hollow-core and/or higher-order radial modes on Δneff and polarization purity. Design strategies for increasing Δneff and polarization purity are discussed in light of robustness to fabrication errors. We finally discuss the scalability and potential limitations of this design.