Light guiding properties of negative-curvature hollow-core fiber

Negative curvature hollow-core fibers have become increasingly attractive as an excellent waveguide platform. Negative curvature fibers have exceptional optical properties, such as high optical damage threshold, low nonlinearity, and tunable dispersion, which make them promising for various applicat...

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Main Author: Wang, Yuxi
Other Authors: Wonkeun Chang
Format: Thesis-Doctor of Philosophy
Language:English
Published: Nanyang Technological University 2022
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Online Access:https://hdl.handle.net/10356/155743
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Institution: Nanyang Technological University
Language: English
id sg-ntu-dr.10356-155743
record_format dspace
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Engineering::Electrical and electronic engineering::Optics, optoelectronics, photonics
spellingShingle Engineering::Electrical and electronic engineering::Optics, optoelectronics, photonics
Wang, Yuxi
Light guiding properties of negative-curvature hollow-core fiber
description Negative curvature hollow-core fibers have become increasingly attractive as an excellent waveguide platform. Negative curvature fibers have exceptional optical properties, such as high optical damage threshold, low nonlinearity, and tunable dispersion, which make them promising for various applications,such as high power beam delivery, telecommunications, and gas-based nonlinear optics. In negative curvature fibers, the presence of the negative curvature at the core-cladding interface, as well as the absence of the nodes between the adjacent cladding element are two crucial structural features that have large impact on the light guidance. Presently, the most widely used family of negative curvature fibers is the single ring negative curvature fiber, where a single ring of dielectric cladding tubes surround the central hollow region. Another successful type is the nested antiresonant nodeless hollow core fiber, which have shown remarkably low transmission loss of 0.22 dB/km. The thesis focuses on the investigation on the light guiding properties of negative-curvature hollow-core fibers. First, we presented a comprehensive numerical investigation on the effect of introducing outer cladding tubes on the guiding properties in double-ring negative-curvature fiber. We determined the range of geometrical parameters, which exhibited the best guiding properties in the double-ring geometry. Our study showed that introducing an outer cladding tube can reduce the confinement loss by up to four orders of magnitude in negative-curvature hollow-core fiber. Bending and modal properties can also be improved. We found that the low-loss region can be shifted by varying the thickness of outer cladding tubes, indicating the loss reduction derived from the enhanced anti-resonant reflections provided by the interface of outer cladding tubes. We carried out a thorough numerical analysis on the bending-induced loss in negative-curvature hollow-core fibers. The result shows that varying structural parameters change the bending performance via altering the resonant coupling and other bending-induced effects. We provided the underlying mechanism on how resonant coupling and other bending-related phenomena influence the bending properties of negative curvature fiber. From this analysis, we identified the structural parameters for achieving light guidance with low bending sensitivity. Our numerical results also show that higher-order modes can be effectively suppressed through the mechanical bending of the fiber. We fabricated several types of single-ring negative curvature fibers. They have exhibited excellentvii light-guiding properties, featuring broadband and low-loss guidance. A seven-tube single-ring negative curvature fiber has demonstrated low-bend sensitivity light guidance in the two-micro region. The fiber can be useful for high power beam delivery and gas-based nonlinear optics. We fabricated and characterized a double ring negative-curvature fiber with a geometrical arrangement identical to that studied in our numerical study. The fiber exhibits superior loss performance than its idealized single ring counterpart, demonstrating its potential as a low-loss waveguide. Our results laid a good foundation for fabricating various double-ring negative-curvature fiber for achieving excellent guiding properties.
author2 Wonkeun Chang
author_facet Wonkeun Chang
Wang, Yuxi
format Thesis-Doctor of Philosophy
author Wang, Yuxi
author_sort Wang, Yuxi
title Light guiding properties of negative-curvature hollow-core fiber
title_short Light guiding properties of negative-curvature hollow-core fiber
title_full Light guiding properties of negative-curvature hollow-core fiber
title_fullStr Light guiding properties of negative-curvature hollow-core fiber
title_full_unstemmed Light guiding properties of negative-curvature hollow-core fiber
title_sort light guiding properties of negative-curvature hollow-core fiber
publisher Nanyang Technological University
publishDate 2022
url https://hdl.handle.net/10356/155743
_version_ 1772827633960091648
spelling sg-ntu-dr.10356-1557432023-07-04T17:49:21Z Light guiding properties of negative-curvature hollow-core fiber Wang, Yuxi Wonkeun Chang School of Electrical and Electronic Engineering wonkeun.chang@ntu.edu.sg Engineering::Electrical and electronic engineering::Optics, optoelectronics, photonics Negative curvature hollow-core fibers have become increasingly attractive as an excellent waveguide platform. Negative curvature fibers have exceptional optical properties, such as high optical damage threshold, low nonlinearity, and tunable dispersion, which make them promising for various applications,such as high power beam delivery, telecommunications, and gas-based nonlinear optics. In negative curvature fibers, the presence of the negative curvature at the core-cladding interface, as well as the absence of the nodes between the adjacent cladding element are two crucial structural features that have large impact on the light guidance. Presently, the most widely used family of negative curvature fibers is the single ring negative curvature fiber, where a single ring of dielectric cladding tubes surround the central hollow region. Another successful type is the nested antiresonant nodeless hollow core fiber, which have shown remarkably low transmission loss of 0.22 dB/km. The thesis focuses on the investigation on the light guiding properties of negative-curvature hollow-core fibers. First, we presented a comprehensive numerical investigation on the effect of introducing outer cladding tubes on the guiding properties in double-ring negative-curvature fiber. We determined the range of geometrical parameters, which exhibited the best guiding properties in the double-ring geometry. Our study showed that introducing an outer cladding tube can reduce the confinement loss by up to four orders of magnitude in negative-curvature hollow-core fiber. Bending and modal properties can also be improved. We found that the low-loss region can be shifted by varying the thickness of outer cladding tubes, indicating the loss reduction derived from the enhanced anti-resonant reflections provided by the interface of outer cladding tubes. We carried out a thorough numerical analysis on the bending-induced loss in negative-curvature hollow-core fibers. The result shows that varying structural parameters change the bending performance via altering the resonant coupling and other bending-induced effects. We provided the underlying mechanism on how resonant coupling and other bending-related phenomena influence the bending properties of negative curvature fiber. From this analysis, we identified the structural parameters for achieving light guidance with low bending sensitivity. Our numerical results also show that higher-order modes can be effectively suppressed through the mechanical bending of the fiber. We fabricated several types of single-ring negative curvature fibers. They have exhibited excellentvii light-guiding properties, featuring broadband and low-loss guidance. A seven-tube single-ring negative curvature fiber has demonstrated low-bend sensitivity light guidance in the two-micro region. The fiber can be useful for high power beam delivery and gas-based nonlinear optics. We fabricated and characterized a double ring negative-curvature fiber with a geometrical arrangement identical to that studied in our numerical study. The fiber exhibits superior loss performance than its idealized single ring counterpart, demonstrating its potential as a low-loss waveguide. Our results laid a good foundation for fabricating various double-ring negative-curvature fiber for achieving excellent guiding properties. Doctor of Philosophy 2022-03-16T02:57:08Z 2022-03-16T02:57:08Z 2021 Thesis-Doctor of Philosophy Wang, Y. (2021). Light guiding properties of negative-curvature hollow-core fiber. Doctoral thesis, Nanyang Technological University, Singapore. https://hdl.handle.net/10356/155743 https://hdl.handle.net/10356/155743 10.32657/10356/155743 en This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0). application/pdf Nanyang Technological University