Fibers

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4 pages, 188 KiB

Open AccessEditorial

Hollow-Core Optical Fibers

by Walter Belardi

Fibers 2019, 7(5), 50; https://doi.org/10.3390/fib7050050 - 24 May 2019

Cited by 10 | Viewed by 6557

Abstract

The possibility of guiding light in air has fascinated optical scientists and engineers since the dawn of optical fiber technology [...] Full article

(This article belongs to the Special Issue Hollow Core Optical Fibers)

Research

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8 pages, 2883 KiB

Open AccessArticle

A Method to Process Hollow-Core Anti-Resonant Fibers into Fiber Filters

by Xiaosheng Huang, Ken-Tye Yong and Seongwoo Yoo

Fibers 2018, 6(4), 89; https://doi.org/10.3390/fib6040089 - 22 Nov 2018

Cited by 22 | Viewed by 7086

Abstract

Hollow-Core Anti-Resonant Fiber (HC-ARF) shows promising applications. Nevertheless, there has been a persistent problem when it comes to all-fiber integration due to a lack of HC-ARF-based fiber components. In response to this remaining challenge, we investigate a reliable, versatile and efficient method to [...] Read more.

Hollow-Core Anti-Resonant Fiber (HC-ARF) shows promising applications. Nevertheless, there has been a persistent problem when it comes to all-fiber integration due to a lack of HC-ARF-based fiber components. In response to this remaining challenge, we investigate a reliable, versatile and efficient method to convert an HC-ARF into a fiber filter. By locally heating an HC-ARF with a CO₂ laser, the fiber structure becomes deformed, and cladding capillaries shrink to produce a thicker wall. This process is analogous to “writing” a new fiber with a thicker wall on the original fiber, resulting in creating new high loss regions in the original transmission bands. Thus, the construction of a fiber filter is realized by “writing” a new fiber on the original fiber. The feasibility of this method is confirmed through experiments, adopting both one- and two-layer HC-ARF. The HC-ARF-based fiber filters are found to have transmission spectra consistent with simulation prediction. Both band pass and band reject fiber filters with more than a 20-dB extinction ratio are obtainable without extra loss. Thus, an in-fiber HC-ARF filter is demonstrated by the CO₂ writing process. Its versatile approach promises controlled band selection and would find interesting applications to be discussed. Full article

(This article belongs to the Special Issue Hollow Core Optical Fibers)

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11 pages, 30796 KiB

Open AccessArticle

Hollow Core Optical Fibers for Industrial Ultra Short Pulse Laser Beam Delivery Applications

by Sebastian Eilzer and Björn Wedel

Fibers 2018, 6(4), 80; https://doi.org/10.3390/fib6040080 - 16 Oct 2018

Cited by 23 | Viewed by 9660

Abstract

Hollow core fibers were introduced many years ago but are now starting to be used regularly in more demanding applications. While first experiments mainly focused on the characterization and analysis of the fibers themselves, they are now implemented as a tool in the [...] Read more.

Hollow core fibers were introduced many years ago but are now starting to be used regularly in more demanding applications. While first experiments mainly focused on the characterization and analysis of the fibers themselves, they are now implemented as a tool in the laser beam delivery. Owing to their different designs and implementations, different tasks can be achieved, such as flexible beam delivery, wide spectral broadening up to supercontinuum generation or intense gas-laser interaction over long distances. To achieve a constant result in these applications under varying conditions, many parameters of these fibers have to be controlled precisely during fabrication and implementation. A wide variety of hollow core fiber designs have been analyzed and implemented into a high-power industrial beam delivery and their performance has been measured. Full article

(This article belongs to the Special Issue Hollow Core Optical Fibers)

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16 pages, 2092 KiB

Open AccessFeature PaperArticle

Combining Hollow Core Photonic Crystal Fibers with Multimode, Solid Core Fiber Couplers through Arc Fusion Splicing for the Miniaturization of Nonlinear Spectroscopy Sensing Devices

by Hanna Izabela Stawska, Maciej Andrzej Popenda and Elżbieta Bereś-Pawlik

Fibers 2018, 6(4), 77; https://doi.org/10.3390/fib6040077 - 11 Oct 2018

Cited by 7 | Viewed by 6590

Abstract

The presence of fiber optic devices, such as couplers or wavelength division multiplexers, based on hollow-core fibers (HCFs) is still rather uncommon, while such devices can be imagined to greatly increase the potential of HCFs for different applications, such as sensing, nonlinear optics, [...] Read more.

The presence of fiber optic devices, such as couplers or wavelength division multiplexers, based on hollow-core fibers (HCFs) is still rather uncommon, while such devices can be imagined to greatly increase the potential of HCFs for different applications, such as sensing, nonlinear optics, etc. In this paper, we present a combination of a standard, multimode fiber (MMF) optic coupler with a hollow core photonic bandgap fiber through arc fusion splicing and its application for the purpose of multiphoton spectroscopy. The presented splicing method is of high affordability due to the low cost of arc fusion splicers, and the measured splicing loss (SL) of the HCF-MMF splice is as low as (0.32 ± 0.1) dB, while the splice itself is durable enough to withstand a bending radius (r_bend) of 1.8 cm. This resulted in a hybrid between the hollow core photonic bandgap fiber (HCPBF) and MMF coupler, delivering 20 mW of average power and 250-fs short laser pulses to the sample, which was good enough to test the proposed sensor setup in a simple, proof-of-concept multiphoton fluorescence excitation-detection experiment, allowing the successful measurement of the fluorescence emission spectrum of 10⁻⁵ M fluorescein solution. In our opinion, the presented results indicate the possibility of creating multi-purpose HCF setups, which would excel in various types of sensing applications. Full article

(This article belongs to the Special Issue Hollow Core Optical Fibers)

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9 pages, 2939 KiB

Open AccessArticle

Geometry of Chalcogenide Negative Curvature Fibers for CO₂ Laser Transmission

by Chengli Wei, Curtis R. Menyuk and Jonathan Hu

Fibers 2018, 6(4), 74; https://doi.org/10.3390/fib6040074 - 30 Sep 2018

Cited by 15 | Viewed by 5340

Abstract

We study the impact of geometry on leakage loss in negative curvature fibers made with As

_{2}

Se

_{3}

chalcogenide and As

_{2}

S

_{3}

chalcogenide glasses for carbon dioxide (CO

_{2}

) laser transmission. The minimum leakage loss decreases when the core [...] Read more.

We study the impact of geometry on leakage loss in negative curvature fibers made with As

_{2}

Se

_{3}

chalcogenide and As

_{2}

S

_{3}

chalcogenide glasses for carbon dioxide (CO

_{2}

) laser transmission. The minimum leakage loss decreases when the core diameter increases both for fibers with six and for fibers with eight cladding tubes. The optimum gap corresponding to the minimum loss increases when the core diameter increases for negative curvature fibers with six cladding tubes. For negative curvature fibers with eight cladding tubes, the optimum gap is always less than 20

μ

m when the core diameter ranges from 300

μ

m to 500

μ

m. The influence of material loss on fiber loss is also studied. When material loss exceeds 10

^{2}

dB/m, it dominates the fiber leakage loss for negative curvature fiber at a wavelength of 10.6

μ

m. Full article

(This article belongs to the Special Issue Hollow Core Optical Fibers)

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12 pages, 4265 KiB

Open AccessEditor’s ChoiceArticle

Understanding Dispersion of Revolver-Type Anti-Resonant Hollow Core Fibers

by Matthias Zeisberger, Alexander Hartung and Markus A. Schmidt

Fibers 2018, 6(4), 68; https://doi.org/10.3390/fib6040068 - 20 Sep 2018

Cited by 14 | Viewed by 7414

Abstract

Here, we analyze the dispersion behavior of revolver-type anti-resonant hollow core fibers, revealing that the chromatic dispersion of this type of fiber geometry is dominated by the resonances of the glass annuluses, whereas the actual arrangement of the anti-resonant microstructure has a minor [...] Read more.

Here, we analyze the dispersion behavior of revolver-type anti-resonant hollow core fibers, revealing that the chromatic dispersion of this type of fiber geometry is dominated by the resonances of the glass annuluses, whereas the actual arrangement of the anti-resonant microstructure has a minor impact. Based on these findings, we show that the dispersion behavior of the fundamental core mode can be approximated by that of a tube-type fiber, allowing us to derive analytic expressions for phase index, group-velocity dispersion and zero-dispersion wavelength. The resulting equations and simulations reveal that the emergence of zero group velocity dispersion in anti-resonant fibers is fundamentally associated with the adjacent annulus resonance which can be adjusted mainly via the glass thickness of the anti-resonant elements. Due to their generality and the straightforward applicability, our findings will find application in all fields addressing controlling and engineering of pulse dispersion in anti-resonant hollow core fibers. Full article

(This article belongs to the Special Issue Hollow Core Optical Fibers)

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8 pages, 818 KiB

Open AccessArticle

Effect of Nested Elements on Avoided Crossing between the Higher-Order Core Modes and the Air-Capillary Modes in Hollow-Core Antiresonant Optical Fibers

by Laurent Provino

Fibers 2018, 6(2), 42; https://doi.org/10.3390/fib6020042 - 18 Jun 2018

Cited by 14 | Viewed by 5969

Abstract

Optimal suppression of higher-order modes (HOMs) in hollow-core antiresonant fibers comprising a single ring of thin-walled capillaries was previously studied, and can be achieved when the condition on the capillary-to-core diameter ratio is satisfied (

d / D \approx 0.68

). [...] Read more.

Optimal suppression of higher-order modes (HOMs) in hollow-core antiresonant fibers comprising a single ring of thin-walled capillaries was previously studied, and can be achieved when the condition on the capillary-to-core diameter ratio is satisfied (

d / D \approx 0.68

). Here we report on the conditions for maximizing the leakage losses of HOMs in hollow-core nested antiresonant node-less fibers, while preserving low confinement loss for the fundamental mode. Using an analytical model based on coupled capillary waveguides, as well as full-vector finite element modeling, we show that optimal

d / D

value leading to high leakage losses of HOMs, is strongly correlated to the size of nested capillaries. We also show that extremely high value of degree of HOM suppression (∼1200) at the resonant coupling is almost unchanged on a wide range of nested capillary diameter

d_{N e s t e d}

values. These results therefore suggest the possibility of designing antiresonant fibers with nested elements, which show optimal guiding performances in terms of the HOM loss compared to that of the fundamental mode, for clearly defined paired values of the ratios

d_{N e s t e d} / d

and

d / D

. These can also tend towards a single-mode behavior only when the dimensionless parameter

d_{N e s t e d} / d

is less than 0.30, with identical wall thicknesses for all of the capillaries. Full article

(This article belongs to the Special Issue Hollow Core Optical Fibers)

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8 pages, 3287 KiB

Open AccessEditor’s ChoiceArticle

Fabrication of Shatter-Proof Metal Hollow-Core Optical Fibers for Endoscopic Mid-Infrared Laser Applications

by Katsumasa Iwai, Hiroyuki Takaku, Mitsunobu Miyagi, Yi-Wei Shi and Yuji Matsuura

Fibers 2018, 6(2), 24; https://doi.org/10.3390/fib6020024 - 18 Apr 2018

Cited by 11 | Viewed by 6739

Abstract

A method for fabricating robust and thin hollow-core optical fibers that carry mid-infrared light is proposed for use in endoscopic laser applications. The fiber is made of stainless steel tubing, eliminating the risk of scattering small glass fragments inside the body if the [...] Read more.

A method for fabricating robust and thin hollow-core optical fibers that carry mid-infrared light is proposed for use in endoscopic laser applications. The fiber is made of stainless steel tubing, eliminating the risk of scattering small glass fragments inside the body if the fiber breaks. To reduce the inner surface roughness of the tubing, a polymer base layer is formed prior to depositing silver and optical-polymer layers that confine light inside the hollow core. The surface roughness is greatly decreased by re-coating thin polymer base layers. Because of this smooth base layer surface, a uniform optical-polymer film can be formed around the core. As a result, clear interference peaks are observed in both the visible and mid-infrared regions. Transmission losses were also low for the carbon dioxide laser used for medical treatments as well as the visible laser diode used for an aiming beam. Measurements of bending losses for these lasers demonstrate the feasibility of the designed fiber for endoscopic applications. Full article

(This article belongs to the Special Issue Hollow Core Optical Fibers)

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Review

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58 pages, 15866 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Hollow-Core Fiber Technology: The Rising of “Gas Photonics”

by Benoît Debord, Foued Amrani, Luca Vincetti, Frédéric Gérôme and Fetah Benabid

Fibers 2019, 7(2), 16; https://doi.org/10.3390/fib7020016 - 18 Feb 2019

Cited by 150 | Viewed by 19908

Abstract

Since their inception, about 20 years ago, hollow-core photonic crystal fiber and its gas-filled form are now establishing themselves both as a platform in advancing our knowledge on how light is confined and guided in microstructured dielectric optical waveguides, and a remarkable enabler [...] Read more.

Since their inception, about 20 years ago, hollow-core photonic crystal fiber and its gas-filled form are now establishing themselves both as a platform in advancing our knowledge on how light is confined and guided in microstructured dielectric optical waveguides, and a remarkable enabler in a large and diverse range of fields. The latter spans from nonlinear and coherent optics, atom optics and laser metrology, quantum information to high optical field physics and plasma physics. Here, we give a historical account of the major seminal works, we review the physics principles underlying the different optical guidance mechanisms that have emerged and how they have been used as design tools to set the current state-of-the-art in the transmission performance of such fibers. In a second part of this review, we give a nonexhaustive, yet representative, list of the different applications where gas-filled hollow-core photonic crystal fiber played a transformative role, and how the achieved results are leading to the emergence of a new field, which could be coined “Gas photonics”. We particularly stress on the synergetic interplay between glass, gas, and light in founding this new fiber science and technology. Full article

(This article belongs to the Special Issue Hollow Core Optical Fibers)

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11 pages, 2593 KiB

Open AccessReview

3D Printed Hollow-Core Terahertz Fibers

by Alice L. S. Cruz, Cristiano M. B. Cordeiro and Marcos A. R. Franco

Fibers 2018, 6(3), 43; https://doi.org/10.3390/fib6030043 - 21 Jun 2018

Cited by 91 | Viewed by 11841

Abstract

This paper reviews the subject of 3D printed hollow-core fibers for the propagation of terahertz (THz) waves. Several hollow and microstructured core fibers have been proposed in the literature as candidates for low-loss terahertz guidance. In this review, we focus on 3D printed [...] Read more.

This paper reviews the subject of 3D printed hollow-core fibers for the propagation of terahertz (THz) waves. Several hollow and microstructured core fibers have been proposed in the literature as candidates for low-loss terahertz guidance. In this review, we focus on 3D printed hollow-core fibers with designs that cannot be easily created by conventional fiber fabrication techniques. We first review the fibers according to their guiding mechanism: photonic bandgap, antiresonant effect, and Bragg effect. We then present the modeling, fabrication, and characterization of a 3D printed Bragg and two antiresonant fibers, highlighting the advantages of using 3D printers as a path to make the fabrication of complex 3D fiber structures fast and cost-effective. Full article

(This article belongs to the Special Issue Hollow Core Optical Fibers)

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26 pages, 6973 KiB

Open AccessEditor’s ChoiceReview

Revolver Hollow Core Optical Fibers

by Igor A. Bufetov, Alexey F. Kosolapov, Andrey D. Pryamikov, Alexey V. Gladyshev, Anton N. Kolyadin, Alexander A. Krylov, Yury P. Yatsenko and Alexander S. Biriukov

Fibers 2018, 6(2), 39; https://doi.org/10.3390/fib6020039 - 7 Jun 2018

Cited by 70 | Viewed by 11267

Abstract

Revolver optical fibers (RF) are special type of hollow-core optical fibers with negative curvature of the core-cladding boundary and with cladding that is formed by a one ring layer of capillaries. The physical mechanisms contributing to the waveguiding parameters of RFs are discussed. [...] Read more.

Revolver optical fibers (RF) are special type of hollow-core optical fibers with negative curvature of the core-cladding boundary and with cladding that is formed by a one ring layer of capillaries. The physical mechanisms contributing to the waveguiding parameters of RFs are discussed. The optical properties and possible applications of RFs are reviewed. Special attention is paid to the mid-IR hydrogen Raman lasers that are based on RFs and generating in the wavelength region from 2.9 to 4.4 μm. Full article

(This article belongs to the Special Issue Hollow Core Optical Fibers)

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