Design of air-guiding modified honeycomb photonic band-gap fibers for effectively singlemode operation

Murao, Tadashi; Saitoh, Kunimasa; Koshiba, Masanori

doi:10.1364/oe.14.002404

Cited by 29 publications

(13 citation statements)

References 16 publications

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“…Photonic bandgap fibers (PBGFs), classified in two categories, namely, the solid-core [1] and the air-core structure [2][3][4][5][6][7], guide light along the fiber length in the low-index defected core region by the photonic bandgap (PBG) effect because the cladding is usually made of periodically arranged two or three different index materials. Recently, researches have made progress in understanding the close relation between the PBG for light with out-of-plane propagation in solid-core photonic bandgap fibers (SC-PBGFs) [8,9], or in air-core structures (but rather more subtle [10,11]), and the theory for anti-resonant reflecting optical waveguides (ARROWs) [12,13].…”

Section: Introductionmentioning

confidence: 99%

Detailed theoretical investigation of bending properties in solid-core photonic bandgap fibers

Murao¹,

Saitoh²,

Koshiba³

2009

Opt. Express

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Abstract:In this paper, detailed properties of bent solid-core photonic bandgap fibers (SC-PBGFs) are investigated. We propose an approximate equivalent straight waveguide (ESW) formulation for photonic bandgap (PBG) edges, which is convenient to see qualitatively which radiation (centripetal or centrifugal radiation) mainly occurs and the impact of bend losses for an operating wavelength. In particular, we show that cladding modes induced by bending cause several complete or incomplete leaky mode couplings with the core mode and the resultant loss peaks. Moreover, we show that the field distributions of the cladding modes are characterized by three distinct types for blue-edge, mid-gap, and red-edge wavelengths in the PBG, which is explained by considering the cladding Bloch states or resonant conditions without bending. Next, we investigate the structural dependence of the bend losses. In particular, we demonstrate the bend-loss dependence on the number of the cladding rings. Finally, by investigating the impacts of the order of PBG and the core structure on the bend losses, we discuss a tight-bending structure.

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Section: Introductionmentioning

confidence: 99%

Detailed theoretical investigation of bending properties in solid-core photonic bandgap fibers

Murao¹,

Saitoh²,

Koshiba³

2009

Opt. Express

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“…It is shown that the change of the absolute value of wave vector for the resonant modes in low-index regions and the effect of modal overlap of rod modes are responsible for the factor of reduction of PBG depth. The validity of the proposed simple formula that can be applied for any structural parameters is verified by means of the vectorial solver based on the finite-element method (FEM) [34]. Finally, a critical reason for decreasing the PBG depth in even-order PBGs is discussed, based on the theory provided here.…”

Section: Introductionmentioning

confidence: 92%

Understanding formation of photonic bandgap edge for maximum propagation angle in all-solid photonic bandgap fibers

Murao¹,

Nagao²,

Saitoh³

et al. 2011

J. Opt. Soc. Am. B

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We propose a simple formula that gives the effective refractive index of the first-order photonic bandgap (PBG) edge for the maximum propagation angle, which corresponds to the PBG floor in all-solid photonic bandgap fibers (PBGFs). In particular, based on an antiresonant reflecting optical waveguide (ARROW) theory incorporating a phase relation between resonant modes in low-index regions for perpendicular direction of the light propagation, we show that the effective index of the PBG edge at a wavelength does not depend on the diameter and refractive index of high-index rods, and is largely determined only by the pitch when normalized rod diameters are small. In other words, it has a constant value for the structural parameters with which the PBG emerges at the same wavelength normalized by the pitch. Moreover, the source of rod-diameter and refractive-index dependences on the condition for the formation of the PBG edge is demonstrated when the diameter and the refractive index of high-index rods are effectively large. Finally, the validity of the proposed simple formula, which can be applied for any structural parameters, is verified with the vectorial solver based on the finite-element method (FEM).

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“…Although the 7-unit-cell hollow-core size is not so large, HOMs exist in it [15] and the difference between the leakage losses of the HOMs and those of the fundamental mode is about one order of magnitude, and as a result it is difficult to realize low-loss single-mode operation using this structure. Recently, it has been reported that, in small core PBGFs with an optimized core and cladding profiles, the leakage losses of the HOMs are found to be at least three orders of magnitude larger than those of the fundamental mode [7]; however, the small core design makes it difficult to suppress the surface roughness scattering [8]. In order to form a largecore PBGF we can remove an additional air-hole ring and the resulting structure is depicted in Fig.…”

Section: Design Strategy For Suppression Of Higher-order Modes In Larmentioning

confidence: 99%

“…Although suppression of HOMs can be observed in small-core PBGFs [7], there exist a fundamental limit of scattering losses due to the surface roughness scattering [8], which prohibits the further reduction of the fiber's attenuation to the level of the conventional fiber. One possible solution to overpass this limit is to consider large hollow-core PBGFs.…”

Section: Introductionmentioning

confidence: 99%

Design of photonic band gap fibers with suppressed higher-order modes: Towards the development of effectively single mode large hollow-core fiber platforms

Saitoh¹,

Florous²,

Murao³

et al. 2006

Opt. Express

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Abstract:The objective of the present investigation is to propose and theoretically demonstrate the effective suppression of higher-order modes in large-hollow-core photonic band gap fibers (PBGFs), mainly for low-loss data transmission platforms and/or high power delivery systems. The proposed design strategy is based on the index-matching mechanism of central air-core modes with defected outer core modes. By incorporating several air-cores in the cladding of the PBGF with 6-fold symmetry it is possible to resonantly couple the light corresponding to higher-order modes into the outer core, thus significantly increasing the leakage losses of the higher-order modes in comparison to the fundamental mode, thus making our proposed design to operate in an effectively single mode fashion with polarization independent propagation characteristics. The validation of the procedure is ensured with a detailed PBGF analysis based on an accurate finite element modal solver. Extensive numerical results show that the leakage losses of the higher-order modes can be enhanced in a level of at least 2 orders of magnitude in comparison to those of the fundamental mode. Our investigation is expected to remove an essential obstacle in the development of large-core single-mode hollow-core fibers, thus enabling them to surpass the attenuation of conventional fibers. T. Murao, K. Saitoh, and M. Koshiba, "Design of air-guiding modified honeycomb photonic band-gap fibers for effectively single mode operation," Opt.

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Design of air-guiding modified honeycomb photonic band-gap fibers for effectively singlemode operation

Cited by 29 publications

References 16 publications

Detailed theoretical investigation of bending properties in solid-core photonic bandgap fibers

Detailed theoretical investigation of bending properties in solid-core photonic bandgap fibers

Understanding formation of photonic bandgap edge for maximum propagation angle in all-solid photonic bandgap fibers

Design of photonic band gap fibers with suppressed higher-order modes: Towards the development of effectively single mode large hollow-core fiber platforms

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