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Kunimasa Saitoh - One of the best experts on this subject based on the ideXlab platform.

  • design of three spatial mode ring core fiber
    Journal of Lightwave Technology, 2014
    Co-Authors: Motoki Kasahara, Takashi Matsui, Kunimasa Saitoh, Kyozo Tsujikawa, Taiji Sakamoto, Nobutomo Hanzawa, Fumihiko Yamamoto
    Abstract:

    We investigate the fiber parameters which meet the design conditions for effectively three-spatial-mode transmission and low Bending Loss in a ring-core fiber for mode-division multiplexing transmission. We also clarify the effective area and the difference of the effective index while satisfying the design conditions.

  • effectively single mode all solid photonic bandgap fiber with large effective area and low Bending Loss for compact high power all fiber lasers
    Optics Express, 2012
    Co-Authors: Masahiro Kashiwagi, Kunimasa Saitoh, Shoichiro Matsuo, Katsuhiro Takenaga, Shoji Tanigawa, Munehisa Fujimaki
    Abstract:

    An effectively single-mode all-solid photonic bandgap fiber with large effective area and low Bending Loss for compact high-power all-fiber lasers is fully investigated. The pitch dependencies of effective area, Bending Loss, and effectively single-mode operation are discussed numerically and experimentally. The calculation results indicate that an effectively single-mode all-solid photonic bandgap fiber with an effective area of more than 500 μm2 and a Bending Loss of less than 0.1 dB/m at a Bending radius of 10 cm can be realized by choosing optimum fiber parameters. In a fabricated effectively single-mode all-solid photonic bandgap fiber with 48.0 μm core, the effective area of 712 μm2, the effectively single-mode operation, and the Bending Loss of less than 0.1 dB/m at a Bending radius of 10 cm are achieved simultaneously at 1064 nm.

  • low Bending Loss and effectively single mode all solid photonic bandgap fiber with an effective area of 650 μm 2
    Optics Letters, 2012
    Co-Authors: Masahiro Kashiwagi, Kunimasa Saitoh, Shoichiro Matsuo, Katsuhiro Takenaga, Shoji Tanigawa, Munehisa Fujimaki
    Abstract:

    A large-mode-area all-solid photonic bandgap fiber with a seven-cell core and five high-index rod rings is investigated. Numerical simulations show that an effective area of more than 500 μm2, a Bending Loss of less than 0.1 dB/m at a Bending radius of 10 cm and effectively single-mode operation can be achieved simultaneously. A core diameter of 44.8 μm and an effective area of 650 μm2 at 1064 nm are achieved in a fabricated fiber. Bending Loss at 1064 nm is 0.09 dB/m at a Bending radius of 7 cm. Effectively single-mode operation is also realized at a Bending radius of 10 cm.

  • design principle for realizing low Bending Losses in all solid photonic bandgap fibers
    Journal of Lightwave Technology, 2011
    Co-Authors: Tadashi Murao, Koyuru Nagao, Kunimasa Saitoh, Masanori Koshiba
    Abstract:

    In this paper, the structural dependence of factor which mainly affects a Bending Loss property is theoretically investigated in all-solid photonic bandgap fibers (PBGFs). A design principle for realizing low Bending Losses is successfully figured out for the first-order photonic bandgap (PBG). In particular, one of the origins which causes the variation of Bending Loss property for each structural parameter is identified. In addition, we show that exploitation of a large pitch relative to a rod diameter, aiming to realize a large-mode area (LMA) structure, leads to a significant degradation of the Bending Loss property. Moreover, it is demonstrated that a V-value which is proposed for all-solid PBGFs is also reduced significantly for the LMA condition. The origin of the degradation is attributed to the newly-excited Bloch state which determines the second-order PBG edge.

  • investigation on multi core fibers with large aeff and low micro Bending Loss
    Optics Express, 2011
    Co-Authors: Katsunori Imamura, Kunimasa Saitoh, Yukihiro Tsuchida, Kazunori Mukasa, Ryuichi Sugizaki, Masanori Koshiba
    Abstract:

    To realize large effective area (Aeff) multi-core fibers (MCFs), the design to suppress the cross-talk and the influence of the cladding diameter on the micro Bending Loss were investigated. As a result, the MCFs with large Aeff over 100 μm2 and low micro Bending Loss were successfully fabricated. The results indicate the importance of fiber design to realize large Aeff MCFs including fiber diameters, which largely affect the micro Bending Loss property. Additionally, MCF with large Aeff, low attenuation Loss and suppressed cross-talk was successfully realized by optimizing the fiber design. The cross-talk properties could be estimated by the simulation based on the coupling power theory taking the influences of the longitudinal fluctuation of core diameter into account.

Masanori Koshiba - One of the best experts on this subject based on the ideXlab platform.

  • design principle for realizing low Bending Losses in all solid photonic bandgap fibers
    Journal of Lightwave Technology, 2011
    Co-Authors: Tadashi Murao, Koyuru Nagao, Kunimasa Saitoh, Masanori Koshiba
    Abstract:

    In this paper, the structural dependence of factor which mainly affects a Bending Loss property is theoretically investigated in all-solid photonic bandgap fibers (PBGFs). A design principle for realizing low Bending Losses is successfully figured out for the first-order photonic bandgap (PBG). In particular, one of the origins which causes the variation of Bending Loss property for each structural parameter is identified. In addition, we show that exploitation of a large pitch relative to a rod diameter, aiming to realize a large-mode area (LMA) structure, leads to a significant degradation of the Bending Loss property. Moreover, it is demonstrated that a V-value which is proposed for all-solid PBGFs is also reduced significantly for the LMA condition. The origin of the degradation is attributed to the newly-excited Bloch state which determines the second-order PBG edge.

  • investigation on multi core fibers with large aeff and low micro Bending Loss
    Optics Express, 2011
    Co-Authors: Katsunori Imamura, Kunimasa Saitoh, Yukihiro Tsuchida, Kazunori Mukasa, Ryuichi Sugizaki, Masanori Koshiba
    Abstract:

    To realize large effective area (Aeff) multi-core fibers (MCFs), the design to suppress the cross-talk and the influence of the cladding diameter on the micro Bending Loss were investigated. As a result, the MCFs with large Aeff over 100 μm2 and low micro Bending Loss were successfully fabricated. The results indicate the importance of fiber design to realize large Aeff MCFs including fiber diameters, which largely affect the micro Bending Loss property. Additionally, MCF with large Aeff, low attenuation Loss and suppressed cross-talk was successfully realized by optimizing the fiber design. The cross-talk properties could be estimated by the simulation based on the coupling power theory taking the influences of the longitudinal fluctuation of core diameter into account.

  • multiple resonant coupling mechanism for suppression of higher order modes in all solid photonic bandgap fibers with heterostructured cladding
    Optics Express, 2011
    Co-Authors: Tadashi Murao, Kunimasa Saitoh, Masanori Koshiba
    Abstract:

    In this paper, we propose a novel mechanism for suppression of higher-order modes (HOMs), namely multiple resonant coupling, in all-solid photonic bandgap fibers (PBGFs) with effectively large core diameters. In an analogy to the well-known tight-binding theory in solid-state physics, multiple anti-resonant reflecting optical waveguide (ARROW) modes bound in designedly arranged defects in the cladding make up Bloch states and resultant photonic bands with a finite effective-index width, which contribute to the suppression of HOMs. In particular, contrary to the conventional method for the HOM suppression using the index-matching of the HOMs in the core of the PBGF and the defect mode arranged in the cladding, the proposed mechanism guarantees a broadband HOM suppression without a precise structural design. This effect is explained by the multiple resonant coupling, as well as an enhanced confinement Loss mechanism which occurs near the condition satisfying the multiple resonant coupling. Moreover, we show that the proposed structure exhibits a lower Bending Loss characteristic when compared to the conventional all-solid PBGFs. The simultaneous realization of the single-mode operation and the low Bending Loss property is due to the novel cladding concept named as heterostructured cladding. The proposed structure also resolves the issue for the increased confinement Loss property in the first-order photonic bandgap (PBG) at the same time.

  • effective area limit of large mode area solid core photonic bandgap fibers for fiber laser applications
    Optical Fiber Technology, 2010
    Co-Authors: Kunimasa Saitoh, Tadashi Murao, Lorenzo Rosa, Masanori Koshiba
    Abstract:

    Abstract We investigate the Bending characteristics of solid-core photonic bandgap fibers (SC-PBGFs) aiming to achieve large mode area (LMA) and effectively single-mode operation with a practically allowable Bending radius for high-power Yb-doped fiber lasers and amplifiers. Through detailed numerical simulations based on the finite element method (FEM), we evaluate the impacts of the order of photonic bandgap on the Bending performance and point out the limits of core size enlargement in the SC-PBGFs with a 1-cell core structure due to the increment of Bending Loss. In addition, under practical constraints, we find that the SC-PBGFs having a 7-cell core can achieve sufficient differential Bending Loss between the fundamental mode and the higher-order modes and a much larger effective area limit as compared with previously-reported index-guiding LMA fibers.

  • design of all solid leakage channel fibers with large mode area and low Bending Loss
    Optics Express, 2009
    Co-Authors: Kunimasa Saitoh, Masanori Koshiba, Lorenzo Rosa, Yukihiro Tsuchida, F Poli, A Cucinotta, S Selleri, Mrinmay Pal, Mukul Chandra Paul, Debashri Ghosh
    Abstract:

    We investigate a novel design for all-solid large mode area (LMA) leakage channel fibers (LCFs) for high-power Yb-doped fiber lasers and amplifiers, based on a single down-doped-silica rod ring surrounding a seven-cell pure-silica core, aiming for effectively single-mode behavior and low Bending Loss characteristics. Through detailed numerical simulations based on the finite element method (FEM), we find that the proposed all-solid LMA-LCFs, having a seven-cell core and two different sizes of down-doped rods, can achieve sufficient differential mode Loss and much lower Bending Loss, as compared with a previously-reported LCF with a one-cell core and six large down-doped-silica rods.

Pramod R Wateka - One of the best experts on this subject based on the ideXlab platform.

Shoichiro Matsuo - One of the best experts on this subject based on the ideXlab platform.

  • optimized graded index two mode optical fiber with low dmd large a eff and low Bending Loss
    Optics Express, 2013
    Co-Authors: Kiminori Sato, Shoichiro Matsuo, Ryo Maruyama, Nobuo Kuwaki, Masaharu Ohashi
    Abstract:

    An optimized two-mode optical fiber (TMF) with the graded index (GI) profile is designed and fabricated. We clarify an appropriate region of GI-TMF satisfying DMD = 0 ps/km, the large effective area Aeff, and the low Bending Loss for LP11 at 1550 nm. According to our fiber design, GI-TMF is successfully fabricated to have the large effective area Aeff of 150 μm2 for LP01 mode, and low DMD below 36 ps/km including zero in the C-band. We expect that our design GI-TMF is suitable for MDM and can reduce MIMO-DSP complexity.

  • effectively single mode all solid photonic bandgap fiber with large effective area and low Bending Loss for compact high power all fiber lasers
    Optics Express, 2012
    Co-Authors: Masahiro Kashiwagi, Kunimasa Saitoh, Shoichiro Matsuo, Katsuhiro Takenaga, Shoji Tanigawa, Munehisa Fujimaki
    Abstract:

    An effectively single-mode all-solid photonic bandgap fiber with large effective area and low Bending Loss for compact high-power all-fiber lasers is fully investigated. The pitch dependencies of effective area, Bending Loss, and effectively single-mode operation are discussed numerically and experimentally. The calculation results indicate that an effectively single-mode all-solid photonic bandgap fiber with an effective area of more than 500 μm2 and a Bending Loss of less than 0.1 dB/m at a Bending radius of 10 cm can be realized by choosing optimum fiber parameters. In a fabricated effectively single-mode all-solid photonic bandgap fiber with 48.0 μm core, the effective area of 712 μm2, the effectively single-mode operation, and the Bending Loss of less than 0.1 dB/m at a Bending radius of 10 cm are achieved simultaneously at 1064 nm.

  • low Bending Loss and effectively single mode all solid photonic bandgap fiber with an effective area of 650 μm 2
    Optics Letters, 2012
    Co-Authors: Masahiro Kashiwagi, Kunimasa Saitoh, Shoichiro Matsuo, Katsuhiro Takenaga, Shoji Tanigawa, Munehisa Fujimaki
    Abstract:

    A large-mode-area all-solid photonic bandgap fiber with a seven-cell core and five high-index rod rings is investigated. Numerical simulations show that an effective area of more than 500 μm2, a Bending Loss of less than 0.1 dB/m at a Bending radius of 10 cm and effectively single-mode operation can be achieved simultaneously. A core diameter of 44.8 μm and an effective area of 650 μm2 at 1064 nm are achieved in a fabricated fiber. Bending Loss at 1064 nm is 0.09 dB/m at a Bending radius of 7 cm. Effectively single-mode operation is also realized at a Bending radius of 10 cm.

  • low Bending Loss single mode fibers for fiber to the home
    Journal of Lightwave Technology, 2005
    Co-Authors: Kuniharu Himeno, Shoichiro Matsuo, Ning Gua, Akira Wada
    Abstract:

    Recent progress on low-Bending-Loss single-mode optical fibers for fiber-to-the-home (FTTH) is reviewed. Designing and manufacturing for three types of fibers-a step-index-profile fiber, a trench-index-profile fiber, and a holey fiber-are discussed. The trench-index-profile fibers and the holey fibers are confirmed to be candidates for indoor wiring because of their low Bending Losses, as well as splice Losses.

  • low Bending Loss and low splice Loss single mode fibers employing a trench index profile
    International Conference on Optical Internet, 2005
    Co-Authors: Shoichiro Matsuo, Masataka Ikeda, Hiroshi Kutami, Kuniharu Himeno
    Abstract:

    A single-mode fiber employing a trench index profile for indoor wiring is proposed to realize low-Bending Loss and low-splice Loss simultaneously. The designs and the advantages of the fiber over fibers with conventional step index profiles are described. The characteristics of manufactured fibers with trench index profiles are also described. One of the manufactured fibers realizes a Bending Loss of 0.018 dB/turn at 1550 nm for a Bending radius of 7.5 mm, and a splice Loss of 0.19 dB at 1550 nm in mechanical splicing to a conventional single mode fiber simultaneously. Other one of the fibers realizes a Bending Loss of 0.01 dB/tum at 1550 nm for a Bending radius of 5 mm, and the splice Loss is 0.37 dB at 1550 nm simultaneously. A total Loss of a fiber employing the trench index is small and stable against the fluctuation of MFD.

Munehisa Fujimaki - One of the best experts on this subject based on the ideXlab platform.

  • effectively single mode all solid photonic bandgap fiber with large effective area and low Bending Loss for compact high power all fiber lasers
    Optics Express, 2012
    Co-Authors: Masahiro Kashiwagi, Kunimasa Saitoh, Shoichiro Matsuo, Katsuhiro Takenaga, Shoji Tanigawa, Munehisa Fujimaki
    Abstract:

    An effectively single-mode all-solid photonic bandgap fiber with large effective area and low Bending Loss for compact high-power all-fiber lasers is fully investigated. The pitch dependencies of effective area, Bending Loss, and effectively single-mode operation are discussed numerically and experimentally. The calculation results indicate that an effectively single-mode all-solid photonic bandgap fiber with an effective area of more than 500 μm2 and a Bending Loss of less than 0.1 dB/m at a Bending radius of 10 cm can be realized by choosing optimum fiber parameters. In a fabricated effectively single-mode all-solid photonic bandgap fiber with 48.0 μm core, the effective area of 712 μm2, the effectively single-mode operation, and the Bending Loss of less than 0.1 dB/m at a Bending radius of 10 cm are achieved simultaneously at 1064 nm.

  • low Bending Loss and effectively single mode all solid photonic bandgap fiber with an effective area of 650 μm 2
    Optics Letters, 2012
    Co-Authors: Masahiro Kashiwagi, Kunimasa Saitoh, Shoichiro Matsuo, Katsuhiro Takenaga, Shoji Tanigawa, Munehisa Fujimaki
    Abstract:

    A large-mode-area all-solid photonic bandgap fiber with a seven-cell core and five high-index rod rings is investigated. Numerical simulations show that an effective area of more than 500 μm2, a Bending Loss of less than 0.1 dB/m at a Bending radius of 10 cm and effectively single-mode operation can be achieved simultaneously. A core diameter of 44.8 μm and an effective area of 650 μm2 at 1064 nm are achieved in a fabricated fiber. Bending Loss at 1064 nm is 0.09 dB/m at a Bending radius of 7 cm. Effectively single-mode operation is also realized at a Bending radius of 10 cm.