The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform
Takaaki Ishigure - One of the best experts on this subject based on the ideXlab platform.
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Index Profile design of graded-Index core tapered polymer waveguide for low loss light coupling
2016 IEEE CPMT Symposium Japan (ICSJ), 2016Co-Authors: Hoshihiko Toda, Takaaki IshigureAbstract:Tapered polymer optical waveguides with graded-Index (GI) circular core are designed and fabricated using the Mosquito method. We show an ideal Index Profile design for the tapered polymer waveguide allowing a low-loss optical coupling between a VCSEL source and a multimode fiber/waveguide with a large misalignment tolerance.
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Index Profile design for low loss crossed multimode waveguide for optical printed circuit board
Optics Express, 2015Co-Authors: Takaaki Ishigure, Keishiro Shitanda, Yutaro OizmiAbstract:We present an Index Profile design for remarkably low loss multimode optical crossed waveguide. In this paper, we theoretically calculate the light propagation loss in crossed waveguides with step-Index (SI) and graded-Index (GI) square cores utilizing a ray tracing simulation. In this simulation, we focus on the Index exponent values for the GI Profile, which allows low crossing loss even if the number of crossing is as large as 50 or even if the crossing angle is as low as 20°. It is revealed that an Index exponent of 2.0 for the GI core strongly contributes to exhibit 35 times lower loss (0.072 dB after 50-perpendicular crosses) compared to the loss of the SI-core counterpart (2.58 dB after the same crossings). The GI cores with a smaller Index exponent exhibit better loss in crossed waveguides with a wide range of crossing angles from 30° to 90°. Furthermore, we discuss the effect of the refractive Index Profile at the intersection on the optical loss of crossed waveguides.
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multichannel parallel polymer waveguide with circular w shaped Index Profile cores
IEEE Photonics Technology Letters, 2007Co-Authors: Yusuke Takeyoshi, Takaaki IshigureAbstract:We fabricate a parallel optical waveguide whose cores are composed of perdeuterated acrylate polymer. We experimentally demonstrate that this waveguide has lower loss by one order of magnitude compared to an acrylate-based waveguide at 850-nm wavelength. The eye diagram measured after a 12.5-Gb/s 15-m transmission shows that this waveguide has sufficiently high bandwidth. In addition, we verify a strong crosstalk reduction due to the specific (W-shaped) refractive Index Profile in the waveguide.
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mode coupling control and new Index Profile of gi pof for restricted launch condition in very short reach networks
Journal of Lightwave Technology, 2005Co-Authors: Takaaki Ishigure, K. Ohdoko, Y Ishiyama, Yasuhiro KoikeAbstract:This paper confirms that numerical aperture (NA) is a key factor in mode coupling [the energy transfer among propagating modes in multimode fibers (MMF)] and that providing a high NA is a viable solution to reduce mode coupling in graded-Index plastic optical fibers (GI POFs). Furthermore, the authors propose a new refractive-Index-Profile design of GI POFs when only small mode groups are launched (restricted-launch condition), which is a combined Profile with the Index exponents lower and higher than optimum value for the core center and periphery, respectively. The advantage of the new Index Profile is investigated both experimentally and theoretically. Furthermore, it is verified that the high-bandwidth performance of GI POF with the new Index Profile under the restricted-launch condition is maintained even when statistical fiber bendings are added to the GI POF and when misalignment is caused at the optical coupling between the light source and the GI POF.
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modal bandwidth enhancement in a plastic optical fiber by w refractive Index Profile
Journal of Lightwave Technology, 2005Co-Authors: Takaaki Ishigure, K. Ohdoko, H Endo, Keita Takahashi, Yasuhiro KoikeAbstract:A plastic optical fiber (POF) having a W-shaped refractive Index Profile (W-shaped POF) was prepared for the first time that had a possibility to realize a higher bit rate transmission than those of the conventional silica-based multimode fiber and graded Index (GI) POF links. Since the W-shaped POF has a valley of the refractive Index at the boundary of the core and cladding of the conventional graded-Index (GI) POF, the group delay of higher order modes is strongly influenced, and the modal dispersion in the GI POF is compensated. By comparing the propagating mode properties of the W-shaped POF with those of the GI POF, we clarified theoretically and experimentally that the Index valley has a remarkable modal dispersion compensation effect.
J. L. Bolzinger - One of the best experts on this subject based on the ideXlab platform.
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Refractive-Index Profile reconstructions in planar waveguides by the WKB inverse method and reflectivity calculations
Journal of the Optical Society of America B, 1995Co-Authors: Pierre Mathey, Pierre Jullien, J. L. BolzingerAbstract:Two formalisms used in Index Profile reconstructions are compared. We develop a novel formulation of the WKB inverse method and show that this method is not sufficient to recover the entire Index Profile in ion-implanted waveguides. A reflectivity calculation involving a matrix formalism solves the problem. The Index Profile parameters are adjusted to fit experimental mode indices. With this formalism, the reconstruction of the entire Index Profile is achieved. An application is shown in a BaTiO3 sample.
Pierre Mathey - One of the best experts on this subject based on the ideXlab platform.
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Numerical analysis of a WKB inverse method in view of Index Profile reconstruction in diffused waveguides
Optics Communications, 1996Co-Authors: Pierre Mathey, P. JullienAbstract:A novel formulation of WKB inverse method is conducted and applied in view of Index Profile reconstruction in diffused waveguides. Systematic and local errors on the effective indices are investigated. The consequences on the Index Profile shapes are studied.
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Refractive-Index Profile reconstructions in planar waveguides by the WKB inverse method and reflectivity calculations
Journal of the Optical Society of America B, 1995Co-Authors: Pierre Mathey, Pierre Jullien, J. L. BolzingerAbstract:Two formalisms used in Index Profile reconstructions are compared. We develop a novel formulation of the WKB inverse method and show that this method is not sufficient to recover the entire Index Profile in ion-implanted waveguides. A reflectivity calculation involving a matrix formalism solves the problem. The Index Profile parameters are adjusted to fit experimental mode indices. With this formalism, the reconstruction of the entire Index Profile is achieved. An application is shown in a BaTiO3 sample.
Seongwoo Yoo - One of the best experts on this subject based on the ideXlab platform.
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large mode area inverse Index fiber with a graded Index Profile for high power single mode operation
Optics Express, 2017Co-Authors: Hyun Su Kim, Seongwoo YooAbstract:We propose a new gain fiber structure with an inverse Index Profile for high power amplification of a Gaussian single mode beam. A large mode area (LMA) design can be fulfilled with the inverse Index Profile by implementing a graded Index in the depressed core. We numerically show that the proposed gain fiber can guide a single mode Gaussian beam with a large beam area and amplify the beam to a kW level output power.
Yasuhiro Koike - One of the best experts on this subject based on the ideXlab platform.
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Methodological Approach To Control the Refractive Index Profile of Graded-Index Polymer Optical Fiber
Industrial & Engineering Chemistry Research, 2011Co-Authors: Makoto Asai, Yoshiki Mukawa, Satoshi Takahashi, Yasuhiro KoikeAbstract:The graded-Index polymer optical fiber (GI-POF) is a promising candidate for high-speed communication medium for very short reach networks such as home networks and office local area networks (LANs). It is well-known that there is an optimum refractive Index Profile to maximize bandwidth properties of GI-POF when the Profile is expressed by the power law equation. The interfacial-gel polymerization technique, one of the major conventional fabrication methods of GI-POF, has many processes, and the formation mechanism of refractive Index Profiles intricately depends on many parameters of fabrication conditions. Thus is very difficult to control and form an optimum radial refractive Index Profile in the GI-POF. Recently, the coextrusion process has been proposed for mass production of GI-POF. In this process, the forming process of refractive Index Profiles can be expressed by a simple advection−diffusion equation. Therefore, we investigated the general methodology to control refractive Index Profiles by num...
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mode coupling control and new Index Profile of gi pof for restricted launch condition in very short reach networks
Journal of Lightwave Technology, 2005Co-Authors: Takaaki Ishigure, K. Ohdoko, Y Ishiyama, Yasuhiro KoikeAbstract:This paper confirms that numerical aperture (NA) is a key factor in mode coupling [the energy transfer among propagating modes in multimode fibers (MMF)] and that providing a high NA is a viable solution to reduce mode coupling in graded-Index plastic optical fibers (GI POFs). Furthermore, the authors propose a new refractive-Index-Profile design of GI POFs when only small mode groups are launched (restricted-launch condition), which is a combined Profile with the Index exponents lower and higher than optimum value for the core center and periphery, respectively. The advantage of the new Index Profile is investigated both experimentally and theoretically. Furthermore, it is verified that the high-bandwidth performance of GI POF with the new Index Profile under the restricted-launch condition is maintained even when statistical fiber bendings are added to the GI POF and when misalignment is caused at the optical coupling between the light source and the GI POF.
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modal bandwidth enhancement in a plastic optical fiber by w refractive Index Profile
Journal of Lightwave Technology, 2005Co-Authors: Takaaki Ishigure, K. Ohdoko, H Endo, Keita Takahashi, Yasuhiro KoikeAbstract:A plastic optical fiber (POF) having a W-shaped refractive Index Profile (W-shaped POF) was prepared for the first time that had a possibility to realize a higher bit rate transmission than those of the conventional silica-based multimode fiber and graded Index (GI) POF links. Since the W-shaped POF has a valley of the refractive Index at the boundary of the core and cladding of the conventional graded-Index (GI) POF, the group delay of higher order modes is strongly influenced, and the modal dispersion in the GI POF is compensated. By comparing the propagating mode properties of the W-shaped POF with those of the GI POF, we clarified theoretically and experimentally that the Index valley has a remarkable modal dispersion compensation effect.
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optimum Index Profile of the perfluorinated polymer based gi polymer optical fiber and its dispersion properties
Journal of Lightwave Technology, 2000Co-Authors: Takaaki Ishigure, Yasuhiro Koike, J W FlemingAbstract:The significant advantages in bandwidth and low material dispersion of perfluorinated (PF) polymer-based graded-Index polymer optical fiber (GI POF) are theoretically and experimentally reported for the first time. It is confirmed that the low attenuation and low material dispersion of the PF polymer enables 1 Gb/s km and 10 Gb/s km transmission at 0.85-/spl mu/m and 1.3-/spl mu/m wavelengths, respectively. The PF polymer-based CI POF has very low material dispersion (0.0055 ns/nm/spl middot/km at 0.85 /spl mu/m), compared with those of the conventional PMMA-based POF and of multimode silica fiber (0.0084 ns/nm km at 0.85 /spl mu/m). Since the PF polymer-based GI POF has low attenuation from the visible to near infrared region, not only the 0.65-/spl mu/m wavelength which is in the low attenuation window of the PMMA-based GI POF, but other wavelengths such as 0.85-/spl mu/m or 1.3-/spl mu/m etc. can be adopted for the transmission wavelength. It is clarified in this paper that the wavelength dependence of the optimum Index Profile shape of the PF polymer-based GI POF is very small, compared to the optimum Index Profile shape of the silica-based multimode fiber. As a result, the PF polymer-based GI POF has greater tolerance in Index Profile variation for higher speed transmission than multimode silica fiber. The impulse response function of the PF polymer-based GI POF was accurately analyzed from the measured refractive Index Profile using a Wentzel, Kramers, Brillouin (WKB) numerical computation method. By considering all dispersion factors involving the Profile dispersion, predicted bandwidth characteristic of the PF polymer-based GI POF agreed well with that experimentally measured.
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formation of the refractive Index Profile in the graded Index polymer optical fiber for gigabit data transmission
Journal of Lightwave Technology, 1997Co-Authors: Takaaki Ishigure, M Satoh, O Takanashi, Eisuke Nihei, Shuntaro Yamazaki, Yasuhiro KoikeAbstract:Bandwidth characteristics of the large core graded Index polymer optical fiber (GI-POF) are theoretically and experimentally clarified. The refractive Index Profile of the GI-POF was controlled by interfacial-gel polymerization to investigate the relation between the Index Profile and the bandwidth characteristics. It was experimentally confirmed that the maximum bandwidth of the poly methyl methacrylate (PMMA) base GI-POF is at most 3 GHz for 100 m transmission using a typical laser diode emitting at 650-nm wavelength (3 nm source spectral width) when its refractive Index Profile is optimized. The maximum bandwidth theoretically estimated by considering both modal and material dispersions is approximately 3 GHz which is exactly the same as the measured value, while higher than 10 GHz for 100 m was expected if only modal dispersion was taken into account. The optimum refractive Index Profile of the PMMA base GI-POF is theoretically and experimentally clarified by considering the Profile dispersion further.
