The Experts below are selected from a list of 25899 Experts worldwide ranked by ideXlab platform
Masanori Koshiba - One of the best experts on this subject based on the ideXlab platform.
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crosstalk suppressed hole assisted 6 core fiber with cladding diameter of 125 μm
2013Co-Authors: Taiji Sakamoto, Masanori Koshiba, Kunimasa Saitoh, Nobutomo Hanzawa, Kyozo Tsujikawa, Fumihiko YamamotoAbstract:We report 125 μm-cladding multi-core fiber for high-density space-division multiplexing transmission. We show numerically that a hole-assisted structure can reduce both crosstalk and Leakage Loss. We achieved 125 μm-cladding 6-core fiber experimentally with a low crosstalk of less than -30 dB/100km and a high normalized core multiplicity of 6.0.
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structural dependence of group velocity and Leakage Loss in 1 d photonic crystal coupled resonator optical waveguide with modulated mode gap
2012Co-Authors: Yuki Kawaguchi, Kunimasa Saitoh, Shuntaro Makino, Masanori KoshibaAbstract:One-dimensional photonic crystal coupled resonator optical waveguide (1-D PC-CROW) based on mode-gap confinement has a possibility to reduce Leakage Losses compared with conventional 1-D PC-CROW constructed by placing defects periodically. However, transmission characteristics of 1-D PC-CROW based on mode-gap confinement have not been investigated so far. In this paper, we evaluate structural dependence of group velocity and Leakage Losses of 1-D PC-CROW by using the 3-D vector finite element method for periodic waveguide analysis. We show that such 1-D PC-CROW can realize small group velocity and low Leakage Losses simultaneously by investigating dispersion relationships of 1-D PC-CROW.
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a design method of lithium niobate on insulator ridge waveguides without Leakage Loss
2011Co-Authors: Emi Saitoh, Yuki Kawaguchi, Kunimasa Saitoh, Masanori KoshibaAbstract:We evaluate structural dependency of Leakage Losses in lithium niobate on insulator ridge waveguides. Generally, shallow ridge waveguides based on isotropic materials have inherent Leakage Loss for TM-like mode. On the other hand, lithium niobate is anisotropic material, thus the optical properties of lithium niobate based ridge waveguides are different from those of isotopic material based ridge waveguides. In this paper, we investigate Leakage Losses of lithium niobate on insulator ridge waveguides. We show that the shallow ridge waveguide structure without Leakage Loss can be realized by choosing the waveguide parameters adequately.
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Generalized Simple Theory for Estimating Lateral Leakage Loss Behavior in Silicon-on-Insulator Ridge Waveguides
2009Co-Authors: Kuniaki Kakihara, Kunimasa Saitoh, Masanori KoshibaAbstract:In this paper, we numerically investigate the lateral Leakage Loss behavior for TM-like modes in silicon-on-insulator ridge waveguides. If the waveguide width is set to satisfy a certain condition, the Leakage Loss of the TM-like mode leads to be a minimum. When utilizing TM-like modes in the ridge waveguides, it is the main drawback that the tolerance for the variations in the waveguide width and operation wavelength is too small. In this paper, we propose a novel ridge waveguide structure, where a dimple is introduced at the ridge region. It is shown from the finite-element analysis that the ridge waveguide with a dimple is both low Loss and fabrication tolerant
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reduced lateral Leakage Losses of tm like modes in silicon on insulator ridge waveguides
2008Co-Authors: Masanori Koshiba, Kuniaki Kakihara, Kunimasa SaitohAbstract:We numerically investigate the lateral Leakage Loss behavior for TM-like modes in silicon-on-insulator ridge waveguides. In order to improve the Leakage Loss properties, we propose a novel ridge waveguide structure where a dimple is introduced at the ridge center. It is shown that the ridge waveguide with a dimple is both low Loss and fabrication tolerant. This behavior is predicted by not only an accurate finite-element-based analysis but also a simple, phenomenological effective-index-based analysis.
Kunimasa Saitoh - One of the best experts on this subject based on the ideXlab platform.
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crosstalk suppressed hole assisted 6 core fiber with cladding diameter of 125 μm
2013Co-Authors: Taiji Sakamoto, Masanori Koshiba, Kunimasa Saitoh, Nobutomo Hanzawa, Kyozo Tsujikawa, Fumihiko YamamotoAbstract:We report 125 μm-cladding multi-core fiber for high-density space-division multiplexing transmission. We show numerically that a hole-assisted structure can reduce both crosstalk and Leakage Loss. We achieved 125 μm-cladding 6-core fiber experimentally with a low crosstalk of less than -30 dB/100km and a high normalized core multiplicity of 6.0.
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structural dependence of group velocity and Leakage Loss in 1 d photonic crystal coupled resonator optical waveguide with modulated mode gap
2012Co-Authors: Yuki Kawaguchi, Kunimasa Saitoh, Shuntaro Makino, Masanori KoshibaAbstract:One-dimensional photonic crystal coupled resonator optical waveguide (1-D PC-CROW) based on mode-gap confinement has a possibility to reduce Leakage Losses compared with conventional 1-D PC-CROW constructed by placing defects periodically. However, transmission characteristics of 1-D PC-CROW based on mode-gap confinement have not been investigated so far. In this paper, we evaluate structural dependence of group velocity and Leakage Losses of 1-D PC-CROW by using the 3-D vector finite element method for periodic waveguide analysis. We show that such 1-D PC-CROW can realize small group velocity and low Leakage Losses simultaneously by investigating dispersion relationships of 1-D PC-CROW.
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a design method of lithium niobate on insulator ridge waveguides without Leakage Loss
2011Co-Authors: Emi Saitoh, Yuki Kawaguchi, Kunimasa Saitoh, Masanori KoshibaAbstract:We evaluate structural dependency of Leakage Losses in lithium niobate on insulator ridge waveguides. Generally, shallow ridge waveguides based on isotropic materials have inherent Leakage Loss for TM-like mode. On the other hand, lithium niobate is anisotropic material, thus the optical properties of lithium niobate based ridge waveguides are different from those of isotopic material based ridge waveguides. In this paper, we investigate Leakage Losses of lithium niobate on insulator ridge waveguides. We show that the shallow ridge waveguide structure without Leakage Loss can be realized by choosing the waveguide parameters adequately.
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reduced lateral Leakage Losses of tm like modes in silicon on insulator ridge waveguides
2008Co-Authors: Masanori Koshiba, Kuniaki Kakihara, Kunimasa SaitohAbstract:We numerically investigate the lateral Leakage Loss behavior for TM-like modes in silicon-on-insulator ridge waveguides. In order to improve the Leakage Loss properties, we propose a novel ridge waveguide structure where a dimple is introduced at the ridge center. It is shown that the ridge waveguide with a dimple is both low Loss and fabrication tolerant. This behavior is predicted by not only an accurate finite-element-based analysis but also a simple, phenomenological effective-index-based analysis.
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novel design of inherently gain flattened discrete highly nonlinear photonic crystal fiber raman amplifier and dispersion compensation using a single pump in c band
2005Co-Authors: Shailendra K. Varshney, Kunimasa Saitoh, Takeshi Fujisawa, Masanori KoshibaAbstract:In this paper, we report, for the first time, an inherently gain-flattened discrete highly nonlinear photonic crystal fiber (HNPCF) Raman amplifier (HNPCF-RA) design which shows 13.7 dB of net gain (with ±0.85-dB gain ripple) over 28-nm bandwidth. The wavelength dependent Leakage Loss property of HNPCF is used to flatten the Raman gain of the amplifier module. The PCF structural design is based on W-shaped refractive index profile where the fiber parameters are well optimized by homely developed genetic algorithm optimization tool integrated with an efficient vectorial finite element method (V-FEM). The proposed fiber design has a high Raman gain efficiency of 4.88 W-1· km-1 at a frequency shift of 13.1 THz, which is precisely evaluated through V-FEM. Additionally, the designed module, which shows ultra-wide single mode operation, has a slowly varying negative dispersion coefficient (-107.5 ps/nm/km at 1550 nm) over the operating range of wavelengths. Therefore, our proposed HNPCF-RA module acts as a composite amplifier with dispersion compensator functionality in a single component using a single pump.
Ke Wu - One of the best experts on this subject based on the ideXlab platform.
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substrate integrated nonradiative dielectric waveguide structures directly fabricated on printed circuit boards and metallized dielectric layers
2011Co-Authors: Feng Xu, Ke WuAbstract:A technique concerning the design and implementation of substrate integrated nonradiative dielectric (SINRD) waveguide is proposed in this paper. Different from the current SINRD waveguides, this scheme of making the SINRD guide structures directly out of the conventional printed circuit boards (PCBs) or similar platforms effectively eliminates cover metallic plates. This class of SINRD waveguides can be realized without resorting to a mechanical assembly as usually is done in the case of developing conventional nonradiative dielectric (NRD) guide circuits owing to the following two facts. First, increasing the width of the dielectric strip will decrease surface electric currents more significantly in the area of NRD strip. Second, the fabrication process and practical implementation are based on the concept of the substrate integration technique. In this case, air via-slot or via-hole arrays are created or punched directly on PCBs or metallized dielectric layers in order to fulfill the basic requirements of an SINRD waveguide design. By carefully choosing the SINRD dimensions and the pattern of via-slots or via-holes, potential Leakage Loss caused by these metallically uncovered via-slots or via-holes can be minimized and reduced to a negligible level. Therefore, the NRD waveguides can be designed and made through various processing techniques in a simple and practical manner for millimeter-wave and terahertz applications. In this paper, simulations and measurements have verified the proposed scheme.
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Finite-Difference Time-Domain Modeling of Periodic Guided-Wave Structures and Its Application to the Analysis of Substrate Integrated Nonradiative Dielectric Waveguide
2007Co-Authors: Feng Xu, Ke Wu, Wei HongAbstract:The finite-difference time-domain (FDTD) method incorporating an equivalent resonant cavity model is presented for the modeling and analysis of guided-wave propagation characteristics of complex periodic structures. By transforming electromagnetic field variables into a new set of periodic variables, which can also be resolved from the Maxwell's equations, one can convert a periodic guided-wave problem into an equivalent resonator problem. Thus, the FDTD method used for a resonant cavity problem can be adopted to simulate periodic guided-wave structures. In addition, the proposed FDTD algorithm can be extended to model Lossy periodic propagation problems. In this study, the substrate integrated nonradiative dielectric waveguide, which is a special type of periodic guided-wave structure subject to a potential Leakage Loss due to its periodic gaps, is investigated as a showcase. The proposed method is first validated and is then used to analyze the guided-wave characteristics of substrate integrated nonradiative dielectric waveguides. It is shown that the substrate integrated nonradiative dielectric waveguide structure, which can easily be fabricated in planar form, has a well-behaved propagation property suitable for high-performance millimeter-wave circuit design.
Feng Xu - One of the best experts on this subject based on the ideXlab platform.
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substrate integrated nonradiative dielectric waveguide structures directly fabricated on printed circuit boards and metallized dielectric layers
2011Co-Authors: Feng Xu, Ke WuAbstract:A technique concerning the design and implementation of substrate integrated nonradiative dielectric (SINRD) waveguide is proposed in this paper. Different from the current SINRD waveguides, this scheme of making the SINRD guide structures directly out of the conventional printed circuit boards (PCBs) or similar platforms effectively eliminates cover metallic plates. This class of SINRD waveguides can be realized without resorting to a mechanical assembly as usually is done in the case of developing conventional nonradiative dielectric (NRD) guide circuits owing to the following two facts. First, increasing the width of the dielectric strip will decrease surface electric currents more significantly in the area of NRD strip. Second, the fabrication process and practical implementation are based on the concept of the substrate integration technique. In this case, air via-slot or via-hole arrays are created or punched directly on PCBs or metallized dielectric layers in order to fulfill the basic requirements of an SINRD waveguide design. By carefully choosing the SINRD dimensions and the pattern of via-slots or via-holes, potential Leakage Loss caused by these metallically uncovered via-slots or via-holes can be minimized and reduced to a negligible level. Therefore, the NRD waveguides can be designed and made through various processing techniques in a simple and practical manner for millimeter-wave and terahertz applications. In this paper, simulations and measurements have verified the proposed scheme.
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Finite-Difference Time-Domain Modeling of Periodic Guided-Wave Structures and Its Application to the Analysis of Substrate Integrated Nonradiative Dielectric Waveguide
2007Co-Authors: Feng Xu, Ke Wu, Wei HongAbstract:The finite-difference time-domain (FDTD) method incorporating an equivalent resonant cavity model is presented for the modeling and analysis of guided-wave propagation characteristics of complex periodic structures. By transforming electromagnetic field variables into a new set of periodic variables, which can also be resolved from the Maxwell's equations, one can convert a periodic guided-wave problem into an equivalent resonator problem. Thus, the FDTD method used for a resonant cavity problem can be adopted to simulate periodic guided-wave structures. In addition, the proposed FDTD algorithm can be extended to model Lossy periodic propagation problems. In this study, the substrate integrated nonradiative dielectric waveguide, which is a special type of periodic guided-wave structure subject to a potential Leakage Loss due to its periodic gaps, is investigated as a showcase. The proposed method is first validated and is then used to analyze the guided-wave characteristics of substrate integrated nonradiative dielectric waveguides. It is shown that the substrate integrated nonradiative dielectric waveguide structure, which can easily be fabricated in planar form, has a well-behaved propagation property suitable for high-performance millimeter-wave circuit design.
Dongxiao Yang - One of the best experts on this subject based on the ideXlab platform.
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achieving both high birefringence and low Leakage Loss in double clad photonic crystal fibers
2010Co-Authors: Dongxiao Yang, Liang Wang, Lei Rao, Le Zhang, Kan Chen, Su LiuAbstract:Abstract In this paper, a novel double-clad photonic crystal fiber (DC-PCF) is proposed for achieving both high birefringence and low Leakage Loss. According to numerical simulation of the proposed PCF, the extraordinarily high birefringence (over 2×10−2) and low Leakage Loss of the order of 0.0001 dB/km over a large wavelength range are achieved simultaneously. Single-polarization single-mode (SPSM) operation with low Leakage Loss is also discussed and can be realized and optimized in the PCF by adopting suitable structure parameters.
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highly birefringent elliptical hole rectangular lattice photonic crystal fibers with modified air holes near the core
2007Co-Authors: Liang Wang, Dongxiao YangAbstract:In this work, modal birefringence and polarization-dependent Leakage Loss for the fundamental mode in elliptical-hole rectangular-lattice photonic crystal fibers (EH-RL-PCFs) with modified air holes near the core are investigated by using a full-vector, finite-difference method in the frequency domain. Numerical results show that by introducing modified air holes, a heightened modal birefringence of the order of 10-2 has been obtained within the wavelengths ranging from 1.0 to 1.6 μm in the proposed PCFs, with a lattice length of 2 μm and with a large lattice length of 3 μm at 1.55 μm.