Article
Optics
Elena A. Anashkina, Alexey Andrianov
Summary: This study comprehensively analyzed the dispersion and nonlinear properties of microstructured tellurite glass fibers with multiple cores, comparing them to single-core fibers in the near- and mid-infrared ranges. Discovered that the dispersion curves for in-phase and out-of-phase supermodes in multicore fibers shift in opposite directions from the dispersion curve for one-core fibers, with stronger effects for larger coupling between cores. Additionally, the dispersion of out-of-phase supermodes can be anomalous even at 1.55 μm, the wavelength of Er-doped fiber lasers.
Article
Engineering, Electrical & Electronic
Cristian Antonelli, Antonio Mecozzi
Summary: The proposed design for coupled-core multi-core fibers aims to achieve extremely low levels of modal dispersion – coined as NEMO fibers. This design sacrifices some fiber mode-mixing effectiveness in exchange for reducing nonlinear signal distortions. A semi-analytical tool developed in this study effectively characterizes the impact of various perturbations on the ideal fiber structure.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2021)
Article
Engineering, Electrical & Electronic
PeiXin Li, ChunCan Wang, ZhiYong Du
Summary: A method based on multicore fibers (MCF) is proposed to achieve large-mode-area (LMA) fibers with low and flat normal group velocity dispersion (GVD) profiles. The coupling between adjacent cores is analyzed to tailor the GVD of the MCF. Different designs of MCFs are used to achieve extremely flat GVD profiles in specific wavelength ranges.
OPTICAL FIBER TECHNOLOGY
(2022)
Article
Optics
Yu Yang, Ruiting Cheng, Jiaxin Liu, Mingqing Zuo, Yuyang Gao, Lei Shen, Lei Wang, Xiaoyu Zhu, Zhangyuan Chen, Yongqi He, Juhao Li
Summary: This paper evaluates the influence of Fan-in/fan-out (FI/FO) devices on short-reach optical interconnect and successfully demonstrates high-speed optical interconnection using low-crosstalk compact devices fabricated by the laser-direct-writing (LDW) technique.
Article
Geosciences, Multidisciplinary
Stefania Tamea, Marta Tuninetti, Irene Soligno, Francesco Laio
Summary: The text describes the establishment of a comprehensive database on water footprint and virtual water trade data for 370 agricultural goods to support national and global assessments of water use in agriculture. The database covers country-specific water footprint and virtual water trade data, differentiated by production and supply, and it traces the international trade of goods back to their production origins. This database, developed within the CWASI project, is available for contributions and improvements from the research community.
EARTH SYSTEM SCIENCE DATA
(2021)
Article
Optics
Zenghui Li, Shuguang Li, Yan Wang, Chun Wang, Pengshuai Hao, Yongze Liang, Enwang Liang, Zhongwei Tan, Tonglei Cheng, Yu Qin, Weiwei Xu, Hui Zhou
Summary: A graded-index 13-core 5-LP mode fiber with high doped core and stairway-index trench structure was successfully prepared using the Hole-drilling method and Plasma vapor deposition. This fiber has 104 spatial channels, enabling large capacity information transmission. Experimental testing showed that the core can stably transmit 5 LP modes with a transmission loss lower than 0.5 dB/km. The inter-core crosstalk (ICXT) analysis revealed that the ICXT can be less than -30 dB/100 km. The results demonstrate that this fiber can reliably transmit 5 LP modes with low loss and crosstalk, addressing the issue of limited fiber capacity.
Article
Automation & Control Systems
Fujin Jia, Junwei Lu, Yongmin Li
Summary: In this article, a control algorithm is proposed to solve the global stabilization control problem of MIMO nonlinear systems with UFVs. The algorithm is based on a Lemma dealing with UFVs and the backstepping method. It effectively solves the global stabilization control problem, reduces conservatism in UFV assumptions, and addresses the explosion of terms problem of backstepping. The algorithm ensures that all signals of the closed-loop system converge to the origin.
INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL
(2023)
Article
Optics
Alexey A. Wolf, Mikhail Skvortsov, Ivan A. Lobach, Alexandr Dostovalov, Sergey A. Babin
Summary: An all-fiber 4-core Yb-doped laser with a cavity formed by fiber Bragg gratings directly inscribed in each core with femtosecond laser pulses and 4% Fresnel reflection from the output fiber end face is demonstrated. The study reveals how the diameter of the active fiber winding affects the power distribution between the cores and proposes a mechanism for radiation concentration based on bending induced stress. The research also explores the optical and radio-frequency spectra of the output laser radiation and observes a narrowband lasing with periodic linear sweeping of central wavelength in the multicore fiber laser for the first time.
Article
Optics
Monserrat Alonso-Murias, David Monzon-Hernandez, Enrique Antonio-Lopez, Axel Schulzgen, Rodrigo Amezcua-Correa, Joel Villatoro
Summary: A nano-displacement sensing method based on an extrinsic hybrid fiber Fabry-Perot interferometer is proposed, achieving a resolution of 0.47 nm. By adjusting the optical path length difference between the air cavity and glass cavity, an interference spectra envelope with a larger period can be generated.
OPTICS AND LASER TECHNOLOGY
(2022)
Article
Optics
Chien-Hung Yeh, Bo-Yin Wang, Wei-Hung Hsu, Wei-Yao You, Jhao-Ren Chen, Chi-Wai Chow, Jing-Heng Chen
Summary: The paper demonstrates a stable erbium-doped fiber multiple-ring laser with self-injection of Rayleigh scattering, achieving single-longitudinal-mode operation and narrow linewidth output. Utilizing a commercial C-band EDF gain medium, stable output characteristics are achieved within a tuning bandwidth of 1524.0-1577.0 nm.
OPTICS AND LASER TECHNOLOGY
(2021)
Article
Environmental Sciences
Imogen Tennison, Sonia Roschnik, Ben Ashby, Richard Boyd, Ian Hamilton, Tadj Oreszczyn, Anne Owen, Marina Romanello, Paul Ruyssevelt, Jodi D. Sherman, Andrew Z. P. Smith, Kristian Steele, Nicholas Watts, Matthew J. Eckelman
Summary: This study presents the carbon footprint accounting and reduction measures of the National Health Service in England since 2008, identifying key areas for emission reduction through disaggregated data. In 2019, the healthcare system's emissions totaled 25 megatonnes of carbon dioxide equivalent, a 26% reduction since 1990.
LANCET PLANETARY HEALTH
(2021)
Article
Computer Science, Information Systems
Giorgio Guerzoni, Elahe Faghand, Giorgio Matteo Vitetta, Loris Vincenzi, Esfandiar Mehrshahi
Summary: This paper proposes two novel calibration methods for radar devices, which simplify the calibration process and improve the accuracy of target parameter estimation.
Article
Optics
Xian Dong, You-Hang Xie, Jia-Le Ou, Chuang Wu, Jie Li, Bai-Ou Guan
Summary: A Bragg grating is successfully formed in a strongly coupled seven-core fiber. Two separate Bragg resonance notches are observed in the transmission spectrum, corresponding to backward coupling of two supermodes of the fiber. The mode coupling mechanism is investigated both theoretically and experimentally, and the results agree well. The device shows potential for simultaneous measurement of temperature and curvature.
Article
Management
Rolf Fare, Hideyuki Mizobuchi, Valentin Zelenyuk
Summary: In this study, two popular notions in production theory, Hicks neutral technical change and homothetic technology, are analyzed. Isoquants in multiple-input and multiple-output situations are determined by input or output combinations. The study shows that under the alpha-returns to scale technology, the conditions for these two notions are equivalent.
OMEGA-INTERNATIONAL JOURNAL OF MANAGEMENT SCIENCE
(2021)
Article
Engineering, Environmental
Arunima Malik, Michael Padget, Sarah Carter, Takako Wakiyama, Isis Maitland-Scott, Aditya Vyas, Sinead Boylan, Georgina Mulcahy, Mengyu Li, Manfred Lenzen, Kate Charlesworth, Arne Geschke
Summary: Climate change is causing various impacts on communities, while the health system in New South Wales is found to have significant environmental impacts, responsible for a considerable portion of greenhouse gas emissions, water use, and waste production in the state's economy. Targeted policies are needed to reduce not only the direct impacts of health systems, but also those from their supply chains connecting with other economic sectors.
RESOURCES CONSERVATION AND RECYCLING
(2021)
Article
Engineering, Electrical & Electronic
Masaki Wada, Taiji Sakamoto, Shinichi Aozasa, Takayoshi Mori, Takashi Yamamoto, Kazuhide Nakajima
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2018)
Article
Engineering, Electrical & Electronic
Masaki Wada, Shinichi Aozasa, Taiji Sakamoto, Takayoshi Mori, Takashi Yamamoto, Kazuhide Nakajima
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2018)
Article
Engineering, Electrical & Electronic
Takayoshi Mori, Taiji Sakamoto, Masaki Wada, Azusa Urushibara, Takashi Yamamoto, Kazuhide Nakajima
OPTICAL FIBER TECHNOLOGY
(2019)
Article
Optics
Yoko Yamashita, Takashi Matsui, Taiji Sakamoto, Shinichi Aozasa, Masaki Wada, Takayoshi Mori, Kazuhide Nakajima
Article
Physics, Applied
Takeshi Fujisawa, Taiji Sakamoto, Masashi Miyata, Takashi Matsui, Toshikazu Hashimoto, Ryoichi Kasahara, Takayoshi Mori, Ryota Imada, Kazuhide Nakajima, Kunimasa Saitoh
Summary: A six-mode scrambler based on cascaded side-wall long-period-grating waveguides on a silica planar lightwave circuit (PLC) platform is proposed for mode-division-multiplexing (MDM) transmission. The mode-dependent loss (MDL) of the system can be reduced with multiple scrambling operations. Fabricated gratings and a fiber-pigtailed module confirm the expected proof-of-concept mode scrambling operation.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2021)
Article
Engineering, Electrical & Electronic
Yuto Sagae, Takashi Matsui, Taiji Sakamoto, Takayoshi Mori, Kazuhide Nakajima
Summary: We propose a multi-core fiber (MCF) with a low-latency core for master-slave carrier phase estimation (MS-CPE). We evaluate the temperature coefficient of skew and the signal-to-noise ratio (SNR) penalty resulting from the temperature dependence of the skew. The study shows that maintaining an SNR penalty of less than 1 dB requires stringent temperature requirements.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Engineering, Electrical & Electronic
Naoto Sugawara, Takeshi Fujisawa, Kodai Nakamura, Yusuke Sawada, Takayoshi Mori, Taiji Sakamoto, Ryota Imada, Takashi Matsui, Kazuhide Nakajima, Kunimasa Saitoh
Summary: A simple and efficient method based on artificial-neural-network (ANN) and optimization method is proposed for estimating multimode near field patterns (NFPs) amplitude and phase. By refining the inferred amplitude and phase with a grey-wolf optimizer (GWO), the image correlation between reproduced and measured NFPs is improved without re-training of ANN, offering an alternative way to enhance correlation without using complicated ANN.
OPTICAL FIBER TECHNOLOGY
(2021)
Article
Optics
Han Wang, Takeshi Fujisawa, Takanori Sato, Takayoshi Mori, Taiji Sakamoto, Yoko Yamashita, Ryota Imada, Kazuhide Nakajima, Kunimasa Saitoh
Summary: We propose 6-mode and 10-mode photonic lantern mode multiplexers based on two-and three-layer silica planar lightwave circuitry, respectively. The 6-mode multiplexer achieves transmission greater than -0.19 dB at a wavelength of 1550 nm for six different modes. The 10-mode multiplexer is designed to excite selected modes and achieves transmission greater than -1.15 dB at a wavelength of 1550 nm.
OPTICS COMMUNICATIONS
(2023)
Article
Engineering, Electrical & Electronic
Nobutomo Hanzawa, Takayoshi Mori, Yuto Sagae, Yusuke Yamada, Takashi Matsui, Kazuhide Nakajima
Summary: This paper investigates the relationship between cross-sectional geometry and splicing loss in a four-core multicore fiber (MCF) with a standard 125-mu m cladding diameter. We show that a binarized cross-sectional image helps accurately determine the cladding/core center. The validity of the measured geometry is demonstrated by comparing the measured and estimated splice loss histograms. Our results suggest that a four-core MCF can potentially achieve a feasible splicing loss property by considering the most stringent geometrical tolerance in the existing standard. However, further improvement to the MCF geometry and/or connector technology will be required to ensure the lowest connector loss standard when an additional tolerance for connector ferrules is needed.
OPTICAL FIBER TECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Yuto Sagae, Taro Iwaya, Takayoshi Mori, Taiji Sakamoto, Takashi Matsui, Kazuhide Nakajima
Summary: The characteristics of crosstalk (XT) noise-to-signal ratio in a distributed Raman amplifier (DRA) for bi-directional multi-core fiber (MCF) transmission are investigated. A model is proposed to calculate XT noise by considering the noise contribution from Rayleigh scattering. The validity of the model is verified numerically and experimentally. The model reveals that the XT noise-to-signal ratio varies with the on-off gain, providing a way to minimize XT noise while maintaining a net gain of less than 0 dB.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Takayoshi Mori, Takeshi Fujisawa, Junji Sakamoto, Yoko Yamashita, Taiji Sakamoto, Ryota Imada, Ryoto Ima, Takanori Sato, Kei Watanabe, Ryoichi Kasahara, Toshikazu Hashimoto, Kunimasa Saitoh, Kazuhide Nakajima
Summary: A low-loss and compact silica-based planar lightwave circuit (PLC) mode-dependent loss (MDL) equalizer is proposed for three-mode transmission. The device selectively attenuates one mode while maintaining low insertion loss for the others, effectively reducing modal gain differences. The variable range of the equalizer has a tradeoff relationship with wavelength bandwidth.
OPTICAL FIBER TECHNOLOGY
(2023)
Proceedings Paper
Engineering, Electrical & Electronic
Takeshi Fujisawa, Takayoshi Mori, Junji Sakamoto, Yoko Yamashita, Taiji Sakamoto, Ryota Imada, Ryoto Ima, Takanori Sato, Kei Watanabe, Ryoichi Kasahara, Toshikazu Hashimoto, Kazuhide Nakajima, Kunimasa Saitoh
Summary: A mode-dependent-loss (MDL) equalizer based on silica-PLC is proposed and experimentally demonstrated for the first time in three-mode transmission. By selectively attenuating specific modes, 1.5-dB MDL equalization is achieved for systems with large mode loss.
2022 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)
(2022)
Proceedings Paper
Engineering, Electrical & Electronic
Kenji Kurokawa, Hiroyuki Iida, Nobutomo Hanzawa, Takaya Oguma, Yoko Yamashita, Takayoshi Mori, Takashi Matsui, Kazuhide Nakajima
Summary: The study demonstrates that 4-core multi-core fiber has a stimulated Raman scattering threshold 2.6 times higher than single-core fiber, enabling signal transmission over 5 km with self-power feeding of more than 600 mW.
2022 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC)
(2022)
Proceedings Paper
Optics
Yoko Yamashita, Takayoshi Mori, Takashi Matsui, Kazuhide Nakajima
Summary: In this paper, a wavelength- and power-tunable in-fiber optical tap inscribed in a two-mode fiber (2MF) using a femtosecond laser was proposed. The optical tap is composed of a long-period fiber grating (LPG) and an asymmetric tap waveguide. By controlling the LPG design, the operation wavelength and branching-power ratio can be adjusted.
NEXT-GENERATION OPTICAL COMMUNICATION: COMPONENTS, SUB-SYSTEMS, AND SYSTEMS XI
(2022)
