Article
Engineering, Electrical & Electronic
Georg Rademacher, Ruben S. Luis, Benjamin J. Puttnam, Roland Ryf, Sjoerd van der Heide, Tobias A. Eriksson, Nicolas K. Fontaine, Haoshuo Chen, Rene-Jean Essiambre, Yoshinari Awaji, Hideaki Furukawa
Summary: This paper compares the use of 3-mode few-mode fibers and 3-core coupled-core multi-core fibers in space-division multiplexed transmission systems. The analysis shows that the coupled-core multi-core fiber achieves higher data rates at shorter transmission distances.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Optics
Pengshuai Shao, Luyao Wang, Yan Wang, Shuguang Li, Zenghui Li, Xiaokai Wang, Liling Ma, Xiaojian Meng, Ying Guo, Jianshe Li, Tonglei Cheng, Yongze Liang, Weiwei Xu, Yu Qin, Hui Zhou
Summary: This study prepares seven-core five-mode fiber and single-core five-mode fiber with the same core structure using plasma chemical vapor deposition. The transmission characteristics of the fibers are measured and characterized, revealing stable transmission of multiple LP modes and low loss and bending resistance in the single-core fiber. The seven-core fiber shows low transmission loss and inter-core crosstalk, enabling high-density and low-crosstalk transmission. These achievements contribute to the development of future communication systems.
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
Yusuke Sasaki, Ryohei Fukumoto, Katsuhiro Takenaga, Shogo Shimizu, Kazuhiko Aikawa
Summary: Combining small-diameter optical-fiber technology with multicore fiber is a promising method to increase the transmission capacity of optical networks. In this study, a four-core fiber with a 200-mu m coating diameter was successfully fabricated and demonstrated excellent performance. It is suitable for applications in high-fiber-count cables.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Computer Science, Hardware & Architecture
Yuya Seki, Yosuke Tanigawa, Yusuke Hirota, Hideki Tode
Summary: Space-division multiplexing elastic optical networks (SDM-EONs) with multi-core fibers (MCFs) have been improved by solving the route, modulation format, core, and spectrum assignment problems, but inter-core crosstalk (IC-XT) still needs to be addressed. This paper proposes a hierarchical core prioritization method to mitigate IC-XT and demonstrates its effectiveness through simulation results.
JOURNAL OF OPTICAL COMMUNICATIONS AND NETWORKING
(2023)
Article
Engineering, Electrical & Electronic
Mayu Nakagawa, Masaki Ohzeki, Katsuhiro Takenaga, Kentaro Ichii
Summary: This paper proposes a novel method for inter-core crosstalk measurement in multi-core fibers using loopback and bidirectional optical time-domain reflectometer (OTDR) technique. The method enables simultaneous measurement of crosstalk and fiber attenuation, using the same measurement system as standard single-mode fibers.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Tristan Kremp, Yue Liang, Alan H. McCurdy
Summary: Multicore fiber is a promising technology to increase the transmission bandwidth of optical fiber links. Fusion splicing is indispensable for connecting multicore fibers, and precise alignment is crucial to minimize insertion loss. This paper presents an azimuthal alignment algorithm based on side-view images, which considers the twist rates of the fibers. The algorithm has been demonstrated to be stable and versatile for various fibers, achieving low splice losses and accurate twist rate detection.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2023)
Article
Optics
Afzal Hossain, S. P. Majumder
Summary: The study found that crosstalk in 9-core and 7-core multi-core optical fibers is more pronounced compared to the 3-core fiber, leading to significant deterioration in Bit Error Rate (BER) performance. Additionally, there is a minimum achievable BER corresponding to specific core pitch and number.
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
Engineering, Electrical & Electronic
Junhe Zhou, Haoqian Pu
Summary: This paper introduces a generalized analytical approach to study random crosstalk in multicore/multimode fibers. The proposed method accurately describes the crosstalk in both weakly coupled and strongly coupled regimes, and can compute the covariance of the modal power.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Optics
Zenghui Li, Luyao Wang, Yan Wang, Shuguang Li, Xiaojian Meng, Ying Guo, Guorui Wang, Han Zhang, Tonglei Cheng, Weiwei Xu, Yu Qin, Hui Zhou
Summary: The novel fiber design proposed in this study can achieve low inter-core crosstalk and large mode differential group delay. The optimized fiber design demonstrates good performance in terms of ICXT and meets fabrication conditions.
Article
Engineering, Electrical & Electronic
Yizhou Wang, Takeshi Fujisawa, Yuto Sagae, Taiji Sakamoto, Takashi Matsui, Kazuhide Nakajima, Kunimasa Saitoh
Summary: This study demonstrates the feasibility of designing multi-core fibers with a simple step-index profile within a standard cladding diameter, showing potential for further increasing core numbers with heterogeneous core arrangements. A novel method of allocating non-identical cores in heterogeneous MCFs is proposed to improve crosstalk and critical bending radius compared to conventional methods, suggesting potential applications of these new types of step-index MCFs in space-division multiplexing systems.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2021)
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
Jitao Gao, Elham Nazemosadat, Yi Yang, Songnian Fu, Ming Tang, Jochen Schroeder, Magnus Karlsson, Peter Andrekson
Summary: This study proposes an optical cross-connect scheme based on nonlinear optical fibers to achieve wavelength and spatial mode conversion, reducing cost and configuration complexity, which is suitable for future WDM-MDM networks.
IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS
(2021)
Article
Engineering, Electrical & Electronic
Yingning Wang, Yuanpeng Liu, Wenqian Zhao, Jian Yang, Wenpu Geng, Yuxi Fang, Changjing Bao, Yongxiong Ren, Zhi Wang, Yan-ge Liu, Zhongqi Pan, Yang Yue
Summary: This paper designs and analyzes a multi-ring-air-core fiber supporting thousands of OAM modes, and investigates the tradeoffs between ring number/density and system performance parameters. Based on the analytical results, the fiber has high transmission rate and spectrum efficiency, and shows great potential for various applications in optical communication systems.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Physics, Applied
Taichi Muratsubaki, Takeshi Fujisawa, Yusuke Sawada, Takanori Sato, Kunimasa Saitoh
Summary: The novel direct-binary-search algorithm proposed enhances the device performance under diameter variation by considering structures based on holes with different diameters. Through the design of a fabrication-tolerant four-mode waveguide crossing in the 2μm waveband, the proposed method shows improved transmission of TE3 mode and good insertion losses and crosstalks despite diameter variations.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Engineering, Electrical & Electronic
Yusuke Sasaki, Ryohei Fukumoto, Katsuhiro Takenaga, Shogo Shimizu, Kazuhiko Aikawa
Summary: Combining small-diameter optical-fiber technology with multicore fiber is a promising method to increase the transmission capacity of optical networks. In this study, a four-core fiber with a 200-mu m coating diameter was successfully fabricated and demonstrated excellent performance. It is suitable for applications in high-fiber-count cables.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Engineering, Electrical & Electronic
Kunimasa Saitoh
Summary: This paper describes the coupling mechanisms and design issues in multi-core fibers (MCFs) for space division multiplexing. For uncoupled MCFs, a design procedure considering random structural perturbations, correlation length, and birefringence beat length on inter-core crosstalk is presented based on coupled mode theory. Furthermore, for coupled MCFs, a numerical estimation method for modal dispersion is described, along with a method to enhance random mode mixing.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Optics
Kodai Nakamura, Takeshi Fujisawa, Kunimasa Saitoh
Summary: A novel hybrid algorithm combining GWO and DBS is proposed for designing mosaic-based devices, resulting in improved average and best performances by 0.5 and 1.6 points compared to designs using DBS alone.
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS
(2022)
Article
Optics
Yizhou Wang, Takeshi Fujisawa, Kunimasa Saitoh
Summary: The paper presents an analytical expression for the mode-coupling coefficient between non-identical step-index cores, allowing for quick estimation of crosstalk in heterogeneous SI multi-core fibers. The analytical results are validated through numerical simulations using FEM and show good agreement. The feasibility of designing Hetero-SI-MCFs within standard cladding diameter is discussed, highlighting potential applications in SDM systems.
OPTICS COMMUNICATIONS
(2022)
Article
Optics
Aichi Muratsubaki, Takeshi Fujisawa, Takanori Sato, Kunimasa Saitoh
Summary: Two types of mosaic-based 2 x 2 3-dB couplers for wavelengths around 2.1 μm are proposed, with different loss and imbalance characteristics, and high fabrication tolerance.
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS
(2022)
Article
Optics
Takeshi Fujisawa, Kunimasa Saitoh
Summary: By introducing air-holes around the core of a ring-core fiber, arbitrary higher-order spatial states generation can be achieved, including orbital angular momentum states. This mechanism, not relying on phase matching, exhibits very low wavelength dependence, providing a novel and efficient approach for manipulating the spatial state of light.
Article
Engineering, Electrical & Electronic
Yuto Sagae, Takashi Matsui, Takayoshi Mori, Taiji Sakamoto, Taro Iwaya, Takanori Sato, Kunimasa Saitoh, Kazuhide Nakajima
Summary: We propose a design concept for a 3-mode 4-core fiber with a common depressed layer and numerically investigate its performance compared to other types of weakly coupled homogeneous 3-mode 4-core fibers. We find that the fiber with the common depressed layer effectively suppresses optical confinement loss while maintaining feasible inter-core crosstalk. We confirm the feasibility of the proposed design through evaluating the fabricated fiber's optical characteristics and further optimize the design to achieve lower loss.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2023)
Article
Optics
Zheyu Zhao, Takanori Sato, Takeshi Fujisawa, Taro Iwaya, Yuto Sagae, Taiji Sakamoto, Takashi Matsui, Kazuhide Nakajima, Kunimasa Saitoh
Summary: This paper investigates the design of C-band double-cladding 2LP mode multicore fiber (2LP-MCF) with 125-mu m cladding diameter by numerical simulation. The results show that using a two-ring layout can improve crosstalk and critical bend radius, leading to significantly reduced crosstalk levels in 8-core and 10-core 2LP-MCFs compared to heterogeneous 2LP-MCFs without a double-cladding layer.
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS
(2023)
Article
Optics
Takeshi Fujisawa, Takuya Mitarai, Takuya Okimoto, Naoya Kono, Naoki Fujiwara, Takanori Sato, Hideki Yagi, Kunimasa Saitoh
Summary: This paper investigates ultracompact mode multiplexers based on a mosaic structure for various wavelength bands. The Bayesian technique is used for the design, showing its superiority in the search for the best structure. The fabricated devices on the Si-waveguide platform demonstrate the potential of mosaic-based devices for future compact optical transceivers.
Article
Optics
Takanori Sato, Takeshi Fujisawa, Masaki Wada, Takayoshi Mori, Taiji Sakamoto, Ryota Imada, Takashi Matsui, Kazuhide Nakajima, Kunimasa Saitoh
Summary: We propose a silica-based LP11 mode rotator with multiple tapered trenches, which is a basic and indispensable optical component for space division multiplexing. Compared with the conventional interference-based LP11 mode rotator with a simple L-shape waveguide, our proposed rotator has advantages in mode conversion efficiency, insertion loss, and fabrication tolerance due to the adiabatic mode conversion principle. By using a shortcut to adiabaticity approach, we effectively miniaturize the device compared to standard tapered structures. Among silica-based mode multi/demultiplexers, our proposed LP11 mode rotator shows considerable promise.
Article
Optics
Zheyu Zhao, Yizhou Wang, Takanori Sato, Takeshi Fujisawa, Kunimasa Saitoh
Summary: The numerical results of 6-core and 8-core step-index 2LP-mode multi-core fibers with 125-μm cladding diameter and two-ring layout for C-band show that the crosstalk less than -51 and -35 dB/km can be obtained respectively. It is found that the two-ring layout is beneficial for improving the crosstalk and critical bending radius, and it is effective for both few-mode and single-mode multi-core fibers.
Proceedings Paper
Optics
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: This study presents a low loss silica PLC based mode dependent loss equalizer with a variable range of 2.5 dB. It demonstrates a variable differential modal gain equalization in a two-LP-mode EDFA over the entire C-band for the first time.
2022 EUROPEAN CONFERENCE ON OPTICAL COMMUNICATION (ECOC)
(2022)
Proceedings Paper
Optics
Yuto Sagae, Takashi Matsui, Taiji Sakamoto, Taro Iwaya, Takayoshi Mori, Takanori Sato, Kunimasa Saitoh, Kazuhide Nakajima
Summary: A higher relative core multiplicity factor of beyond 12 is achieved in a 125-mu m cladding diameter uncoupled multi-core fibre by using a common depressed layer design. Feasible inter-core crosstalk below -40 dB/km and effective area over 80 mu m(2) in C-L band are successfully obtained simultaneously.
2022 EUROPEAN CONFERENCE ON OPTICAL COMMUNICATION (ECOC)
(2022)
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)
