Article
Engineering, Electrical & Electronic
Tetsuya Hayashi, Taiji Sakamoto, Yusuke Yamada, Roland Ryf, Rene-Jean Essiambre, Nicolas Fontaine, Mikael Mazur, Haoshuo Chen, Takemi Hasegawa
Summary: Randomly-coupled multi-core fiber (MCF) technology has gained attention for its applicability in long-haul transmission systems. Compared to weakly-coupled MCFs, randomly-coupled MCFs can achieve higher spatial channel density and lower transmission loss using existing single-mode fiber core designs. This article provides an overview of the advancements in randomly-coupled MCF technology, including its classification, design, optical property characterization methods, and performance improvements in transmissions.
PROCEEDINGS OF THE IEEE
(2022)
Article
Engineering, Electrical & Electronic
Shimpei Shimizu, Takayuki Kobayashi, Takushi Kazama, Takeshi Umeki, Masanori Nakamura, Koji Enbutsu, Takahiro Kashiwazaki, Ryoichi Kasahara, Kei Watanabe, Yutaka Miyamoto
Summary: The optical parametric amplifier (OPA) is a promising technology for optical communications due to its wideband, high gain, and fast transient response. It enables various optical signal processing and wavelength conversion using idler light generated during amplification. A PPLN waveguide serves as the amplification medium, allowing for wideband and high-gain amplification. This paper presents the configuration and applications of a 4-port PPLN module, including wideband inline amplification demonstration and inter-band wavelength conversion between C- and S-bands.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Engineering, Electrical & Electronic
Benjamin J. Puttnam, Ruben S. Luis, Georg Rademacher, Yoshinari Awaji, Hideaki Furukawa
Summary: By investigating the recirculating transmission of a wideband S-, C-, and L-band signal in a 4-core fiber, we have discovered the potential to increase data-rates in long-haul optical fiber transmission, including the S-band. Additionally, our experiment confirms that 125 mu m diameter multi-core fibers can multiply transmission capacity and offer the benefits of resource sharing and integration.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Engineering, Electrical & Electronic
Shimpei Shimizu, Takayuki Kobayashi, Takushi Kazama, Takeshi Umeki, Masanori Nakamura, Koji Enbutsu, Ryoichi Kasahara, Yutaka Miyamoto
Summary: This paper presents a method using CD pre-equalization based on PPLN-based PSA to achieve 2-THz WDM single-span transmission. The CD is accurately estimated by estimating the gain characteristic of the PSA and compensated through a CD controller. Experimental results show that this method enables high-symbol-rate and wideband WDM signal transmission.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
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
Engineering, Electrical & Electronic
Vladimir Gordienko, Filipe M. Ferreira, Chandra B. Gaur, Nick J. Doran
Summary: The study focuses on polarization insensitive fiber optical parametric amplifiers utilizing a balanced polarization diversity loop with at least two unidirectional gain fibers. Three variants of looped polarization insensitive FOPAs optimized for noise figure, mitigation of nonlinear impairments, and their trade-off are described and compared. Testing results demonstrate the ability of these FOPAs to deliver low noise figures <6 dB for output signal power as high as 29 dBm while enabling polarization insensitive gain.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2021)
Article
Engineering, Electrical & Electronic
Shimpei Shimizu, Takayuki Kobayashi, Takushi Kazama, Masanori Nakamura, Akira Kawai, Koji Enbutsu, Takeshi Umeki, Yutaka Miyamoto
Summary: This paper investigates the conversion of gain saturation into nonlinear amplitude distortion in a 64-Gbaud 64QAM WDM signal in a periodically poled LiNbO3 (PPLN) based optical parametric amplifier (OPA). The results show that increasing the number of WDM channels can suppress nonlinear amplitude distortion, and for a 75-GHz-spacing 64-channel WDM configuration, the total input power tolerance was improved by about 10 dB compared to a single-channel case. The experiment also confirms that there is almost no wavelength dependence of the effect of gain saturation on the signal distortion.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Themistoklis Chrysostomidis, Ioannis Roumpos, Konstantinos Fotiadis, Jinfeng Mu, Athanasios Manolis, Christos Vagionas, Meindert Dijkstra, Sonia Garcia Blanco, Theonitsa Alexoudi, Konstantinos Vyrsokinos
Summary: This paper presents a comprehensive study on the high-speed wavelength-division multiplexing (WDM) transmission capabilities of a monolithically integrated Al2O3:Er3+ spiral waveguide amplifier. The results demonstrate high-performance transmission at different data rates and without the need for digital signal processing (DSP) applied on the transmitter or receiver side.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Engineering, Electrical & Electronic
Hrishikesh Srinivas, Oleksiy Krutko, Joseph M. Kahn
Summary: Scaling up cable capacity in long-haul optical communication is a goal of spatial-division multiplexing (SDM). Multicore or multimode fiber systems promise higher integration, but efficient coupling of pump light and mode-dependent gain control pose challenges. We propose an integrated multimode amplifier design that excites only four pump spatial modes and predicts flat gain, low noise figure, and minimal mode-dependent gain over a wide bandwidth.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Chawaphon Prayoonyong, Bill Corcoran
Summary: Microring resonators can act as selective filters for amplified optical frequency combs, reducing the impact of broadband noise. Comb distillation, the approach used in amplifying low-power microcombs, can significantly lower the required optical-carrier-to-noise ratio for optical communications. This paper establishes closed form solutions for noise after distillation and directly links it to achievable system signal-to-noise ratio, allowing for the assessment of system performance with changes in the bandwidth and coupling loss of the distilling MRR device. This can help predict the increased usability of microcombs for superchannel transmission or space-division-multiplexing systems based on a distilled microcomb.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Taiji Sakamoto, Masaki Wada, Shinichi Aozasa, Ryota Imada, Takashi Yamamoto, Kazuhide Nakajima
Summary: By adjusting the length of the erbium-doped fiber, a 12-core EDFA can operate in both C and L bands, demonstrating good amplification characteristics and applicability for inline amplified transmission systems. The study found that for long-distance SDM transmission, MDL impacts the power efficiency of randomly coupled multi-core EDFAs.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2021)
Article
Engineering, Electrical & Electronic
Ximeng Zhang, Min Zhang, Yuchen Song, Xiaotian Jiang, Fan Zhang, Danshi Wang
Summary: In modern optical transmission systems, accurate and reliable simulation of optical fiber is crucial for various applications. Machine learning (ML) has contributed to novel developments in this field by solving the problem of slow computation. However, many ML-based optical channel models sacrifice flexibility. Deep operator network (DeepONet) is proposed as an alternative solution for multiple application scenarios.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Youichi Akasaka, Paparao Palacharla, Shigehiro Takasaka, Ryuichi Sugizaki
Summary: Optical amplification using fiber nonlinearities can extend beyond the traditional C and L-bands. This paper proposes a hybrid amplifier that combines parametric wavelength conversion, Raman amplification, and phase-sensitive amplification to achieve sufficient gain in new bands while suppressing amplified spontaneous emission. The prototype of the amplifier achieved a wide gain bandwidth, high net gain, and reduced ASE level.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2023)
Article
Materials Science, Multidisciplinary
Haoyang Ren, Yingning Wang, Wenpu Geng, Wenqian Zhao, Runzhou Zhang, Zhongqi Pan, Yang Yue
Summary: This paper presents a design of a multi-ring air-core trench-assisted fiber that supports transmission over the entire C + L band with low inter-ring crosstalk. The effects of the ring spacing, wavelength range, and doping concentration on the crosstalk suppression are systematically investigated. The complexity of the MIMO processing system is greatly reduced with a fewer-optical-core structure while keeping low inter-ring crosstalk.
RESULTS IN PHYSICS
(2023)
Article
Engineering, Electrical & Electronic
Haihong Bao, Wei Jin, Yingzhen Hong, Hoi Lut Ho, Shoufei Gao, Yingying Wang
Summary: Photothermal interferometry with hollow core fibers enables highly sensitive spectroscopic gas sensors. By exploiting the optical-phase-modulation amplifying effect of an HCF resonating cavity, significant improvement in the limit of detection is achieved, enabling ultra-sensitive gas detection.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Criminology & Penology
Vania Ceccato, Tulio Kahn, Christopher Herrmann, Anders Ostlund
Summary: Studies have shown that the COVID-19 pandemic has had a significant impact on crime levels in cities worldwide, with breaks in trends observed after the implementation of stay-at-home orders in New York, Sao Paulo, and Stockholm. The effect varies by crime type and city context, with residential burglary decreasing and nonresidential burglary increasing overall. Vehicle theft levels and geography also changed, with more cold spots observed and existing crime concentrations solidifying in certain areas.
JOURNAL OF CONTEMPORARY CRIMINAL JUSTICE
(2022)
Article
Business, Finance
Mats Wilhelmsson, Vania Ceccato, Manne Gerell
Summary: This study uses a regression discontinuity design method to estimate the short-term effects of shootings on housing values. The findings indicate that shootings have direct impacts on those affected and indirect impacts on the surrounding environments. The indirect effects on housing values are momentary and long-lasting, with prices not returning to pre-shooting levels even 100-200 days after the incidents.
JOURNAL OF EUROPEAN REAL ESTATE RESEARCH
(2022)
Article
Computer Science, Hardware & Architecture
Ruben S. Luis, Benjamin J. Puttnam, Georg Rademacher, Satoshi Shinada, Tetsuya Hayashi, Tetsuya Nakanishi, Yuki Saito, Tetsu Morishima, Hideaki Furukawa
Summary: This study demonstrates the use of spatial division multiplexing (SDM) to implement spine-leaf datacenter network topologies. Two possible scenarios are considered. The first scenario utilizes high-capacity multicore fiber interconnects, achieving a combined throughput of 12.8 Tb/s. The second scenario utilizes multicore fiber interconnects to establish multiple connections between pairs of spin-leaf switches, reducing the number of cables required.
JOURNAL OF OPTICAL COMMUNICATIONS AND NETWORKING
(2023)
Book Review
Criminology & Penology
Vania Ceccato
CRIME PREVENTION & COMMUNITY SAFETY
(2023)
Article
Geography
Reka Solymosi, David Buil-Gil, Vania Ceccato, Eon Kim, Ulf Jansson
Summary: This article discusses the emerging ethical issue of geodata privacy in geographical research, emphasizing the importance of considering privacy challenges and providing explicit ways for researchers and practitioners to address these issues. It highlights key problems in this area, introduces open research areas and questions, and recommends approaches to manage legal and ethical frameworks while promoting openness and transparency.
Article
Geography
Jacob Hassler, Vania Ceccato
Summary: This study analyzes the spatial and temporal variations in ambulance demand in southern Sweden and explores the association between land use factors, sociodemographic factors, and demand variations. The study uses ambulance dispatch data in southern Sweden in 2018 to calculate a standardized ambulance demand ratio (SADR). The findings reveal that while rural areas have a higher risk of requiring an ambulance (especially during the daytime), the higher dispatches in urban areas may obscure this risk. Factors such as the presence of bars, nightclubs, schools, industrial areas, and road crossings contribute to temporal variations in ambulance demand. Land use factors and sociodemographic factors, such as the proportion of older adults and median income, are associated with variations in ambulance demand. Population size alone may not be an accurate indicator of ambulance demand, and planning should consider daily changes in population sizes and compositions.
GEOGRAFISKA ANNALER SERIES B-HUMAN GEOGRAPHY
(2023)
Article
Information Science & Library Science
Vania Ceccato, Emrah Ercin, Julia Hazanov, Sara Elfstroem, Adriana Sampaio
Summary: This study explores the safety experiences and concerns of library visitors and personnel to understand the safety conditions of a library. The analysis is based on a small sample survey, interviews, and incident records in a library in Stockholm, Sweden. The findings show that the staff feel most unsafe when dealing with visitors under the influence of drugs/alcohol or when intimidated by groups of young individuals. Visitors declare witnessing problems of public disturbance and disorderly conduct, fights, and other types of aggression. The study emphasizes the importance of the environment in ensuring the safety conditions of the library.
LIBRARY MANAGEMENT
(2023)
Article
Engineering, Electrical & Electronic
Ruben S. Luis, Georg Rademacher, Benjamin J. Puttnam, Giammarco Di Sciullo, Andrea Marotta, Robert Emmerich, Nicolas Braig-Christophersen, Ralf Stolte, Fabio Graziosi, Antonio Mecozzi, Colja Schubert, Giuseppe Ferri, Frank Achten, Pierre Sillard, Roland Ryf, Lauren Dallachiesa, Satoshi Shinada, Cristian Antonelli, Hideaki Furukawa
Summary: This paper extends a recent demonstration of a 2-line side 15-mode spatial division multiplexing network node. The node uses fifteen 2 x 2 wavelength cross-connects (WXCs) to direct up to six 5 Tb/s, 15-mode, spatial super channels (SSCs). The network node is demonstrated using a 6.1 km, 15-mode, multi-mode fiber (MMF) and further extended to support up to 20 SSCs for a throughput per line side of 100 Tb/s. MIMO requirements for this type of systems are strongly dependent on the differential delays of the different modes propagating within the network node.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2023)
Article
Ecology
Yuhao Kang, Jonatan Abraham, Vania Ceccato, Fabio Duarte, Song Gao, Lukas Ljungqvist, Fan Zhang, Per Nasman, Carlo Ratti
Summary: The perception of safety in the built environment is crucial for public policies aimed at improving urban safety. This study in Stockholm, Sweden, used a geospatial artificial intelligence (GeoAI) approach to measure residents' safety perceptions. The results showed that while the GeoAI-based measures captured people's instant impressions of the built environment across the city, the survey-based measures reflected their overall daily experiences in specific areas.
LANDSCAPE AND URBAN PLANNING
(2023)
Article
Engineering, Civil
Subeh Chowdhury, Priya Patel, Varun Giridharan, Vania Ceccato
Summary: The study focuses on young ethnic minority women's challenges and adaptive behavior when using public transport. Findings show that these women commonly engage in pre-planning nighttime trips, rely on their phones to act confident and communicate with family en-route, and appear disinterested to reduce unwanted attention. Their experiences highlight the level of anxiety they face due to their ethnicity and the culture of stranger-danger, which erodes their confidence to travel independently. The current design of public transport systems does not adequately meet the travel needs of certain groups of women, and public transport authorities are encouraged to gain deeper insights and develop inclusive design strategies.
TRANSPORTATION RESEARCH RECORD
(2023)
Article
Urban Studies
Vania Ceccato, Omkar Parishwad, Ned Levine
Summary: This study investigates the spatiotemporal patterns of public disturbance acts in Stockholm, Sweden. Using crowdsourced data, the number of records before and after the COVID-19 pandemic stay-at-home measures is compared, controlling for seasonal trends. Poisson-Gamma-CAR regression models are utilized to assess the impact of land use on the spatial distribution of public disturbance acts, considering pandemic restrictions and neighborhood context. The findings reveal an increase in public disturbance records after the 2020 stay-at-home restrictions, except for abandoned vehicles. Parks, transport hubs, and to a lesser extent, schools are significantly associated with public disturbances, taking into account neighborhood characteristics and reporting practices. Recommendations for further research and practice are provided.
Article
Criminology & Penology
Vania Ceccato, Emrah Ercin, Adriana Sampaio, Julia Hazanov, Sara Elfstrom
Summary: This study utilizes environmental criminology and CPTED principles to investigate the spatiotemporal nature of crime and safety-related incidents in public libraries. The findings show that although staff feel safe in the library, there are certain unsafe situations that they avoid by taking precautionary measures. The study also emphasizes the role of design and layout in the safety conditions of public libraries, noting that some areas are more challenging due to the activities they attract.
Article
Transportation
Temidayo James Aransiola, Marcelo Justus, Vania Ceccato
Summary: The objective of this study is to empirically test four hypotheses of cargo theft causes, namely: the space-time dynamics hypothesis, the economic attractiveness hypothesis, the social structure hypothesis, and the deterrence hypothesis. The study focuses on the economic core of Sao Paulo state, which is known for its high cargo theft rates globally. Using Autorrregressive Distributed Lag models (ARDL), the study finds that the number of cargo thefts in a certain area can be predicted based on its own history as well as the neighboring areas, indicating a significant autoregressive and cointegrated nature of cargo theft time series. The study also shows that police activity plays a role in reducing cargo theft in the metropolitan area and inland municipalities of Sao Paulo state.
JOURNAL OF TRANSPORTATION SECURITY
(2023)
Article
Environmental Sciences
Vania Ceccato, Chloe Martin
Summary: This article reviews the research design of VR light research focusing on the profile of participants. The study found that a quarter of the studies integrate the participants' characteristics into the results, but the nature of the samples may put into doubt the external validity of the results. The article discusses the implications of these findings for research and practice.
SUSTAINABLE FUTURES
(2023)
Article
Criminology & Penology
Vania Ceccato, Linda Langefors, Per Nasman
Summary: This study investigates the impact of fear on young people's mobility and precautionary behavior, using a dataset collected in Stockholm. The findings suggest that previous victimization and poorly maintained transit environments affect young people's travel patterns.
EUROPEAN JOURNAL OF CRIMINOLOGY
(2023)
