Takeo Sasai
YOU?
Author Swipe
View article: Optical Link Tomography: First Field Trial and 4D Extension
Optical Link Tomography: First Field Trial and 4D Extension Open
Optical link tomography (OLT) is a rapidly evolving field that allows the multi-span, end-to-end visualization of optical power along fiber links in multiple dimensions from network endpoints, solely by processing signals received at coher…
View article: Beyond Redundancy: Toward Agile Resilience in Optical Networks to Overcome Unpredictable Disasters
Beyond Redundancy: Toward Agile Resilience in Optical Networks to Overcome Unpredictable Disasters Open
Resilience in optical networks has traditionally relied on redundancy and pre-planned recovery strategies, both of which assume a certain level of disaster predictability. However, recent environmental changes such as climate shifts, the e…
View article: Design of Fiber-Longitudinal Optical Power Monitor
Design of Fiber-Longitudinal Optical Power Monitor Open
This paper presents analytical results on the accuracy of fiber-longitudinal optical power monitoring (LPM) at arbitrary positions. To quantify the accuracy, the position-wise variance and power-profile SNR of LPM are defined and analyzed,…
View article: Digital Inverse Multiplexing for Transmitters With Symbol Rates Over DAC Bandwidth Limit
Digital Inverse Multiplexing for Transmitters With Symbol Rates Over DAC Bandwidth Limit Open
Broadband signal generation technology plays a pivotal role in increasing the data rate of optical transceivers. To overcome the bandwidth limitation of digital-to-analog converters (DACs), techniques that generate a single broadband signa…
View article: Semi-Automatic Line-System Provisioning with Integrated Physical-Parameter-Aware Methodology: Field Verification and Operational Feasibility
Semi-Automatic Line-System Provisioning with Integrated Physical-Parameter-Aware Methodology: Field Verification and Operational Feasibility Open
We propose methods and an architecture to conduct measurements and optimize newly installed optical fiber line systems semi-automatically using integrated physics-aware technologies in a data center interconnection (DCI) transmission scena…
View article: Linear Least Squares Estimation of Fiber-Longitudinal Optical Power Profile
Linear Least Squares Estimation of Fiber-Longitudinal Optical Power Profile Open
This paper presents a linear least squares method for fiber-longitudinal power profile estimation (PPE), which estimates the optical signal power distribution throughout a fiber-optic link at a coherent receiver. The method finds the globa…
View article: Linear Least Squares Estimation of Fiber-Longitudinal Optical Power Profile
Linear Least Squares Estimation of Fiber-Longitudinal Optical Power Profile Open
This paper presents a linear least squares method for fiber-longitudinal power profile estimation (PPE), which estimates an optical signal power distribution throughout a fiber-optic link at a coherent receiver. The method finds the global…
View article: Performance Limit of Fiber-Longitudinal Power Profile Estimation Methods
Performance Limit of Fiber-Longitudinal Power Profile Estimation Methods Open
This paper presents analytical results on longitudinal power profile estimation (PPE) methods, which visualize signal power evolution in optical fibers at a coherent receiver. The PPE can be formulated as an inverse problem of the nonlinea…
View article: Performance Limit of Fiber-Longitudinal Power Profile Estimation Methods
Performance Limit of Fiber-Longitudinal Power Profile Estimation Methods Open
This paper presents analytical results on longitudinal power profile estimation (PPE) methods, which visualize signal power evolution in optical fibers at a coherent receiver. The PPE can be formulated as an inverse problem of the nonlinea…
View article: Dynamic optical path provisioning for alien access links: architecture, demonstration, and challenges
Dynamic optical path provisioning for alien access links: architecture, demonstration, and challenges Open
With the spread of Data Center Interconnect (DCI) and local 5G, there is a growing need for dynamically established connections between customer locations through high-capacity optical links. However, link parameters such as signal power p…
View article: Post Deadline Paper (PDP) Program
Post Deadline Paper (PDP) Program Open
We report distributed-fiber-optic-sensing results on impulsive acoustic events localization/classification over telecom networks.A deep-learning-based model was trained to classify starter-gun and fireworks signatures with high accuracy of…
View article: Digital Longitudinal Monitoring of Optical Fiber Communication Link
Digital Longitudinal Monitoring of Optical Fiber Communication Link Open
Optical transmission links are generally composed of optical fibers, optical amplifiers, and optical filters. In this paper, we present a channel reconstruction method (CRM) that extracts physical characteristics of multiple link component…
View article: Physics-oriented learning of nonlinear Schrödinger equation: optical fiber loss and dispersion profile identification
Physics-oriented learning of nonlinear Schrödinger equation: optical fiber loss and dispersion profile identification Open
In optical fiber communication, system identification (SI) for the nonlinear Schrödinger equation (NLSE) has long been studied mainly for fiber nonlinearity compensation (NLC). One recent line of inquiry to combine a behavioral-model appro…
View article: Wiener-Hammerstein model and its learning for nonlinear digital pre-distortion of optical transmitters
Wiener-Hammerstein model and its learning for nonlinear digital pre-distortion of optical transmitters Open
We present a simple nonlinear digital pre-distortion (DPD) of optical transmitter components, which consists of concatenated blocks of a finite impulse response (FIR) filter, a memoryless nonlinear function and another FIR filter. The mode…
View article: Dual-Carrier 1-Tb/s Transmission Over Field-Deployed G.654.E Fiber Link Using Real-Time Transponder
Dual-Carrier 1-Tb/s Transmission Over Field-Deployed G.654.E Fiber Link Using Real-Time Transponder Open
We demonstrated 1-Tb/s-class transmissions of field-deployed large-core low-loss fiber links, which is compliant with ITU-T G.654.E, using our newly developed real-time transponder consisting of a state-of-the-art 16-nm complementary metal…
View article: Real-time 400 Gbps/carrier WDM transmission over 2,000 km of field-installed G.654.E fiber
Real-time 400 Gbps/carrier WDM transmission over 2,000 km of field-installed G.654.E fiber Open
We combine erbium-doped fiber amplifier (EDFA) and backward distributed Raman amplifier (DRA) to achieve the real-time wavelength division multiplexing (WDM) transmission of 400 Gbps/carrier polarization division multiplexing (PDM) 16 quad…
View article: Laser Phase Noise Tolerance of Uniform and Probabilistically Shaped QAM Signals for High Spectral Efficiency Systems
Laser Phase Noise Tolerance of Uniform and Probabilistically Shaped QAM Signals for High Spectral Efficiency Systems Open
We numerically and experimentally investigate the laser phase noise tolerance\nof probabilistically shaped (PS) and uniformly shaped (US) quadrature amplitude\nmodulation (QAM) signals. In the simulations, we compare PS-64QAM to US-16QAM,\…