Shigeki Aisawa

A 1580-nm band WDM transmission technology employing optical duobinary coding

This paper reports 1580-nm band wavelength division multiplexed (WDM) transmission employing optical duobinary coding over dispersion-shifted fibers. By using the 1580 nm band, the generation of four-wave mixing (FWM) over dispersion-shifted fibers (DSFs) can he suppressed. Optical duobinary coding is dispersion-tolerant because of its narrow bandwidth, and enables the use of the conventional binary intensity modulated direct detection (IM-DD) receiver. First, comparisons are made for WDM transmission performance in the 1580-nm band between conventional binary nonreturn-to-zero (NRZ) coding with and without postdispersion compensation, and optical duobinary coding by computer simulation is described. From the numerical simulations, it is found that the optical duobinary coding has superior transmission performance to the conventional binary coding without any dispersion compensation, and that the difference in the transmission performance between two coding methods is very small even if postdispersion compensation at the optical receiver is applied to the NRZ coding method. Second, transmission performance between the conventional binary NRZ and the optical duobinary signals without any dispersion compensation is compared with the straight-line experiment over 500-km dispersion-shifted fiber. The experimental results reveal that the transmission distance with optical duobinary coding is doubled in comparison with that of the conventional binary NRZ signals. Finally, 16-channel, 10-Gb/s optical duobinary WDM signals in the 1580-nm band are successfully transmitted over 640 km (80 km/spl times/8) of DSF without any dispersion compensation or management.

Interwavelength-band nonlinear interactions and their suppression in multiwavelength-band WDM transmission systems

We describe the effects of interwavelength-band nonlinear interactions, such as nondegenerate four-wave mixing, stimulated Raman scattering, and cross-phase modulation in multiwavelength-band WDM transmission systems. Through both numerical analysis and transmission experiments, these interactions are shown to cause serious degradation, especially when the walk-off between the utilized wavelength bands is small. Focusing on suppressing both these interwavelength-band nonlinear interactions and traditional intrawavelength-band nonlinear interactions, we present the guidelines for designing ultra wide-band WDM transmission systems over various types of fibers. The guidelines include band-by band bidirectional transmission, which offers large walk-off and minimizes the degradation caused by interwavelength-band nonlinear interactions. Finally, several dual-wavelength-band transmissions over dispersion-shifted fibers and standard single-mode fibers are demonstrated according to the guidelines.

OTN technology for multi-flow optical transponder in elastic 400G/1T transmission era

We study the multi-flow optical transponder from the viewpoint of OTN. Rate flexible OTU and multiplexing hierarchy for the elastic network are studied in detail and the required OTN standard extension is elucidated.

Optimized multi-layer optical network using in-service ODU / wavelength path re-grooming

We propose a multi-layer network with in-service traffic re-grooming. The combination of colorless multi-degree ROADM and ODU cross-connect with ODU reallocation functionality can offer significant cost reduction with no impact of re-grooming on services.

Fully transparent multiplexing and transport of 10GbE-LANPHY signals in 44.6-Gbit/s-based RZ-DQPSK WDM transmission

Abstract: We successfully demonstrate transparent 10GbE-LANPHY transport in 44.6-Gbit/s RZ-DQPSK WDM transmission for the first time. A single-chip 43/44-Gbit/s OTN framer LSI that supports fully transparent STM-64/10GbE multiplexing and DQPSK precoding are adopted.

Neural-processing-type optical WDM demultiplexer

A neural-processing-type optical WDM demultiplexer consisting of a multimode waveguide, a detector array, and an electrical neural network (NN) is described. This demultiplexer regenerates the original signals by recognizing the different speckle patterns of each channel with the pattern-recognition function of an NN. The demultiplexing properties can be flexibly changed, in the electrical domain, by modifying the parameters of the NN, and only simple optical components are required for implementation. Three 150-Mb/s WDM signals are successfully demultiplexed with a silica-based multimode planar waveguide, a four-channel detector array, and two high-speed analog neural network integrated circuits (ANNICs), each of which has sixteen modifiable weights and four sigmoidal transfer functions. >

Novel ODU path switching for ODU reallocation without bit disruption using dynamic delay control scheme

A novel ODU path switching using dynamic delay difference compensation for ODU reallocation without bit disruption is proposed. The proposed bit-loss-free path switching is successfully demonstrated for 10Gbit/s ODU2 path.

Performance of NRZ-versus RZ-WDM transmission around zero dispersion wavelength over dispersion-shifted fiber

Performances of nonreturn-to-zero (NRZ) and return-to-zero (RZ) wavelength-division-multiplexing (WDM) signals employing unequal channel spacing around zero-dispersion wavelength over dispersion-shifted fiber are compared by numerical simulation. In multirepeater WDM transmission systems employing installed dispersion shifted fiber, NRZ signals offer superior performance to RZ signals except in special cases.

Recirculating loop experiment for 1580-nm-band large-scale WDM network using dispersion-shifted fiber

Feasibility of a 1580-mm-band large-scale wavelength-division multiplexing (WDM) network employing add-drop. Multiplexers (ADMs) is shown from the results of a recirculating loop experiment. The limitation due to four-wave mixing (FWM) are avoided by shifting the signal wavelength band from the conventional 1550-1580-nm band, which enables us to construct a 1200-km large-scale network with the large-node spacing of 120 km over dispersion-shifted fiber.

Remote image classification through multimode optical fiber using a neural network.

A novel method of classifying remote image through a multimode optical fiber by using neural networks is proposed and experimentally tested. A neural network is used to recognize the original image from a pattern transmitted through an optical fiber.