Yoshihiko Suemura

Hybrid hierarchical optical networks

Hybrid hierarchical optical cross-connects enhance the performance/cost ratio of optical networks by providing transparent (optical) switching of sets of wavelengths (wavebands) in addition to opaque (electrical) switching of individual wavelengths. As network bandwidth gets cheaper, and the performance bottleneck moves to switching nodes, these systems provide an attractive scalable solution for next-generation optical networks. We describe key technological components (including flexible nonuniform wavebands) of hybrid hierarchical optical cross-connects and discuss their performance/cost implications.

QoS-Aware Scheduling over Hybrid Optical Wireless Networks

Hybrid optical wireless networks present the future-proof solution to the currently deployed copper access infrastructure. Purposing to increase the network throughput under the hybrid framework, we propose a scheduling scheme to deliver diverse services by taking the quality of service (QoS) requirement into consideration. Simulation results demonstrate that our scheme is capable of collecting the QoS requirement information throughout the network, and the centralized process facilitates the reduction of network transmission overhead.

Hierarchical routing in layered ring and mesh optical networks

We consider hierarchical optical networks with different granularities of paths (wavelengths and wavebands). We introduce classification layers for routing models in these networks (separated and integrated routing, homogeneous and heterogeneous networks, online and offline routing). We also propose and analyze two heuristic routing and aggregation algorithms (online and offline) to be used for homogeneous networks in the separate routing framework. The analysis is based on ring topology; its results are supported by simulations of large scale networks (Europe and USA). These simulations demonstrate a significant cost reduction achieved by employing hierarchical routing (from 33% in the online algorithm to almost 60% in the offline one).

A 2.56-Tb/s multiwavelength and scalable switch-fabric for fast packet-switching networks

We propose an implementation of a terabits-per-second crossbar-equivalent switch-fabric for packet-switching networks. It consists of switch-modules employing semiconductor optical amplifier gates (SOAGs), arrayed waveguide grating routers, and multiple wavelength-channels. It offers large modularity and a small internal loss. The number of SOAGs in a 256/spl times/256 switch-fabric is one-eighth that of a conventional switch-fabric. Scalability up to 2.56 Tb/s is demonstrated by a 10 Gb/s transmission experiment in which the input level into the switch-module was observed to possess a dynamic range of 6 dB.

A 2.56 Tb/s throughput packet/cell-based optical switch-fabric demonstrator

A packet/cell-based optical switch-fabric demonstrator has been successfully developed that is upgradable to 2.56 Tb/s throughput. The number of optical components in a 256/spl times/256 switch-fabric is dramatically reduced to one-eighth that of a conventional switch-fabric.

An adaptive wavelength tunable optical filter employing an angle-tuned interference filter and an intelligent digital controller

This paper describes an adaptive wavelength tunable optical filter, which is composed of an angle-tuned interference optical filter and an intelligent digital controller. The new angle-tuned interference filter consists of a dielectric interference optical filter and a piezoelectric angle-tuning mechanism. It achieves quick wavelength switching within 2.5 ms in a 30 nm tuning range and a sufficiently low crosstalk less than -30 dB. The intelligent digital controller has two functions: wavelength tracking and wavelength channel selection. Combining these technologies, we have developed a practical low-cost tunable filter suitable for a post-optical-amplifier filter in a high-sensitivity detection system and a channel selector in a WDM system that requires 10-100 ms channel selection time. With a wavelength tracking operation, we have confirmed -35 dBm high-sensitivity detection in 20 nm wavelength range in a 10 Gb/s system. We have also confirmed a wavelength channel selection operation within 18 ms in a three-channel wavelength division multiplexed (WDM) system whose channel spacing is 4.4 nm.

Improving Access Performance with an Integrated PON and WiMAX with MIMO

We propose and evaluate a near-optimal antenna allocation approach for a PON+WiMAX network with MIMO that takes advantage of the optical wireless integration to achieve a high throughput and good resilience.

Skewless optical data-link subsystem for massively parallel processors using 8 Gb/s x 1.1 Gb/s MMF array optical module

A high-capacitance, compact, low-cost, and convenient optical data-link subsystem for parallel computers is developed using an 8 Gb/s/spl times/1.1 Gb/s multimode fiber (MMF) array optical module and newly developed data-link IC. Although the subsystem uses an MMF ribbon, parallel data is successfully transmitted over 1 km due to /spl plusmn/15-ns deskew operation of the IC. The subsystem operated stably in a processor networking testbed system of the Real World Computer-1, a newly constructed parallel computer. Random packets are transmitted without any error for over 17.5 h, corresponding to a bit-error rate (BER) of less than 10/sup -15/.

Optical Wireless Integration at Network Edge

Optical-wireless integrated system can help reduce the capital and operational expenses by simplifying the network architecture and improving the resource usage efficiency. It can also deliver QoS guaranteed services to the customers. This paper will discuss the architecture and performance improvements coming from the optical and wireless integration at the edge node.

10-Gb/s/port gated divider passive combiner optical switch with single-mode-to-multimode combiner

A novel space-division optical switch configuration is proposed that incorporates a low-loss single-mode-to-multimode (SM-to-MM) combiner. We have confirmed the feasibility of a 16/spl times/16 10-Gb/s/port optical crossbar switch through an experiment with a silica waveguide combiner.