We propose a novel Bragg grating filter synthesis method using a Fourier transform of the target scattering matrix. Multiple scattering processes are taken into account by iteration to improve the synthesis accuracy.

A Rayleigh backscattered signal over a 64 km single-mode fiber has been successfully observed by a long-range OTDR utilizing a 1.5µm LD and an InGaAs/InP APD cooled to 0 with a Peltier's thermodevice, which improves 9.0 dB in the detector sensitivity in comparison with a Ge-APD at room temperature.

In this paper, we consider an automatic warehouse, in which rc-k palettes are arranged two-dimensionally on a grid with r rows c columns. The palettes in the warehouse can slide independently and simultaneously with the use of k spaces, unless they come into collision. Then, we show the minimum number of sliding operations required to move a specified palette to a specified position, where one sliding operation is a set of slides of palettes which are executed simultaneously in a unit time withouto any collision.

Wavelength division multiplex (WDM) photonic networks are expected as the key for the global communication infrastructure. Recent increase of communication demands require large-scale highly-dense WDM systems, which results in severe requirements for optical cross-connect systems, such as cross-talk specification. In this paper, we propose a new optical path cross-connect system (OPXC) using matrix-WDM scheme, which makes it possible to reduce cross-talk requirements of WDM filters and to construct OPXC in modular structures. The matrix-WDM scheme is a concept of two-layered optical paths, which provides wavelength group managements in the fiber dispersion equalization and EDFA gain equalization.

We have developed an OC-48c (2.4 Gbps) PCI-compliant network interface card and drivers with the aim of evaluating the effectiveness of our proposed link layer protocol MAPOS. In this paper, we study the effectiveness of MAPOS particularly from the viewpoint of the influence of packet sizes up to the 64-kbyte jumbo MTU size and the effectiveness of our new implementation of the non-interrupt-driven sending process and interrupt batching receiving process deployed to improve the throughput in short-packet transmissions. Our main findings are as follows; Enlarging the packet size up to 64-kbyte MTU improves the performance in transmission. OC-48c wire speed is achieved with packet sizes larger than 16 kbytes. Implementation of the non-interrupt-driven sending process and the interrupt batching receiving process improves the performance of short-packet transmission. In particular, the transmission throughput is improved by 50% when 64-byte short packets are used. The maximum loss-free receive rate is also raised by 50% when 4-kbyte packets arrive. With a high-performance CPU, the data-transfer speed of the DMA controller for jumbo packets cannot keep up with the packet-queueing speed of the CPU. Our proposed procedure for adaptive algorithm switching method can resolve this problem. The maximum TCP throughput observed in our measurement using the latest PCs and MAPOS OC-48c PCI card was 2342.5 Mbps. This throughput represents the highest performance in a legacy-PCI-based system according to the results database of the benchmarking software.

Wavelength division multiplex (WDM) photonic networks are expected as the key for the global communication infrastructure. Recent increase of communication demands require large-scale highly-dense WDM systems, which results in severe requirements for optical cross-connect systems, such as cross-talk specification. In this paper, we propose a new optical path cross-connect system (OPXC) using matrix-WDM scheme, which makes it possible to reduce cross-talk requirements of WDM filters and to construct OPXC in modular structures. The matrix-WDM scheme is a concept of two-layered optical paths, which provides wavelength group managements in the fiber dispersion equalization and EDFA gain equalization.

To apply network monitoring functions to emerging high-quality video streaming services, we proposed an application-coexistent monitor (APCM). In APCM, a streaming server can works as an active monitor and a passive monitor. In addition, IP packets sent from the server carry monitoring information together with application's data such as video signals. To achieve APCM on a 10-Gbps network, we developed a network interface card for an application-coexistent wire-rate network monitor (AWING NIC). It provides (1) a function to append GPS-based accurate timestamps to every packet that streaming applications send and receive, which can be used for real-time monitoring of delays and inter-packet gap, and (2) functions to capture and generate 10-Gbps wire-rate traffic without depending on packets' size, achieved by our highly-efficient DMA-transfer mechanisms. Such monitoring capability are unprecedented in existing PC-based systems because of the limitation in PC system's architecture. As an evaluation of APCM in an actual network, we conducted an experiment to transmit a 6-Gbps high-quality video stream over an IP network with the system in which we installed the AWING NIC. The results revealed that the video stream became highly bursty by passing through the network, and the observed smallest inter-packet gap corresponds to the value of 10-Gbps wire-rate traffic, which supports the effectiveness of our development.

Wavelength Division Multiplex (WDM) photonic networks are expected as key for global communication infrastructure. The accurate measurement methods for AWG-MUX/DMUX are desirable for WDM network design. We measured a transfer function matrix of an AWG-MUX to find that polarization mode dispersion (PMD) and polarization dependent loss (PDL) shows the bandpass characteristics, which may limit the maximum size and the bit rate of the system. These bandpass characteristics of PMD and PDL are reproduced by a simple AWG-MUX model: The phase constant difference of 0.5% between orthogonal modes in arrayed waveguides is sufficient to obtain the measured passband characteristics of PMD and PDL. We find phase distribution difference between two orthogonal modes in the arrayed waveguide grating gives arise to complex PMD.

Wavelength Division Multiplex (WDM) photonic networks are expected as key for global communication infrastructure. The accurate measurement methods for AWG-MUX/DMUX are desirable for WDM network design. We measured a transfer function matrix of an AWG-MUX to find that polarization mode dispersion (PMD) and polarization dependent loss (PDL) shows the bandpass characteristics, which may limit the maximum size and the bit rate of the system. These bandpass characteristics of PMD and PDL are reproduced by a simple AWG-MUX model: The phase constant difference of 0.5% between orthogonal modes in arrayed waveguides is sufficient to obtain the measured passband characteristics of PMD and PDL. We find phase distribution difference between two orthogonal modes in the arrayed waveguide grating gives arise to complex PMD.