Three-dimensional MEMS optical switches(3D-MEMS) and planar lightwave circuit thermo-optical switches (PLC-TOSW) are suitable for use in large-scale photonic cross-connect switches (PXCs). Usually, such large-scale optical switches are created by integrating many small switch elements (such as 12 switches). Therefore, the reliability or lifetime of the individual switch element greatly affects the reliability of the PXC system. In this paper, the effect of the number and failure probability of switch elements on PXC reliability is statistically estimated. First, the equivalent number of switch elements needed to compose a large-scale PXC is determined for the switch types mentioned above. Based on this evaluation, yields and lifetimes of switch modules are estimated for each switch type. The improvement in reliability due to switch duplication (preparing spare switches) is also estimated and discussed.

A very-high-speed ten-neuron analog neural network LSI chip is fabricated for the first time using super self-aligned Si bipolar process technology. The LSI consists of ten neurons and 100 electrically modifiable synaptic weights. The neural network nonlinear mapping function to solve the four-bit parity problem is successfully demonstrated at 150 mega-patterns/sec. The operation speed of this neural network is, to the best of the authors, knowledge, the fastest yet reported.

Loss increase due to hydroxyl group formation of a fiber expose to hydrogen gas in measured. Experimental result shows that the loss increase is proportional to 0.57 power of exposure time. Temperature dependence of the loss increase is also estimated from the result.

A multichannel crossover switching network using interconnection channels of collimated lights is proposed and demonstrated. Diffraction losses of the switching network are theoretically estimated.

This letter proposes a new-type of two-dimensional multichannel optical switch employing polarization control techniques. This switch has small-size and low-driving-power characteristics. It is demonstrated by an 88 optical switch.

This paper describes the requirements for fault recovery on photonic networks and proposes a fast restoration scheme for recovering optical networks. The proposed scheme is a type of pre-assignment restoration. The features of the scheme are that it is suitable for multi-recovery classes aimed at fine control of the optical paths and that it establishes harmonization between restoration control and distributed network control such as in IP networks. The scheme is implemented on Photonic multi protocol label switching (MPLS) routers. A restoration demonstration was performed and recovery was achieved within 500ms in the optical layer.

Phenomenon of silica-fiber loss increase, which is induced by an electric current applied in water, is reported. It is found from experimental results that the loss increase is caused by hydrogen molecules, which are electrolytically produced and are diffused into the fiber interstitially. Furthermore, both infrared loss and Ramanscattering spectra are measured for a fiber dissolved by H2, HD, and D2 molecules to make clear assignment for loss peak. As a result, it is found that the absorption loss peaks are associated with a connection between molecular vibration and SiO4 tetrahedral vibrations in the silica glass.

Optical time- and wavelength-domain paths in future very-high-speed optical communications networks are discussed taking into account trends in current optical transmission and optical signal processing technologies. It is important to investigate optical STM cross-connect systems for time-domain paths in the earlier research phase to ensure the deployment of optical cross-connect technology. The configuration of an optical cross-connect system and the issues that need to be investigated are presented. We also report, for the first time, a preliminary experiment of an optical STM cross-connect system, using 20 Gbit/s optical signals.