A high-speed, large-scale architecture, three-dimensional micro-optical switching system (3-D MOSS) is proposed. A switching network is divided into subnetwork blocks, followed by stacking them to construct a multilayer structure. The interblock waveguide connection is replaced with short-distance vertical optical wiring, that is, optical z connections. Thus, 3D-MOSS, in contrast with conventional planar structures, reduces waveguide cross points, wiring length, and system size. Expected applications are switching for fiber communications, reconfigurable 3-D micro optoelectronic (OE) systems, and so on. 3D-MOSS consists of OE films, in which thin-film high-speed micro-optical switches are embedded. Two critical issues for 3D-MOSS, micro-optical switch and optical z connection, are investigated. The beam propagation method (BPM) calculation shows that waveguide-prism-deflector microoptical switch (WPD-MOS), in which prism-shaped electrodes are formed on an electro-optic slab waveguide, is suitable for the microoptical switch. The finite difference time domain method (FDTD)/BPM coupled simulation demonstrates a possibility of low-loss optical z connection in a 4-m width waveguide-based 3-D micro-optical network. Performance of 3D-MOSS for a 32ϫ32 Banyan network is assessed as follows: system size is 2250 (length)ϫ600 (width)ϫ320 (height) m 3 , operation voltage 110 V, switching speed Ͻ1 s, power consumption 520 mW at a switching rate of 3ϫ10 5 /s, and maximum insertion loss 14 dB. This indicates the viability of 3D-MOSS from viewpoints of channel count, switching speed, thermal management, and power budget. A material/cost-saving device integration process ''photolithographic packaging with selectively occupied repeated transfer (PL-Pack with SORT)'' is briefly described as an example of a fabrication method for 3D-MOSS.

SUMMARYTo handle the drastic increase in communication capacity, the need for large-scale, high-speed switching systems is expected. As a solution, we proposed a 3-Dimensional Micro Optical Switching System (3D-MOSS) that arranges many thin-film micro optical switches in multiple layers and connects them with Optical Z-Connections. This implementation requires a micro optical switch having fast, stable operation. In this paper, we propose a waveguideprism-deflector type micro optical switch (WPD-MOS) as a candidate 3D-MOSS thin-film micro optical switch and analyze its operation. This optical switch forms a prism electrode in a slab waveguide having the electro-optical effect. The application of voltage produces a dynamic waveguide prism and deflects the optical beam. A feature is the insensitivity of the processing precision to strong temperature fluctuations. An evaluation by the Beam Propagation Method (BPM) demonstrated the ability to implement 2 × 2 micro optical switches having a length of 390 µm, crosstalk ≤ -12 dB, and insertion losses ≤ 0.96 dB at the drive voltage of 110 V. We also studied a 3 × 3 WPD-MOS.

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