Shigeru Kawai

Fiber-image-guide-based bit-parallel optical interconnects

We propose a scalable bit-parallel optical interconnect method for use in large-bandwidth interprocessor communications. Flexible fiber image guides are used to transmit spatially parallel optical data between a vertical-cavity surface-emitting laser array and a photodetector array. We have studied a lens-based and a fiber-image-taper-based input-output coupling scheme and have modeled power-loss mechanisms and resolution-degradation mechanisms associated with the schemes. We have also performed some experiments to confirm the operational principles of the proposed schemes and to investigate the power efficiency and imaging-resolution performance of the interconnect schemes. Our study indicates that the proposed interconnects can offer a scalable method to transmit hundreds of channels of multigigabyte per second per channel optical data in parallel.

Reconfigurable optical interconnection using a two‐dimensional vertical to surface transmission electrophotonic device array

A dynamic reconfiguration of optical interconnections for enhanced flexibility in photonic switching systems is realized using a two‐dimensional vertical to surface transmission electrophotonic (VSTEP) device array. A matrix operational scheme for the VSTEP array is proposed and demonstrated. Through this operation, functions for light emission and for electrically programmable spatial light modulation are obtained in a single chip of the VSTEP array and a high‐speed electronic addressing of 1 ns per one line for the matrix is also confirmed.

Distributed crossbar interconnects with vertical-cavity surface-emitting laser–angle multiplexing and fiber image guides

We report on the implementation of an optical crossbar interconnectconsisting of a centralized free-space beam-steering subsystem, adistributed array of vertical-cavity surface-emitting lasers andphotoreceivers, a fiber image guide, and a large-core polymer fiberarray. The interconnect can in principle handle more than 350cross-bar channels, but our implementation demonstrated only 240channels. Transmissions of 500-Mbit/s per channel weredemonstrated. Approximately 12.7-dB end-to-end optical channelattenuation was measured. Details of component design, packaging, system integration, and testing are presented and discussed.

Optical Crossbar Interconnection Using Vertical-To-Surface Transmission Electro-Photonic Devices (Vstep)

A new optical interconnection is proposed, using one dimensional electro-photonic semiconductor arrays (vertical-to-surface transmission electro-photonic devices). It realizes variable interconnection, signal summation and thresholding functions for optical neural networks and parallel processing. Experimental results showed 8 Mbps data rate operations and certified the interconnection feasibility.

Electrophotonic computer networks with strictly nonblocking and self-routing functions

Three-stage optical interconnection networks for use in massively parallel processors are proposed. Wavelength-division- and space-division-multiplexing switches used in these networks are described, and free-space optics to assist in the construction of networks that are small and provide high throughput are discussed.

Two-dimensional optical buses for massively parallel processing

Optical interconnections using two-dimensional waveguides are presented. Light beams whose incident angles are greater than the critical angle of a waveguide can propagate within that waveguide, which behaves as an optical bus. Such optical buses are suitable for massively parallel processing because they have a large number fan-outs and no skew. Estimated propagation distance in the waveguides is roughly 500 mm. One to several hundred interconnections may be achieved. Glass plates with concave lenses are used to demonstrate bus operations.

Modified signed-digit optical processors using computer-generated holograms.

Modified signed-digit (MSD) numbers offer convenient parallel addition and subtraction of bits. The parallel addition of any two MSD numbers, no matter what the values of their bits may be, requires only three bit-pattern transformations. To perform such transformations optically, however, MSD data must be represented in a form suitable for cascade connection. Proposed here is a new cascade-connective MSD optical processor. Adding principles are successfully demonstrated by using an optical threshold device array in addition to new computer-generated holograms that are adjusted to equalize the intensity of their diffracted light beams.

Skew-Free Optical Interconnections Using Fiber Image Guides for Petabit-per-Second Computer Networks

Parallel interconnections using vertical-cavity surface-emitting laser (VCSEL)-based fiber image guides (FIGs) have been proposed. The FIGs consist of many individual optical fibers. The core in each optical fiber is small, and thus, modal distortions may be small. All optical fibers in an array are fabricated under the same conditions. Characteristics for each optical fiber are almost uniform, and skew in FIGs is expected to be small. Interconnections using FIGs are advantageous for both free-space optics and optical fiber communications. They may enable the achievement of highly dense and large-channel communications, and easy alignment. Optical interconnections with FIGs and large-core fibers are proposed. Experiments and discussions show that the optical interconnections have very small skew and distortion. The interconnections also have merits for low cost and light weight. Module concepts and applications to petabit/s optical networks for PetaFLOPS computing are described.

Vertical to Surface Transmission Electro-Photonic Device for the Application of Optical Interconnection and Processing

Electro-photonic incorporation in the VSTEp reconfiguration of optical interconnectio significant function in optical switching and It is because non-linear characteristics controllable in the VSTEP. Variable optical i example of the dynamic reconfiguration, has achieved in a pnpn-VSTEP array through a matr speed electric addressing of Ins per one confi rmed. permits a dynamic nS, which is a computing systems. are electrically nterconnection, one been successfully ix operation. Highelement has been

PLANAR-OPTICAL MESH-CONNECTED TREE INTERCONNECTS : A FEASIBILITY STUDY

The mesh-connected tree is a two-dimensional interconnect topology that combines aspects of a conventional tree network and a two-dimensional nearest-neighbor mesh network. Because of its topological features, a mesh-connected tree has the potential to be implemented with planar optoelectronic interconnect concepts. We examine the feasibility of employing vertical-to-surface-transmissionelectro-photonic optical array switches together with planar micro-optical components for the future implementation of an optoelectronic mesh-connected tree interconnect.