Three-dimensional optical data communication in glass

Abstract

For data communication over long and medium distances, optical transmission based on silica optical fiber has become the dominant technology over the past decade. For short and very short distances (on the order of meters down to millimeters), however, physical advantages of optical communications have for a long time been offset until now by technological problems. However, as the communications bottleneck in computers turns into a ser ious limitation of the processing capabilities, optical interconnection technology becomes an Interesting alternative to electrical wires. Unlike electrical signals, light beams do not suffer from electromagnetic interference and signal-frequency dependent attenuation. Both, waveguide-optical and free-space optical solutions are being considered. Freespace optics offers the chance to use the third dimension, thereby solving one of the major limitations of a 2 D wiring technology. In order to tap the potential of freespace optics for data communications inside a computer, suitable Integration techniques need to be developed. Here, we present a specific approach, calied „planar integrated free-space optics" (PIFSO). It is based on the use of lithographic fabrication in glass to build miniaturized optical systems. The fabrication approach is suitable for batch processing in a similar fashion as electronic chips are fabricated. In combination with suitable hybrid Integration techniques, the PIFSO-concept Is a viable approach to the practical realization of an optoelectronic systems technology. Here. we describe the concept of planar integrated free-space optics and describe some of the demonstration experiments for optical Interconnection.