Chapter 6 - Interconnection with Optics

Abstract

This chapter describes the necessary building blocks of the board-level guided wave optical interconnection. To make optical interconnects acceptable to computer companies, it is important to make the insertion of optics compatible with the standard PC board fabrication process so that technology improvement can be achieved in a cost-effective manner. The elements involved in providing high-speed optical communications within one board include a vertical cavity-surface emitting laser (VCSEL), surface-normal waveguide couplers, a polyimide-based channel waveguide functioning as the physical layer of optical bus, and a photoreceiver. The polymer-based optical bus can be employed to upgrade interconnection speed and distance. The driving electrical signal to modulate the VCSEL and the demodulated signal received at the photoreceiver are all through electrical vias connecting to the surface of the PC board. The board-level optical interconnection layers can be sandwiched between electrical interconnection layers. Assurance of the flatness and compatibility of the insertion of optical layers is crucial to ensure a technology transferable to the computer industry. Compatible optical-to-electrical and electrical-to optical conversions are very important for system packaging.