<title>Electro-optical circuit boards with four-channel butt-coupled optical transmitter and receiver modules</title>

Abstract

Chip-to-chip interconnects on printed circuit boards within high-speed electronic systems act increasingly as a limiting bottleneck for the achievable system performance, since local processing speed often exceeds the bandwidth capabilities of conventional electrical interconnects. In addition, rising signal frequencies or clock rates also result in increased susceptibility to electromagnetic interference. The well known limitations and problems of electrical interconnects can be overcome with optical interconnects, which have made their way from long haul telecommunication networks to parallel fiber optical modules for board-to-board interconnects within systems. Extending the advantages of optical signal transmission for very short reach interconnect applications, i.e. board or module level interconnects, therefore is a consequent logical step. This paper presents the integration of optical waveguides into conventional printed circuit boards to achieve hybrid electrical-optical boards with high- bandwidth optical interconnects. The realization of such electrical-optical boards is demonstrated with boards containing 4-channel transmitter and receiver modules, utilizing lead-frame based array GaAs-VCSEL and Si-PIN-diode components. The waveguides are manufactured by hot embossing and laminated into the boards within a standard printed circuit board production process. To couple light into and out of the optical waveguides a butt-coupling technique is applied.