Integrated Microlens Array for Optical Interconnects

Abstract

As Multi-Chip Modules (MCMs) grow in chip count and complexity, increasingly large numbers of Input/Output (I/O) channels will be required for connection to other MCMs or printed wiring boards. In applications such as digital signal processing, large increases in processing density (number of operations in a given volume) can be obtained in stacked MCM arrangements. The potential pin counts and required I/O densities in these stacked architectures will require technology beyond the limits of present day capabilities. This problem is particularly acute if easy separation of layers is needed to meet MCM testing and yield requirements. One solution to this problem is the use of optoelectronic data channels that operate in large arrays [1]. These arrays will emit and detect signals traveling normal to the surface of the MCM stack as in Fig. 1. In order to maximize compatibility with present MCM packaging techniques, the chips that form the arrays should include both the active devices (sources such as vertical cavity surface emitting lasers (VCSELs) and detectors as shown in the demonstration cross-section in Fig. 2) and any collimation and/or focusing optics that are needed to compensate for misalignments and accommodate small detector areas.