2-Dimensional Integrated VCSEL and PiN Photodetector Arrays for a Bidirectional Optical Links

We have designed, fabricated, and characterized separate and monolithically integrated 2-dimentional vertical cavity surface emitting laser (VCSEL) and photodetector arrays for optical board-to-board communications. The arrays of VCSELs, detectors, and integrated arrays have been fabricated on a hexagonal grid so as to maximize the number of devices that can be coupled to a circular waveguide. The integrated laser/detector arrays are in intermeshed hexagonal grids of the same period but are offset one half of a period. This results in die that have mirror symmetry after a rotation of 60 degrees. The photodetector epilayers are grown epitaxially on top of a conventional VCSEL structure. A novel fabrication process is employed which enables etching down to carefully expose the top laser facet. Device characteristics are observed to be uniform across the entire array. This in addition to the mirror symmetry of the die allow for the usage of these arrays as optical transceivers.