Abstract

The inherent parallelism associated with arrays of vertical-cavity surface-emitting lasers (VCSELs) makes them ideal for applications in optical-interconnect technology, such as multichip modules (MCM). In our application,¹ VCSELs are to transmit information optically to heterojunction-bipolar-transistor ( HBT) detectors located 850 μm away, through a 100-μm-diameter via hole drilled in the Si carrier, as shown in Fig. 1. Integrating a bottom-emitting VCSEL array with a polyimide microlens array would decrease beam divergence, which would increase tire tolerances in packaging and alignment, and would couple significantly more power through the pinhole. We report integration of polyimide microlenses with a VCSEL array and demonstrate the expected improvement in performance. Similar lenses fabricated in photoresist have been demonstrated by others,² but they have not been integrated with VCSELs. The polyimide is more transparent than the photoresist in the near-infrared wavelength range, and it melts at higher temperatures, thus offering greater thermal stability.

© 1995 Optical Society of America