Solder bonding alignment of microlens in hybrid receiver for free space optical interconnections

A hybrid optical receiver consisting of a 2×2 microlens array, a 2×2 photodiode array, transimpedance amplifiers, and the associated passive circuitry is designed, fabricated and tested. The main emphasis is to bond and align a 2×2 microlens array to the 2×2 photodiode array using the self alignment capability of the flip-chip solder bonds. The key fabrication techniques required for the implementation of the hybrid optical receiver namely the flip-chip solder bonding process using electroplating and the PROM (photoresist refractive optics by melting) microlens process were developed. Finally, the fabricated hybrid optical receiver was tested at 50 Mbit/s and the time delay of the output signal was measured to be 3 ns