Optoelectronics on ferrule: Challenges and opportunities for fiber-to-laser coupling

Optoelectronics on fiber technology represents a promising approach for realizing extremely compact devices directly integrated and efficiently coupled to optical fiber. In this direction, we propose a new approach, compatible with scalable manufacturing, based on bonding the optoelectronic chip on a metallized ferrule, allowing the insertion and fine adjustment of the fiber inside the ferrule after the chip integration. This new flexible configuration enables the same chip to be tested under different conditions, for investigating the influence of different parameters on the coupling efficiency. As a proof-of-concept, our approach was applied to the integration of miniaturized Vertical-Cavity Surface-Emitting Lasers (VCSELs). The effects of the laser-to-fiber distance and radial and angular offsets on the coupling efficiency were investigated both numerically and experimentally. A coupling efficiency of more than 60 % for the SMF was obtained, representing a significant improvement over the state-of-the-art.