Alignment Tolerant Slim Optical Interconnect for On-Board Interconnections

A four-channel slim optical interconnect is proposed and realized, featuring relaxed structural tolerance along with passive alignment. A compact micro-optic beam coupler in plastic, in which a prism and lens are integrated with a plastic optical fiber (POF) guide in a single body, is commonly incorporated in the transmitter (Tx) and receiver (Rx). A pair of finely controlled reference holes is created in a printed circuit board (PCB), onto which a vertical cavity surface emitting laser (VCSEL) and photodetector (PD) are mounted. The optical coupling for VCSEL-to-POF and POF-to-PD was meticulously performed via the pick-and-place scheme in a cost effective manner, through the mediation of the beam coupler in conjunction with the reference holes. For the manufactured slim interconnect, the effective thicknesses of the Tx and Rx modules were only 1.43 mm. The achieved 3-dB alignment tolerances were 28 and 46 μm for the VCSEL and PD, respectively. The proposed optical interconnect was finally demonstrated to deliver high speed video data at 5.4 Gb/s with high fidelity.