Optical interconnection technology on electro/optical PCB (EOPCB)

Abstract

A chip-to-chip optical interconnection solution on PCB is presented in this paper. Both electrical and optical interconnections are used in common printed circuit board (PCB) to construct electro/optical PCB (EOPCB). An additional optical layer with waveguide structure is used in the PCB. So the EOPCB integrates the information medium into the board. Optical transmitter is vertical cavity surface emitting laser (VCSEL) array. Optical receiver is PIN array. VCSEL array with its driver IC chip and PIN with its receiver IC chip are bonded with LSI chip by ball-grid array (BGA) technology. Then the LSI chips with VCSEL and PIN arrays are bonded on PCB by surface-mount technology (SMT). Multimode waveguides are used as optical layer in PCB. In order to couple light beam between optical transmitter/receiver with waveguide layer, a direct coupling method by the waveguide with 45° end face is presented. VCSEL chip is placed close to the 45° end face of the waveguide. The light beams from VCSEL array are emitted into the 45° end face directly and reflected by 90°, then coupled into the waveguide layer. No microlens arrays are needed for collimating light beam array in this configuration. A proof-of-principle experiment is made to verify the feasibility of this approach.