FPC-based compact 25-Gb/s optical transceiver module for optical interconnect utilizing novel high-speed FPC connector

A compact (22.6 × 9.1 × 0.86 mm), 25-Gb/s, flexible printed circuit based optical transceiver module was developed. The module consists of a 25-μm-thick FPC substrate on which a vertical-cavity surface-emitting laser array, driver, photodiode array, and a transimpedance amplifier are mounted by flip-chip bonding. The polymer waveguide is laminated from the backside of the FPC via microlens-imprinted film for the optical coupling. Its compactness and high-speed characteristics were realized by using a 0.35-mm-pitch novel FPC connector accurately designed by using a three-dimensional electromagnetic simulation. It was confirmed that the bandwidth of the FPC connector was more than 40 GHz. Also the measured results of the frequency response corresponded with the simulation results. Clear eye openings and error-free operation of all eight channels at 25 Gb/s were obtained with the fabricated optical transceiver.