48-Channel Matrix Optical Transmitter on a Single Direct Fiber Connector

Abstract

In this paper, 4 pairs of commercial 12-channel electronic and photonic dies have been assembled on a patterned wet etched silicon interposer for a terabit/s class optical interconnect. In the scheme, the optical dies are flip-chip bonded to form a ${4} \times {12}$ optical matrix with 250- $\mu \text{m}$ pitch in both the ${x}$ - and ${y}$ -directions. A single compact optical connector, which is designed based on the commercial PRIZM MT ferrule, is employed to enable a single and direct connection of four fiber ribbons to all 48 channels. The alignment tolerance of the suggested optical connector is tested, and the best case loss is 1.0 dB. The electrical interface, for the connection of CMOS ICs and vertical-cavity surface-emitting laser dies, is designed and patterned on the silicon interposer. The process and assembly are also detailed. In performance testing, clear eye patterns for all the 48 channels are captured at 15 Gb/s with a pseudorandom bit stream 231 – 1 patterns. The bit error rate curves of all the channels are recorded at 10 Gb/s and show a receiver sensitivity spread of less than 2.1 dB across all 48 channels at 10−12 level. In addition, crosstalk effects are also characterized, showing a negligible power penalty of less than 0.2 dB. The fully assembled module can offer for the first time 0.72 Tb/s optical data output, within an area of 1.32 cm2 by using low cost processes and commercially available dies.