Ultradense Silicon Photonic Interface for Optical Interconnection

A scalable ultradense silicon photonic interface with 61 compact vertical grating couplers on a pitch of $42.3~\mu \text{m}$ is designed and fabricated to match a pitch reducing optical fiber array (PROFA) hexagonal channel pattern. Experimental results show that the designed grating couplers with a minimum insertion loss of 4.5 dB and a 3-dB bandwidth of 50 nm are obtained. The crosstalk between different channels is less than −50 dB and the maximum loss difference across the PROFA interface is $\sim 0.7$ dB. High-speed data transmission indicates that a bandwidth density as large as 27 Tb/s/mm $^{\mathrm {\mathbf {2}}}$ could be achieved within a footprint of 0.096 mm $^{\mathrm {\mathbf {2}}}$ , demonstrating the potential of silicon photonics for broadband optical interconnection.