High-density MDM-WDM silicon photonic transmitter chiplet based on MRMs and dual-mode GC for 4 × 56 Gbps 3D co-packaged optical interconnects

In this Letter, a four-channel silicon photonic mode-division-multiplexing (MDM) and wavelength-division multiplexing (WDM) transmitter chiplet is proposed over a 1.65 mm² footprint, utilizing add-drop micro-ring modulators to simultaneously achieve electro-optic modulation and two-wavelength multiplexing. A dual-mode grating coupler with a side-distributed Bragg reflector for equalized two-mode coupling is realized with high chip-to-fiber coupling efficiency, so as to support the MDM optical fiber interface. A high data rate of up to 4 × 56 Gbps signaling is experimentally demonstrated, featuring applications like 200G quad small form-factor pluggable (QSFP) transceivers and indicating significant potential for high-density and large-capacity 3D co-packaged optical interconnects through flip-chip-based electronic-photonic packaging.