100  nm broadband and ultra-compact multi-dimensional multiplexed photonic integrated circuit for high-capacity optical interconnects

Chip-scale multi-dimensional multiplexing technology that combines wavelengths and spatial modes on a silicon photonic integrated circuit (PIC) is highly promising for the link-capacity scaling of future optical interconnects. However, current multi-dimensional multiplexed PICs face significant challenges in simultaneously achieving broad optical bandwidth, low mode crosstalk, and dual-polarization modes in an ultra-compact footprint as the number of spatial modes increases. To address the issue, a topology-optimization-based inverse design assisted by a novel manufacturing calibration method (MCM) is utilized. Based on a 220 nm silicon-on-insulator (SOI) platform, a 100 nm broadband and ultra-compact (6 μm ×6 μm ) multi-dimensional multiplexed PIC supporting TE 0 , TE 1 , TM 0 , and TM 1 modes with modes crosstalk <−16 dB ranging from 1500 to 1600 nm is demonstrated for the first time, to the best of our knowledge. Furthermore, the PIC is implemented to experimentally enable a single-wavelength 4-modes ×100 Gbit/s PAM-4 direct modulation data transmission over 51 wavelengths with 0.8 nm channel spacing. This work shows the potential of utilizing multi-dimensional multiplexed PICs as optical interconnects to effectively address the speed limits of data transfer for future high-performance chip-to-chip interconnection.