Ultra-Dense and Multidimensional 98-Channel Chip-to-Fiber Optical I/O With Real-Time Control

The rapid advancement of co-packaged optics (CPO) has highlighted the spatial arrangement of a large number of optical fibers attached to photonic chips as a critical challenge. In this study, we present an ultra-compact, multidimensional silicon photonic chip-fiber coupling interface, occupying a mere footprint of$\mathbf {\text{0.2 }mm^{2}}$while accommodating a total of 98 physical channels. Our ultra-dense optical I/O (UDOIO) features an array of 49 compact, polarization-insensitive two-dimensional grating couplers (2DGCs), which achieve coupling efficiency of −3.47 dB and exhibit channel crosstalk of −31.32 dB. To facilitate real-time, on-chip polarization control, we employ field-programmable gate arrays (FPGAs) to adaptively reconfigure integrated Mach-Zehnder interferometers. Experimental results demonstrate that polarization crosstalk can be mitigated to below −18.8 dB within 690$\mathbf {\mu s}$, and the actual crosstalk can be reduced to less than −32.5 dB using wide dynamic range optical power meters. In the high-speed data communication, we experimentally validate the signal integrity by transmitting 192 Gbps polarization-multiplexed signals using silicon microring modulators. Open high-speed eye diagrams can be successfully recovered with low bit error rate (BER) penalties.