Ultra-High Bandwidth Density and Power Efficiency Chip-To-Chip Multimode Transmission through a Rectangular Core Few-Mode Fiber

Optical interconnects have emerged as promising solutions for assisting electrical interconnects in short-reach scenarios, where high bandwidth density and energy efficiency are of particular importance. Mode-division multiplexing (MDM), capable of enhancing the bandwidth density and energy efficiency of optical systems, has drawn tremendous interest. However, the chip-to-chip MDM optical interconnects are impeded by the multimode chip-fiber interfaces, where the transverse modes on the MDM chip mismatch with the linear polarization modes in the circular core few-mode fiber (CCF). Moreover, the high differential group delays (DGDs) of a conventional CCF make the digital signal processing (DSP) computation complex thus consuming high power. To overcome these bottlenecks, a new multimode coupling solution based on a rectangular core few-mode fiber with ultra-low DGDs and an integrated multimode coupler is proposed. Based on this coupling scheme, a chip-to-chip MDM transmission experiment is performed on the TE00, TM00, TE10, and TM10 modes, and the highest bandwidth density of 19.4 Tb s mm -1 is realized at the chip facet. The DSP power consumption is & AP;6% of a conventional CCF-based system. It is believed that this work will pave the way for ultra-compact, high density, low cost, and low computation-complexity optical interconnects, such as data centers, cloud computing, and telecommunications. The multimode chip-fiber interface is a bottleneck in achieving high bandwidth-density optical interconnects employing mode-division multiplexing because the transverse modes of a waveguide on chip mismatch with the linear polarization modes of a conventional few-mode fiber. Here a new coupling solution based on a rectangular core few-mode fiber and an integrated multimode coupler is proposed to achieve high bandwidth-density.image