Fiber Array-Integrated Metasurface Enabling Multichannel Bidirectional Communication with High Interchannel Isolation

Space-division multiplexing has the potential to meet the escalating channel capacity demands of sixth-generation (6G) high-performance optical backbone networks. However, conventional multiplexing devices exhibit fundamental limitations in simultaneously supporting multichannel bidirectional transmission and maintaining low interchannel crosstalk at high data rates. In this study, we present a compact, metasurface (MS)-integrated fiber array system that enables multichannel bidirectional optical communication with minimal crosstalk. The system incorporates a single, precisely designed MS mounted on the facet of a fiber array composed of three single-mode or multimode fibers. This MS performs efficient collimation of three incident free-space beams in the forward direction and enables low-aberration focusing in the reverse direction. The system, formed by combining three spatial fiber channels with wavelength-division multiplexing, achieves an aggregate data rate of 75 Gbps, with interchannel crosstalk suppressed below −38 dB. An average bit error rate of 2.2 × 10–11 per channel is maintained across data rates ranging from 2.5 to 12.5 Gbps at high received power. This scalable and integrable platform for high-speed, low-latency, and bidirectional optical interconnects is suitable for advanced applications such as chip-to-chip optical links, data center communications, and optical neural networks.