Dual-Polarization IMDD System for Data-Center Connectivity

We present a dual-polarization (DP) IMDD short-reach transmission system for intra data-center application scenario. Two polarization tributaries are multiplexed in an external modulated laser (EML) based transmitter assembly and demultiplexed in a silicon photonics (SiPh) integrated receiver. As the key enabler of the fast and robust polarization tracking, a novel Stokes vector based polarization recovery algorithm is proposed and implemented. Aided by an auxillary endless enablement stage, the polarization demultiplexer provides robust tracking with random polarization scrambling or hand shaking/twisting applied on the fiber link. A realtime 2 × 106.25 Gbit/s transmission experiment, under a dynamic scrambling case, shows stable pre-FEC BERs of ∼10⁻⁷ level and −8 dBm receiver sensitivity on both polarizations. A post-FEC experiment verifies the codeword error free transmission in at least 2 minutes. The experiment proves the feasibility that the DP solution is capable of doubling system capacity for short-reach transmission with robust polarization tracking.