Data Center Mode Division Multiplexing at Net 1.6 Tb/s Per Wavelength w/o MIMO Processing

Space division multiplexing (SDM) is a promising solution to increase the capacity of optical communications within data centers. We focus on mode division multiplexing (MDM) architectures with fibers supporting multiple modes. We show that network hardware is significantly less complex for MDM with orbital angular momentum (OAM) compared to MDM with linearly polarized (LP) modes. The advantage stems from low crosstalk among OAM modes, hence limited digital signal processing (DSP) complexity. Unlike demonstrations of MDM with LP, our demonstrations have no multiple-input multiple-output (MIMO) processing. We transmit 16 OAM channels at 56 Gbaud quadrature phase-shift keying (QPSK) over 400 m (distance sufficient for links within data centers). The net throughput of 1.6 Tbit/s per wavelength is the highest reported OAM-MDM throughput, even among demonstrations with much greater DSP complexity. We can span the entire C-band, with throughput of 1.3 Tbit/s at the band edges. To reduce latency and power consumption, 8-channel transmission can achieve a net throughput of 0.8 Tbit/s per wavelength across the C-band with wide margin. The OAM MDM approach can flexibly trade-off throughput, latency, and complexity.