Gaozhu Peng

SDM transmission of real-time 10GbE traffic using commercial SFP + transceivers over 0.5km elliptical-core few-mode fiber

We experimentally demonstrate the first few-mode space division multiplexed (SDM) transmission of real-time 10Gb/s Ethernet (10GbE) traffic using commercial small form-factor pluggable SFP + transceivers without coherent detection or multiple input multiple output digital signal processing (MIMO-DSP) over 0.5km elliptical-core few-mode-fiber, achieving <-26dB crosstalk between LP(11e) and LP(11o) modes at 1.3μm.

Mode crosstalk matrix measurement of a 1 km elliptical core few-mode optical fiber.

The spatial modes of a 1 km elliptical core few-mode optical fiber (6 spatial modes) are analyzed by using liquid crystal on silicon spatial light modulators to measure the fibers mode crosstalk matrix in Hermite-Gaussian, Laguerre-Gaussian, and linearly polarized spatial mode bases. It is shown that the fibers spatial modes can be described by Hermite-Gaussian modes, which can propagate 1 km over the optical fiber with <-20  dB (1%) average mode crosstalk even when the fiber has multiple 1 cm diameter bends. The use of elliptical core few-mode optical fibers for space division multiplexing in data centers is discussed.

Spatial mode analysis of an elliptical-core, few-mode, optical fiber for MIMO-less space-division-multiplexing

We measure the mode coupling matrix for a 0.5km elliptical-core few-mode fiber supporting six spatial modes (HG₀₀, HG₀₁, HG₁₀, HG₀₂, HG₂₀, and HG₁₁) at 980nm. We demonstrate low crosstalk <;-16dB between any pairs of modes even under severe bending. EC-FMFs are suitable for short-reach MIMO-less transmission.

Real-time Bi-directional 10GbE transmission using MIMO-less space-division-multiplexing with spatial modes

Bi-directional transmission using MIMO-less space-division-multiplexing with spatial modes is experimentally demonstrated. 10GbE real-time data-streams are bi-directionally transmitted error-free (<;-22.0dB mode crosstalk) using LP01↔LP11° and LP11°↔LP11e modes over a 0.5km, elliptical-core, few-mode optical fiber full-duplex.

MIMO equalization analysis for SDM transmission over 2km elliptical-core few-mode fiber for datacenter applications

As intra-datacenter networks (DCN) continue to experience exponential traffic growth, techno-economic reasons, such as cabling footprint reduction, are driving increases in the number of data channels per optical fiber. Optical space division multiplexing (SDM), wherein independent data channels are carried over a single fiber through a multiplicity of spatial modes are thus gaining prominence for intra-DCN transmission. In this paper, we present a time and frequency domain MIMO equalization analysis for experimental space division multiplexed (SDM) transmission of LP01 and LP11e modes over 2km of elliptical core few-mode fiber (EC-FMF). For 19Gbaud dual polarization quadrature phase shift keying (DP-QPSK) transmission with coherent detection, we observe polarization mode dispersion (PMD) durations of about 12 and 15 taps at half-baud-rate equalizer tap spacing for LP01 and LP11e modes, respectively. Since modal crosstalk between LP01 and LP11e modes is very low, 2×2 MIMO processing is sufficient for dual-polarization and dual-mode SDM transmission over the EC-FMF. By efficiently enabling channel density gains, the EC-FMF SDM approach can be attractive for next-generation intra-DCN.