Long-Haul Dense Space-Division Multiplexed Transmission Over Low-Crosstalk Heterogeneous 32-Core Transmission Line Using a Partial Recirculating Loop System

In this paper, we present long-haul 32-core dense space-division-multiplexed (DSDM) unidirectional transmission over a single-mode multicore transmission line. We developed a low-crosstalk heterogeneous 32-core fiber with a square lattice arrangement, and a novel partial recirculating loop system. The span crosstalk of the 51.4-km 32-core transmission line was less than -34.5 dB. This allowed the transmission of polarization-division-multiplexed 16 quadrature amplitude modulation (PDM-16QAM) signals through all 32 cores over a long distance exceeding 1000 km. We demonstrate 32-core DSDM 20 wavelength-division-multiplexed PDM-16QAM transmission over 1644.8 km with a high aggregate spectral efficiency of 201.46 b/s/Hz Additionally, we examine the effect of crosstalk on the transmission performance of each core, and show that the Q-penalty has strong correlation with intercore crosstalk.