Analog nonlinear MIMO receiver for optical mode division multiplexing transmission

Abstract

The complexity and the power consumption of digital signal processing are crucial issues in optical transmission systems based on mode division multiplexing and coherent multiple-input multiple-output (MIMO) processing at the receiver. In this paper the inherent characteristic of spatial separation between fiber modes is exploited, getting a MIMO system where joint demultiplexing and detection is based on spatially separated photodetectors. After photodetection, one has a MIMO system with nonlinear crosstalk between modes. The paper shows that the nonlinear crosstalk can be dealt with by a low-complexity and non-adaptive detection scheme, at least in the cases presented in the paper.

Direct-detection mode-division multiplexing in modal basis using phase retrieval

“…Since only the intensities of the received modal fields are available in DD systems, the MIMO channel estimation methods used in coherent systems are not applicable. Prior work on DD-MDM has assumed that multiplexed data streams are mapped/demapped to/from spatially non-overlapping regions of the multi-mode beam, and the MIMO signal processing is performed in the basis of spatial samples [7,8]. This approach does not enable the MIMO signal processing to be performed separately for different mode groups, which may yield good performance while greatly reducing complexity in the systems having negligible inter-group coupling.…”