Transmission performance of an MDM switching node with FM-EDFAs for high-speed DP-QPSK signals

Mode division multiplexing (MDM) technology has been extensively investigated for improving the fiber transmission capacity. The researchers have started to devote their energies to multi-dimensional optical switching nodes compatible with spatial modes. We focus on a promising MDM switching node based on wavelength-selective switches and evaluate its crosstalk performance by the power transfer matrix method. The simulation shows that the number of cascaded nodes permitted for error-free transmission exponentially decreases with the crosstalk increase of the mode demultiplexers/multiplexers. An MDM switching node supporting four linearly polarized modes is constructed using homemade four-mode erbium-doped fiber amplifiers for the transmission of 100 Gb/s dual-polarization quadrate phase shift keying signals. The experimental results show that the receiver sensitivity degradation of all channels in DROP, ADD, EXPRESS, and EXCHANGE scenarios is no more than 2, 4.4, 6.4, and 6 dB compared with the back-to-back cases, respectively.