A modified partitioned frequency domain equalization algorithm for 3-LP mode multiplexed systems with few mode fibers

In recent years, mode division multiplexing (MDM) which use the few mode fibers(FMF) as transmission link has attracted widespread attention and many MDM systems were demonstrated. However, some drawbacks arising with MDM cannot be ignored, such as mode coupling, differential mode group delay(DMGD) and etc. Fortunately, many of them can be conveniently mitigated by digital equalization at a low cost. In order to solve the problems of slow convergence speed and poor equalization effect of digital equalizer in the polarization division multiplexed (PDM)-MDM system (PDM-MDM), a modified partitioned frequency domain equalization algorithm is proposed in this paper. In the proposed algorithm, the filter length is divided into several partitions and consequently each partitions’ average power model was rebuilt with its individual length. The performance of 3-LP MDM system is investigated in terms of convergence speed, constellation diagram and symbol error rate(SER). From the simulation results, the modified partitioned frequency domain algorithm can get better SER performance by about an order of magnitude and improve the convergence rate by about 10 % compared to traditional algorithm.