Adaptive loading with extended memory to relax the impact of the phase noise-impaired ICXT in DD-OFDM MCF-based systems

The impact of the laser phase noise on the inter-core crosstalk (ICXT) of orthogonal frequency division multiplexing (OFDM) multicore fiber (MCF) based systems employing direct detection (DD) is experimentally investigated. Random fluctuations of the ICXT and system performance induced by the laser phase noise are observed in both time and frequency. The origin of these fluctuations is the random phase mismatch of the photodetected ICXT that results from the beating between signals originating from different cores and generated by two independent laser sources. Adaptive bit loading employing extended time memory is proposed and demonstrated experimentally as a possible approach to counteract the large performance variation of the DD-OFDM MCF systems induced by laser phase noise and ICXT.