This paper describes the state-of-the-art of polarization multiplexing for optical networks transmission. The use of polarization\ndivision multiplexing (PDM) permits to multiply the user capacity and increase the spectral efficiency. Combining PDM and\northogonal frequency division multiplexed (OFDM) modulation allows maximizing the optical transmission capacity. The\nexperimental demonstration of transmitting OFDM signals following ECMA-368 ultrawide band (UWB) standard in radio-overfiber\nusing PDM in passive optical networks is herein reported. The impact of cross-polarization and cochannel crosstalk is\nevaluated experimentally in a three-user OFDM-UWB subcarrier multiplexed (SCM) configuration per polarization. Each SCM\nuses up to three OFDM-UWB channels of 200Mbit/s each, achieving an aggregated bitrate of 1.2 Gbit/s with 0.76 bit/s/Hz spectral\nefficiency when using PDM transmission. The experimental results for the polarization-multiplexed SCM indicate that a 4 dB\nadditional polarization crosstalk interference can be expected compared to a nonpolarization-multiplexed transmission system\nwhich translates to 2.4 dB EVM penalty in the UWB signals. The successful PDM transmission of SCM multiuser OFDM-UWB\nover a passive optical network of 25 km standard-single mode fiber (SSMF) reach is demonstrated.
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