Application Research on Transmission of 128Gbit/s PDM-NRZ Signal Using HDB3 Code in FSO System

In order to explore the potential of free space optical (FSO) system in high-speed communication, we investigate the transmission of third-order high density bipolar (HDB3) codes, and combine with polarization division multiplexing (PDM) technology to improve the spectral efficiency. For Gamma-Gamma channels with moderate-to-strong turbulence, the performance of 128Gbit/s HDB3 coded PDM-NRZ signal in FSO system is analyzed from the aspects of optical spectrums, eye diagrams, transmission distance under different weather conditions after transmission over 1km FSO channel. This PDM-NRZ signal with HDB3 code can transmit about 2.55km in sunny weather, and the bit error rate (BER) after transmission is less than 10
⁻⁸
in moderate fog weather.