120 Gbit/s high-speed WDM-QPSK free-space optical transmission through 1 km atmospheric channel
The free-space optical communication of high-speed 120 Gbit/s wavelength-division multiplexing (WDM) QPSK signals is demonstrated in an outdoor atmospheric channel with a distance of about 1 km. A pair of optical terminal systems with the capture and tracking functions is used to establish the atmospheric channel. The power fluctuation through the atmospheric turbulence agrees well with the exponentiated Weibull distribution. At the BER of 3.8 × 10−3, the required receiving powers for the three WDM channels are similar, which are all <−15.4 dBm.