Digital Domain Power Division Multiplexing Optical OFDM for Free Space Optical Communication (FSOC) Using 10-GHz Bandwidth Optical Components

We put forward and provide the first illustration of a high capacity and high spectral efficient free space optical communication (FSOC) system using digital domain power division multiplexing orthogonal-frequency-division-multiplexed (DDPD-O-OFDM) signal utilizing 10-GHz class optical components. In the proof-of-concept demonstration, a data rate of 2 x 30.8 Gbit/s can be achieved for each polarization multiplexed wavelength channel, fulfilling the pre-forward-error-correction bit-error-ratio (pre-FEC BER = 3.8 x 10(-3)). By employing the DDPD-O-OFDM here, the FSOC per channel capacity can be enhanced not only allowing the spectral overlapping of different orthogonal subcarriers, as in the case of OFDM; but also allowing channel multiplexing in the power domain to increase the spectral efficiency. The principle of DDPD-O-OFDM is discussed; and BER and signal-to-noise ratio (SNR) of different DDPD channels are experimentally measured.