Experimental demonstration of 7.09Gb/s DML based real-time optical OFDM transmission with spectral efficiency up to 6.93bits/s/Hz over 50km SSMF

7.09Gb/s real-time optical OFDM transmissions with record high spectral efficiency up to 6.93bits/s/Hz are experimentally demonstrated in DML-based 50km SSMF IMDD systems in cooperated with DACs/ADCs whose sampling rates are as low as 2GS/s.