Reversely Modulated Optical Single Sideband Scheme and Its Application in a 60-GHz Full Duplex ROF System

The reversely modulated optical single sideband scheme (IM-OSSB) based on a parallel Mach-Zehnder modulator (P-MZM) is proposed. In this P-MZM, one sub-MZM is employed for data modulation and the other is used for optical millimeter wave (mm-wave) generation. Due to the individual modulation, this scheme is data-format-transparent and can be used to generate a high performance optical mm-wave signal at the optimized direct current (dc) bias. There is electrical mixer free at the transmitter and thus the bandwidth limitation, nonlinearity and conversion loss from the electrical mixer are released in this scheme. Moreover, the modulation power efficiency of IM-OSSB can be improved by adjusting the dc bias in the modulator. Based on IM-OSSB, we demonstrate a 60-GHz full duplex radio-over-fiber system. The experimental results show that the power penalty of 2.9-Gb/s on-off keying data carried by 58-GHz mm-wave after transmission over 50-km SMF-28 is negligible.