Optical independent-sideband modulation for bandwidth-economic coherent transmission

We proposed and implemented a bandwidth-economic coherent optical transmission technology using optical independent-sideband (OISB) modulation. Generation of two software-defined, 30-GBd O-ISB channels per wavelength sharing one set of transmitter hardware was demonstrated, which was made possible by digital single-sided upconversion, channel pre-equalization and optical IQ modulation with precise amplitude and delay matching between driving signals. With 120- Gb/s PM-QPSK per O-ISB channel, we successfully delivered 16 O-ISB channels in 8 wavelengths at 3.86-bits/s/Hz over 2100 km SSMF. In addition, the system performance was evaluated by using regular and enhanced Rx DSP, respectively. For metro and regional network applications where small footprint, low power consumption and low cost are required features, the proposed two-channels-per-wavelength O-ISB modulation may be considered an economic option.