8 Tb/s (80 × 107 Gb/s) DWDM NRZ-VSB transmission over 510 km NZDSF with 1 bit/s/Hz spectral efficiency

Next-generation optical transport systems are expected to operate at channel data rates of 100Gb/s and beyond. Currently various system concepts and modulation formats for serial 100Gb/s are under consideration running at different symbol rates, e.g., 28 Gbaud, 56 Gbaud, or 112 Gbaud, and offering different trade-offs among modulation speed, spectral efficiency system tolerance to transmission impairments, subsystem complexity, and cost. Here, we focus in particular on serial binary 100Gb/s non-return-to-zero on-off keying (NRZ-OOK) modulation systems operating at the highest symbol rate (100 Gbaud, 1 bit/symbol). On one hand, this symbol rate offers the least system complexity but, on the other hand, this approach is most challenging in terms of speed requirements of electronic and opto-electronic components and with respect to transmission impairment tolerances. Another critical aspect of the serial binary 100Gb/s modulation format is the relatively high spectral width (approximately 200 GHz), which is not compatible with the standardized channel grid (100 GHz channel spacing) of current dense wavelength division multiplexing (DWDM) transmission platforms. Here we report on an advanced serial binary 107Gb/s NRZ-OOK format in combination with vestigial sideband (VSB) filtering enabling a considerable enhancement of spectral efficiency and chromatic dispersion (CD) tolerance. A total capacity of 8 Tb/s has been transmitted over 510 kilometers of single mode fiber by using 80x107Gb/s NRZ-VSB DWDM channels on a 100GHz grid, showing a double spectral efficiency (i.e., 1 bit/s/Hz) and nearly doubled CD tolerance-i.e., ± 15ps/nm, at a 2 dB optical signal-to-noise ratio (OSNR) penalty-as compared to the standard NRZ-OOK format. In this pioneering experiment we demonstrated multi-Terabit/s overall capacity transmission over several hundred kilometers of fiber at a high symbol rate (100 Gbaud) for the first time with a standard 100GHz DWDM platform compatible channel spacing.