Transmission of 3×253-Gb/s OFDM-Superchannels over 764 km Field Deployed Single Mode Fibers

Abstract

We demonstrate transmission of 3x253-Gb/s optical OFDM-superchannels in 100-GHz spacing co-propagating with 112-Gb/s NRZ-QPSK DWDM signals over 764 km field deployed fibers and compare system performance with and without inline DCF modules at the repeater amplifiers. IntroductionOrthogonal Frequency Division Multiplexing (OFDM) has emerged as a very promising modulation format for high-speed and high-capacity optical transmission due to its high spectral efficiency and its resilience in the presence of fiber dispersion and PMD. Several transmission experiments [1-4] have shown, that optical OFDM is capable to transport Tb/s capacities over several 100 km link length. Due to the almost rectangular shape of the optical OFDM spectra, multiple OFDM signals can be closely arranged in the frequency domain without guard intervals to form high-capacity superchannels [5], leaving the classical system architecture with fixed 50-GHz or 100-GHz channel grids.Although these results often propose new system concepts and link designs, there has to be a migration path for the transmission of new modulation formats over existing fiber infrastructure. This paper reports, to our knowledge for the first time, on the transmission of optical OFDM signals carrying more than 100 Gb/s over field deployed fibers. We used 10 G.652 fiber spans, provided by Deutsche Telekom AG (DTAG), with a total length of 764 km. The OFDM signals were generated as 253-Gb/s superchannels, consisting of 15 tributaries, covering a bandwidth of 90 GHz and enabling a setup in a 100 GHz spaced DWDM system with 2.5 bit/s/Hz spectral efficiency. All transmission results were obtained with several 112-Gb/s NRZ-QPSK channels in co-propagation as additional system load.

Evolution from Wavelength-Switched to Flex-Grid Optical Networks

“…In that kind of super-channel, the super-channel capacity is adjusted by varying the number of subcarriers and their data rate. The spectral efficiency of the super-channel will depend on: the rate associated to each sub-carrier the spacing between the sub-carriers [35,36] and the distance that has to be covered by the super-channel; the smaller it is, the narrower spacing that can be adopted [37,38].…”

Proposal and Performance Evaluation of an Efficient RZ-DQPSK Modulation Scheme in All-Optical OFDM Transmission Systems

“…Most current research focuses on non-return-to-zero (NRZ) schemes when adopting optical OFDM systems [25,26]. On the other hand, it has been shown in [27] and [28] that for the same average optical power, returnto-zero (RZ) outperforms NRZ, even when employing the same receiver bandwidth.…”