Time frequency packed DP-QPSK superchannel field trial transmission over installed link

Time frequency packing technique was demonstrated in a superchannel field trial transmission over long-haul distances. The technique allows a high spectral efficiency even with low order modulation formats. The transmission was successfully performed on an installed link between Milan and Finkenstein (Austria) in a loop back configuration, which included 2 ×660 km of ITU-T G.655 fiber. The superchannel is composed by eight subchannels with low-level modulation format, i.e. polarization multiplexed (PM)-quadrature phase shift keying (QPSK). The use of low order modulation format guarantee better robustness in terms of optical signal to noise ratio (OSNR) and reduced complexity with respect to higher order formats. Coherent detection was used together with iterative maximum a posteriori probability (MAP) detection and decoding at the receiver. A 992 Gb/s PM-QPSK superchannel was successfully transmitted between Milan-Finkenstein-Milan with a spectral efficiency (SE) of 6.2 bit/s/Hz. Long term measurements confirm the system reliability.