We report the first successful field trial of a real-time alien superchannel over a 410-km DCM-less optical fiber link using only EDFA amplification. We have demonstrated a record 1.4-Tb/s alien superchannel transported alongside native 40G and 100G wavelengths over a third party optical infrastructure using software reconfigurable DP-16 QAM/QPSK production hardware, achieving spectral efficiency of up to 5.7 bit/s/Hz. Stable long term error-free performance was measured in a real network environment for subchannel spacing as narrow as 36 GHz, giving a spectral efficiency improvement of ∼40% compared with standard 50 GHz grid. We have also demonstrated, for the first time, software reconfigurable modulation and capacity of an optical superchannel with subminute switching time. The subchannels can be flexibly and independently reconfigured to enable variable capacity in future flexible optical networks. In addition, robust PMD tolerance of the DP-16 QAM superchannel is measured, which allows network operators to make use of their old, high PMD fibers without the requirement of fiber measurement and selection.