Terabit/s single-carrier transmission based on coherent time-division demultiplexing

The authors present a single-wavelength channel (single-carrier) Terabit/s transmission system and its application in transmission experiments up to 1040 km. The transmission system comprises a Terabit/s transmitter which uses in particular advanced modulation formats (RZ-QPSK, RZ-8-PSK, Star-16-QAM) and optical time-division multiplexing to generate optical data signals up to 5.1 Tb/s. For the receiver they employ a digital coherent receiver with a pulsed local oscillator to demodulate and simultaneously demultiplex the received data signal. This approach allows to overcome the speed and bandwidth limitations of the available electronic components (modulator, driver, A/D converter, DSP). Furthermore, the presented Terabit/s receiver comprises an electro-optical clock recovery to synchronize the pulsed local oscillator to the received data signal up to symbol rates of 320 Gbaud. This enables ultra-high speed fiber transmission experiments without the need for simultaneous clock transmission. They demonstrate error-free transmission of single-polarization 0.32 Tb/s RZ-QPSK data signals over 1040 km dispersion managed fiber and of alternating-polarization 0.96 Tb/s RZ-8-PSK data (net 0.90 Tb/s considering UFEC with 7% overhead) over 480 km. In comparison to the Star-16-QAM results they find significantly better performance for the pure PSK formats, even at comparable bit-rates.