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Recent advances toward 1 Tbit/s/ch transmission over long distances were overviewed. 1) Ultrahigh-speed transmission at 640 Gsymbol/s per polarization (640 Gbit/s DPSK or 1.28-2.56 Tbit/s DQPSK) have been demonstrated. 2) Subpicosecond pulse transmission over long distances, however, suffers from serious transmission impairments caused by long-term PMD variation and higher-order PMD. 3) Signal processing such as time-domain OFT technique and bandwidth reduction by employing multi-level RZ-QAM are expected to overcome such limitations and realize Tbit/s transmission over 500-1000 km. 4) All-optical and OTDM technologies are expected to contribute not only to ultrahigh-speed data transmission but also to network flexibility and low power consumption.