A 640Gbit/s TDM signal has been successfully demultiplexed to 10Gbit/s with a walk-off free, ultrafast, 450m long nonlinear optical loop minor (NOLM). The NOLM consists of nine 50m long sections of dispersion flattened fibre (DFF) with different group delay characteristics. The walk-off between the signal and control pulses for each of the nine fibres was within +/-400fs. By properly connecting them, a total walk-os of < 100fs has been achieved.