A novel, purely optical technique for demultiplexing highspeed time-division multiplexed data is proposed and demonstrated. The technique uses optical fibre nonlinearity induced four-wave mixing with a data signal and a probe signal located at different wavelengths. Using only semiconductor laser light sources, 1:4 demultiplexing of 20 ps long, subpicojoule, 215 – 1 RZ pulses at a data rate of 16 Gbit/s with less than 1 dB penalty is demonstrated.