A simultaneous two-channel optical time division multiplexing (OTDM) demultiplexing is proposed and experimentally demonstrated by using a bidirectionally operated highly nonlinear fiber followed by a narrow-band offset filter. The performance of the proposed demultiplexer is evaluated in an 80 Gbit/s OTDM transmission system. A maximum power penalty of 2.6 dB is obtained for the worst demultiplexed channel. The proposal might be interesting since it offers a powerful tool for developing ultrafast photonic networks.