A novel all-optical scheme for the conversion of quaternary-to-binary data is proposed and demonstrated experimentally in dispersion-flatten high nonlinearity microstructure fiber.Based on the self-phase-modulation(SPM) in microstructure fiber,the broadening of the spectrum varies with the intensity of the ps-pulse changes.In our experiments,three-way 10 Gb/s binary signals are filtered out at different wavelength from one-way 10 GB/s quaternary signal.The three signals are coupled into one-way20 Gb/s signa...