All-opticaltwo-channelformatconversionisproposedandexperimentallydemonstratedfroma40Gbit/spolarizationmultiplexing(Pol-MUX)non-return-to-zeroquadraturephase-shiftkeying(QPSK)signaltoPol-MUXbinaryphase-shiftkeying(BPSK)signalsbyusingphase-doubledfour-wavemixingeffectswithtwopolarization-angledpumpsinasiliconwaveguide.TheeyediagramsandconstellationdiagramsoftheoriginalQPSKsequencesandtheconvertedBPSKsequencesofeachchannelareclearlyobservedonthetwopolarizationstates.Moreover,thebiterrorrates(BERs)ofthetwoconvertedidlersaremeasured.ThepowerpenaltiesofalltheseconvertedBPSKsequencesonbothXandYpolarizationstatesarelessthan3.4dBataBERof3.8×10-3.