We experimentally demonstrate $40–320\mathrm{Gbit}/\mathrm{s}$ phase-coherent multiplexing based on cross-phase modulation and subsequent $320–40\mathrm{Gbit}/\mathrm{s}$ demultiplexing using cross-phase-modulation-induced frequency shift in highly nonlinear fibers. An average penalty of approximately $7\mathrm{dB}$ at a ${10}^{-9}$ bit-error rate is observed after the nonlinear processes. We also show the generation of a phase-coherent $320\mathrm{GHz}$ optical pulse train. A delay-line interferometer based on differential group delay is used to verify the phase coherence characteristic of the multiplexed $320\mathrm{Gbit}/\mathrm{s}$ signal and the generated $320\mathrm{GHz}$ pulses.