320/640 GHz high-quality pulse sources based on multiple four-wave mixing in highly nonlinear optical fibre

Ultra-high repetition rate quality pulse trains have been generated in a highly nonlinear optical fibre through the compression of a dual-frequency beat-signal based on a multiple four-wave mixing process. FROG analyses show that 500 and 300 fs transform-limited pulses have been generated at 320 and 640 GHz, respectively, over a 20 nm wavelength range.