Talbot self-imaging and cross-phase modulation for generation of tunable high repetition rate pulse trains

We report generation of an ultra-high speed tunable pulse source with a repetition rate of 10, 30 or 40 GHz by a technique implementing a tunable chirped fibre Bragg grating. An optical pulse train of variable repetition rate is derived in a tunable dispersion compensator via the fractional temporal Talbot effect, acting on the output of a 10 GHz mode-locked laser. This ultra-high speed modulation is then used for phase modulation of a spectrally tunable probe by cross-phase modulation in highly nonlinear fibre, which is converted into constant-phase intensity modulation by spectral filtering.