a, b,c, Tuning ranges of the Er- and Yb-doped fibre power amplifiers. The Er-arm is frequency doubled to provide the pump beam. d, e, Optical auto-correlations of the pump and Stokes pulses. f, Measurement of the timing jitter. Intensity noise at the peak (red) and half maximum (blue) of the optical cross-correlation (inset) over 5 minutes.