Figure 7. High stability and quality of periodic sinc pulses.

(a) Colour-grade figure for one of the measured sinc-pulse sequences. In this case, a frequency comb with N=9 spectral components separated by Δf=10 GHz is generated (corresponding to the case depicted in Fig. 6a,b, but with no averaging). Measurement indicates a jitter of 82 fs and a SNR>40 dB. Other generated pulse sequences exhibit it similar levels of jitter and SNR. (b) r.m.s. error between measured pulses and the theoretical Nyquist pulse intensity derived from equation (1) as a function of the roll-off factor β. The r.m.s. error is minimized for β=0, indicating that the generated pulses match very well the ideal sinc shape with an error of 0.98%. Waveforms measured with other modulating frequencies exhibit similar behaviour.