Dual Semiconductor Laser System With Rapid Time-Delay for Ultrafast Measurements

We present a dual semiconductor laser system at 1.55 mum with femtosecond pulse widths and very low timing jitter for rapid pump-probe measurements. Synchronizing the two lasers to the same low-noise radio frequency-oscillator allows the use of an electrical phase shifter for the relative time delay between the lasers. This leads to a large scanning window that nearly matches the pulse period of 2.5 ns, as well as achieving a discrete time step of below 100 fs. The timing jitter of the complete dual laser system including all electronics is only 540 fs across the whole time delay. The nonlinear pulse compression using especially designed comb-like dispersion profiled fiber leads to autocorrelation widths of 310 fs. The system performance, i.e., the high time resolution is demonstrated by optical cross correlation of the pump and probe pulse, showing a very low full-width at half maximum of 1.3 ps