Synchronization of Two Spectra-Physics Spitfire Pro Amplifiers for Pump-Probe Experiments

2 the delay between two amplified pulses by delaying one of the replicas. The repetition rate of the oscillator is around 80 MHz, which means every seed pulse is inherently separated by around 12 ns. As a result, we can introduce a time delay between two replica pulses of up to 12 ns. Here, we utilize an optical delay line covering this 12 ns delay range with better than 30 fs resolution. The described approach also provides cost savings compared with a two oscillator setup. Although in this note we describe the operation of the slave amplifier (Spitfire ®-slave) only, the block diagram of the entire setup is presented in figure 1. The Tsunami ® oscillator output is split in an 80/20 ratio with 20% of the beam seeding the master amplifier (Spitfire ®-master). The remaining 80% is directed to a delay line of 0.6 m travel range. The delay line is equipped with two corner cube retroreflectors allowing a total of 8 passes. Over the full range of travel, it can provide 16 ns optical delay; more than enough for a 12 ns pulse separation. After traversing the delay line, a small portion of the beam is sent to the photodiode to trigger the slave Time Delay Generator (TDG), while most of the beam is directed to the slave amplifier. In this configuration, the timing between the Empower ® of the slave amplifier and the seed pulse would not be affected by the delay of the seed pulse. Fig. 1. Block diagram setup for synchronizing two amplifiers with a single oscillator. PD-photodiode; TDG-time delay generator. Figure 2 shows the beam routing at the Tsunami oscillator output. 80% of the beam is reflected by the beamsplitter and directed toward the delay line shown in figure 3. Before entering the delay line, the beam passes through a 2x telescope, reducing the divergence of the beam. Careful alignment of the beam is performed with each additional set