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Because the stretched-pulse duration is of the order of hundreds of picoseconds, the DPA delay is induced using a freespace interferometer with reasonable arm lengths of few tens of centimeters. The use of a common interferometer to divide and recombine temporal pulse replicas, together with the Sagnac geometry, results in an identical optical path for all four replicas. Therefore, the whole spatio-temporal combining architecture is passive, avoiding the need for active electronic stabilization systems. Because we only use two temporal replicas, the system is immune to differential saturation levels or B-integrals between successive pulses: this is compensated by controlling the amplitude of both pulses at the input of the amplifying setup. This setup allows the generation of 1 mJ, 300 fs compressed pulses at 50 kHz repetition rate, corresponding to 50 W output average power, with a combining efficiency above 90% at all power levels. |
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Fiber amplifiers
Optical amplifiers
Interferometers
Polarization
Energy efficiency
Fiber lasers
Phase shift keying
