Long-term Phase Stabilization of Intense Few-Cycle Pulses

The authors demonstrated an improved scheme for phase stabilization, in which the feedback loops are independent. The second feedback loop, stabilizing the phase of the amplifier controls the dispersion in the prism-compressor in order to stabilize the phase. This improved scheme not only increases the time period over which phase-stable pulses can be provided, it provides as well a much smaller phase noise. After compressing the phase stabilized 25-fs output pulses from the amplifier to 5 fs in a hollow fiber-chirped mirror compressor, a fraction of the compressed output to measure the carrier envelope phase of the pulses with a phase-detector based on threshold ionization was used.