COMPENSATION OF HIGHER-ORDER FREQUENCY-DEPENDENT PHASE TERMS IN CHIRPED-PULSE AMPLIFICATION SYSTEMS

We have developed a system that provides monotonic tuning of the higher-order frequency-dependent phase of ultrashort laser pulses. This technique utilizes geometric aberrations that arise from adjustments to the relative alignment of the elements of an air-spaced doublet lens. In a system such as a diffraction-grating stretcher, the spectral components of the optical pulses are spatially dispersed, and lens aberrations introduce frequency-dependent phase shifts. A numerical model of a general chirped-pulsed amplification system has been developed and verified by comparison with experimental and analytical results. Numerical results indicating that higher-order phase terms can be compensated by a properly adjusted air-spaced doublet design within the pulse stretcher are presented.