Spectral combination of ultrashort laser pulses

An ultrashort and ultraintense pulses combination method is proposed, based on the spectral combination of parallel laser pulses, with complementary spectra, in chirped pulse amplification (CPA) laser systems. In a proof-of-principle experiment, it is demonstrated that two long pulses of 330 fs can be overlapped in a collinear way, to produce a shorter pulse, of 190 fs. As a consequence, it is shown that the power for the combined pulse obtained is up to a factor of 1.7 larger than the sum of the peak powers of each individual pulse. The spectral phase of the combined pulse was characterized with λ/10 accuracy, using spectral interferometry. A way to implement the method at parallel CPA laser facilities, using no transmission optics, is indicated.