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Ultra-broadband optical parametric chirped pulse amplification by the matching of both the group velocity and pulse front

The problem of phase-mismatch-compensation for ultra-broadband OPCPA is first studied theoretically by us, and a scheme for phase-mismatch-compensation is proposed, which is based on the matching of both the group velocity and pulse front between signal and idler by the combination of the no collinear-phase-match and pulse-front-tilt that is accomplished by angular dispersion of the interacting rays. By this Scheme, the phase mismatch to first order in frequency shift can be completely compensated, and then an ultra-broadband OPCPA is realized. It is shown that the phase mismatch to both first and second order can be completely compensated simultaneously in some cases, and this leads to an extremely broadband spectral width. Therefore the important criterion for constructing an ultra-broadband OPCPA that both pulse-front and group-velocity between signal and idler are exactly matched simultaneously. Finally, specific numerical calculations and simulations are presented for BBO-OPCPA with type-I noncollinear angularly dispersed geometry.