High-order harmonic enhancement using the quasi-phase-matching in laser plasma

The quasi-phase-matching of the high-order harmonics generating in the multiple plasma jets produced on the surfaces of perforated Ag, V, and Mn targets is demonstrated. The $20{\times}$ and $30{\times}$ enhancement factors of quasi-phase-matched harmonics of $804$ nm radiation in the range of 35th harmonic in the cases of silver and vanadium plasmas were achieved.