Quasi-phase-matching of laser harmonics using variable multi-jet plasmas

In this paper, we demonstrate the enhancement of high-order harmonics induced by the quasi-phase-matching (QPM) in different spectral ranges. The tuning of QPM harmonics was accomplished by changing the sizes of multiple plasma jets. The 40× and 15× enhancement factors for the QPM harmonics were achieved in the silver and manganese multiple-jet plasmas for the 35th and 55th harmonics.