Relativistic laser harmonic generation from plasmas with density ripple

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Singh, K P
Gupta, V L
Tripathi, V K
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A high intensity laser obliquely incident on an underdense plasma with density ripple produces resonant second and third-harmonic radiation in the reflected component. The highest efficiency of harmonic generation occurs when the pump laser is incident at critical angle and the angle between ripple wave vector q and the surface normal has a specific value =m, at which phase-matching condition is satisfied. As the electron density varies from low densities to critical density, value of m varies from 90° to 45° for second-harmonic and from 110° to 60° for third-harmonic. The efficiency of phase-matched harmonic generation is an order of magnitude higher than the efficiency without phase-matching. The intensity of second and third-harmonic is proportional to square and cube of laser intensity respectively, when a0<<1 and proportional to laser intensity when a0>>1, where a0 is the normalized electric field parameter of the pump wave.
laser, plasma with density ripple, harmonic, harmonic generation, density