title: Enhancement of harmonic generation by Fresnel-lensing effects.
abstract: We present experimental results of enhanced second- and third-harmonic generation efficiency from Fresnel-lensing effects. We obtained enhancement by a factor of 6 in the third-harmonic yield by simply limiting the laser beam with an iris. Higher enhancement factors (up to 16) were obtained with a Fresnel zone plate. The experimental findings are in good agreement with the results of a simple theoretical analysis.
authors.affiliation: Dipartimento di Fisica and LENS, Universitá di Firenze, Via G. Sansone, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Cavalieri
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Fini
authors.forename: Emiliano
authors.initials: E
authors.lastname: Sali
authors.forename: Roberto
authors.initials: R
authors.lastname: Buffa