title: Third harmonic frequency generation by type-I critically phase-matched LiB3O5 crystal by means of optically active quartz crystal.
abstract: We present a method of third harmonic generation at 355 nm by frequency mixing of fundamental and second harmonic radiation of an ytterbium nanosecond pulsed all-fiber laser in a type-I phase-matched LiB(3)O(5) (LBO) crystal where originally orthogonal polarization planes of the fundamental and second harmonic beams are aligned by an optically active quartz crystal. 8 W of ultraviolet light at 355 nm were achieved with 40% conversion efficiency from 1064 nm radiation. The conversion efficiency obtained in a type-I phase-matched LBO THG crystal was 1.6 times higher than the one achieved in a type-II LBO crystal at similar experimental conditions. In comparison to half-wave plates traditionally used for polarization alignment the optically active quartz crystal has much lower temperature dependence and requires simpler optical alignment.
authors.affiliation: NTO «IRE-Polus», Vvedensky Sq.1, Fryazino Moscow 141190, Russia.
authors.forename: Valentin P
authors.initials: VP
authors.lastname: Gapontsev
authors.forename: Valentin A
authors.initials: VA
authors.lastname: Tyrtyshnyy
authors.forename: Oleg I
authors.initials: OI
authors.lastname: Vershinin
authors.forename: Boris L
authors.initials: BL
authors.lastname: Davydov
authors.forename: Dmitri A
authors.initials: DA
authors.lastname: Oulianov
mesh_terms: D001881:Borates / Q000737:chemistry*; D003460:Crystallization / Q000379:methods*; D008027:Light; D018020:Lithium Compounds / Q000737:chemistry*; D008422:Materials Testing; D044367:Phase Transition; D012031:Refractometry; D012542:Scattering, Radiation
chemical_list: D001881:Borates; D018020:Lithium Compounds; C021051:lithium borate