title: Quasi-phase matching via femtosecond laser-induced domain inversion in lithium niobate waveguides.
abstract: We demonstrate an all-optical fabrication method of quasi-phase matching structures in lithium niobate (LiNbO3) waveguides using a tightly focused femtosecond near-infrared laser beam (wavelength of 800 nm). In contrast to other all-optical schemes that utilize a periodic lowering of the nonlinear coefficient χ(2)by material modification, here the illumination of femtosecond pulses directly reverses the sign of χ(2)through the process of ferroelectric domain inversion. The resulting quasi-phase matching structures, therefore, lead to more efficient nonlinear interactions. As an experimental demonstration, we fabricate a structure with the period of 2.74 μm to frequency double 815 nm light. A maximum conversion efficiency of 17.45% is obtained for a 10 mm long waveguide.
authors.forename: Xin
authors.initials: X
authors.lastname: Chen
authors.forename: Pawel
authors.initials: P
authors.lastname: Karpinski
authors.forename: Vladlen
authors.initials: V
authors.lastname: Shvedov
authors.forename: Andreas
authors.initials: A
authors.lastname: Boes
authors.forename: Arnan
authors.initials: A
authors.lastname: Mitchell
authors.forename: Wieslaw
authors.initials: W
authors.lastname: Krolikowski
authors.forename: Yan
authors.initials: Y
authors.lastname: Sheng