title: One-step photoinscription of asymmetrically oriented fresnoite-type crystals in glass by ultrafast laser.
abstract: Oriented fresnoite-type crystals (Sr(2)TiSi(2)O(8)) were photoinduced directly in bulk silica-based glass by femtosecond laser irradiation at high repetition rate (typ. 300 kHz). Unlike related results obtained from other researchers, asymmetrical polar-axis orientation of those nonlinear crystals in transverse direction of the cross section has been demonstrated by electron backscattered diffraction and micro-second-harmonic generation (SHG). The nonlinear optical property of laser lines has been further characterized by SHG measurement. We found that the preferential directions of the polar axis were in the laser motion direction with a small dispersion in part of the heated volume. The other part of the crystallized volume shows an axis perpendicular to the writing direction. The mechanism of asymmetric orientation of femtosecond-laser-induced crystallization also is discussed.
authors.forename: Xuan
authors.initials: X
authors.lastname: He
authors.forename: Bertrand
authors.initials: B
authors.lastname: Poumellec
authors.forename: Qiming
authors.initials: Q
authors.lastname: Liu
authors.forename: Francois
authors.initials: F
authors.lastname: Brisset
authors.forename: Matthieu
authors.initials: M
authors.lastname: Lancry