title: Broadband quasi-phase-matched second-harmonic generation in MgO-doped periodically poled LiNbO_3 at the communications band.
abstract: A novel scheme for broadband second-harmonic generation was developed with type I quasi phase matching by use of an off-digital nonlinear optical coefficient d(31) . This was achieved by matching of the group velocities of the second harmonic and the fundamental, while the phase velocities were quasi phase matched. The desired group-velocity dispersion could be obtained with LiNbO(3) doped with 5 mol. % of MgO. Efficient second-harmonic generation with a bandwidth of 52 nm was obtained for the fundamental wavelength centered at 1566 nm in MgO-doped periodically poled LiNbO(3) , compared with a bandwidth of 1.3 nm for the conventional scheme using d(33) . Efficient frequency doubling of an ultrafast pulse is expected without group-velocity walk-off or pulse distortion.
authors.forename: Nan Ei
authors.initials: NE
authors.lastname: Yu
authors.forename: Jung Hoon
authors.initials: JH
authors.lastname: Ro
authors.forename: Myoungsik
authors.initials: M
authors.lastname: Cha
authors.forename: Sunao
authors.initials: S
authors.lastname: Kurimura
authors.forename: Takunori
authors.initials: T
authors.lastname: Taira