Periodical poling of 3mm-thick MgO:LiNbO/sub 3/ crystals for high-power nonlinear wavelength conversion

In this paper, we investigate field poling characteristics and demonstrate periodical poling in 3mm-thick MgO:LN crystals. LiNbO/sub 3/ (LN) is an attractive material for quasiphase-matching (QPM) devices because of its large nonlinear coefficient. Although periodically poled LN (PPLN) devices can perform many kinds of wavelength conversion such as second harmonic generation, difference frequency generation and optical parametric oscillation, problems about photorefractive damage and high coercive field remain in PPLNs. MgO-doped LN (MgO:LN) has been investigated and developed because of its higher resistance to photorefractive damage and a lower coercive field than that of nondoped LN. Therefore, MgO:LN is a suitable material for large aperture QPM devices for high-power/short-pulse operation.