摘要
Femtosecond laser writing is a powerful three dimensional(3D)engineering technique for materials processing.It has been used to modify the refractive index of dielectric materials(e.g.,glass,crystals)to construct optical waveguides for diverse applications.Lithium niobate(LiNbO3)is a multifunctional crystal with excellent nonlinear optical properties.Nonlinear photonic crystal(NPC)could control nonlinear optical interactions through quasi-phase matching(QPM)due to the periodical nonlinear coefficients.Although the 1D and 2D NPCs have been fabricated by electric-field poling,the implementation of 3D NPCs remains as a major challenge in nonlinear optics because of the limitation of traditional poling methods.
