Ultralow-Loss Femtosecond Laser Slicing of Lithium Niobate Enabled by Anisotropic Thermal Dissipation-Guided Vector Scanning

Abstract Lithium niobate (LiNbO3) crystals have been widely used in photonic and electronic devices owing to their outstanding intrinsic optoelectronic properties. However, fabricating hundreds-of-micrometer-thick LiNbO3 wafers remains dominated by diamond wire sawing, which causes substantial material loss. Although ultrafast laser processing offers a promising alternative, the intrinsic noncentrosymmetric lattice, spontaneous polarization, and anisotropic photothermal response of LiNbO3 severely hinder high-quality laser cutting. Here, a thermal dissipation-guided vector scanning technology is proposed to realize ultrafast laser slicing of LiNbO3 crystals for the first time. By tailoring the scanning direction according to the anisotropic thermal dissipation, we achieve crystal exfoliation with an ultrathin subsurface damage layer of 10 μm and an exceptionally high-quality separation surface. The results establish vector scanning technology as an innovative route for high-quality femtosecond laser processing and low-damage separation of anisotropic crystals.