Enhanced red-light photorefractive response speed of LiNbO3 crystals for full color holographic display

As a promising candidate material for holographic displays, lithium niobate (LN) is limited by its slow photorefractive (PR) response. Recently, it was discovered that Bi3+, with its lone-pair electrons, can effectively enhance the PR speed of LN crystals. However, this enhancement is only effective in the short-wavelength range of visible light, and the response time remains inadequate for full-color dynamic displays. In this paper, a theoretical framework is established to guide the shallow energy-level PR doping of LN crystals. We simulate the energy band structure, electron mobility, and other properties of LN crystals doped with Tl, Pb, and Sb ions, which feature lone-pair electrons, using first-principles calculations. The theoretical results indicate that when Sb occupies the Nb site (SbNb0), the defect level position in the bandgap is shallow, and the electron mobility is 79.029 cm2 V–1 s–1 subsequently, we grew a series of LN:Sb and LN:Sb,Mg crystals and characterized their crystalline quality and PR properties. High-resolution x-ray rocking curve results demonstrate that all the as-grown crystals exhibit excellent crystalline quality, with FWHM values ranging from approximately 0.007° to 0.008°. Notably, the LN:Sb1.0,Mg6.0 crystal demonstrates a rapid PR response time of 1.67 s at 671 nm, nearly three times faster than that of the LN:Bi1.0,Mg6.0 crystal.