Wang Weiwei, Liu Hongde, Zheng Dahuai, Liu Yue, Kong Yongfa, Xu Jingjun
Department of Mathematics and Physics, Shijiazhuang Tiedao University, Shijiazhuang 050043, China.
MOE Key Laboratory of Weak-Light Nonlinear Photonics, TEDA Institute of Applied Physics and School of Physics, Nankai University, Tianjin 300457, China.
Phys Chem Chem Phys. 2024 Dec 11;26(48):29922-29928. doi: 10.1039/d4cp03944k.
Lithium niobate on insulator (LNOI) has attracted widespread interest due to the excellent optical performance of lithium niobate crystals and the integration characteristics of thin film devices. With the improvement of the integration level of photonic integrated chips and the increase in light intensity inside the chip, the impact of optical damage in LNOI on-chip performance has attracted attention. One effective way to suppress the optical damage of lithium niobate is to dope it with Zr to form LiNbO (LiNbO:Zr), which is famous for its high resistance to optical damage from ultraviolet to visible spectrum. However, the mechanism behind the outstanding resistance to optical damage in LiNbO:Zr is still unclear. Here, the density of states, photorefractive center, refractive index, and birefringence of LiNbO:Zr are analyzed as functions of dopant concentrations by first-principle calculations. Electronic property analysis shows that the electrons in the Zr 4d state are all transferred to the Nb 4d state, occupying the shallow impurity level. The refractive index and birefringence change when the doping concentration reaches a threshold concentration of about 2.0 mol%. As the most stable full shell state, Zr-Nb can effectively suppress the photorefractive effect and result in the lowest refractive index and birefringence. These calculations not only establish the defect model corresponding to the different doping concentrations to investigate the optical properties of LN:Zr but also explain the mechanism underlying the high resistance to optical damage in LiNbO:Zr.
绝缘体上铌酸锂（LNOI）因其铌酸锂晶体优异的光学性能和薄膜器件的集成特性而受到广泛关注。随着光子集成芯片集成度的提高以及芯片内部光强的增加，LNOI中的光学损伤对片上性能的影响受到关注。抑制铌酸锂光学损伤的一种有效方法是用Zr对其进行掺杂，形成LiNbO（LiNbO:Zr），它以在紫外到可见光谱范围内具有高抗光学损伤能力而闻名。然而，LiNbO:Zr中突出的抗光学损伤背后的机制仍不清楚。在此，通过第一性原理计算分析了LiNbO:Zr的态密度、光折变中心、折射率和双折射随掺杂浓度的变化。电子性质分析表明，Zr 4d态中的电子全部转移到Nb 4d态，占据浅杂质能级。当掺杂浓度达到约2.0 mol%的阈值浓度时，折射率和双折射发生变化。作为最稳定的满壳层状态，Zr-Nb可以有效抑制光折变效应，并导致最低的折射率和双折射。这些计算不仅建立了对应于不同掺杂浓度的缺陷模型来研究LN:Zr的光学性质，还解释了LiNbO:Zr中高抗光学损伤的潜在机制。
