Exploring materials that balance the second harmonic generation (SHG) effect and laser-induced damage threshold (LIDT) is the frontier of nonlinear optical (NLO) crystal research at present. In this work, the NLO property of anhydrous aluminum iodate is extensively explored and discussed first. It exhibits a strong SHG intensity of 18.3 × KH₂PO₄ (KDP) and a high-powder LIDT of 1.4 × KDP at 1064 nm. Combining experimental and theoretical studies at the atomic level and electronic levels, it is found that the cations in the structure are replaced by cations with small radius and high valence, enabling the production of materials with large SHG responses. Unbonded and antibonding orbitals play a crucial positive role in the SHG response of the structure, whereas bonding orbitals produce a large negative contribution. This provides a scarce example of materials in which bonding orbitals make significant negative contributions.

中文翻译：

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无水碘酸铝：由非键合和反键合轨道带来的强二次谐波产生效应

探索平衡二次谐波产生（SHG）效应和激光诱导损伤阈值（LIDT）的材料是目前非线性光学（NLO）晶体研究的前沿。在这项工作中，首先对无水碘酸铝的 NLO 性质进行了广泛的探索和讨论。它在 1064 nm 处表现出 18.3 × KH ₂ PO ₄ (KDP)的强 SHG 强度和 1.4 × KDP 的高粉末 LIDT。结合原子水平和电子水平的实验和理论研究，发现结构中的阳离子被半径小、价态高的阳离子取代，从而能够生产具有大SHG响应的材料。非键合轨道和反键合轨道在结构的二次谐波响应中发挥着至关重要的积极作用，而成键轨道则产生很大的负贡献。这提供了一个稀有的材料例子，其中键合轨道产生显着的负面贡献。