The exploration and improvement of excellent mid-infrared nonlinear optical (NLO) materials is still in great demand. The perovskite-type Sr₂Nb₂O₇ is found to be a good predictor of NLO properties due to the similar band gap and NLO coefficients to KTiOPO₄ (KTP). In this paper, we systematically investigated the electronic structures, linear and nonlinear properties of pure and V-doped Sr₂Nb₂O₇ based on DFT. It is found that the V-doped Sr₂Nb₂O₇ doubles the NLO coefficient and exhibits higher birefringence, which is moderate and sufficient for phase-matching. The results are helpful to the further development of the mid-infrared NLO crystals with perovskite structure.

仍然需要对优异的中红​​外非线性光学（NLO）材料进行探索和改进。由于与KTiOPO ₄（KTP）相似的带隙和NLO系数，钙钛矿型Sr ₂ Nb ₂ O ₇被认为是NLO性能的良好预测指标。在本文中，我们基于DFT系统研究了纯和V掺杂Sr ₂ Nb ₂ O ₇的电子结构，线性和非线性性质。发现掺杂V的Sr ₂ Nb ₂ O ₇NLO系数加倍，并显示出更高的双折射，这是适中的并且足以进行相位匹配。结果有助于钙钛矿结构的中红外NLO晶体的进一步发展。