PbB5O7F3: A High-Performing Short-Wavelength Nonlinear Optical Material

Nonlinear optical materials are the vital components of future photonic technologies as they can transfer and process data at the speed of light. However, the necessary prerequisites for a practical nonlinear optical material are very strict, and it is still a huge challenge to achieve the perfect balance among three critical parameters for nonlinear optics, including short cutoff edges, strong second-harmonic generation responses, and a suitable birefringence. Herein, via the introduction of the lone pair Pb2+ cations with stereochemical activity and the F– anions with the largest electronegativity into borate, a new fluorooxoborate PbB5O7F3 was obtained successfully. It exhibits a short cutoff edge (∼225 nm), a strong second-harmonic generation response (approximately 6 × KDP@1064 nm), and a large birefringence (cal. 0.12@1064 nm), achieving the optimal balance among the three critical parameters mentioned above for nonlinear optical applications in the short-wavelength region. The first-principles calculations were carried out to investigate the structure–property relationship of PbB5O7F3.

非线性光学材料（Nonlinear Optical Materials, NLO）是未来光子技术的核心组成部分，可实现光速级的数据传输与处理。然而，实用化非线性光学材料的制备条件极为严苛，实现非线性光学三大核心参数——短截止边、强倍频响应与合适的双折射（Birefringence）——间的完美平衡，仍是一项极具挑战性的课题。本文通过将具有立体化学活性的孤对电子Pb²+阳离子与电负性最高的F–阴离子引入硼酸盐（Borate）体系，成功合成了一种新型氟氧硼酸盐（Fluorooxoborate）PbB5O7F3。该材料展现出约225 nm的短截止边、约为1064 nm波长下KDP的6倍的强倍频效应（Second-Harmonic Generation, SHG）响应，以及计算值为0.12@1064 nm的大双折射，实现了短波区非线性光学应用所需上述三大核心参数的最优平衡。本文通过第一性原理计算（First-Principles Calculations），对PbB5O7F3的结构-性能关系（Structure-Property Relationship）进行了研究。