Birefringent materials play indispensable roles in modulating the polarization of light and are vital in the laser science and technology. Currently, the design of birefringent materials operating in the deep-ultraviolet region (DUV, λ ≤200 nm) is still a great challenge. In this work, we developed a new DUV birefringent crystal LiBO₂ based on [BO₂]^∞ infinite chains in the Li-B-O system, which simultaneously achieves the shortest UV cutoff edge (164 nm) and the largest birefringence (≥0.168 at 266 nm) among all the reported borate-based DUV birefringent materials. Single crystals of LiBO₂ with dimensions up to Ø55 × 34 mm³ were grown by the Czochralski method, providing access to large-sized single crystal with low cost. Moreover, it has a high laser damage threshold and stable physicochemical properties. These outstanding characters unambiguously support that LiBO₂ can be an excellent birefringent material for DUV application.

双折射材料在调制光的偏振方面起着不可或缺的作用，在激光科学技术中起着至关重要的作用。目前，工作在深紫外区（DUV，λ≤200 nm）的双折射材料的设计仍然是一个很大的挑战。在这项工作中，我们开发了一种基于Li-BO系统中[BO ₂ ] ^∞无限链的新型DUV双折射晶体LiBO ₂，​​同时实现了最短的UV截止边（164 nm）和最大的双折射（≥0.168 at 266 nm）在所有报道的基于硼酸盐的 DUV 双折射材料中。尺寸高达 Ø55 × 34 mm ^{3的 LiBO} ₂单晶由 Czochralski 方法生长，提供了以低成本获得大尺寸单晶的途径。此外，它具有高激光损伤阈值和稳定的物理化学性质。这些突出的特性明确支持 LiBO ₂可以成为用于 DUV 应用的优秀双折射材料。