本研究利用搭建的高精度单颗粒偏振光谱表征系统，测量了六方相NaYF₄：Sm³⁺和单斜相BiPO₄：Sm³⁺单颗粒微米晶体的偏振发光特性，并结合偏振庞加莱球法和偏振拟合法对偏振发光峰进行了分析。结果表明，两种晶相中的Sm³⁺离子均发射部分偏振光，不同的是，六方相发光峰的线偏角精确沿着或垂直于结晶c轴，而单斜相发光的线偏角与结晶c轴存在非平行或正交的夹角。基于局部点群对称性和晶体宏观对称性，揭示了六方相发光峰的正交线偏角起源于光学跃迁偶极子绕结晶c轴的旋转对称分布，而单斜相中偶极子不具备旋转对称性，导致其发光峰的线偏角随机取向。该发现对于利用晶体结构获得具有理想偏振发光特性的稀土单颗粒晶体具有指导意义。

In this paper, the polarized luminescence of single hexagonal NaYF₄∶Sm³⁺ and monoclinic BiPO₄∶Sm³⁺ microcrystals are measured by using high-precision single-particle polarization-resolved spectroscopy. Experimental results are analyzed by applying Poincare? sphere and polarization fitting methods, which show that the emissions from Sm³⁺ ions in hexagonal and monoclinic microcrystals are partially polarized. However, the linear polarization angles of emissions from hexagonal microcrystals are completely parallel and perpendicular to the crystalline c-axis, whereas the angles of monoclinic microcrystals are not. From the perspectives of point group theory and macroscopic crystal symmetry, the orthogonally linear polarization angles of hexagonal microcrystals are due to the rotational symmetry of optical transition dipoles around the c-axis. However, the transition dipoles in the monoclinic phase do not allow rotational symmetry, resulting in the random linear polarization angles of the emissions. This finding will facilitate the achievement of rare-earth-ion-doped single micro/nanocrystals with desirable polarization properties originating from their crystal structure design.