Xu Hao, Ding Baofu, Xu Youan, Huang Ziyang, Wei Dahai, Chen Shaohua, Lan Tianshu, Pan Yikun, Cheng Hui-Ming, Liu Bilu
Shenzhen Geim Graphene Center, Tsinghua-Berkeley Shenzhen Institute & Institute of Materials Research, Shenzhen International Graduate School, Tsinghua University, Shenzhen, China.
Institute of Technology for Carbon Neutrality/Faculty of Materials Science and Engineering, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.
Nat Nanotechnol. 2022 Oct;17(10):1091-1096. doi: 10.1038/s41565-022-01186-1. Epub 2022 Aug 11.
Birefringence is a fundamental optical property that can induce phase retardation of polarized light. Tuning the birefringence of liquid crystals is a core technology for light manipulation in current applications in the visible and infrared spectral regions. Due to the strong absorption or instability of conventional liquid crystals in deep-ultraviolet light, tunable birefringence remains elusive in this region, notwithstanding its significance in diverse applications. Here we show a stable and birefringence-tunable deep-ultraviolet modulator based on two-dimensional hexagonal boron nitride. It has an extremely large optical anisotropy factor of 6.5 × 10 C J m that gives rise to a specific magneto-optical Cotton-Mouton coefficient of 8.0 × 10 T m, which is about five orders of magnitude higher than other potential deep-ultraviolet-transparent media. The large coefficient, high stability (retention rate of 99.7% after 270 cycles) and wide bandgap of boron nitride collectively enable the fabrication of stable deep-ultraviolet modulators with magnetically tunable birefringence.
双折射是一种基本光学特性，可引起偏振光的相位延迟。在当前可见光和红外光谱区域的应用中，调节液晶的双折射是光操纵的核心技术。由于传统液晶在深紫外光下存在强吸收或不稳定性，尽管其在各种应用中具有重要意义，但在该区域仍难以实现可调谐双折射。在此，我们展示了一种基于二维六方氮化硼的稳定且双折射可调的深紫外调制器。它具有6.5×10 C J m的极大光学 anisotropy 因子，产生了8.0×10 T m的特定磁光科顿-穆顿系数，这比其他潜在的深紫外透明介质高出约五个数量级。氮化硼的大系数、高稳定性（270次循环后保留率为99.7%）和宽带隙共同使得能够制造出具有磁可调双折射的稳定深紫外调制器。
