Using the well-known LiB 3 O 5 as the template, by improving the angle between B 2 O 5 units in its structure to reduce birefringence, two novel birefringent crystals Li 2 MLaB 18 O 30 (M = Rb, Cs) for preparing zero-order wave-plates are obtained by a high-temperature solution method in a closed system. Interestingly, the neighboring B 2 O 5 units are aligned almost perpendicularly, making them exhibit tiny birefringence, which is much smaller (0.0032@532 nm and 0.0027@532 nm, respectively) than that of the commercial quartz crystal (Δ n ~0.0092@visible region). Moreover, the ultraviolet cutoff edges of Li 2 MLaB 18 O 30 (M = Rb, Cs) crystals are below 200 nm, demonstrating that they can be applied as zero-order waveplate materials in the deep-ultraviolet region.
Shaohua Liu,Li-Li Zhang,Ke Li,Xiaotian Ma,Xifa Long,Yun Yang
The capability of zero-order waveplates to manipulate the polarization of fundamental-frequency light has garnered significant attention in light of the rapid advancements in laser technology. In particular, zero-order waveplate materials in the deep-ultraviolet range (DUV; λ < 200 nm) are in urgent and short supply. In this study, three aluminum fluorides, AlF3 (P6/mmm), BaAlF5 (I4/m), and Li2KAl2F9 (C2/m), have been successfully designed and synthesized through a strategy that combines perfluorinated [AlF6] group with alkali and alkaline-earth metals. The results of experimental and theoretical calculations indicate that all three new aluminum fluorides have a short cutoff edge (λ < 200 nm) and small birefringence (0.0006 ~ 0.0056 @1064 nm). Theoretical calculations indicate that AlF3 (P6/mmm) has the shortest wavelength of 125 nm, which is comparable to the shortest wavelength of the commercially available MgF2. However, its birefringence of 0.0006 @1064 nm is about 20 times lower than that of the MgF2 (0.012 @546 nm), making it highly advantageous for fabricating deep-ultraviolet zero-order waveplate materials. Further microscopic analysis reveals that the [AlF6] group exhibits a substantial band gap of 9.17 eV and small polarizability anisotropy, indicating that the aluminum fluorides are potential candidates for designing suitable compounds for DUV zero-order waveplate materials.
Waveplates are important optical components to control the polarization of light. Currently, they are often fabricated from uniaxial crystals, and there is no report about waveplates based on the biaxial crystals. In this work, a novel biaxial crystal MgTe 2 O 5 with a structure constructed by 0D Te 2 O 5 groups is designed and grown as waveplate materials for the first time. The exciting result is that the birefringence in the (001)-plane is smaller than 0.0028 in the range from 0.4 to 5 µm, which is significantly smaller than that of the current waveplate materials. The polarization modulations of the MgTe 2 O 5 devices working at 532 nm indicate that excellent zero-order half and quarter waveplates have been successfully prepared. In addition, achromatic waveplates used in the visible, near-infrared, and mid-infrared ranges have also been calculated. The MgTe 2 O 5 crystal not only exhibits a high laser damage threshold of up to 2.7 GW cm −2 but also shows a wide transmission range from 0.37 to 6.3 µm. These results provide an excellent waveplate crystal and explore the applications of biaxial crystals.
危险品化学品经营许可证（带存储）