Design of Deep-Ultraviolet Zero-Order Waveplate Materials by Rational Assembly of [AlO₂F₄] and [SO₄] Groups

Abstract

Zero-order waveplates are widely used in the manufacture of laser polarizer waves, which are important in polarimetry and the laser industry. However, there are still challenges in designing deep-ultraviolet (DUV) waveplate materials that satisfy large band gaps and small optical anisotropy simultaneously. Herein, three cases of aluminum sulfate fluorides: Na 2 AlSO 4 F 3 , Li 4 NH 4 Al(SO 4 ) 2 F 4 , and Li 6 K 3 Al(SO 4 ) 4 F 4 , with novel [AlSO 4 F 3 ] layers or isolated [AlS 2 O 8 F 4 ] trimers were designed and synthesized by the rational assembly of [AlO 2 F 4 ] and [SO 4 ] groups through a hydrothermal method. Experiments and theoretical calculations imply that these three possess short cutoff edges (λ < 200 nm) and small birefringence (0.0014−0.0076 @ 1064 nm), which fulfils the prerequisite for potential DUV zero-order waveplate materials. This work extends the exploration of DUV zero-order waveplate materials to the aluminum sulfate fluoride systems.

Hg4(Te2O5)(SO4): A Giant Birefringent Sulfate Crystal Triggered by a Highly Selective Cation

“…Sulfate crystals are receiving increasing attention in the research of optoelectronic functional materials due to their tetrahedral building unit, wide optical band gap, short UV cutoff edge, and easy crystal growth. , The long overlooked SO 4 tetrahedron has been found to be a good type of functional unit used in nonlinear optical materials. , However, the highly symmetrical SO 4 groups often result in a low birefringence of sulfates, such as LiNH 4 SO 4 (0.0078@532 nm) and LiKSO 4 (0.00025@546 nm) . Such a small birefringence prevents many sulfates from achieving phase matching by a direct second-harmonic generation process, hindering the application of sulfate crystals. , …”