Na₃Ba₂(B₃O₆)₂F: Next Generation of Deep-Ultraviolet Birefringent Materials

Abstract

Birefringent materials are of great importance in optical communication and the laser industry, as they can modulate the polarization of light. Limited by their transparency range, few birefringent materials, except α-BaB2O4 (α-BBO), can be practically used in the deep ultraviolet (UV) region. However, α-BBO suffers from a phase transition and does not have enough transparency in the deep UV region. By introducing the relatively small alkali metal Na+ cation and the F– anion to keep the favorable structural features of α-BBO, we report a new birefringent crystal Na3Ba2(B3O6)2F (NBBF), which has the desirable optical properties. NBBF not only maintains the large birefringence (Δn = n o – n e = 0.2554–0.0750 from 175 nm to 3.35 μm) and extends its UV cutoff edge to 175 nm (14 nm shorter than α-BBO) but also eliminates the phase transition and has the lowest growth temperature (820 °C) among birefringent materials. These results demonstrate that NBBF is an attractive candidate for the next generation of deep UV birefringent materials.

Ba3Mg3(BO3)3F3 polymorphs with reversible phase transition and high performances as ultraviolet nonlinear optical materials

“…Second, substituting oxygen with fluorine in [BO 4 ] 5− maternal blocks to form [BO x F 4− x ] ( x +1)− ( x  = 0, 1, 2, 3) fundamental building blocks can make the anionic groups more flexible, and the negative effective charges at the terminal oxygen will be partly reduced, resulting in a suitable SHG coefficient and birefringence 26–29 . Third, the introduction of fluoride-containing flux can effectively decrease the viscosity of the borate systems during the growth of single crystals, which is a desirable choose for growing the large single crystals 20,24,25,30 .…”

Predicting Global Minimum in Complex Beryllium Borate System for Deep-ultraviolet Functional Optical Applications

“…Viable DUV (<200 nm) optical materials play a critical role in optical communication and the laser industry12345, as they possess wide transparency range and high damage threshold678910. Among them, birefringent or nonlinear optical (NLO) materials are utilized in polarization beam splitters, optical isolators, semiconductor photolithography and laser micromachining1112131415.…”

Sn2B5O9Cl: A Material with Large Birefringence Enhancement Activated Prepared via Alkaline‐Earth‐Metal Substitution by Tin

“…Of these, the BO 3 unit is considered as an excellent birefringent functional unit. First, borates with parallel‐aligned isolated BO 3 , B 2 O 5 , or B 3 O 6 groups can give large birefringence, such as α‐BBO (0.122 at 546 nm), Na 3 Ba 2 (B 3 O 6 ) 2 F (0.114 at 546 nm), Ba 2 Ca(B 3 O 6 ) 2 (0.125 at 546 nm) and Li 2 Na 2 B 2 O 5 (0.097 at 546 nm) . Therefore, the more highly polymerized coplanar BO 3 groups are expected to have the larger average anisotropic polarizability.…”