Birefringent Materials Research Articles

From B3O3(OH)3 to B3O3F3: Uncovering Series of New Functional Units Based on [BO2F] Beneficial for Deep‐Ultraviolet Birefringence

AbstractBirefringent materials play indispensable roles in modulating the polarization of light and are vital in laser science and technology. Units with π‐conjugation are regarded as potential functional modules for large optical anisotropy, such as planar [BO3]3−, [B3O6]3−, and [B3O3(OH)3]. However, the discovery of deep‐ultraviolet (DUV, λ ≤200 nm) birefringent materials still faces a serious challenge due to the limited band gap. Replacing hydroxyl anions [OH]− with fluorine anions F− in borates can cause the blueshift of the ultraviolet (UV) cutoff edge, however, the effect of this replacement on π‐conjugation units has not been systematically studied. Herein, based on template materials metaboric acid α‐B3O3(OH)3 with planar [B3O3(OH)3] units, we proposed an OH/F substitution strategy designing potential DUV birefringent materials. The designed B3O3(OH)2F, B3O3(OH)F2, and B3O3F3 exhibit large birefringence from 0.123 to 0.146 at 546 nm with DUV transparency based on first‐principles calculations, exceeding the performance of traditional α‐BaB2O4. Further electronic structure analysis reveals the band edge and bonding difference between [OH]− and F−, indicating the corresponding designed novel [BO2F], [B3O3(OH)2F], [B3O3(OH)F2] and [B3O3F3] units can act as potential DUV birefringent‐active functional modules with large structure anisotropy. This work offers the chemical difference of F− and [OH]− anions, and design‐strategy of new DUV birefringent materials.

First-principles study of three isomers of the large birefringent crystal Sb4O4F4: electronic structure and optical properties

Abstract Metal oxyhalides are becoming an important branch of birefringent materials due to their rich structural types and stable physicochemical properties. In this work, the electronic structure and optical properties of three isomers of antimony oxyhalide Sb4O4F4 (I- Pna21), Sb4O4F4 (II- Pnma), and Sb4O4F4 (III- Pnma) were investigated using first principles method. The results show that the band gap of I and III reaches the ultraviolet region (4.10 eV (I), 3.87 eV (III)). In particular, I-III all exhibit large birefringence of 0.138–0.266 at 1064 nm. Born effective charge, and project density of states results show that the large birefringence of I-III is mainly from the stereochemically active lone pair electrons around the antimony atom. Finally, structure–property relationship studies of I-III indicate that different Sb-F bonds and structural arrangements are the key factors leading to the significantly different properties.

LaAgSiS4: Increasing Optical Birefringence in Rare Earth Chalcogenide by Addition of Planar [AgS3] Groups.

Optoelectronic materials with excellent birefringent properties are of significant importance in the fields of optical communications and laser technology. Recently, rare earth (RE) chalcogenides with anisotropic [RESn] groups have been proven to be high-performance infrared birefringent materials. Herein, we demonstrate that the addition of planar groups can further increase the birefringence in RE chalcogenides, as realized by incorporating planar [AgS3] groups into the RE-I-IV-S4 family for the first time. The newly obtained LaAgSiS4 compound shows higher polarity anisotropy than its homologue LaLiSiS4 and LaKSiS4, which resulted in a larger birefringence (0.12@600 nm) at least twice as large as that of the latter two compounds (0.05/0.06@600 nm). The structure-property relationship of LaAgSiS4 was investigated through structural analysis and first-principles calculations. The results indicate that the increased optical birefringence in LaAgSiS4 originates from the synergic effects of the distorted [LaSn] polyhedra and planar [AgS3] triangles. This work provides an effective strategy for enhancing optical birefringence in IR chalcogenides.

(C10N2H10)(HI2O6)(HIO3)(IO3): A Birefringent Material Featuring Large π-Conjugated Organic Cation and Two Types of Iodate Anions.

Birefringent crystals, which can modulate and polarize light, play a vital role in the development of optical sensors and optoelectronic devices. Herein, we synthesized a new birefringent crystal [(C10N2H10)(HI2O6)(HIO3)(IO3)] with large birefringence by integrating the large π-conjugated 4,4'-bipyridine group with two types of iodates anions ([IO3]- and [HI2O6]-) characterized by high polarizability anisotropy and strong stereochemically active lone pairs (SCALP). The crystal exhibits a large measured birefringence of 0.171 at 550 nm, surpassing most organic-inorganic hybrid iodate birefringent materials reported in the literature. Theoretical analyses reveal that the optical properties of the crystal arise primarily from the synergistic interactions between the π-conjugated 4,4'-bipyridine group and I-O groups. This research presents an effective method for the strategic integration of large π-conjugated organic cations into iodates, facilitating the design of novel birefringent materials and encouraging further exploration of superior birefringent substances.

Minimize flow-induced uncertainty in polarization sensitive optical coherence tomography imaging using eigen decomposition.

Blood flow alters the scattering behavior of penetration light, causing instability in the polarization state to emerge at the underlying tissue during polarization-sensitive optical coherence tomography (PSOCT). We propose an eigen decomposition method to meet this challenge, where the static and dynamic scattering signals are separated for PSOCT to provide the polarization measurements of the tissue of interest that is located beneath the blood flow. Using flow phantoms made by Intralipid solution and 3D-printed birefringent material, we show the flow-induced effects on the measurements of sample birefringent properties of optical axis, phase retardation, and degree of polarization uniformity. We demonstrate the usefulness of the proposed method through in vivo imaging of the human nail fold.

An idiosyncratic reaction to the synthetic biologic membrane on a surgical wound

Abstract Introduction/Objective Biodegradable temporizing matrix (BTM) is a synthetic polymer used to temporarily close wounds and aid the body in generating new tissue. BTM is applied to a debrided wound.BTM acts as a scaffold aiding the migration of granulation tissue into the matrix. Once the tissue is fully integrated throughout the BTM, the sealing membrane is removed. The matrix slowly deteriorates until fully absorbed at approximately 18 weeks. Methods/Case Report An 80-year-old woman with a past medical history of eczema, rheumatoid arthritis and gout presented with swelling of the left third metatarsal. Imaging showed an abscess which was eventually drained and cultured to show mycobacterium chelone. The patient was started on antibiotics for mycobacterium. On follow up she reported a nodule on left forearm recently increased in size. MRI on 9/28 showed abscess of the dorsal aspect of phalanx. She underwent surgical debridement 10/31 on her finger and the forearm nodule. After debridement a polynovo BTM graft was placed. Histopathology showed skin and subcutaneous tissue with necrotizing granulomas of the finger and the forearm. Cultures and stains for mycobacterium returned negative.The patient was subsequently followed up for wound healing. She reported nodules on the left forearm at the scar from previous surgical site which were biopsied. Histopathology showed granulomatous inflammation, rare foreign body giant cells, and birefringent material. The stains for Ziehl-Neelsen, Fite and Gomori’s Methenamine Silver for Urate Crystals were all negative excluding the possibility of gouty tophi or mycobacterium. Results (if a Case Study enter NA) NA Conclusion The complex history of the patient with mycobacterium, gout, the giant cell reaction and the unique appearing birefringent crystals presented a puzzling problem. Given the negative stain results for mycobacteria and the presence of birefringent (foreign) material, we deem these granulomas most likely an idiosyncratic reaction to the synthetic biologic membrane applied during her prior procedure. There are no known cases of giant cell reaction and similar morphology of birefringent (foreign) material in literature.

Pb2TeV2O10: A Lead Vanadate Tellurate with Wide Mid-IR Transparency and Large Birefringence Induced by Multiple Birefringence-Active Groups.

Birefringent materials as the key materials in laser science and technology have attracted continuous attention due to their ability to modulate polarized light. Herein, a new lead vanadate tellurate, Pb2TeV2O10, has been synthesized through the rational integration of different kinds of birefringence-active functional units. Pb2TeV2O10 features a unique two-dimensional (2D) [TeV2O10]∞ layered structure consisting of [VO6]7- and [TeO6]6- octahedra, and Pb2+ cations reside between the [TeV2O10]∞ layers. In addition, the rare edge-sharing mode of [VO6]7- and [TeO6]6- octahedra was found in this structure. Attributed to the high polarizability and appropriate arrangement of PbO8, VO6, and TeO6 units, Pb2TeV2O10 possesses a great theoretical birefringence of 0.275 at 532 nm, which is the largest among the vanadate tellurate family. The spectral tests also prove that Pb2TeV2O10 showcases a broad transparency window (439 nm-10 μm), covering an important mid-infrared (IR) atmospheric window (3-5 μm). In addition, in order to improve the transparency, alkali and alkaline earth metal cations were introduced by the substitution strategy, and then the compound K2Sr2Te2O9 was synthesized. It owns a shorter ultraviolet (UV) cutoff edge of 234 nm and a wider transparency window (234 nm-13.8 μm). The findings of Pb2TeV2O10 and K2Sr2Te2O9 enrich the structure chemistry of the tellurate family and provide new insights for designing new compounds with large optical anisotropy and wide spectral transparency.

Li2NaB3S2O12: A Deep-UV Transparent Borosulfate with Moderate Birefringence Derived from the [B3S2O12]∞ Infinite Chain Designed by the High Boron-to-Sulfur Ratio Strategy.

The first mixed alkali metal borosulfate compound, Li2NaB3S2O12 (LNBSO), which contains [BO3] groups, was designed and synthesized by using a high boron-to-sulfur ratio strategy through the high temperature solution method. LNBSO exhibits a birefringence of 0.057@546.1 nm in experiments, which was mainly contributed by the [BO3] groups, and possesses a short absorption edge at 184 nm, and the space group of LNBSO is P21/c. This newly synthesized borosulfate compound holds potential as a promising birefringent material within the deep-ultraviolet wavelength range. Moreover, the investigation on the relationship among the ratio of boron to sulfur, the dimensionality of the anionic framework, and the formation of [BO3] groups has been conducted on available borosulfate, providing insights for the synthesis of borosulfate with desirable performances.

Broadband and widely tunable second harmonic generation in suspended thin-film LiNbO3 rib waveguides

Our study demonstrates second harmonic generation (SHG) in a high confinement LiNbO3 rib waveguide through type-I birefringence phase matching of fundamental modes. The combination of micro-waveguide dispersion and material birefringence reveals unique SHG characteristics that complement the performance of standard LiNbO3 on insulator (LNOI) components. Dual-pump wavelength phase matching in the near-infrared and mid-infrared regions is shown in a given waveguide. These two wavelengths can be positioned in the 1.1–3.5 μm range or converge near 1.5 μm by adjusting the core waveguide size or through temperature tuning. A 25 °C temperature change enables a broad pump tunability band of 300 nm, ranging from 1350 to 1650 nm, with a conversion efficiency exceeding 40 %/W/cm2 within a single waveguide. A temperature tuning range of up to 900 nm is foreseen by tailoring the waveguide core size. In addition, a broadband response of 150 nm within the telecom window is demonstrated experimentally. The nonlinear waveguide, etched in a thin film membrane, is combined with titanium-indiffused waveguides to form a monolithic LiNbO3 component. This configuration provides low coupling losses of 0.8 dB and single-mode operation. It paves the way for a new generation of versatile and cost-effective frequency conversion components with wide-band spectral responses suitable for optical communications, environmental sensing, and quantum information processing.

Unusual Triple-State Switching of Thermally Induced Birefringence in a Two-Dimensional Perovskite Ferroelectric.

Birefringent crystals hold a significant position in optical and optoelectronic fields due to their capability to control polarized light. Despite various chemical strategies devoted to designing birefringent crystals, it remains a challenge to switch and manipulate birefringence under physical stimuli. Here we present an unusual triple-state switching of birefringence in a 2D perovskite ferroelectric, (N-methylcyclohexylammonium)2PbCl4 (1), which exhibits two reversible phase transitions at 361 and 373 K. The in-plane birefringence of 1 (Δnbc) shows three distinctive states inside the bc plane, namely, the low-, high-, and zero-Δnbc states. Strikingly, a huge augmentation of Δnbc is solidly confirmed up to ∼400% between its low and high states, far beyond other birefringent materials. The origin of this triple-state switching of birefringence involves the variation of the ferroelastic strain and domain in the vicinity of the phase transition. As an entirely new mode of switching birefringence, this work facilitates the further development of new intelligent nonlinear optics.

C2H12N6C4O4·2H2O and Na2C4O4·3H2O: Two Ultraviolet Birefringent Compounds with the [C4O4]2- Group.

In modern optics, birefringent materials that can manipulate light polarization play important roles in lasers and information fields. The search for ultraviolet (UV) crystals with large birefringence is the focus of attention in the field of optical materials. In this work, we synthesized two birefringent crystals, C2H12N6C4O4·2H2O and Na2C4O4·3H2O, containing planar π-conjugated [C4O4]2- groups. Attributed to the large structural anisotropy and relatively ordered arrangement of the [C4O4]2- groups, C2H12N6C4O4·2H2O and Na2C4O4·3H2O possess large birefringence of 0.20-0.21 at 1064 nm. Meanwhile, they exhibit short ultraviolet cutoff edges at about 280-300 nm, corresponding to the large band gaps of 4.35 and 4.24 eV, respectively. Using structural analysis and first-principles calculations, the origins of such large birefringence are investigated and discussed. This work provides two potential UV birefringent crystals and prompts the search for novel birefringent materials.

Functional Modules Map of Unexplored Chemical Space: Guiding the Discovery of Giant Birefringent Materials

AbstractFinding birefringent material with giant optical anisotropy is urgent for photonic applications. However, the application of existing birefringent materials is limited by restricted transparency wavelength or optical anisotropy. The process of trial and error is time‐consuming and inefficient in terms of resources, especially when compared to the vast design spaces for materials. The immense chemical space necessitates a high‐throughput approach for giant optical anisotropy materials design. Here, a full‐applied wavelength map of birefringent materials is constructed, from conventional visible expanding to ultraviolet and deep‐ultraviolet region by high‐throughput screening methods. And highlighted 579 materials birefringence exceeds the one of available commercial birefringent materials in corresponding regions. Significantly, 54 materials possess giant birefringence above 0.5 @1064 nm. Via developing a high‐throughput screening technique for microscopic structures with given coordination number, the study further characterizes a comprehensive map of functional modules featuring birefringent activeness. According to the macroscopic and microscopic dual‐functional maps, and a novel crystal Li2(HC3N3S3)∙5H2O with birefringence difference 0.532 @546 nm is designed and synthesized successfully. This study identifies desired materials with high performance in unheeded chemical spaces.

Halogen Bond Unlocks Ultra‐High Birefringence

AbstractAnisotropy is crucial for birefringence (Δn) in optical materials, but optimizing it remains a formidable challenge (Δn >0.3). Supramolecular frameworks incorporating π‐conjugated components are promising for achieving enhanced birefringence because of their structural diversity and inherent anisotropy. Herein, we first synthesized (C6H6NO2)+Cl− (NAC) and then constructed a halogen‐bonded supramolecular framework I+(C6H4NO2)− (INA) by halogen aliovalent substitution of Cl− with I+. The organic moieties are protonated and deprotonated nicotinic acid (NA), respectively. The antiparallel arrangement of birefringent‐active units in NAC and INA leads to significant differences in the bonding characteristics between the interlayer and intralayer domains. Moreover, the [O⋅⋅⋅I+⋅⋅⋅N] halogen bond in 1D [I+(C6H4NO2)−] chain exhibits stronger interactions and stricter directionality, resulting in a more pronounced in‐plane anisotropy between the intrachain and interchain directions. Consequently, INA exhibits exceptional birefringent performance, with a value of 0.778 at 550 nm, twice that of NAC (0.363 at 550 nm). This value significantly exceeds those of commercial birefringent crystals, such as CaCO3 (0.172 at 546 nm), and is the highest reported value among ultraviolet birefringent crystals. This work presents a novel design strategy that employs halogen bonds as connection sites and modes for birefringent‐active units, opening new avenues for developing high‐performance birefringent crystals.

Halogen Bond Unlocks Ultra-High Birefringence.

Anisotropy is crucial for birefringence (Δn) in optical materials, but optimizing it remains a formidable challenge (Δn >0.3). Supramolecular frameworks incorporating π-conjugated components are promising for achieving enhanced birefringence because of their structural diversity and inherent anisotropy. Herein, we first synthesized (C6H6NO2)+Cl- (NAC) and then constructed a halogen-bonded supramolecular framework I+(C6H4NO2)- (INA) by halogen aliovalent substitution of Cl- with I+. The organic moieties are protonated and deprotonated nicotinic acid (NA), respectively. The antiparallel arrangement of birefringent-active units in NAC and INA leads to significant differences in the bonding characteristics between the interlayer and intralayer domains. Moreover, the [O⋅⋅⋅I+⋅⋅⋅N] halogen bond in 1D [I+(C6H4NO2)-] chain exhibits stronger interactions and stricter directionality, resulting in a more pronounced in-plane anisotropy between the intrachain and interchain directions. Consequently, INA exhibits exceptional birefringent performance, with a value of 0.778 at 550 nm, twice that of NAC (0.363 at 550 nm). This value significantly exceeds those of commercial birefringent crystals, such as CaCO3 (0.172 at 546 nm), and is the highest reported value among ultraviolet birefringent crystals. This work presents a novel design strategy that employs halogen bonds as connection sites and modes for birefringent-active units, opening new avenues for developing high-performance birefringent crystals.

Giant Optical Anisotropy in 2D Metal-Organic Chalcogenates.

Optical anisotropy is a fundamental attribute of some crystalline materials and is quantified via birefringence. A birefringent crystal gives rise to not only asymmetrical light propagation but also attenuation along two distinct polarizations, a phenomenon called linear dichroism (LD). Two-dimensional (2D) layered materials with high in-plane and out-of-plane anisotropy have garnered interest in this regard. Mithrene, a 2D metal-organic chalcogenate (MOCHA) compound, exhibits strong excitonic resonances due to its naturally occurring multiquantum well (MQW) structure and in-plane anisotropic response in the blue wavelength (∼400-500 nm) regime. The MQW structure and the large refractive indices of mithrene allow the hybridization of the excitons with photons to form self-hybridized exciton-polaritons in mithrene crystals with appropriate thicknesses. Here, we report the giant birefringence (∼1.01) and the tunable in-plane anisotropic response of mithrene, which stem from its low symmetry crystal structure and strong excitonic properties. We show that the LD in mithrene can be tuned by leveraging the anisotropic exciton-polariton formation via the cavity coupling effect, exhibiting giant in-plane LD (∼77.1%) at room temperature. Our results indicate that mithrene is a polaritonic birefringent material for polarization-sensitive nanophotonic applications in the short wavelength regime.

Programmable Photonic Quantum Circuits with Ultrafast Time-Bin Encoding.

We propose a quantum information processing platform that utilizes the ultrafast time-bin encoding of photons. This approach offers a pathway to scalability by leveraging the inherent phase stability of collinear temporal interferometric networks at the femtosecond-to-picosecond timescale. The proposed architecture encodes information in ultrafast temporal bins processed using optically induced nonlinearities and birefringent materials while keeping photons in a single spatial mode. We demonstrate the potential for scalable photonic quantum information processing through two independent experiments that showcase the platform's programmability and scalability, respectively. The scheme's programmability is demonstrated in the first experiment, where we successfully program 362 different unitary transformations in up to eight dimensions in a temporal circuit. In the second experiment, we show the scalability of ultrafast time-bin encoding by building a passive optical network, with increasing circuit depth, of up to 36 optical modes. In each experiment, fidelities exceed 97%, while the interferometric phase remains passively stable for several days.

Strategically designed metal-free deep-ultraviolet birefringent crystals with superior optical properties.

Finding new birefringent materials with deep-ultraviolet (DUV, λ < 200 nm) transparency is urgent, as current commercial materials cannot meet the rapidly growing demands in related application fields. Herein, three guanidinium-based compounds, C(NH2)3CH3SO3, β-C(NH2)3Cl, and γ-C(NH2)3Cl, all featuring [C(NH2)3·X]∞ (X = CH3SO3 and Cl) pseudo layers, were designed through structural motif tailoring. Theoretical calculations indicate that these metal-free compounds all possess broad bandgaps (6.49-6.71 eV, HSE06) and remarkable birefringence (cal. 0.166-0.211 @ 1064 nm). Centimeter-sized C(NH2)3CH3SO3 crystals have been grown using a feasible aqua-solution method. Subsequently, to further optimize the properties, β/γ-C(NH2)3Cl was remolded by further tailoring the [C(NH2)3]+ cationic unit and the acceptor Cl- anion, and then the fourth compound NH2COF was theoretically constructed. Interestingly, NH2COF exhibits the desired coexistence of a wider bandgap (7.87 eV, HSE06) and giant birefringence (cal. 0.241 @ 1064 nm) attributed to its higher density of well-aligned birefringence-active groups (BAGs). Furthermore, among these four designed compounds, C(NH2)3CH3SO3 has been experimentally synthesized and exhibits a short UV cutoff edge. Centimeter-sized crystals have been grown using a feasible aqueous solution method. This study provides an effective strategy to optimize the density of BAGs for large birefringence and offers valuable insights into the strategic design of metal-free DUV birefringent crystals.

Sulfate Derivatives with Heteroleptic Tetrahedra: New Deep-Ultraviolet Birefringent Materials in which Weak Interactions Modulate Functional Module Ordering.

Deep-ultraviolet (UV) birefringent materials are urgently needed to facilitate light polarization in deep-UV lithography. Maximizing anisotropy by regulating the alignment of functional modules is essential for improving the linear optical performance of birefringent materials. In this work, we proposed a strategy to design deep-UV birefringent materials that achieve functional module ordering via weak interactions. Following this strategy, four compounds CN4H7SO3CF3, CN4H7SO3CH3, C(NH2)3SO3CH3, and C(NH2)3SO3CF3 were identified as high-performance candidates for deep-UV birefringent materials. The millimeter-sized crystals of CN4H7SO3CF3, CN4H7SO3CH3, and C(NH2)3SO3CH3 were grown, and the transmittance spectra show that their cutoff edges are below 200 nm. CN4H7SO3CF3 exhibits the largest birefringence (0.149 @ 546 nm, 0.395 @ 200 nm) in the deep-UV region among reported sulfates and sulfate derivatives. It reveals that the hydrogen bond can modulate the module ordering of the heteroleptic tetrahedra and planar π-conjugated cations, thus greatly enhancing the birefringence. Our study not only discovers new deep-UV birefringent materials but also provides an upgraded strategy for optimizing optical anisotropy to achieve efficient birefringence.

Sulfate Derivatives with Heteroleptic Tetrahedra: New Deep‐ultraviolet Birefringent Materials in which Weak Interactions Modulate Functional Module Ordering

Sulfate Derivatives with Heteroleptic Tetrahedra: New Deep‐ultraviolet Birefringent Materials in which Weak Interactions Modulate Functional Module Ordering

Breaking Boundaries: Giant Ultraviolet Birefringence in Dimension‐Reduced Zn‐Based Crystals

AbstractBirefringent crystals have essential applications in optical communication areas. Low‐dimensional structures with inherited structural anisotropy are potential systems for investigating birefringent materials with large birefringence. In this work, the zero‐dimensional (0D) [(p‐C5H5NO)2ZnCl2] (1) and [p‐C5H6NO]2[ZnCl4] (2) were obtained by introducing the π‐conjugated p‐C5H5NO (4HP) into the three‐dimensional (3D) ZnCl2. Remarkably, 1 exhibits a giant birefringence of 0.482@546 nm, which is the largest among Zn‐based ultraviolet (UV) compounds and 160 times that of ZnCl2. According to structural and theoretical calculation analyses, the large optical polarizability, high spatial density, ideal distribution of the [(4HP)2ZnCl2]0 cluster, and the low dimension of 1 result in the dramatically increased birefringence compared to ZnCl2. This work will provide a valid route for accelerating the design and synthesis of compounds with excellent birefringence in low‐dimensional systems.