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To date, the orientational birefringence and the photoelastic birefringence of alternating copolymers have not been studied in detail. We focused on N-substituted maleimide (RMI) and styrene (St) as alternating copolymers and analyzed the birefringence, refractive index, and glass transition temperature (Tg) of the alternating copolymers. It was found that the photoelastic coefficient and Tg exhibit a nonlinear relationship with the composition ratio of RMI and St. It is considered that the alternating copolymerization of RMI and St confirms that the conformation is inhibited by interacting with each other. A zero–zero-birefringence polymer that exhibits no birefringence was obtained by using N-ethylmaleimide and St and adjusting the composition ratio. This polymer showed a high Tg, low haze, and a low temperature dependence of birefringence. [ABSTRACT FROM AUTHOR]

We discuss the nonlinear process of optical parametric amplification inside a chiral crystal. We show that circular birefringence, induced by chirality, leads to two different nonlinear processes with different phase-matching conditions that are associated with the opposite states of circular polarizations. A single nonlinear process occurs only when the states of polarization of the incident pump and signal beams are both circular and orthogonal. When these beams are linearly polarized initially, their state of polarization evolves in an elliptical fashion because of the two competing nonlinear processes taking place in parallel. We also discuss the properties of singly and doubly resonant optical parametric oscillators made by placing a chiral nonlinear crystal inside an optical cavity. [ABSTRACT FROM AUTHOR]

We provide an update to S. di Serego Alighieri, Int. J. Mod. Phys. D 24 (2015) 1530016, arXiv:1501.06460 [astro-ph.CO], focusing on recent developments regarding constraints on Cosmic Polarization Rotation (CPR), also known as Cosmic Birefringence (CB), derived from Cosmic Microwave Background (CMB) polarization data. [ABSTRACT FROM AUTHOR]

Mesoscopic billiard systems for electrons and light, realized as quantum dots or optical microcavities, have enriched the fields of quantum chaos and nonlinear dynamics not only by enlarging the class of model systems, but also by providing access to their experimental realization. Here, we add yet another system class, two-dimensional billiards with anisotropies. One example is the anisotropic dispersion relation relevant in bilayer graphene known as trigonal warping, and another is the birefringent closed optical disk cavity. We demonstrate that the established concept of ray–wave correspondence also provides useful insight for anisotropic billiard systems. First, we approach the dynamics of the anisotropic disk from the ray-tracing side that takes the anisotropy in momentum space into account, based on the non-spherical index ellipsoid. Second, we use transformation optics to solve the wave problem and find the resonances to be those of the isotropic elliptical cavity. We illustrate ray–wave correspondence and mark differences in the description of optical and electronic anisotropic systems. [ABSTRACT FROM AUTHOR]

The notched stick, also known as the Gee-Haw-Whammy-Diddle, is a wooden toy able to convert linear vibration into rotational motion, whose behavior has been intriguing both children and physicists for decades. The oldest scientific article one can find on this subject was published 87 years ago in the present journal. Here, we derive an analytical model of the system, supported by experimental results. We predict the direction of rotation and explain why the device is so easy to operate, even without fine control of the various parameters. The potential importance of the vertical displacement of the finger exerting the perturbation force is also highlighted. We finally discuss similarities between the mechanical system described here and the optical effect of birefringence. Editor's Note: Many readers have asked the question: why does the Gee-Haw-Whammy-Diddle spin the way it does? They would ask this question if they had seen someone rub a wooden dowel against a notched stick with a propeller attached at its end and claim to cause the propeller to rotate one way by exclaiming "gee!" and the other way by exclaiming "haw!" Well, these authors have a new and more complete explanation for how the trick works: it is all about how you hold the notched stick. In addition to a persuasive model and video demonstration, they present an elegant experimental test of the model that might make a nice project or demo in your classical mechanics courses. [ABSTRACT FROM AUTHOR]

Mineral separates mounted in thin section help introduce mineralogy students to concepts of relief, color, pleochroism, and birefringence and serve as reference materials both for research and teaching. Here, a simple method is described to produce materials that can be sent to thin section manufacturers to construct sets of mineral mounts. The method is relatively inexpensive, requires only simple equipment and few skills, and allows mounting of multiple minerals (easily 10–20) in a single thin section. The key to the method is to create first a slurry of 500–1000 mg of each crushed mineral plus ∼300 mg (500 μL) of epoxy and use a microspoon spatula to spoon each slurry into a 4 cm long tube made from 6 mm (or ¼″) diameter, standard wall, glass tubing. After epoxy sets, the 4 cm long tubes can be bundled together and shipped to thin section makers, who can set the bundles in epoxy (ends down) and make 10 or more duplicate sections. Photomicrographs are presented for selected mineral reference slides produced by this method, along with detailed instructions on how to create them. These methods allow both randomly oriented mineral separates and oriented crystals to illustrate isotropic appearance in quartz and reverse pleochroism in tourmaline. [ABSTRACT FROM AUTHOR]

In recent years, rare-earth(RE) borate materials have attracted much attention because of their rich structures and excellent optical properties. In this paper, we use a first-principles high-throughput screening tool to obtain five high-performing short-wavelength rare-earth boronate materials and further investigate their electronic structures and optical properties. The results show that the UV cut-off edges and birefringences of these materials are 210 nm, 0.0934@1064 nm (LaB3O6), 246 nm, 0.0880@1064 nm (LaBO3), 347 nm, 0.0815@1064 nm (LuBO3), 272 nm, 0.0914@1064 nm ( ScBO3), 279 nm, 0.0920@1064 nm (Sc3B5O12). In this paper, we analyzed the mechanism of the influence of each atomic and ionic group on the birefringence using the projected density of states, real space atomic real cuts, and Born effective charge, and the results showed that RE-O groups and B-O polyhedra make the main contributions in determining the optical properties. [ABSTRACT FROM AUTHOR]

We report the first homologous series of methylene-linked cyanobiphenyl- and cyanoterphenyl-based liquid crystal (LC) dimers (CBnCT). To induce the heliconical twist-bend nematic (NTB) phase through bent molecular shapes, the CBnCT homologs have an odd-numbered flexible alkylene spacer (n) ranging from 1 to 17. Polarized optical microscopy and differential scanning calorimetry are used to identify phases and analyze the phase-transition behavior. Except for n = 1, all the CBnCT homologs exhibit the conventional nematic (N) and NTB phases. The CBnCT dimers with n = 3 and 5 show a monotropic NTB phase, while those with n = 7, 9, 11, 13, 15, and 17 demonstrate an enantiotropic NTB phase below the conventional N phase temperature. The NTB phases of the CBnCT dimers (n = 7, 9, and 11) remain stable down to room temperature and vitrify without crystallization. Compared with cyanobiphenyl-based LC dimer homologs (CBnCB), the CBnCT dimers show significantly broader N and NTB phase temperature ranges with higher isotropic and NTB–N phase-transition temperatures. The NTB phase temperature ranges of CBnCT (n = 7, 9, 11, and 13) are over 100 °C. Additionally, more CBnCT homologs exhibit the enantiotropic NTB phase than the CBnCB ones. These enhancements result from increased π-conjugation and asymmetric molecular structures. Furthermore, CB9CT exhibits higher birefringence than CB9CB owing to its longer π-conjugated terphenyl moiety. [ABSTRACT FROM AUTHOR]

Birefringence is crucial for birefringent crystals to modulate polarized light and nonlinear optical crystals to enable phase-matching. It is closely related to the arrangement of advantageous functional groups with large microcosmic polarizability anisotropy in the structure. Currently, designing crystals with large birefringence by modulating the arrangement of advantageous functional groups is still a challenge. In this work, the arrangement of the advantageous [B3O7] groups is optimized by introducing rigid tetrahedral [SO4] groups, resulting in a novel boron-rich borosulfate, Na2B6SO13, which exhibits unprecedented [B6SO13]∞ double chain and an enhanced birefringence (Δn = 0.07 at 589.3 nm) against the borate parent LiB3O5. Theoretical calculations confirm that the birefringence is mainly attributable to the uniform alignment of [B3O7] groups. Na2B6SO13 also possesses a deep ultraviolet (DUV) cutoff edge (λ < 185 nm). This work provides a feasible method to design DUV birefringent crystals with large birefringence by inducing the arrangement of advantageous functional groups. [ABSTRACT FROM AUTHOR]

Designing ultraviolet (UV) and deep-UV materials remains a great challenge, especially designing those with multiple anions. By incorporating [NO3] units into borates and using the high-temperature solution method, a new alkali metal borate-nitrate crystallizing in the acentric space group Pca21 was designed and synthesized successfully in sealed quartz tubes. This borate-nitrate, having the formula Rb1.87Cs1.13B8O13(NO3), consists of interpenetrating porous 3D covalent [B8O13] and ionic [(NO3)(Rb/Cs)3] lattices. It shows a short UV cut-off edge of about 228 nm, and a moderate birefringence (0.047@1064 nm) and SHG response (0.3 × KDP). First principles calculations show that B–O units and [NO3] units make the predominant contribution to the SHG effects. [ABSTRACT FROM AUTHOR]

Recently, a polarimetric method for thermally-induced polarization change-driven power loss (TIPCL) mitigation in complex laser systems has been developed. However, the final optimization relies on a four-parameter numerical process. This article provides a fully analytical direct calculation alternative to this optimization process. The validity of this approach is demonstrated in previously published data from the pulsed laser system Bivoj/DiPOLE100. The new approach provides a deeper insight into the polarimetric method for TIPCL suppression and also brings a more precise, reliable, and faster alternative to the numerical process used earlier. [ABSTRACT FROM AUTHOR]

Signal amplitudes obtained from retinal scanning depend on numerous factors. Working with polarized light to interrogate the retina, large parts of which are birefringent, is even more prone to artifacts. This article demonstrates the necessity of using normalization when working with retinal birefringence scanning signals in polarization-sensitive ophthalmic instruments. After discussing the pros and cons of employing a normalization signal obtained by means of added optoelectronic hardware, the study shifts over and focuses on a numerical normalization method based on merely the s- and p-polarization components without additional optical or electronic hardware. This minimizes the adverse effects of optical asymmetries, the presence of certain instrumental noise, device-to-device variability, pupil diameter, retinal reflectivity, subject-to-subject variations, the position of the eye in the exit pupil of the device, and even signal degradation by cataracts. Results were experimentally and numerically tested on human data from 15 test subjects and clearly demonstrated the signal standardization achieved by numerical normalization. This is expected to lead to substantial improvement in algorithms and decision-making software, especially in ophthalmic screening instruments for pediatric applications, without added hardware cost. The proposed normalization method is also applicable to other polarization-sensitive optical instruments. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Based on density functional theory, a systematic investigation of the geometric structure, electronic structure, and optical properties of Ba3 (PO4) 2, Pb3 (PO4) 2, BiPO4, and YPO4, which are composed of P—O coordination tetrahedra with Y, Ba, Pb, and Bi, has been conducted. The research indicates that the substitution of metal atoms can alter the structural framework of compound, thereby regulating its band gap and optical properties, providing an effective approach for designing materials with excellent comprehensive performance. All four compounds are indirect band gap materials with relatively wide band gaps, with band gaps of 5.188, 3.879, 3.870, and 4.886 eV for Ba3 (PO4) 2, Pb3 (PO4) 2, BiPO4, and YPO4, respectively. According to Mulliken population analysis, the cations Ba, Pb, Bi, and Y form O—X (X = Ba, Pb, Bi, and Y) bonds with oxygen, which have similar bond lengths and exhibit strong ionic bond characteristics. The bottom of the conduction band in the four compounds is occupied by the outermost orbitals of the metal cation, and the main contributor to the top of the valence band is the O-2p orbital. The 2p orbitals of the oxygen atoms also exhibit strong localization near the Fermi level, and the P-3p orbitals bond with the O-2p orbitals, showing strong covalent P—O bonds. The birefringence of the four crystals Ba3 (PO4) 2, Pb3 (PO4) 2, BiPO4, and YPO4 are 0.003 7, 0.027 0, 0.059 0 and 0.149 0, respectively, with BiPO4 and YPO4 showing the highest birefringence and anisotropy among the four systems, which is due to the asymmetric crystal structural framework caused by different cations. [ABSTRACT FROM AUTHOR]

The photonic aspects of semiconducting hexagon-shaped photonic crystal fiber including effective mode area, effective mode index, dispersion, and confinement loss, have already been investigated. The finite element method has been used to compute the maximum distribution of the studied photonic crystal fiber by COMSOL software. The linear modifications from both the effective mode index and an effective mode area have been investigated. Dispersion and confinement loss are examined in terms of air hole ring number and wavelength. For every wavelength, the effective-index model implies that the studied fiber can indeed be single mode. Even though its practical single-mode range inside the opacity aperture of silica appears large, it is eventually confined by a bend-loss edge at both brief & medium wavelengths. Moreover, the reported fiber offers minimal confinement loss of almost 10−8 dB/cm, birefringence 0.0012, and dispersion around 10−11 ps/km nm. [ABSTRACT FROM AUTHOR]

Systemic amyloidosis involves the deposition of misfolded proteins in organs/tissues, leading to progressive organ dysfunction and failure. Congo red is the gold-standard chemical stain for visualizing amyloid deposits in tissue, showing birefringence under polarization microscopy. However, Congo red staining is tedious and costly to perform, and prone to false diagnoses due to variations in amyloid amount, staining quality and manual examination of tissue under a polarization microscope. We report virtual birefringence imaging and virtual Congo red staining of label-free human tissue to show that a single neural network can transform autofluorescence images of label-free tissue into brightfield and polarized microscopy images, matching their histochemically stained versions. Blind testing with quantitative metrics and pathologist evaluations on cardiac tissue showed that our virtually stained polarization and brightfield images highlight amyloid patterns in a consistent manner, mitigating challenges due to variations in chemical staining quality and manual imaging processes in the clinical workflow.

Hybrid organic–inorganic halides have attracted widespread attention due to their multiple optical performances. The combination of distorted metal cation polyhedra and π‐conjugated organic ions is an effective strategy to derive hybrid nonlinear optical (NLO) and birefringent crystals. Here, a new acentric 4‐cyanopyridine mercury halide, (C6H5N2)HgCl3, have been obtained via replacing an inorganic cation with an organic cation based on parent compound CsHgCl3. (C6H5N2)HgCl3 shows the strongest second harmonic generation (SHG) effect among mercury‐pyridine hybrid metal halides, with an intensity of 3.04 times of KH2PO4 (KDP) at 1.064 µm laser radiation. The crystal structure of (C6H5N2)HgCl3 is composed of specially [HgCl3]∞ chains and [(C6H5N2)+] cations. Additionally, (C6H5N2)HgCl3 shows an outstanding experimental birefringence (Δn = 0.360@0.546 µm), which is the largest value among mercury‐based hybrid halides, and its birefringence is greater than those of all inorganic metal halide birefringent crystals. The discovery of (C6H5N2)HgCl3 indicates the potential advantage of mercury‐based hybrid halides in optical materials. [ABSTRACT FROM AUTHOR]

Polarization-sensitive optical coherence tomography (PS-OCT) measures the polarization state of backscattered light from tissues and provides valuable insights into the birefringence properties of biological tissues. Contrastive unpaired translation (CUT) was used in this study to generate a synthetic PS-OCT image from a single OCT image. The challenges related to extensive data requirements relying on labeled datasets using only pixel-wise correlations that make it difficult to efficiently regenerate the periodic patterns observed in PS-OCT images were addressed. The CUT model captures birefringence patterns by leveraging patch-wise correlations from unpaired data, which allows learning of the underlying structural features of biological tissues responsible for birefringence. To demonstrate the performance of the proposed approach, three generative models (Pix2pix, CycleGAN, and CUT) were compared on an in vivo dataset of injured mouse tendons over a six-week healing period. CUT outperformed Pix2pix and CycleGAN by producing high-fidelity synthetic PS-OCT images that closely matched the original PS-OCT images. Pearson correlation and two-way ANOVA tests confirmed the superior performance of CUT (p-value < 0.0001) over the comparison models. Additionally, a ResNet-152 classification model was used to assess tissue damage, which achieved an accuracy of up to 90.13% compared to the original PS-OCT images. This research demonstrates that CUT is superior to conventional methods for generating high-quality synthetic PS-OCT images and offers better improvements in most scenarios, in terms of efficiency and image fidelity. [ABSTRACT FROM AUTHOR]

Anisotropic 2D materials are gaining interest recently as building blocks for angular‐dependent optical/electrical devices. However, the fundamental understanding of their structure‐property‐relationship is limited, which hinders further modulation of their unique characteristics via structure tailoring. Here the in‐plane structural anisotropy and the tunable optical/electrical properties of a series of radiation‐sensitive (X‐ray, e‐beam) metal‐organic chalcogenide (MOC) single crystals are comprehensively revealed with ligands of variable length/parity. Their monoclinic crystallography is determined at atomic resolution by a simple method that couples X‐ray/electron diffraction with first‐principles calculations. The in‐plane inorganic backbone of the MOCs exhibits a strong lattice anisotropy with odd/even alternations, which originates from that of the out‐of‐plane organic motifs via organic/inorganic accommodation. Such structural anisotropy is implied mechanically by the preferred orientation of crystal cleavage. It triggers a maximum ≈8 × distinction of in‐plane electrical conductivity of the semiconducting MOCs, plus a distinct birefringence (maximum Δn ≈ 0.03) with a dispersive orientation of dielectric axes, which rotate up to 25.7° from UV to visible‐light regime, inspiring an emerging pathway for color filtering via single crystal rotation. Such in‐plane optical characteristics also exhibit odd/even alternation and can be flexibly tuned by the designable out‐of‐plane ligands. [ABSTRACT FROM AUTHOR]

Anisotropic materials featured with ordered arrangement of sub‐structures are ubiquitous in living organisms, and possess rapidly increasing relevance to emerging technologies in smart materials, soft robotics, flexible displays, and biomedicines. However, the integration and programming of multiple properties into anisotropic materials, which endow themselves with extended intrinsic capabilities and utilities, still remain a challenge. Herein, we report a multi‐programmable anisotropic material by embedding ferromagnetic two‐dimensional nanoplates into hydrogel matrix. The nanoplate exhibits not only a disc‐like non‐isotropic shape, but also an intrinsic easy magnetization axis perpendicular to its basal plane. Using a directional external magnetic field, we can precisely control the orientation of nanoplates inside hydrogel precursor solution and then fix them via photolithographic polymerization, leading to the fabrication of anisotropic hydrogel with on‐demand ordered alignment of nanoplates. Such deliberate arrangement of nanoplates brings in extraordinary optical properties due to birefringence, enabling us to encrypt pattern information into hydrogel materials that is only visible under polarized light. Soft actuators with programmable optical, mechanical and magnetic properties are engineered, which allow to encode diverse deformation and locomotion modes, determine the actuation sites, and monitor the sub‐structural anisotropy all simultaneously, opening new avenues for the design of anisotropic soft materials. [ABSTRACT FROM AUTHOR]

Advancing laser technologies requires maximizing the anisotropy of crystalline media and overcoming current birefringence limitations. We introduce the strategy of linear π group anisotropic structure building units (ABUCB), leading to an unprecedented large birefringence (Δn), a record‐high Δnobv. of 0.152 in sodium bis(dicyanoborato)fluoride (Na[BF2(CN)2]), the highest reported among deep ultraviolet (DUV) materials. This value is 35 % greater than state‐of‐the‐art α‐BBO and 1167 % greater than MgF2. Density functional theory analyses suggest that the linear π group enhances bulk optical anisotropy and ensures a shorter DUV absorption edge. These results establish Na[BF2(CN)2] as a groundbreaking DUV birefringent material and open new avenues for research into extending π groups and exploring additional possibilities. [ABSTRACT FROM AUTHOR]

Lead halide perovskites exhibit superior properties compared to classical III–V semiconductor quantum wells for room‐temperature polaritonic applications, particularly owing to the significant crystalline anisotropy. This anisotropy results in a sizeable split in condensate energy, which can profoundly influence polariton interactions and spin relaxation pathways. Besides, trapped exciton‐polariton (TEP) exhibits a quantized energy landscape, which is essential for modulating polaritonic logical circuits. Herein, spin‐orbit coupled TEP lasing is demonstrated in birefringent perovskite. Cascade condensate processes between orthogonally polarized polariton branches happen considering the dominance of reservoir exciton–polariton or polariton–polariton scattering within each stage. Such condensation adequately is verified via the input‐output "S" curve, the narrowed linewidth, the energy blueshift, and the real space spatial coherence of the orthogonally polarized modes. This trapped anisotropic condensate holds great promise for room‐temperature polaritonic and spintronics. [ABSTRACT FROM AUTHOR]

Birefringent crystal, which has the capacity to manipulate polarization light, holds an indispensable position in optics and optoelectronics, while it remains challenging to fulfill the modulation of birefringence. Here, we present wide spectral photo‐pyroelectric effect in a silver‐based hybrid pyroelectric, (N‐CHM)Ag2I3 (N‐CHM=N‐cyclohexylmethylamine), serving as a feasible strategy to regulate birefringence through light stimuli. As the first silver‐based hybrid pyroelectric, (N‐CHM)Ag2I3 exhibits strong room‐temperature photo‐pyroelectricity with a large polarization of ~3.23 μC/cm2 and high voltage responsivity of ~0.96 m2/C across the UV–NIR spectral region. Strikingly, the photomodulation of its in‐plane birefringence is established through pyroelectric effect, giving a saturation value of ~1.68×10−2 that is among the highest level achieved to date. This study on the birefringence photomodulation of lead‐free hybrid pyroelectric is anticipated to boost future development of new smart optical and optoelectronic devices. [ABSTRACT FROM AUTHOR]

Salts and co‐crystals composed of planar π‐conjugated functional units represent a fascinating class of materials, featuring both enlarged birefringence and a strong SHG effect. Herein, the optical properties of π‐conjugated (C4H7N3)2+ functional unit within 2‐aminopyrimidine (2‐AP) family are investigated for the first time. Furthermore, twelve novel compounds are successfully synthesized by applying four different strategies. In these strategies, (C4H7N3)2+, (C4H6N3)+, and (C4H5N3) functional units are introduced into the crystal structure, both solely and in combination, to analyze the alteration in birefringence. Remarkably, a birefringence rule with (C4H7N3)2+ < (C4H6N3)+ < (C4H5N3), stating that an increase in net charge over π‐conjugated functional unit leads to a reduced birefringence, is discovered. Consequently, the inclusion of a charge‐neutral (C4H5N3) functional unit within the crystal structure along with coplanar arrangement is a promising approach to enhance birefringence. Furthermore, D‐2 [(C4H5N3)(H3C3N3O3)] realizes Δncalc = 0.412 maximum in the (2‐AP) family. Notably, both A‐1 [(C4H7N3)(CF3SO3)2] and B‐1 [(C4H6N3)2(IO3)2(H2O)] crystalize in the non‐centrosymmetric space groups, with B‐1 exhibiting SHG efficiency of ≈1.4 × KDP @ 1064 nm, with the shortest λPM at 384 nm. This work provides new insight into discovering novel birefringent and non‐linear optical materials with high performances in the wide chemical space. [ABSTRACT FROM AUTHOR]

Finding 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. [ABSTRACT FROM AUTHOR]

Two new members of the pentaborate family, NaKB5O8(OH)·H2O (I) and KB5O8·2H2O (II), were successfully synthesized, which crystallize in the space groups of P1¯ and Fddd, respectively. In compound I, [B5O10(OH)] fundamental building blocks (FBBs) form a two-dimensional (2D) 2[B5O8(OH)]∞ layer through corner-sharing, whereas in compound II, [B5O10] FBBs form two independent interpenetrating 3D 3[B5O8]∞ networks by sharing common O atoms. The UV-vis-NIR diffuse reflectance spectrum and first-principles calculations suggest that the two compounds possess deep-ultraviolet (DUV) transparency windows. Real-space atom-cutting and response electron distribution anisotropy (REDA) analyses show that the birefringence of both compounds mainly originates from the π-conjugated units. [ABSTRACT FROM AUTHOR]