Journal articles: 'Birefringence'

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Wang, Ning, and Xiao Xia Li. "The Electrically Controlled Birefringence Measurement Influence of Liquid Crystal Caused by Absorption Effect in Infrared Region." Advanced Materials Research 875-877 (February 2014): 467–71. http://dx.doi.org/10.4028/www.scientific.net/amr.875-877.467.

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The electrically controlled birefringence of nematic liquid crystal BL-009 was measured by polarized interference method. The influence of LC absorption effect, the birefringence variation, is discussed in this paper. The experiments results showed the influence to birefringence is big in infrared region. Not only the birefringence value is greatly different with that of unconsidering absorption effect, but also the gradient changing of birefringence curves is obvious. Furthermore, the electrically controlled birefringences of two conditions are compared when the absorption coefficients of ordinary light and the extraordinary light are nearly same and greatly different. The analysis demonstrated the approximate method of absorption coefficient is feasible.

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Afsharan, Hadi, Dilusha Silva, Chulmin Joo, and Barry Cense. "Non-Invasive Retinal Blood Vessel Wall Measurements with Polarization-Sensitive Optical Coherence Tomography for Diabetes Assessment: A Quantitative Study." Biomolecules 13, no. 8 (August 8, 2023): 1230. http://dx.doi.org/10.3390/biom13081230.

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Diabetes affects the structure of the blood vessel walls. Since the blood vessel walls are made of birefringent organized tissue, any change or damage to this organization can be evaluated using polarization-sensitive optical coherence tomography (PS-OCT). In this paper, we used PS-OCT along with the blood vessel wall birefringence index (BBI = thickness/birefringence2) to non-invasively assess the structural integrity of the human retinal blood vessel walls in patients with diabetes and compared the results to those of healthy subjects. PS-OCT measurements revealed that blood vessel walls of diabetic patients exhibit a much higher birefringence while having the same wall thickness and therefore lower BBI values. Applying BBI to diagnose diabetes demonstrated high accuracy (93%), sensitivity (93%) and specificity (93%). PS-OCT measurements can quantify small changes in the polarization properties of retinal vessel walls associated with diabetes, which provides researchers with a new imaging tool to determine the effects of exercise, medication, and alternative diets on the development of diabetes.

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Winterstein, Donald F., Gopa S. De, and Mark A. Meadows. "Twelve years of vertical birefringence in nine‐component VSP data." GEOPHYSICS 66, no. 2 (March 2001): 582–97. http://dx.doi.org/10.1190/1.1444950.

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Since 1986, when industry scientists first publicly showed data supporting the presence of azimuthal anisotropy in sedimentary rock, we have studied vertical shear‐wave (S-wave) birefringence in 23 different wells in western North America. The data were from nine‐component vertical seismic profiles (VSPs) supplemented in recent years with data from wireline crossed‐dipole logs. This paper summarizes our results, including birefringence results in tabular form for 54 depth intervals in 19 of those 23 wells. In the Appendix we present our conclusions about how to record VSP data optimally for study of vertical birefringence. We arrived at four principal conclusions about vertical S-wave birefringence. First, birefringence was common but not universal. Second, birefringence ranged from 0–21%, but values larger than 4% occurred only in shallow formations (<1200 m) within 40 km of California’s San Andreas fault. Third, at large scales birefringence tended to be blocky. That is, both the birefringence magnitude and the S-wave polarization azimuth were often consistent over depth intervals of several tens to hundreds of meters but then changed abruptly, sometimes by large amounts. Birefringence in some instances diminished with depth and in others increased with depth, but in almost every case a layer near the surface was more birefringent than the layer immediately below it. Fourth, observed birefringence patterns generally do not encourage use of multicomponent surface reflection seismic data for finding fractured hydrocarbon reservoirs, but they do encourage use of crossed‐dipole logs to examine them. That is, most reservoirs were birefringent, but none we studied showed increased birefringence confined to the reservoir.

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Bai, Zhiyong, Chun-Li Hu, Dongmei Wang, Lehui Liu, Lizhen Zhang, Yisheng Huang, Feifei Yuan, and Zhoubin Lin. "[Al(H2O)6](IO3)2(NO3): a material with enhanced birefringence induced by synergism of two superior functional motifs." Chemical Communications 56, no. 78 (2020): 11629–32. http://dx.doi.org/10.1039/d0cc04813e.

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A new strongly birefringent material was developed, and its strong birefringence was attributed to the synergy of the effects of its two superior birefringence-favourable anionic FBUs, namely (NO₃)⁻ and (IO₃)⁻ groups.

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Chen, Jianbang, Mengfan Wu, Jie Zhang, and Xuchu Huang. "Linear unit BN₂: a novel birefringence-enhanced fundamental module with sp orbital hybridization." RSC Advances 12, no. 23 (2022): 14757–64. http://dx.doi.org/10.1039/d2ra02135h.

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The linear unit BN2 is discovered as a novel birefringence-enhanced fundamental module. Particularly, Ca3(BN2)N exhibits a large birefringence (0.411 at 1064 nm), which is about 2.0–3.5 times of the commercial used birefringent crystals, such as α-BaB2O4, CaCO3 and YVO4.

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Lee, Sung Mook, Dong Woo Kang, Jinn-Ouk Gong, Donghui Jeong, Dong-Won Jung, and Seong Chan Park. "Cosmic birefringence by dark photon." Journal of Cosmology and Astroparticle Physics 2024, no. 08 (August 1, 2024): 037. http://dx.doi.org/10.1088/1475-7516/2024/08/037.

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Abstract We study the kinetic mixing between the cosmic microwave background (CMB) photon and the birefringent dark photon. These birefringent dark photon may exist in parity-violating dark sector, for example, through the coupling to axion field. We show that the birefringence of the dark photon propagates to the CMB photon, but the resulting birefringence may not be isotropic over the sky, but will be anisotropic in general. Moreover, our investigation sheds light on the essential role played by kinetic mixing in the generation of two fundamental characteristics of the CMB: circular polarization and spectral distortion.

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Li, Jian Hua, Fei Huang, Yi Yang, Bao Fu Zhang, and Hua Zhou. "High Birefringent Terahertz Photonic Crystal Fiber Based on Material-Filled Structure." Applied Mechanics and Materials 462-463 (November 2013): 599–603. http://dx.doi.org/10.4028/www.scientific.net/amm.462-463.599.

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A novel kind of high birefringent terahertz (THz) photonic crystal fibers (PCFs) with material-filled structure is proposed in this paper. Based on the material-filled technology, which different materials are selectively filled into four air holes of the inner first circle near the central core in the designed THz PCFs, high birefringence are obtained from the structural and material-filled induced asymmetry in large frequency ranges near 1THz. Modal birefringence with different structural parameters and diverse refractive indices of the filled materials are investigated by plane wave expansion (PWE) method. The numerical results show that high birefringence up to 10-3can be obtained and its structure is simpler than that of the early proposed highly birefringent THz PCFs. It is helpful for PCFs design and real fabrication in the potential THz applications.

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Ohkita, H., A. Tagaya, and Y. Koike. "Synthesis of a Zero-Birefringence Polymer Doped with an Inorganic Birefringent Crystal." Solid State Phenomena 99-100 (July 2004): 143–48. http://dx.doi.org/10.4028/www.scientific.net/ssp.99-100.143.

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Birefringence induced by the orientation of polymer main chains during injectionmoulding or extrusion processing restricts the application of optical polymers to optical devices that require the polarization state of incident light to be maintained. To compensate this birefringence of polymers we propose using the “birefringent crystal dopant method” - homogeneous doping with an opposite birefringent needle-like crystal. Strontium carbonate (SrCO3) was selected for this purpose and synthesized, with a length of about 200nm and a width of about 20nm. SrCO3 was doped into poly(MMA/BzMA= 78/22(wt./wt.)) film. The film was uniaxially drawn at 130°C and 4mm/min. For the first time, the positive birefringence of the drawn copolymer film at a wavelength of 633nm was compensated by doping with 0.3wt.% of SrCO3 without loss of transparency and thermostability.

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Koral, Can, and Fulya Bagci. "A Hybrid Design for Frequency-Independent Extreme Birefringence Combining Metamaterials with the Form Birefringence Concept." Photonics 11, no. 9 (September 12, 2024): 860. http://dx.doi.org/10.3390/photonics11090860.

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With advances in terahertz technology, achieving high and nearly constant birefringence over a wide frequency range plays an extreme role in many advanced applications. In the past decade, significant research efforts have been devoted to creating new systems or elements with high birefringence. To our knowledge, the maximum birefringence attainable using artificial crystals, intrinsic liquid crystals or fiber-based systems has been less than unity. More importantly, the birefringence created in previous studies has exhibited a strong frequency dependence, limiting their practical applications. In this work, we propose a novel approach to achieve extraordinarily high birefringence over a broad terahertz frequency band (>100 GHz). To address the limitation of frequency dependence, we combined the principle of metamaterials with the form birefringence concept. First, we designed a metamaterial with an exceptionally high refractive index, thoroughly characterizing it using simulations and analytical analysis. Next, we systematically investigated the form birefringence concept, exploring its frequency response, geometric limitations, and complex refractive index differences between constituent elements. Finally, we designed a hybrid material system, combining the strengths of both metamaterials and form birefringence. Our results demonstrate the feasibility of achieving a birefringent medium exceeding three orders of magnitude higher than previous reports while maintaining a time-invariant frequency response in the sub-terahertz regime.

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Tiner, J. D. "Birefringent Spores Differentiate Encephalitozoon and Other Microsporidia from Coccidia." Veterinary Pathology 25, no. 3 (May 1988): 227–30. http://dx.doi.org/10.1177/030098588802500307.

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Tissue sections containing protozoa with birefringent spores indicate an infection by microsporidia. Hematoxylin and cosin (HE) does not affect spore birefringence, but some special stains (Goodpasture, Brown and Brenn, or Gram) obscure it. Encephalitozoon cuniculi from an infected puppy, Glugea stephani from the winter flounder Pseudopleuronectes americanus. and Plistophora sp. from the Japanese eel Anguilla japonica all have birefringent spores. Encephalitozoon was studied first and then the two genera from fishes were included for comparison. Small masses of newly formed spores (pseudocysts) line Glugea cysts and then merge into the contents of the cyst as it enlarges and bulges through the intestinal musculature to become subserosal. The birefringence of Plistophora is present in fully mature spores contained in pseudocysts, but may disappear when the spores are released and become involved in granulomas. Coccidians from various hosts were always non-birefringent. Whenever a protozoan organism in a tissue could be either microsporidian or coccidian, a test for birefringence, if positive, resolves the question. There may be no need to use a special stain.

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Zeng, Jian Hui, Xu You Li, and Wen Bin Hu. "A Novel High-Birefringent Photonic Crystal Fiber and its Polarization Maintaining Properties." Advanced Materials Research 760-762 (September 2013): 185–89. http://dx.doi.org/10.4028/www.scientific.net/amr.760-762.185.

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A novel high-birefringent photonic crystal fiber (PCF) was proposed and analyzed by full-vector finite element method (FEM). The modal field and birefringence properties were investigated. All of air holes in proposed PCF are round, and their diameters are the same. It is greatly reduce the difficulty of fabrication. According to the results of numerical analysis, it can be observed that the mode birefringence of this novel PCF can be easily achieve the order of 10-3at 1.55μm. This research provides effective theoretical method for the fabrication, development and construction of high-birefringence photonic crystal fiber.

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Wang, Jinhui, Xinyuan Zhang, Fei Liang, Zhanggui Hu, and Yicheng Wu. "Co-crystal AX·(H3C3N3O3) (A = Na, Rb, Cs; X = Br, I): a series of strongly anisotropic alkali halide cyanurates with a planar structural motif and large birefringence." Dalton Transactions 50, no. 33 (2021): 11555–61. http://dx.doi.org/10.1039/d1dt02217b.

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Abghari, Arefe, Raelyn M. Sullivan, Lukas T. Hergt, and Douglas Scott. "Constraints on cosmic birefringence using E-mode polarisation." Journal of Cosmology and Astroparticle Physics 2022, no. 08 (August 1, 2022): 033. http://dx.doi.org/10.1088/1475-7516/2022/08/033.

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Abstract A birefringent universe could show itself through a rotation of the plane of polarisation of the cosmic microwave background photons. This is usually investigated using polarisation B modes. Here we point out an independent method for extracting the birefringence angle using only temperature and E-mode signals. We forecast that, with an ideal cosmic-variance-limited experiment, we could constrain a birefringence angle of 0.3° with 3σ statistical significance, which is close to the current constraints using B modes. We explore how this method is affected by the systematic errors introduced by the polarisation efficiency. In the future, this could provide an additional way of checking any claimed B-mode derived birefringence signature.

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Kefer, Stefan, Tobias Limbach, Natalie Pape, Kathrin Klamt, Bernhard Schmauss, and Ralf Hellmann. "Birefringence in Injection-Molded Cyclic Olefin Copolymer Substrates and Its Impact on Integrated Photonic Structures." Polymers 16, no. 2 (January 5, 2024): 168. http://dx.doi.org/10.3390/polym16020168.

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This contribution quantifies the birefringence within injection-molded cyclic olefin copolymer plates and discusses its impact on the mechanical properties of the plates. It also focuses on the impact of birefringence on integrated waveguides and Bragg gratings and provides fabrication guidelines for such structures. The anisotropy in all three dimensions of the workpiece is examined by means of polarimetry and a prism coupler. It is found that the birefringence is inhomogenously distributed within the workpieces, whereas the maximum birefringence not only varies locally, but also depends on the observation direction. Overall, a maximum birefringence of 10 × 10−4 is found at the plate’s surface near the injection gate. The anisotropy then reduces exponentially towards the center of the workpiece and saturates at 1.8 × 10−4, in a depth of 0.4 mm. Thus, the birefringence strongly affects near-surface photonic structures. It is found that, depending on their orientation and the local birefringence of the substrate, waveguides and Bragg gratings fabricated with comparable parameters behave completely differently in terms of polarization-dependent optical attenuation, cross-sectional intensity distribution and Bragg reflection signal. For example, the support of the TM mode can vary between total loss and an optical attenuation of 0.9 dB × cm−1. In consequence, this study underlines the importance of quantifying the birefringent state of an injection-molded cyclic olefin copolymer workpiece if it is supposed to serve as a substrate for integrated photonic structures. The study furthermore demonstrates that birefringence effects can be omitted by burying the photonic structures deeper into the volume of the thermoplastic.

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Mutailipu, Miriding, Min Zhang, Bingbing Zhang, Zhihua Yang, and Shilie Pan. "The first lead fluorooxoborate PbB5O8F: achieving the coexistence of large birefringence and deep-ultraviolet cut-off edge." Chemical Communications 54, no. 49 (2018): 6308–11. http://dx.doi.org/10.1039/c8cc02694g.

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Chen, Xinglong, Fangfang Zhang, Yunjing Shi, Yanzhou Sun, Zhihua Yang, and Shilie Pan. "MBaYB6O12(M = Rb, Cs): two new rare-earth borates with large birefringence and short ultraviolet cutoff edges." Dalton Transactions 47, no. 3 (2018): 750–57. http://dx.doi.org/10.1039/c7dt04223j.

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Kwon, Oh-Tae, Geonwoo Kim, Hyungjin Bae, Jaeyeol Ryu, Sikwan Woo, and Byoung-Kwan Cho. "Development of a Mercury Bromide Birefringence Measurement System Based on Brewster’s Angle." Sensors 23, no. 9 (April 23, 2023): 4208. http://dx.doi.org/10.3390/s23094208.

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Mercury bromide (Hg2Br2) has been used to develop acousto-optic tunable filters (AOTFs) because it has several advantages, including a high refractive index, a broad optical bandwidth, and a relatively high figure of merit. Therefore, the measurement of its birefringence is a highly important factor for ensuring AOTF quality. However, for single crystals, it is difficult (at the millimeter scale) to quantify the birefringence using an ellipsometer, as this equipment is only designed to conduct measurements on thin films. In this study, a simple birefringence measurement system for Hg2Br2 was developed based on Brewster’s angle at the millimeter scale. The planar distributions of the Hg2Br2 crystal along the (100), (010), and (001) planes were used in the experiments. The developed measurement system can measure the reflected light intensity of the Hg2Br2 crystal depending on the incidence angles (rotations at 0.01125° steps) and can calculate the ordinary and extraordinary refractive indices and birefringence. The calculated birefringence of the Hg2Br2 crystal was 0.8548; this value exhibits an error of 0.64% compared with a value of 0.86 reported in the literature. The developed measurement system demonstrates the ability to be used to evaluate the quality of birefringent single crystals.

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Ademgil, Huseyin. "Highly birefringent large mode area photonic crystal fiber-based sensor for interferometry applications." Modern Physics Letters B 30, no. 36 (December 30, 2016): 1650422. http://dx.doi.org/10.1142/s0217984916504224.

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In this work, highly birefringent large mode area (LMA) photonic crystal fiber (PCF) structure for interferometric sensor applications is proposed. The effective mode area, birefringence and the sensitivity coefficient of the proposed PCF structure by employing the full vectorial finite element method (FV-FEM) have been thoroughly investigated. The numerical results have shown that proposed structure simultaneously offers high birefringence of order 10[Formula: see text], adequately LMA and high sensitivity for various liquid analytes by employing the elliptical liquid core holes.

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Liu, Shuo, Yuanwei Li, Rui Ma, Linwan Zhao, Jiaqi lv, and Xiaolong Dong. "Study on the High-Birefringence Hollow-Core Anti-Resonant Fiber with Semicircular Cladding." International Journal of Optics 2021 (May 21, 2021): 1–10. http://dx.doi.org/10.1155/2021/5520142.

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For the purpose of satisfying the demands of polarization-maintaining fibers for fiber optic gyroscopes, this article proposes a semicircular cladding birefringent hollow-core anti-resonant fiber. The influence of structural parameters on the birefringence, loss, and bending loss of the fiber is studied. The simulation results demonstrate that at 1550 nm, the ultimate loss of the fundamental mode of x and y polarization is 1.76 dB/m and 0.93 dB/m, respectively. The birefringence can reach 1 × 10−4, and the wavelength range of birefringence greater than 10−4 can reach 60 nm. This indicates that it has excellent bending properties. The proposed optical fiber has excellent performance in polarization maintenance and can supply ideas for the research of high-precision fiber optic gyroscopes and other optical devices.

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Tian, Jing, Heng Yao, Maxime Cavillon, Enric Garcia-Caurel, Razvigor Ossikovski, Michel Stchakovsky, Celine Eypert, Bertrand Poumellec, and Matthieu Lancry. "A Comparison between Nanogratings-Based and Stress-Engineered Waveplates Written by Femtosecond Laser in Silica." Micromachines 11, no. 2 (January 24, 2020): 131. http://dx.doi.org/10.3390/mi11020131.

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This paper compares anisotropic linear optical properties (linear birefringence, linear dichroism, degree of polarization) and performances (absorption coefficient, thermal stability) of two types of birefringent waveplates fabricated in silica glass by femtosecond laser direct writing. The first type of waveplate is based on birefringence induced by self-organized nanogratings imprinted in the glass. One the other hand, the second design is based on birefringence originating from the stress-field formed around the aforementioned nanogratings. In addition to the provided comparison, the manufacturing of stress-engineered half waveplates in the UV-Visible range, and with mm-size clear aperture and negligible excess losses, is reported. Such results contrast with waveplates made of nanogratings, as the later exhibit significantly higher scattering losses and depolarization effects in the UV-Visible range.

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Dong, Hui, Hailiang Zhang, and Dora Juan Juan Hu. "Polar Decomposition of Jones Matrix and Mueller Matrix of Coherent Rayleigh Backscattering in Single-Mode Fibers." Sensors 24, no. 6 (March 8, 2024): 1760. http://dx.doi.org/10.3390/s24061760.

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The Jones matrix and the Mueller matrix of the coherent Rayleigh backscattering (RB) in single-mode fibers (SMFs) have been derived recently. It has been shown that both matrices depict two polarization effects—birefringence and polarization-dependent loss (PDL)—although the SMF under investigation is purely birefringent, having no PDL. In this paper, we aim to perform a theoretical analysis of both matrices using polar decomposition. The derived sub-Jones/Mueller matrices, representing birefringence and PDL, respectively, can be used to investigate the polarization properties of the coherent RB. As an application of the theoretical results, we use the derived formulas to investigate the polarization properties of the optical signals in phase-sensitive optical time-domain reflectometry (φ-OTDR). For the first time, to our knowledge, by using the derived birefringence–Jones matrix, the common optical phase of the optical signal in φ-OTDR is obtained as the function of the forward phase and birefringence distributions. By using the derived PDL–Mueller matrix, the optical intensity of the optical signal in φ-OTDR is obtained as the function of the forward phase and birefringence distributions as well as the input state of polarization (SOP). Further theoretical predictions show that, in φ-OTDR, the common optical phase depends on only the local birefringence in the first half of the fiber section, which is occupied by the sensing pulse, irrelevant of the input SOP. However, the intensity of the φ-OTDR signal is not a local parameter, which depends on the input SOP and the birefringence distribution along the entire fiber section before the optical pulse. Moreover, the PDL measured in φ-OTDR is theoretically proven to be a local parameter, which is determined by the local birefringence and local optical phase distributions.

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Wang, Shuang, Xie Han, and Kewu Li. "Snapshot Multi-Wavelength Birefringence Imaging." Sensors 24, no. 16 (August 10, 2024): 5174. http://dx.doi.org/10.3390/s24165174.

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A snapshot multi-wavelength birefringence imaging measurement method was proposed in this study. The RGB-LEDs at wavelengths 463 nm, 533 nm, and 629 nm were illuminated with circularly polarized light after passing through a circular polarizer. The transmitted light through the birefringent sample was captured by a color polarization camera. A single imaging process captured light intensity in four polarization directions (0°, 45°, 90°, and 135°) for each of the three RGB spectral wavelength channels, and subsequently measured the first three elements of Stokes vectors (S0, S1, and S2) after the sample. The birefringence retardance and fast-axis azimuthal angle were determined simultaneously. An experimental setup was constructed, and polarization response matrices were calibrated for each spectral wavelength channel to ensure the accurate detection of Stokes vectors. A polymer true zero-order quarter-wave plate was employed to validate measurement accuracy and repeatability. Additionally, stress-induced birefringence in a PMMA arch-shaped workpiece was measured both before and after the application of force. Experimental results revealed that the repeatability of birefringence retardance and fast-axis azimuthal angle was better than 0.67 nm and 0.08°, respectively. This approach enables multispectral wavelength, high-speed, high-precision, and high-repeatability birefringence imaging measurements through a single imaging session.

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Clark, Alexander T., Sophia D’Anna, Jessy Nemati, Phillip Barden, Ian Gatley, and John Federici. "Evaluation of Fossil Amber Birefringence and Inclusions Using Terahertz Time-Domain Spectroscopy." Polymers 14, no. 24 (December 15, 2022): 5506. http://dx.doi.org/10.3390/polym14245506.

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Using a cross-polarization transmission geometry, stress maps for the normalized birefringence and intrinsic stress direction of polymeric materials may be obtained using terahertz nondestructive evaluation. The analysis method utilizes a deconvolution method to determine the arrival times and amplitude of the cross-polarized terahertz pulses through a birefringent material. Using amber (a naturally occurring polymer) as a material of interest, stress maps show that inclusion-free Lebanese amber samples behave as classic uniaxial birefringent (photoelastic) materials whose principal stress directions, as inferred in the terahertz spectral range, agree well with visible photoelasticity measurements. Since amber samples, depending upon their source, may be either transparent or opaque to visible light, comparing birefringence measurements in the visible and terahertz spectral ranges cross-validates the stress measurements, thereby establishing a strong and unique stress analysis methodology for visibly opaque samples. While the material of interest for this paper is amber, the method is generally applicable for any terahertz-transparent polymer. The cross-polarization experimental configuration enables stress levels within the amber matrix to be visualized while also outlining highly localized regions of stress surrounding inclusions. Birefringence stress maps clearly show localized increases in stress magnitude and directional changes surrounding inclusions.

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Lin, Samuel I. En. "Stress Birefringence in Photonic Crystal Fibers Used in a Novel Field Installable LC Type Optical Connector." Key Engineering Materials 364-366 (December 2007): 404–7. http://dx.doi.org/10.4028/www.scientific.net/kem.364-366.404.

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Photonic crystal fibers (PCFs) have recently attracted a great deal of interest because of their unique characteristics and many controllable features. They include a wide range of single mode operation, highly birefringent characteristics (~10-3), high-power light transmission, etc. The field-installable LC connectors tend to be of the larger connector types in the fiber-to-the-home (FTTH) distribution units. In these designs, fibers are clamped inside a splice assembly and are stressed within the connector. In this research, we first developed a novel cam-type mechanism for field-use LC connector. The fiber stress was analyzed via a commercial available finite element program. The stress birefringence distributions of single mode fiber and air-silica based PCFs were calculated by stress photoelastic effect. We further studied the effect of air-hole size on the stressinduced birefringence of PCFs. The results indicate that stress-induced birefringence decreases as air-hole size increase. On the other hand, the birefringence increases as applied clamping force increases on the single mode fiber.

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Rumpa, Ramin Chapa. "Ultra-High Birefringence Property and Low Confinement Loss of Circular Photonic Crystal Fiber for Telecommunication Application." International Journal for Research in Applied Science and Engineering Technology 12, no. 3 (March 31, 2024): 3366–81. http://dx.doi.org/10.22214/ijraset.2024.58219.

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Abstract: A redesigned PCF structure with minimal confinement loss and high birefringence is proposed in this research paper. It employs a circular lattice arrangement with one ring of identical air holes. High birefringence and low confinement loss are two of the properties that have been numerically studied using the finite element method with circular perfectly matched layer boundary conditions. By adjusting the hole size and spacing, it is possible to achieve both properties simultaneously. At an excitation wavelength of 1550 nm, a numerically obtained modal birefringence of 2.3179×10-2 is observed. Simultaneously, by methodically evaluating the cladding rings, the center-to-center distance between the air holes, and the number of cladding rings with equal diameters, a minimal confinement loss (<10-1) may be achieved. Additionally, the suggested PCF verifies that it is feasible to acquire. Our extremely birefringent fiber can be controllably created thanks to the development of birefringence with structural modifications. The suggested structure has better optical characteristics, making it a potential contender for sensing and broadband dispersion correction.

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Egorov, Yuriy, Bogdan Sokolenko, Aziz Aliev, Ruslan Dzhemalyadinov, Ervin Umerov, and Alexander Rubass. "Bessel Beams in Gyroanisotropic Crystals with Optical Activity." Physics 7, no. 1 (February 10, 2025): 6. https://doi.org/10.3390/physics7010006.

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Using a Bessel beam as an example, it is shown that such a beam with the initial circular polarization, propagating through an optically active medium devoid of linear birefringence, generates an optical vortex in the orthogonally polarized component. It is shown that a medium with genuine optical activity allows the mutual conversion of beams with radial and azimuthal polarization distributions. It is also shown that a considerably weak perturbation of a medium with genuine optical activity by linear birefringence leads to the destruction of an isotropic point. In the vicinity of this point, the optical activity is suppressed by linear birefringence, so that a medium with a combined type of anisotropy responds as a medium with genuine linear birefringence. The structure of the fields of the eigenmodes of Bessel beams in a birefringent uniaxial crystal with optical activity is similar to the structure of the modes of a medium with genuine optical activity. The findings of the current study are believed to expand the understanding of physical processes in the developing field of polarization and the phase profilometry of materials.

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Heyl, Jeremy, and Ilaria Caiazzo. "Strongly Magnetized Sources: QED and X-ray Polarization." Galaxies 6, no. 3 (July 21, 2018): 76. http://dx.doi.org/10.3390/galaxies6030076.

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Radiative corrections of quantum electrodynamics cause a vacuum threaded by a magnetic field to be birefringent. This means that radiation of different polarizations travels at different speeds. Even in the strong magnetic fields of astrophysical sources, the difference in speed is small. However, it has profound consequences for the extent of polarization expected from strongly magnetized sources. We demonstrate how the birefringence arises from first principles, show how birefringence affects the polarization state of radiation and present recent calculations for the expected polarization from magnetars and X-ray pulsars.

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Tan, Melissa, Alexander T. Martin, Alexander G. Shtukenberg, and Bart Kahr. "Tuning the optical isotropic point of mixed crystals of ethylenediammonium sulfate/selenate." Journal of Applied Crystallography 53, no. 1 (February 1, 2020): 51–57. http://dx.doi.org/10.1107/s1600576719015863.

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In anisotropic crystals, optical isotropic points are wavelengths where linear birefringence disappears because the refractive indices for both eigenmodes are accidentally equivalent. Here, the optical isotropic point of ethylenediammonium selenate (EDSe) is tuned by generating a solid-solution series of EDSe doped with sulfate. Mueller matrix polarimetry and single-crystal X-ray diffraction are used to correlate changes in linear birefringence with the crystal composition of EDS x Se1−x . A scheme for using mixed crystals with isotropic points as tunable birefringent optical bandpass filters is proposed and their performance is modeled.

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KIM, AHYOUNG, J. W. WU, S. H. HAN, BYOUNGCHOO PARK, and HIDEO TAKEZOE. "ELECTRO-OPTIC AND ELECTRO-GYRATION EFFECTS IN CHIRAL MOLECULAR SYSTEMS." Journal of Nonlinear Optical Physics & Materials 13, no. 03n04 (December 2004): 397–404. http://dx.doi.org/10.1142/s0218863504002018.

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The linear electro-optic (EO) and electro-gyration (EG) effects are studied in an optically active material systems including Bi 12 SiO 20 (BSO) oxide and bent-core liquid crystals. In an isotropic BSO sample, the breaking of intrinsic centro-symmetry allowed the EO modulation of the refractive index. In a mixture of bent-shaped liquid crystalline molecules having both optical activity and birefringence, the observed intensity modulation is investigated, which is related to the nonlinear optical responses of both the optical rotatory power and the birefringence. Both the linear EO and EG effects are understood in terms of the superposition principle of linear and circular birefringences.

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30

Huband, S., D. S. Keeble, N. Zhang, A. M. Glazer, A. Bartasyte, and P. A. Thomas. "Crystallographic and optical study of LiNb1 − xTaxO3." Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 73, no. 3 (June 1, 2017): 498–506. http://dx.doi.org/10.1107/s2052520617004711.

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Powders of lithium niobate-tantalate across the full compositional range have been made and crystals grown using a lithium vanadate flux growth technique. The Li-content of a lithium tantalate crystal has been determined using the zero-birefringence temperature and Curie measurements, confirming the Li content is between that of congruent and stoichiometric crystals. X-ray diffraction measurements show the Nb/Ta displacement and octahedral tilt both decrease as the Ta content is increased. This also results in a decrease in the lattice parameters from lithium niobate to lithium tantalate. Birefringence measurements on the crystals as a function of temperature have been used to determine the point that the crystals become zero-birefringent, and by comparison with the structural studies have confirmed that it is not related to a phase transition and the structures remain polar through the zero-birefringence points.

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31

Fan, Hua, Meguya Ryu, Reo Honda, Junko Morikawa, Zhen-Ze Li, Lei Wang, Jovan Maksimovic, Saulius Juodkazis, Qi-Dai Chen, and Hong-Bo Sun. "Laser-Inscribed Stress-Induced Birefringence of Sapphire." Nanomaterials 9, no. 10 (October 3, 2019): 1414. http://dx.doi.org/10.3390/nano9101414.

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Birefringence of 3 × 10 - 3 is demonstrated inside cross-sectional regions of 100 μ m, inscribed by axially stretched Bessel-beam-like fs-laser pulses along the c-axis inside sapphire. A high birefringence and retardance of λ / 4 at mid-visible spectral range (green) can be achieved using stretched beams with axial extension of 30–40 μ m. Chosen conditions of laser-writing ensure that there are no formations of self-organized nano-gratings. This method can be adopted for creation of polarization optical elements and fabrication of spatially varying birefringent patterns for optical vortex generation.

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32

Greco, Alessandro, Nicola Bartolo, and Alessandro Gruppuso. "Cosmic birefrigence: cross-spectra and cross-bispectra with CMB anisotropies." Journal of Cosmology and Astroparticle Physics 2022, no. 03 (March 1, 2022): 050. http://dx.doi.org/10.1088/1475-7516/2022/03/050.

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Abstract Parity-violating extensions of Maxwell electromagnetism induce a rotation of the linear polarization plane of photons during propagation. This effect, known as cosmic birefringence, impacts on the Cosmic Microwave Background (CMB) observations producing a mixing of E and B polarization modes which is otherwise null in the standard scenario. Such an effect is naturally parametrized by a rotation angle which can be written as the sum of an isotropic component α 0 and an anisotropic one δα(n̂). In this paper we compute angular power spectra and bispectra involving δα and the CMB temperature and polarization maps. In particular, contrarily to what happens for the cross-spectra, we show that even in absence of primordial cross-correlations between the anisotropic birefringence angle and the CMB maps, there exist non-vanishing three-point correlation functions carrying signatures of parity-breaking physics. Furthermore, we find that such angular bispectra still survive in a regime of purely anisotropic cosmic birefringence, which corresponds to the conservative case of having α o = 0. These bispectra represent an additional observable aimed at studying cosmic birefringence and its parity-violating nature beyond power spectrum analyses. They provide also a way to perform consistency checks for specific models of cosmic birefringence. Moreover, we estimate that among all the possible birefringent bispectra,〈δαTB〉and〈δαEB〉are the ones which contain the largest signal-to-noise ratio. Once the cosmic birefringence signal is taken to be at the level of current constraints, we show that these bispectra are within reach of future CMB experiments, as LiteBIRD.

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Kudryashov, Sergey, Alexey Rupasov, Roman Zakoldaev, Mikhail Smaev, Aleksandr Kuchmizhak, Alexander Zolot’ko, Michail Kosobokov, Andrey Akhmatkhanov, and Vladimir Shur. "Nanohydrodynamic Local Compaction and Nanoplasmonic Form-Birefringence Inscription by Ultrashort Laser Pulses in Nanoporous Fused Silica." Nanomaterials 12, no. 20 (October 15, 2022): 3613. http://dx.doi.org/10.3390/nano12203613.

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The inscription regimes and formation mechanisms of form-birefringent microstructures inside nano-porous fused silica by tightly focused 1030- and 515-nm ultrashort laser pulses of variable energy levels and pulsewidths in the sub-filamentary regime were explored. Energy-dispersion X-ray micro-spectroscopy and 3D scanning confocal Raman micro-spectroscopy revealed the micro-tracks compacted by the multi-shot laser exposure with the nanopores hydrodynamically driven on a microscale to their periphery. Nearly homogeneous polarimetrically acquired subwavelength-scale form-birefringence (refractive index modulation ~10−3) was simultaneously produced as birefringent nanogratings inside the microtracks of wavelength-, energy- and pulsewidth-dependent lengths, enabling the scaling of their total retardance for perspective phase-modulation nanophotonic applications. The observed form-birefringence was related to the hierarchical multi-scale structure of the microtracks, envisioned by cross-sectional atomic-force microscopy and numerical modeling.

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34

Tang, Ru-Ling, Xin Lian, Wen-Dong Yao, Wenlong Liu, and Sheng-Ping Guo. "K₃Na(TaF₇)(SiF₆): a mixed-anion pentanary fluoride with zero-dimensional anions exhibiting a large band gap." Dalton Transactions 50, no. 45 (2021): 16562–67. http://dx.doi.org/10.1039/d1dt03320d.

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A pentanary fluoride K3Na(TaF7)(SiF6) having a zero-dimensional anionic framework representing a new type of chemical composition and structure exhibits a large band gap and larger birefringence compared to the commercial birefringent crystal MgF2.

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35

Sukharenko, Vitaly, and Roger Dorsinville. "Polarization Sensitive Imaging with Qubits." Applied Sciences 12, no. 4 (February 15, 2022): 2027. http://dx.doi.org/10.3390/app12042027.

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We compare reconstructed quantum state images of a birefringent sample using direct quantum state tomography and inverse numerical optimization technique. Qubits are used to characterize birefringence in a flat transparent plastic sample by means of polarization sensitive measurement using density matrices of two-level quantum entangled photons. Pairs of entangled photons are generated in a type-II nonlinear crystal. About half of the generated photons interact with a birefringent sample, and coincidence counts are recorded. Coincidence rates of entangled photons are measured for a set of sixteen polarization states. Tomographic and inverse numerical techniques are used to reconstruct the density matrix, the degree of entanglement, and concurrence for each pixel of the investigated sample. An inverse numerical optimization technique is used to obtain a density matrix from measured coincidence counts with the maximum probability. Presented results highlight the experimental noise reduction, greater density matrix estimation, and overall image enhancement. The outcome of the entanglement distillation through projective measurements is a superposition of Bell states with different amplitudes. These changes are used to characterize the birefringence of a 3M tape. Well-defined concurrence and entanglement images of the birefringence are presented. Our results show that inverse numerical techniques improve overall image quality and detail resolution. The technique described in this work has many potential applications.

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36

Inoue, Tadashi, Kazuyuki Fujiwara, Deug-Soo Ryu, Kunihiro Osaki, Michiaki Fuji, and Kazuo Sakurai. "Viscoelasticity and Birefringence of Low Birefringent Polyesters." Polymer Journal 32, no. 5 (May 2000): 411–14. http://dx.doi.org/10.1295/polymj.32.411.

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37

Lane, C., F. Baumann, and T. Rösgen. "Shear Rate Imaging Using A Polarization Camera And A Birefringent Aqueous Cellulose Nanocrystal Suspension." Proceedings of the International Symposium on the Application of Laser and Imaging Techniques to Fluid Mechanics 20 (July 11, 2022): 1. http://dx.doi.org/10.55037/lxlaser.20th.140.

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Two aqueous cellulose nanocrystal suspensions are used to experimentally measure the shear and strain rates in a two-dimensional fluid flow. Cellulose nanocrystals are rod-like particles that align when subjected to shear, whereas at rest, they are randomly orientated by Brownian motion. The alignment causes birefringence, a phenomenon also known as flow-induced birefringence. The amount of birefringence is measured using a rotatable linear polarizer and a polarization camera. The linear polarizer is rotated to nine different positions. At each position, light from a light source becomes linear polarized before entering the birefringent fluid. Because of the birefringence the state of polarization is changed. This change is measured by the polarization camera. From the nine measurements the two-dimensional birefringence distribution is determined and from the amount of birefringence the strain rate is derived with the help of the data published by Lane et al. (2022a). We define Λ_0 as the angle between the (maximum) strain rate and the direction of flow. A shearing flow leads to Λ_0=45°, whereas Λ_0=0° and Λ_0=90° describe a flow down the centerline of a symmetrically converging and diverging channel, respectively. The measured strain rates are compared to simulations. The reference data in (Lane et al., 2022a) was taken at Λ_0=45°. For Λ_0≈45°, measurements and simulations correspond well to each other. If Λ_0≈0° is assumed, measured strain rates appear too high whereas they are too low for Λ_0≈90°. These results may be of interest for two reasons. First, shear rate imaging gave satisfying results in areas where Λ_0≈45°. Therefore, we propose the study of shear rates in a two-dimensional shearing flow by means of the presented method. Second, the results indicate that the flow state affects the degree of particle alignment and thus birefringence. This finding is in line with the statements made by Wayland (1960, 1964). The study of particle alignment and its influencing factors is of interest, and the experimental approach presented here is thought to be practicable for such studies.

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38

Qiu, Lin, Liang Ma, Wenlong Liu, Yuanyuan Sun, and Ru‐Ling Tang. "Unearthing Hydrogen Bonded Metal‐Free Crystal with Remarkable Optical Anisotropy." Advanced Optical Materials, April 11, 2025. https://doi.org/10.1002/adom.202500149.

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AbstractBirefringent crystals are crucial in modulating the polarization state of light within contemporary technological applications. Organic molecules with π‐conjugated structure are known to exhibit significant birefringence effect owing to their unique electronic properties. This study demonstrates that 4, 5‐dichocyanimidazole can be used as a new crystal building block for birefringent crystals. Crystals of C5N4H2 (DCI) and C5N4H2·H2O (DCI‐w) are obtained by evaporation at room temperature. It is worth noting that DCI and DCI‐w exhibit significant birefringence. At 546 nm, the experimental birefringence of DCI is 0.417 and the calculated birefringence of DCI‐w reaches 0.618. The birefringence of DCI‐w is significantly larger than those of all commercial birefringent crystals and exceeds most metal‐free birefringent crystals. First‐principles calculations and structural analysis show that this remarkable birefringence is mainly due to the strong anisotropy of the planar π‐conjugated C5N4H2 molecules and the well‐organized arrangement of the groups. This discovery opens up new possibilities for the development of high‐performance birefringent optical materials.

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Huang, Weiqi, Xianyu Song, Yanqiang Li, Yang Zhou, Qianting Xu, Yipeng Song, Han Wang, Minjuan Li, Sangen Zhao, and Junhua Luo. "Designing a Hybrid Perovskite with Enlarged Birefringence and Bandgap for Modulation of Light Polarization." Small, October 20, 2023. http://dx.doi.org/10.1002/smll.202306158.

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AbstractBirefringent crystals have important applications in optoelectronics areas due to their ability to modulate and polarize light. Despite increasing discovery of the birefringence potential of new crystals, it remains a great challenge to optimize both birefringence and bandgap simultaneously. Herein, a 1D chain‐like hybrid perovskite birefringent crystal designed by 3D‐to‐1D dimensional tailoring, (GAM)2PbI7·H2O (GAM = C5N10H10), is presented, showing enlarged birefringence of 0.49@550 nm and enlarged optical bandgap (2.48 eV). Consequently, the birefringent quality factor of (GAM)2PbI7·H2O is up to 2.8 times that of the template MAPbI3. In particular, the birefringence is much larger than those of commercial birefringent crystals and surpasses that of the vast majority of hybrid perovskite known to date. Theoretical calculations reveal that the strongly anisotropic arrangement of (GAM)2.5+ π‐conjugated cations and ordered PbI6 octahedra contributes to the large birefringence and wide bandgap of (GAM)2PbI7·H2O. It is believed that this work will provide a new pathway toward the rational design and synthesis of hybrid perovskite birefringent crystals for compact wide‐bandgap polarization dependent devices.

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40

Sun, Yayong, Yanqiang Li, Xianyu Song, Sangen Zhao, Tianhua Zhou, and Jian Zhang. "A Robust Phosphonate‐Based Hydrogen‐Bonded Organic Framework Birefringent Crystal." Advanced Functional Materials, August 27, 2024. http://dx.doi.org/10.1002/adfm.202413107.

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AbstractBirefringent crystals as an important optical anisotropic material play a crucial role in modulating the polarization state of light. To date, most birefringent crystals are purely inorganic compounds with small birefringence. Developing large birefringent crystals remains a great challenge primarily because of the absence of tunable anisotropic structural units for inorganic materials. Herein, a hydrogen‐bonding self‐assembly strategy is reported to construct a robust hydrogen‐bonded organic framework (HOF, namely m‐H3L) birefringent crystal, which consists of π‐conjugated benzene rings and tetrahedral phosphonate groups interconnected via multiple H‐bonding interactions. Interestingly, the birefringence is as large as ∆n = 0.17@550 nm and catches up with those of commercial birefringent crystals. A combination of theoretical calculation and single‐crystal structural analyses reveals that the H‐bonding interactions control the dihedral angle of π‐conjugated benzene rings and the smaller the dihedral angle, the greater the birefringence. This discovery opens the door for the tunable HOFs to be used as a promising new class of birefringence materials.

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41

Chen, Chong-An, Yang Li, Hongbo Huang, Congcong Jin, Bingbing Zhang, and Kang Min Ok. "Giant Birefringence Enabled by the Highly Anisotropic Linear IX2‐ (X = Cl, Br) Building Blocks." Angewandte Chemie International Edition, April 16, 2025. https://doi.org/10.1002/anie.202506625.

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Birefringent crystals are essential for polarized optical devices, yet achieving large birefringence through rational design remains challenging. The key lies in constructing birefringence‐active groups (BAGs) with giant polarization anisotropy and optimal spatial arrangements. Here, we report the successful construction of linear interhalogen BAGs, IX2‐ (X = Cl, Br), enabling giant polarization anisotropy. This was accomplished by simple halogenation of IO3‐ groups in an aqueous solution. Four novel birefringent crystals were synthesized: [H‐4AP][ICl2] (1, 4AP = 4‐aminopyridine), [HDMA]2[ICl2]·Cl (2, DMA = dimethylamine), [H‐4AP][IBr2] (3), and [HDMA]2[IBr2]·Br (4). In all these compounds, the linear IX2‐ BAG adopts parallel arrangements, effectively maximizing synergistic polarization anisotropy. As a result, compounds 1–4 exhibit giant birefringence values in both the visible (0.647, 0.585, 0.836, and 0.782 at 546 nm) and near‐infrared (NIR) regions (0.510, 0.356, 0.762, and 0.509 at 1064 nm), surpassing commercial birefringent crystals and many state‐of‐the‐art materials. Furthermore, these compounds achieve an optimal balance between giant birefringence and moderate bandgap among linear BAG‐based materials. Detailed theoretical calculations confirm that the IX2‐ BAGs play a dominant role in this exceptional birefringence. This study demonstrates the remarkable potential of linear interhalogen anions for developing high‐performance birefringent crystals.

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42

Chen, Chong-An, Yang Li, Hongbo Huang, Congcong Jin, Bingbing Zhang, and Kang Min Ok. "Giant Birefringence Enabled by the Highly Anisotropic Linear IX2‐ (X = Cl, Br) Building Blocks." Angewandte Chemie, April 16, 2025. https://doi.org/10.1002/ange.202506625.

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Birefringent crystals are essential for polarized optical devices, yet achieving large birefringence through rational design remains challenging. The key lies in constructing birefringence‐active groups (BAGs) with giant polarization anisotropy and optimal spatial arrangements. Here, we report the successful construction of linear interhalogen BAGs, IX2‐ (X = Cl, Br), enabling giant polarization anisotropy. This was accomplished by simple halogenation of IO3‐ groups in an aqueous solution. Four novel birefringent crystals were synthesized: [H‐4AP][ICl2] (1, 4AP = 4‐aminopyridine), [HDMA]2[ICl2]·Cl (2, DMA = dimethylamine), [H‐4AP][IBr2] (3), and [HDMA]2[IBr2]·Br (4). In all these compounds, the linear IX2‐ BAG adopts parallel arrangements, effectively maximizing synergistic polarization anisotropy. As a result, compounds 1–4 exhibit giant birefringence values in both the visible (0.647, 0.585, 0.836, and 0.782 at 546 nm) and near‐infrared (NIR) regions (0.510, 0.356, 0.762, and 0.509 at 1064 nm), surpassing commercial birefringent crystals and many state‐of‐the‐art materials. Furthermore, these compounds achieve an optimal balance between giant birefringence and moderate bandgap among linear BAG‐based materials. Detailed theoretical calculations confirm that the IX2‐ BAGs play a dominant role in this exceptional birefringence. This study demonstrates the remarkable potential of linear interhalogen anions for developing high‐performance birefringent crystals.

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43

Wang, Yuefeng, Meng Xia, Jiaxin Zhou, Di Huang, Yuhua Chen, and Xingwang Zhang. "Resonantly Enhanced Optical Birefringence in Ultrathin High‐Index WS₂ Metasurfaces." Laser & Photonics Reviews, February 23, 2024. http://dx.doi.org/10.1002/lpor.202301088.

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AbstractOptical birefringence plays an important role in the manipulation of polarization states of light. However, the weak birefringence in common birefringent materials restricts the device thickness to tens of microns for desired phase retardation. Although recent advances in dielectric metasurfaces have enabled remarkable birefringence using structurally anisotropic nanostructures, the refractive index contrast between the dielectric and the air cladding fundamentally limits the thickness of metasurfaces to a fraction of a micron to obtain the required phase retardation. Here, birefringent resonances in high‐index tungsten disulfide (WS2) metasurfaces are utilized to push the thickness limit down to the deep subwavelength scale. The inherent high‐index property of WS2 enables birefringent resonances in WS2 metasurfaces which consist of anisotropic nanostructures with a thickness of only 50 nm. Such birefringent resonances enhance the light‐matter interaction and produce an unprecedented birefringence (Δneff) about 4. As a result, it is experimentally realized that circular‐to‐linear polarization conversion with a normalized efficiency of ≈90% within an incident angle range up to ±10°. The results break the fundamental limit of birefringent devices and provide strategies for creating ultimate thin polarization optical devices.

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Xu, Qianting, Weiqi Huang, Han Wang, Yanqiang Li, Yang Zhou, Linxi Hou, Sangen Zhao, and Junhua Luo. "Designing a Dimension Reduced Hybrid Perovskite with Robust Large Birefringence by Expanding Cationic π‐Delocation." Small, August 24, 2023. http://dx.doi.org/10.1002/smll.202304333.

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AbstractIt is in great demand to discover new materials with large birefringence for the miniaturization of optical communication devices. In this work, a new one‐dimensional hybrid halide perovskite, (C6N10H8)Pb2Br6, is obtained successfully through structural design of dimension reduction from the notable three‐dimensional halide perovskite CsPbBr3. Remarkably, (C6N10H8)Pb2Br6 exhibits a significantly enhanced birefringence of ∆n = 0.42@550 nm, which is the largest among halide perovskites so far. Furthermore, its birefringence performance is robust in a wide temperature range of 300–440 K. Theoretical calculations reveal that this outstanding birefringence results from the synergistic effect of [PbBr6]4− octahedra and [C6N10H8]2+ cations with expanding π‐delocation. According to further structural analyses, the structural dimension reduction cooperating with the increase of [PbBr6]4− octahedral distortion leads to the enhanced birefringence. This work uncovers the great promise of hybrid halide perovskites as robust birefringent crystals in future optical communication and would shed useful insights on the design and synthesis of new birefringent crystals.

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45

Jin, Congcong, Fuming Li, Zhihua Yang, Shilie Pan, and Miriding Mutailipu. "[C₃N₆H₇]₂[B₃O₃F₄(OH)]: a new hybrid birefringent crystal with strong optical anisotropy induced by mixed functional units." Journal of Materials Chemistry C, 2022. http://dx.doi.org/10.1039/d2tc01123a.

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A new hybrid fluorooxoborate was discovered following the strategy of combining two birefringence-active units. The large birefringence and short absorption edge make it a potential short-wavelength ultraviolet birefringent crystal.

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46

Shen, Yaoguo, Mingliang Ding, Gang Chen, Yingjie Luo, Sangen Zhao, and Junhua Luo. "C₉H₇NBrX (X = Cl, Br, NO₃): Three Excellent Birefringent Crystals with Distinct Optical Anisotropy Regulated by Anions." Small, May 10, 2024. http://dx.doi.org/10.1002/smll.202400549.

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AbstractA large optical anisotropy is the most important parameter of birefringent crystals. Integrating π‐conjugated groups with large polarizable anisotropy into target compounds is a common strategy for constructing brilliant birefringent crystals. However, the key problem is to enhance the density of the birefringence‐active units and further arrange them parallelly. In this study, three novel birefringent crystals, C9H7NBrX (X = Cl, Br, NO3), are successfully synthesized by introducing a new birefringence‐active [C9H7NBr]+ unit. Interestingly, these compounds feature similar layered structures but exhibit different optical anisotropies at 550 nm (0.277 for C9H7NBrCl, 0.328 for C9H7NBrBr, and 0.401 for C9H7NBrNO3) owing to the different anions in them. Particularly, the small trigonal planar NO3 anions perfectly fill the interstices of the π‐conjugated [C9H7NBr]+ groups with large optical anisotropy, with the resulting compound C9H7NBrNO3 showing superior optical properties compared to the others. The above findings provide strategies for designing new optical materials with large birefringence by matching birefringence‐active groups of different sizes. Additionally, a new theory for predicting and comparing the polarizability anisotropy of compounds is proposed, which would guide in exploring large birefringent crystals.

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47

Nishiwaki, Yoichi. "Optical birefringence measurements of antiferromagnets with Ising spin chains." International Journal of Modern Physics B, June 26, 2023. http://dx.doi.org/10.1142/s0217979224502679.

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Optical birefringence measurements were performed on Ising-spin antiferromagnets with the chemical formula ACo[Formula: see text]. The temperature dependences of the birefringences of CsCoCl3 and CsCoBr3 reflect the thermal shrinkage of the crystal lattice and the development of magnetic short-range correlation in Ising spin chains. Moreover, the temperature dependences of the birefringences of RbCoBr3 and TlCoCl3 show marked anomalies at structural phase transition points. We demonstrate a method of numerically analyzing the birefringence in magnetic compounds that undergo structural phase transitions.

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48

Wu, Tianhui, Xingxing Jiang, Kaining Duanmu, Chao Wu, Zheshuai Lin, Zhipeng Huang, Mark G. Humphrey, and Chi Zhang. "Giant Optical Anisotropy in a Covalent Molybdenum Tellurite via Oxyanion Polymerization." Advanced Science, January 30, 2024. http://dx.doi.org/10.1002/advs.202306670.

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AbstractLarge birefringence is a crucial but hard‐to‐achieve optical parameter that is a necessity for birefringent crystals in practical applications involving modulation of the polarization of light in modern opto‐electronic areas. Herein, an oxyanion polymerization strategy that involves the combination of two different types of second‐order Jahn–Teller distorted units is employed to realize giant anisotropy in a covalent molybdenum tellurite. Mo(H2O)Te2O7 (MTO) exhibits a record birefringence value for an inorganic UV‐transparent oxide crystalline material of 0.528 @ 546 nm, which is also significantly larger than those of all commercial birefringent crystals. MTO has a UV absorption edge of 366 nm and displays a strong powder second‐harmonic generation response of 5.4 times that of KH2PO4. The dominant roles of the condensed polytellurite oxyanions [Te8O20]8− in combination with the [MoO6]6− polyhedra in achieving the giant birefringence in MTO are clarified by structural analysis and first‐principles calculations. The results suggest that polymerization of polarizability‐anisotropic oxyanions may unlock the promise of birefringent crystals with exceptional birefringence.

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Li, Yang, and Kang Min Ok. "Breaking Boundaries: Giant Ultraviolet Birefringence in Dimension‐Reduced Zn‐Based Crystals." Angewandte Chemie, June 26, 2024. http://dx.doi.org/10.1002/ange.202409336.

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Birefringent 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) [(o‐C5H5NO)2ZnCl2] (1) and [o‐C5H6NO]2[ZnCl4] (2) were obtained by introducing the π‐conjugated o‐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.

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Li, Yang, and Kang Min Ok. "Breaking Boundaries: Giant Ultraviolet Birefringence in Dimension‐Reduced Zn‐Based Crystals." Angewandte Chemie International Edition, June 26, 2024. http://dx.doi.org/10.1002/anie.202409336.

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Abstract:

Birefringent 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) [(o‐C5H5NO)2ZnCl2] (1) and [o‐C5H6NO]2[ZnCl4] (2) were obtained by introducing the π‐conjugated o‐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.

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