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The epsilon‐near‐zero (ENZ) frequency regime of transparent conducting oxide materials is known to yield large enhancements in their optical nonlinearity and electro‐optic response. Here, Faraday rotation is investigated in Gd and In‐doped CdO films and it is found that the Verdet constant peaks at values >3 105 deg T−1 m−1 near the ENZ frequency, which is tunable in the wavelength range 2 < λ< 10 µm by varying the doping concentration. These results are among the highest reported to date in the mid‐infrared spectral range and are in good agreement with the Drude model, which confirms that the magneto‐optic response of doped CdO derives from its free carriers. The combination of a tunable Verdet constant, low optical loss compared to other plasmonic materials, and the ability to deposit CdO on Si with no loss in performance make this material a promising platform for integrated magneto‐optic and magnetoplasmonic devices that operate across the mid‐infrared. [ABSTRACT FROM AUTHOR]

Copyright of Experimental Technology & Management is the property of Experimental Technology & Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Recent progress in the development of optical communication and high power laser systems in the near-infrared (NIR) region (1.5 to 2.0 μm) increased the demand for magneto-optic (MO) devices employing MO materials. These MO materials are required with lower optical absorption coefficients and higher Verdet constants at spectral range of interest. In this study, two series of highly Dy3+-doped GeO2–B2O3 glasses with and without P2O5 were fabricated using a simple melt-quenching technique. The glasses were characterized through various techniques (Raman, UV–VIS-NIR, and DTA) for the evaluation of characteristic properties with respect to the Dy2O3 concentration and glass composition. Faraday rotation measurement was carried out at 1550 nm to quantify the Verdet constant of the glasses. The Verdet constant values were found to increase linearly with increasing Dy3+ concentration for both the glass systems. The increase in Dy3+ concentration and, consequently, the number of unpaired electrons, leads to an increase in the Verdet constant. The GeO2-B2O3 glass doped with 30 mol% of Dy2O3 exhibited the highest Verdet constant of −5.36 rad/(T⋅m) at 1550 nm. The glasses exhibited a good optical transparency (>70 %) in the region covering from 400 to 2400 nm. The thermo-physical, optical, and polarizability properties of both glass systems were also investigated. The results indicate that the highly Dy3+-doped glasses are attractive for magneto-optics at 1550 nm.

Magneto-optical and thermo-optical characteristics of transparent Tb2Ti2O7 ceramics were investigated. The dependence of the index of refraction on the wavelength in the 0.29–2 μm range, the wavelength and temperature dependence of the Verdet constant, as well as the dependence of thermally induced depolarization on laser radiation power were measured. The value of the Verdet constant in Tb2Ti2O7 surpasses that in Tb3Ga5O12 by more than 1.68 times. The thermo-optical characteristic Qeff was estimated to be (1.8–3.7)∙10−8 1/K, which is record small compared to Qeff of the known magneto-optical materials. The small value of Qeff makes Tb2Ti2O7 a highly promising magneto-optical material for Faraday isolators and rotators for high average power lasers.

Transparent Gd2O3 ceramics with a cubic crystal structure were successfully synthesized for the first time. The Gd2O3 ceramics subjected to hot isostatic press (HIP) at 1070 ℃ consisted of uniform grains of 2–3 μm, and only a few residual pores could be detected inside the materials. X-ray diffraction (XRD) shows that the obtained polycrystalline materials have a cubic crystal structure, and the transmission polarized light observation shows that there is no birefringence inside the materials, indicating inherent optical properties of the cubic crystal structure. The optical absorption edge is 640 nm (optical band gap: 2.1 eV), and the transmittance in the visible to near-infrared region is 72%, which is close to the theoretical transmittance calculated from Fresnel loss. Verdet constant of this material is almost wavelength-independent, and it is diamagnetic since it has the opposite polarity to that of common paramagnetic materials.

Extensive efforts have been devoted to magneto-optical (MO) glass, owing to its remarkable potential in modern optics, encompassing diverse applications such as optical isolation, modulation, and sensing. Although the Tb ions doped glass has good MO properties, high concentrations of Tb ions tend to cluster, resulting in glass crystallization. To further improve the performance of MO glass, we must improve the solubility of Tb ions and inhibit the oxidation of paramagnetic Tb3+ to diamagnetic Tb4+ by adjusting the glass composition. In this work, we conducted a comparative study on GeO 2 -B 2 O 3 -X 2 O 3 glasses doped with Tb 2 O 3 (TGBX, where X represents Ga or La) to elucidate the effects of Ga 2 O 3 and La 2 O 3 on glass properties. Our findings reveal that TGBG glasses exhibit superior MO performance compared to TGBL glasses. Notably, the Verdet constant of TGBG glass with 45 mol.% Tb 2 O 3 at 650 nm reaches 105 rad/(T·m). Although TGBL glass exhibits a lower Verdet constant, its higher glass network connectivity and higher concentration of Tb3+ ions suggest its potential for preparing larger-sized glasses with an increased Tb3+ molar ratio. [ABSTRACT FROM AUTHOR]

Anti-resonant fiber (ARF) works well in a relatively strong magnetic field due to its weak Faraday effect, which results from the fundamental mode mainly transmitting in the air core. Accurately measuring the Faraday effect strength, i.e., the effective Verdet constant, of an ARF determines its applicable scenarios. However, the effective Verdet constant of ARF is ~3 orders of magnitude lower than that of a standard single-mode fiber, which is very difficult to measure. In this paper, we reveal that intermodal interference is the main obstacle to measuring the ultralow effective Verdet constant of ARF and propose using a narrow-band low-coherence light to suppress it. The measured effective Verdet constant of ARF is 0.423 ± 0.005 mrad/T/m at 1550 nm. [ABSTRACT FROM AUTHOR]

Optical frequency rulers (OFRs) can be used as optical wavelengths or frequency references for spectra modulation or to determine unknown wavelengths. In the past, difficult-to-perform and complicated mechanisms were used to make OFRs, such as double slits with a high-speed fluid or an external circuit to control the liquid crystal birefringence. Since then, a later research study introduced a simple structure for producing OFRs by utilizing the optical activity block and two polarizers. This achieved a movable OFR that was controllable by simply rotating one of the polarizers. However, this mechanical rotation hindered its high-speed applicability. In this article, a more advanced, scalable OFR scheme using the Faraday effect is proposed. It is controlled by varying the magnetic field intensity, which is not a mechanical method, and it can be changed at high speeds. The numerical results demonstrate that those OFR spectral ticks can be scaled to reach a higher or lower tick density, greatly benefiting the wavelength decision jobs. [ABSTRACT FROM AUTHOR]

With the development of high-power solid-state lasers and fiber lasers, the demand for optical isolators in the visible and near-infrared regions is gradually increasing. At present, equipment components are tending towards miniaturization. The most widely used terbium gallium garnet (TGG) crystal in industry cannot meet the needs of future high-power lasers due to its small Verdet constant. Tb2 O3 has a high Verdet constant, but its high melting point and phase transition mechanism make it difficult to achieve single crystals by Czochralski. The crystal growth of (Tbx Y1 - x)2 O3 at different doping concentrations was explored by doping Y2 O3 into Tb2 O3 in this study. When the ratio of n(Tb)∶n(Y) was 1∶1, TbYO3 single crystals were grown by laser floating zone (LFZ) method, while undoped Tb2 O3 and (Tb0. 3 Y0. 7)2 O3 single crystals cannot be synthesized by this method. The TbYO3 crystal has high Verdet constants (529 rad·T-1·m-1 at 445 nm and 116 rad·T-1 ·m-1 at 880 nm), which is 1.51 to 2.37 times that of terbium gallium garnet (TGG) crystal (350 rad·T-1·m-1 at 445 nm and 49 rad·T-1·m-1 at 880 nm). Therefore, the TbYO3 crystal can effectively reduce the medium length for constructing optical isolators or decrease the magnetic field intensity required for embedding optical isolators. In addition, TbYO3 crystal also has a moderate thermal conductivity of 11 W·m-1 ·K-1 and a high laser induced damage threshold of 1. 67 GW·cm-2. These advantages make TbYO3 crystal an attractive magneto-optical material. [ABSTRACT FROM AUTHOR]

Anti-resonant fiber (ARF) works well in a relatively strong magnetic field due to its weak Faraday effect, which results from the fundamental mode mainly transmitting in the air core. Accurately measuring the Faraday effect strength, i.e., the effective Verdet constant, of an ARF determines its applicable scenarios. However, the effective Verdet constant of ARF is ~3 orders of magnitude lower than that of a standard single-mode fiber, which is very difficult to measure. In this paper, we reveal that intermodal interference is the main obstacle to measuring the ultralow effective Verdet constant of ARF and propose using a narrow-band low-coherence light to suppress it. The measured effective Verdet constant of ARF is 0.423 ± 0.005 mrad/T/m at 1550 nm.

Optical frequency rulers (OFRs) can be used as optical wavelengths or frequency references for spectra modulation or to determine unknown wavelengths. In the past, difficult-to-perform and complicated mechanisms were used to make OFRs, such as double slits with a high-speed fluid or an external circuit to control the liquid crystal birefringence. Since then, a later research study introduced a simple structure for producing OFRs by utilizing the optical activity block and two polarizers. This achieved a movable OFR that was controllable by simply rotating one of the polarizers. However, this mechanical rotation hindered its high-speed applicability. In this article, a more advanced, scalable OFR scheme using the Faraday effect is proposed. It is controlled by varying the magnetic field intensity, which is not a mechanical method, and it can be changed at high speeds. The numerical results demonstrate that those OFR spectral ticks can be scaled to reach a higher or lower tick density, greatly benefiting the wavelength decision jobs.

Heavily-doped and fully concentrated 2.78 % Tb:Y 2 O 3 and Tb 2 O 3 single crystals with high optical quality and very low levels of impurities have been grown and studied for their luminescence and Faraday rotation properties. Absorption, emission and fluorescence decay measurements performed vs excitation wavelength and temperature and their confrontation with Judd-Ofelt and crystal-field calculations show the contributions of two types of luminescent centers: dominant ones with a 5D 4 emission lifetime of 23 μs corresponding to coupled near-neighbor Tb3+ ions, all in C 2 symmetry sites, and minority ones with a 5D 4 emission lifetime of about 2 ms corresponding to coupled Tb3+ ions in C 2 and C 3i near-neighbor symmetry sites. Faraday rotation measurements confirm Tb 2 O 3 as the Tb-based Faraday crystalline material with the largest ever measured Verdet constant, at all temperatures and from the visible to the near-infrared. They also show that the dominant luminescent centers contribute more particularly to this large Verdet constant thanks to a favorable crystal-field splitting of their 7F 6 ground multiplet and also to the contributions of both types of spin-allowed and spin-forbidden 4f-5d absorption bands. • 2.78 % Tb:Y 2 O 3 and Tb 2 O 3 single crystals luminescence and Faraday rotation properties are studied. • The existence of two types of luminescent centers with 5D 4 emission lifetimes of 23 μs and 2 ms is revealed. • Verdet constant measurements highlight the importance of the dominant luminescent centers, all in C 2 symmetry sites. [ABSTRACT FROM AUTHOR]

• Two series of highly Dy3+-doped GeO 2 -B 2 O 3 glasses were successfully fabricated. • Structural and thermal properties of the glasses were investigated. • MO properties of the glasses were investigated at 1550 nm. • The highest Dy 2 O 3 -doped glass exhibited the largest V of −5.36 rad/(T⋅m). • Compositional effect on V was investigated in the studied glasses. Recent progress in the development of optical communication and high power laser systems in the near-infrared (NIR) region (1.5 to 2.0 μm) increased the demand for magneto-optic (MO) devices employing MO materials. These MO materials are required with lower optical absorption coefficients and higher Verdet constants at spectral range of interest. In this study, two series of highly Dy3+-doped GeO 2 –B 2 O 3 glasses with and without P 2 O 5 were fabricated using a simple melt-quenching technique. The glasses were characterized through various techniques (Raman, UV–VIS-NIR, and DTA) for the evaluation of characteristic properties with respect to the Dy 2 O 3 concentration and glass composition. Faraday rotation measurement was carried out at 1550 nm to quantify the Verdet constant of the glasses. The Verdet constant values were found to increase linearly with increasing Dy3+ concentration for both the glass systems. The increase in Dy3+ concentration and, consequently, the number of unpaired electrons, leads to an increase in the Verdet constant. The GeO 2 -B 2 O 3 glass doped with 30 mol% of Dy 2 O 3 exhibited the highest Verdet constant of −5.36 rad/(T⋅m) at 1550 nm. The glasses exhibited a good optical transparency (>70 %) in the region covering from 400 to 2400 nm. The thermo-physical, optical, and polarizability properties of both glass systems were also investigated. The results indicate that the highly Dy3+-doped glasses are attractive for magneto-optics at 1550 nm. [ABSTRACT FROM AUTHOR]

• Magnetooptical Faraday and Kerr effects are studied in the nanosized BiY 2 Fe 5 O 12 films on the Gd 3 Ga 5 O 12 substrates. • The specific Faraday rotation for the nanosized Bi 0.5 Y 1.5 Fe 5 O 12-δ films reaches about 140000 deg/cm close to that for bulk BiY 2 Fe 5 O 12. • Defining the magnetooptical parameters and Verdet constant for the Gd 3 Ga 5 O 12 substrate permits to separate correctly the substrate contribution. Magnetooptical Faraday and Kerr effects are studied in the nanosized BiY 2 Fe 5 O 12 films within the spectral region of 1.3 eV< E <4.5 eV and magnetic fields of up to 10 kOe. It is shown that the thin-films BiY 2 Fe 5 O 12 with the thicknesses ranging from 5 to 51 nm obtained by magnetron sputtering on the single-crystalline Gd 3 Ga 5 O 12 substrates have high magneto-optical quality. The specific Faraday rotation for the nanosized Bi 0.5 Y 1.5 Fe 5 O 12-δ films reaches about 140000 deg/cm close to that for bulk BiY 2 Fe 5 O 12. Meanwhile, the polar Kerr effect reaches about 30 min within the range of 1.6 eV–4.1 eV at the magnetic fields above 2 kOe. It is shown that the strong paramagnetic contribution of Gd 3 Ga 5 O 12 substrates significantly affects the Faraday and Kerr effect for the films. The defining of magnetooptical parameters and Verdet constant for the Gd 3 Ga 5 O 12 substrate permitted to separate the substrate contribution and reveal peculiarities of spectral dependences of both Faraday and Kerr effects for magnetic films of various thicknesses. The estimated critical thickness of the film-substrate interface region is as large as 35 lattice constants of BiY 2 Fe 5 O 12. It is shown that the magnetooptical effects for the thin films with the thickness above the critical one correspond to those for bulk BiY 2 Fe 5 O 12. For samples with the smallest thicknesses of the film (5 nm) the contributions from magnetically dead and magnetically passive layers lead to a drastic reduction in the observable Faraday and Kerr effects with a dominating contribution from the substrate. The high density of displacement dislocations at the film-substrate interface leads to the decrease the magnetooptical quality of the nanosized films. [ABSTRACT FROM AUTHOR]

• We synthesized the new xB2O3-yGa2O3-zTb2O3 magneto-optical glass and determined the glass formation region. • Increasing B2O3 raised the Verdet constant; XPS confirmed more Tb3+ with higher B2O3. • Achieved highest Verdet constant of −128.958 rad/(T⋅m) at 532 nm with 35 mol% Tb2O3 doping. • We assembled the B-Ga-Tb glass into a magnetic field sensor with high sensitivity (0.206 rad/T) and excellent stability, indicated by an R2 value of 0.998. Rare-earth-doped glass, prized for its transparency and high Verdet constant, holds promise in sensing and laser systems. However, the magneto-optical (MO) properties and glass structure can be influenced by the concentration of rare-earth ions and substrate doping. Here, we synthesized x B 2 O 3 - y Ga 2 O 3 - z Tb 2 O 3 (x + y + z = 100) MO glass, aiming to analyze the optimal ratio of Tb ions to the substrate by adjusting the glass composition. The Verdet constant for the 35mol% Tb 2 O 3 glass peaks at -128.958 rad/(T⋅m) at 532 nm and -11.579 rad/(T⋅m) at 1550 nm. Our findings revealed that an increase in B 2 O 3 led to a proportional increase in the Verdet constant, with the high sensitivity of magnetic field measurement reaching 0.206 rad/T. This result underscores the potential for tailoring glass compositions to optimize magneto-optical characteristics, and will contribute to the broader application of MO glasses in magnetic sensing and laser systems. [ABSTRACT FROM AUTHOR]

The ternary TeO2–La2O3–WO3 glasses with a formula of (100 − y − x)TeO2–yLa2O3–xWO3 (y = 5 and 10 mol%; x = 10 to 25 mol%) were made by the melting and casting method for high Verdet constant diamagnetic magneto-optical (MO) materials in the application of MO devices operating at 1550 nm. The compositional effects of WO3 and La2O3 contents on key glass properties of thermal stability, Knoop hardness, optical transmission, and Verdet constant, were systematically studied for both series of glasses. High transparency level (T: >70 %) in the region from 0.4 to 5.2 μm and a high refractive index (n: 2.05 at 1550 nm) were obtained in the studied glasses. The tellurite glasses with 5 mol% of La2O3 exhibited higher thermal stability and refractive indices than those with 10 mol% La2O3. The 85TeO2–5La2O3–10WO3 glass exhibited a large Verdet constant value of 3.95 rad/(T·m) at 1550 nm among the studied glasses. These results show that the presented TeO2–La2O3–WO3 glasses have considerable potential as diamagnetic MO materials for MO device applications operating at 1550 nm.

In this study, nano-sized individual Tb2O3 particles synthesized by the laser ablation method were extensively characterized and assessed as suitable precursors for the fabrication of transparent magneto-optical ceramics without requiring the introduction of grain growth inhibitors and stabilizing additives. The as-produced powder comprised 13 nm particles with a spherical shape and monoclinic crystal structure, whose full transformation into cubic phase was achieved after heating at 950 °C and 700 °C under vacuum and Ar gas, respectively. After subjecting the nanopowder compact to pre-sintering at 1350 °C, the microstructural features were investigated along with their correlation to the optical transmittance of Tb2O3 ceramic hot isostatically pressed (HIPed) for 2 h at 1450 °C under 200 MPa. The as-HIPed sample had a brownish color, with an optical transmittance of 65.3% at a wavelength of 1060 nm and an average grain size of 14 μm. The Verdet constant measured at wavelengths of 633 nm and 1060 nm was 471 rad T−1 m−1 and 142 rad T−1 m−1 to confirm a very high content of magneto-active Tb3+ ions. The obtained results indicate that laser ablation synthesis of nanoparticles followed by pre-sintering and HIP is a promising approach for the manufacture of magneto-optical Tb2O3 ceramics without specific sintering aids. [ABSTRACT FROM AUTHOR]

Temperature is the main factor restricting the application of all-fiber current sensors. To comprehensively analyze temperature influences, the influences of temperature on Verdet constant, birefringence, and phase delay of the quarter-wave plate are modeled and simulated by the Jones matrix and Matlab. Basing on the normalized scale coefficient, the relationship between the normalized ratio coefficient and temperature is discussed. Finally, we get the conclusion that the normalized proportional coefficient of feedback phase shift fluctuates on both sides of the reference temperature. Keeping the temperature in a narrow range is a practical scheme to improve the system performance.

New magnetic glass compositions, based on system (100-x) (60GeO2 -25B2O3 –4Al2O3 -10Na2O–1PbO) – xTb4O7 were prepared by the melt-quenching technique. The materials were systematically characterized with respect to their structural (XRD, EXAFS, XANES and Raman), thermal (DSC), morphological, optical, magnetic and magneto-optical (MO) properties. Morphological and magnetic measurements show the homogeneous distribution of the Tb3+ ions as the magnetic susceptibility increases proportionally to the rare earth content. The optical window covers the range from 0.5 up to 1.6 μm, limited by absorption due to 4f8 -> 4f7 5 d 1and 4f8 -> 4f8 transitions of Tb3+. XANES and EXAFS measurements at the Ge–K edge show that the germanium atoms are always tetrahedrally coordinated, while results at the Tb-LIII edge shows terbium atoms to be eight-coordinated and exclusively present in the oxidation state 3+ independently of the glass composition. MO measurements show that the Verdet constant (VB) increases linearly with the Tb3+ concentration reaching the value of −83.9 rad T−1m−1 at 650 nm for glass containing 8 mol% of Tb4O7. Good thermal stability (ΔT = 200 °C) allowed obtaining an optical fiber of a glass containing 4 mol% of Tb4O7 featuring VB values of −37.9, −23.6 and −5.89 rad T−1 m−1, at 500, 650 and 1550 nm, respectively.

Magnetic particles of BaFe 12 O 19 were synthesized using a high-temperature solid-phase method. Magneto-optical glass samples were prepared by incorporating different concentrations of Fe3+ ions (ranging from 0 to 0.25 mol%) into the glass matrix with a constant doping of Tb 2 O 3 (30 mol%) using a high-temperature melting method. The glasses are composed of B 2 O 3 -GeO 2 -Al 2 O 3 -ZnO-BaO-Tb 2 O 3 (BGAZBa-T30-xFe). The effects of varying Fe3+ ion concentrations on the structure, physical properties, and magneto-optical performance of BGAZBa-T30 glass were investigated. The study reveals that the density and magneto-optical properties of the glass are enhanced with the increase of Fe3+ ion concentration. When the Fe3+ ion concentration reaches 0.20 mol%, the Verdet constant of BGAZBa-T30 glass increases from −82.51 rad/(T·m) to −91.90 rad/(T·m) at an incident light wavelength of 633 nm. Meanwhile, the density rises from 4.93 g/cm3 to 4.98 g/cm3. Notably, the BGAZBa-T30-0.20Fe glass sample exhibits excellent magneto-optical performance, with a Verdet constant value of −142.50 rad/(T⋅m) at an incident light wavelength of 515 nm, which is 1.2 times that of the glass matrix main body (−118.28 rad/(T·m)). This presents potential research value in the field of optoelectronic functionality. • Introducing Fe3+ ion enhances magneto-optical properties of BGAZBa glass. • At 515 nm, the Verdet constant of 0.20Fe glass reaches −142.50 rad/(T·m). • Introducing a certain amount of Fe3+ can improve the magnetic properties of glass. [ABSTRACT FROM AUTHOR]

Magneto-optical materials based on transparent ceramics are providing promising opportunities for modern Faraday isolators. Titanium (Ti)，Cerium (Ce), co-doped Tb 3 Ga 5 O 12 (Ti/Ce:TGG) ceramics with high transmittance were prepared using the coprecipitated powders. The Ti/Ce:TGG magneto-optical ceramic with best quality was sintered at around 1500 °C for 8 h. It is noted that as-prepared ceramic presents the highest transmittance, corresponding to 81.0% at the wavelengths of 550–1450 nm. No secondary phase or obvious pores can be detected from the sample using field emission scanning electron microscopy (FE-SEM). The Verdet constant of Ti/Ce:TGG ceramic at 1064.0 nm is as high as 65.5 rad m−1 T−1, which is much higher than that of pure TGG ceramic. The excellent optical and magneto-optical properties make Ti/Ce:TGG ceramic an attractive magneto-optical material. [ABSTRACT FROM AUTHOR]

The magnetic susceptibility and the Faraday effect in DyAlO3 single crystal samples are studied in the temperature range of 78–300 K along the easy-magnetization axis b of the orthorhombic crystal. The studies are supplemented with similar investigations of terbium orthoaluminate TbAlO3. The Faraday rotation and the natural birefringence typical for crystals of the orthorhombic syngony are found from the temperature and spectral dependences of the rotation angles Θ of the major axis of the light polarization ellipse measured in the wavelength range of 440–750 nm. The linearity of the dependence of the Verdet constant V on the magnetic susceptibility χ of the DyAlO3 crystal at a wavelength of 506 nm allowed calculation of the paramagnetic Verdet constant Ср of DyAlO3. The Ср constants and the effective frequencies ω0 of allowed transitions found in rare-earth RAlG garnets (R = Tb3+, Dy3+) are compared with the corresponding values determined in RAlO3 crystals. The possibility of practical application of RAlO3 crystals studied in this work is briefly discussed. [ABSTRACT FROM AUTHOR]

The magnetic susceptibility and the Faraday effect in DyAlO3 single crystal samples are studied in the temperature range of 78–300 K along the easy-magnetization axis b of the orthorhombic crystal. The studies are supplemented with similar investigations of terbium orthoaluminate TbAlO3. The Faraday rotation and the natural birefringence typical for crystals of the orthorhombic syngony are found from the temperature and spectral dependences of the rotation angles Θ of the major axis of the light polarization ellipse measured in the wavelength range of 440–750 nm. The linearity of the dependence of the Verdet constant V on the magnetic susceptibility χ of the DyAlO3 crystal at a wavelength of 506 nm allowed calculation of the paramagnetic Verdet constant Ср of DyAlO3. The Ср constants and the effective frequencies ω0 of allowed transitions found in rare-earth RAlG garnets (R = Tb3+, Dy3+) are compared with the corresponding values determined in RAlO3 crystals. The possibility of practical application of RAlO3 crystals studied in this work is briefly discussed. [ABSTRACT FROM AUTHOR]

Abstract Transparent ceramics are at the heart of modern magneto-optical materials providing promising opportunities for Faraday isolators. 1.0 at% RE:Tb3Ga5O12 (rare earth (RE) = Pr, Tm, Dy) transparent ceramics were successfully prepared by air sintering and sequential HIP technique using the coprecipitated powders as the raw material. All the powders have shown to be a pure cubic terbium gallium garnet (TGG) phase and exhibit good dispersion. Additionally, a change could not be observed in particle shape with the different doped ions. After the two-step sintering, all the obtained ceramics have good optical quality, and the in-line transmittances at 1070 nm are higher than 80%. Moreover, no secondary phase can be detected from the microstructures. However, the pores which remain entrapped in the ceramics can be noted. The Verdet constant of ceramic samples is optimized by RE doping, and the Verdet constant at 632.8 nm is about −143 rad·T−1·m−1, which is about 5% higher than that of TGG ceramics. Finally, the thermo-optical properties of 1.0 at% RE:TGG transparent ceramics are compared. The annealed TGG ceramic showed the best thermo-optical properties, and the thermally induced depolarization of 1.0 at% Ce:TGG and 1.0 at% Tm:TGG was inferior to that of annealed TGG ceramic.

Copyright of Journal of Heilongjiang University of Science & Technology is the property of Journal of Heilongjiang University of Science & Technology Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Novel Tb 3 Sc 2 Al 3 O 12 (TSAG) magneto-optical transparent ceramic was fabricated by vacuum sintering. The phase composition, microstructure, optical quality, thermal properties, and magneto-optical properties of TSAG ceramic were measured. It is shown that the increase in holding time has an effect on the grain size of TSAG ceramic. It is noted that TSAG35 ceramic presents the highest transmittance, corresponding to 81.5 % at the wavelength of 1064 nm. The thermal properties of TSAG ceramic are close to or superior to that of the reported TSAG and TGG crystals. The Verdet constant of TSAG ceramic is comparable to that of reported TSAG crystal, and 1.2 times that of TGG crystal. The results indicate that the novel TSAG ceramic is comparable to TSAG crystal in terms of magneto-optical properties and superior to TGG crystal, making it a candidate material for magneto-optical materials to be used in high-power lasers. [ABSTRACT FROM AUTHOR]

Sensitive magnetometer technology is desirable for biomagnetic field detection and geomagnetic field measuring. Signal amplification materials such as magneto-optical crystals or ceramics are crucial for enhancing detection sensitivity, but severe optical scattering and low Verdet constant further limit its application. To develop high-sensitivity magnetometers for quantum weak measurement schemes, we have conducted investigations on the powder calcining dynamics and prepared a series of high-optical-quality (Ho/Dy) 2 Zr 2 O 7 transparent ceramic samples. The Verdet constant of magneto-optical materials was measured across a continuous wavelength spectrum, exhibiting a peak at 283 ± 5 rad/(T·m). We further established an electron transition mechanism to elucidate the exceptional magneto-optical attributes of dysprosium. In addition, samples demonstrated superior performance in weak-value amplification, reaching a low detectable magnetic field threshold of 3.5 × 10 -8 T and continuously worked over 6 h with high stability. Our work developed a highly sensitive magnetometer using optimized magneto-optical ceramics and provided guidance on design, fabrication, and application for magneto-optical ceramics in quantum weak measurement.

Magneto-optical (MO) polymer nanocomposites have emerged as alternatives to conventional MO crystals, particularly in nanophotonics applications, thanks to their better processing flexibility and superior Verdet constants. However, a higher Verdet constant commonly comes with excessive optical loss due to increased absorption and scattering, resulting in a constant or reduced figure-of-merit (FOM) defined as the Verdet constant over optical loss. By doping magnetite (Fe 3 O 4 ) nanoparticles with Tb 3+ ions, we report a new strategy to enhance the Verdet constant without increasing the optical loss. The Fe 3 O 4 :Tb 3+ nanocomposite is one of a kind that simultaneously achieves a state-of-the-art Verdet constant of 5.6 × 10 5 °/T·m and a state-of-the-art FOM of 31°/T in the near-infrared region.

• Tb 2 Ti 2 O 7 transparent ceramics were fabricated from co-precipitated nano-powders by two-step sintering. • The in-line transmittance of Tb 2 Ti 2 O 7 ceramics reaches 65.5 % at 1064 nm. • The Verdet constant of Tb 2 Ti 2 O 7 ceramics (−229.0 ± 0.6 rad·T−1 m−1@633 nm) is 71 % higher than TGG crystals. • Tb 2 Ti 2 O 7 ceramics are very promising magneto-optical materials for Faraday isolators. Transparent Tb 2 Ti 2 O 7 magneto-optical ceramics were fabricated from co-precipitated nano-powders by vacuum pre-sintering with hot isostatic pressing (HIP) post-treatment. The formation of pyrochlore phase, decomposition of the precursor, and the morphology of powders calcined at different temperatures were investigated. The in-line transmittance of Tb 2 Ti 2 O 7 ceramics, which were pre-sintered at 1350 ℃ for 2 h with HIP post-treatment at 1450 ℃ for 3 h and subsequently annealed at 800 ℃ for 20 h in NH 3 atmosphere, reaches 65.5 % at 1064 nm. The Verdet constant of Tb 2 Ti 2 O 7 ceramics is −229.0 ± 0.6 rad·T−1 m−1 at the wavelength of 633 nm, which is 71 % higher than that of the commercial Tb 3 Ga 5 O 12 crystals. Tb 2 Ti 2 O 7 magneto-optical ceramics show a promising application for Faraday rotators. [ABSTRACT FROM AUTHOR]

Large magnetic optical rotary dispersion (Faraday rotation) has been demonstrated recently in methylammonium lead bromide. Here, we investigate the prospect of extending the active spectral range by altering the halogen. We also investigate the origins of large Faraday rotation in these diamagnetic materials using magnetic circular dichroism (MCD) spectroscopy and the Kramers–Kronig relations. We find that, while MAPbCl3 (MA = methylammonium) single crystals exhibit a large Verdet constant in the blue, no appreciable Faraday rotation is observed in the red/near infra‐red for MAPbI3 single crystals. However, in all film samples, we find clear evidence of large MCD resulting from the Zeeman splitting of the highly resonant 1s exciton state. Our Kramers–Kronig calculations of Faraday rotation based on MCD data matches well with the dispersion of our experimental data for MAPbCl3 and MAPbBr3, with some deviation in magnitude—demonstrating the excitonic nature of Faraday rotation in these materials. However, our calculations predict significant Faraday rotation in MAPbI3, contrary to our experimental results, indicating a potential discrepancy between the properties of the thin film and single crystal. [ABSTRACT FROM AUTHOR]

In this study, GeO 2 -Bi 2 O 3 –B 2 O 3 –SiO 2 (GBBS) glass was prepared and studied. Used XRD and FT-IR tests were to characterize glass structures, and it was found that GBBS magneto-optical glass has an amorphous structure with [GeO 6 ], [BO 3 ], [BO 4 ], and [BiO 6 ] as the main network-forming bodies. The physical parameters and theoretical optical alkalinity were calculated by formulas. It was found that when the content of Tb 2 O 3 grew, the values of physical parameters increased. At the same time, it can be seen that the chemical stability of GBBS magneto-optical glass has also been enhanced. It increases with the rise of Tb3+ ion doping concentration. It is worth noting that when studying the influence of different wavelengths and different temperatures regarding the magneto-optical characteristics of the GBBS glass, when the temperature is 273.15 K and the wavelength is 633 nm, it has been observed that GBBS glass has a Verdet constant of −173.28 rad/(T·m), and the Verdet constant value of GBBS glass is −162.60 rad/(T·m) at 633 nm and the temperature of 298.15 K, which is greater than Tb 3 Ga 5 O 12 (−134 rad/(T·m)). The fluorescence spectrum shows that the emission peak intensity is also strongest at 544 nm, and decreases with the increase of Tb3+ ion content. • The Verdet constant of GBBS glass is −162.60 rad/(T·m), which is greater than TGG. • The magneto-optical properties of the GBBS magneto-optical glass is enhanced by introducing Tb3+ ion. • The GBBS glass with a higher Verdet constant has a transmittance of approximately 75%. [ABSTRACT FROM AUTHOR]

Novel (Tb 1-x Lu x) 2 O 3 magneto-optical transparent ceramics were prepared through a solid-solution method via vacuum pre-sintering followed by hot isostatic pressing (HIP). The Lu-containing samples were solid-solution phases between Tb 2 O 3 and Lu 2 O 3 , which effectively stabilized the phase transition of Tb 2 O 3 during the sintering process. A typical component of (Tb 1-x Lu x) 2 O 3 ceramic with x = 0.5 was selected to study the densification behavior and microstructure evolution in detail. The polished (Tb 0.5 Lu 0.5) 2 O 3 ceramics with a thickness of 3 mm vacuum pre-sintered at 1700 °C under 1.0 × 10−3 Pa combined with HIP post-treatment at 1600 °C showed good magneto-optical property. The Verdet constant measured at 633 nm was -224.33 rad·T−1 m−1, 30% higher than that of Tb 3 Al 5 O 12 (TAG). However, the in-line transmittance was 73.6% at 633 nm, lower than that of TAG. The (Tb 1-x Lu x) 2 O 3 ceramics will be a promising material for Faraday devices after further improving the optical quality. [ABSTRACT FROM AUTHOR]

Ho 2 O 3 transparent ceramics were fabricated by vacuum pre-sintering combined with hot isostatic pressing (HIP) post-treatment at relatively low temperature from high-purity Ho 2 O 3 powder calcined at 1000 °C for 4 h. The optimal Ho 2 O 3 ceramic sample prepared by vacuum pre-sintering at 1250 °C and HIP post-treating at 1450 °C has a dense microstructure with average grain size of 0.77 μm, and the in-line transmittances reach 80.7 % at 1550 nm and 76.7 % at 1064 nm. The effect of air annealing on the optical quality of Ho 2 O 3 ceramics was studied, and the existence of compressed pores in the HIP-ed Ho 2 O 3 ceramics was confirmed. The Verdet constants of Ho 2 O 3 ceramics were measured to be -47.4 rad/(T m at 1064 nm and -15.4 rad/(T m at 1561 nm. High transmittance and large Verdet constant in the wavelength regions 1–1.07 μm, 1.3–1.5 μm make Ho 2 O 3 transparent ceramics promising for magneto-optical devices for lasers based on Yb-, Nd-doped materials and telecom lasers. [ABSTRACT FROM AUTHOR]

As a kind of promising material for a Faraday isolator used in the visible and near infrared range, Dy2O3 transparent ceramics were prepared by vacuum sintering from the nano-powders synthesized by the liquid precipitation method using ammonium hydrogen carbonate as precipitant with no sintering aids. The synthesized precursor was calcinated at 950 °C-1150 °C for 4 h in air. The influences of the calcination temperature on the morphologies and phase composition of Dy2O3 powders were characterized. It is found that the Dy2O3powder calcinated at 1000 °C for 4 h is superior for the fabrication of Dy2O3 ceramics. The Dy2O3 transparent ceramic sample prepared by vacuum sintering at 1850 °C for 10 h, and subsequently with air annealing at 1400 °C for 10 h, from the 1000 °C-calcined Dy2O3 powders, presents the best optical quality. The values of in-line transmittance of the optimal ceramic specimen with the thickness of 1.0 mm are 75.3% at 2000 nm and 67.9% at 633 nm. The Verdet constant of Dy2O3ceramics was measured to be -325.3 ± 1.9 rad/(T•m) at 633 nm, about 2.4 times larger than that of TGG (Tb3Ga5O12) single crystals. [ABSTRACT FROM AUTHOR]

Transparent ceramics based on ytterbium oxide have been successfully produced by vacuum sintering of self-propagating high-temperature synthesized powders with use of a La2O3 sintering aid. Phase composition and microstructure of the initial powders were studied by X-ray diffraction analysis and scanning electron microscopy. It was found that addition of 5 mol.% of La2O3 does not cause formation of secondary phases in the Yb2O3 powders. The 4% La:Yb2O3 ceramics showed the best in-line transmittance of 73% at a wavelength of 2 µm among the studied samples. Dependence of the Verdet constant on wavelength was investigated in the range of 0.4-2 µm. The most promising finding is use of the obtained material as Faraday isolators in the wavelength region of ~1.5 µm, where there are no absorption bands, and the Verdet constant is 8.6 rad/(T*m). [ABSTRACT FROM AUTHOR]

We have studied experimentally the Faraday effect in monoclinic TlIn(S1-xSex)2 solid solutions with selenium concentrations x changing in the range 0 = x = 0.25. The Verdet constant VF and the effective Faraday coefficient F33 are determined at the light wavelength λ = 632.8 nm under normal conditions. We show that the both coefficients tend to increase when the Se concentration increases from 0 to 0.25. This behaviour is explained by dispersion of the Faraday coefficients and a shift of the absorption edge towards long-wavelength spectral range, which occurs with increasing amount of selenium. [ABSTRACT FROM AUTHOR]

The transparent MgO sample was obtained by the arc plasma melting procedure using micro-sized powder. The structure of the sample was examined using X-ray diffraction. The transmittance of MgO was close to 75% in the wavelenght range from 430 to 1100 nm. The value of the optical angle of polarization rotation in transparent MgO has been measured at energy from 1.5 eV to 3.1 eV. The band gap energy determined from Tauc relation was estimated as 3.94 eV. The magnesium oxide transparent ceramics have a potential to be applied in high temperature furnaces. [ABSTRACT FROM AUTHOR]

• AgNPs were synthesized and characterized by TEM and UV–Vis spectroscopy and refraction method. • Faraday rotation (FR) enhancement of individual AuNPs and AgNPs were measured. • Collective modes of the surface plasmon resonance (SPR) were observed for AgNPs coated by polymer. • Coupling of both SPRs in the mixture of AuNPs and AgNPs was very weak. • The Kramers-Kronig transformation could be successfully applied to SPR band. So far, magnetooptical (MO) properties of silver nanoparticles (AgNPs) have been studied only by magnetic circular dichroism (MCD) spectroscopy at the surface plasmon resonance (SPR) band. However, direct knowledge of the Faraday rotation effect (FR) is very important in fundamental research and applications. In the present work, we study an enhancement of FR of individual gold nanoparticles (AuNPs) and AgNPs and their mixture of colloidal aqueous suspension. The Au and Ag spherical NPs were synthesized independently as colloids in an aqueous suspension and then such mixtures were studied (AgNPs were also studied as a suspension in hexane). The noble metal NPs were characterized by TEM, UV–Vis, and refraction methods. The enhancement of FR of individual NPs was observed and it is consistent with available MCD results. For the mixtures, observed changes of magnitude of FR is small, and coupling of both SPR is rather weak. The obtained FR spectra associated with SPR band have been successfully converted to MCD spectra using the Kramers-Kronig transformation. Calculated MCD spectra are consisted with that obtained by direct measurements. [ABSTRACT FROM AUTHOR]

High heavy metal oxides (60–100 mol.%) ternary PbO–Bi2O3–B2O3 (PBB) glasses were fabricated and characterized. Using a homemade single lightway DC magnetic setup, Verdet constants of PBB glasses were measured to be 0.0923–0.1664 min/G cm at 633 nm wavelengths. Glasses with substitution of PbO by Bi2O3 were studied in terms of their Faraday effects. PbO–Bi2O3–B2O3 = 50–40–10 mol.% exhibited good thermal stability, high Verdet constant (0.1503 min/G cm) and good figure of merit (0.071). Based on this glass, a magneto optical current sensor prototype was constructed and its sensitivity at different currents was evaluated to be 8.31 nW/A.

(Tb 1-x Tm x) 3 Al 5 O 12 transparent ceramics were successfully fabricated using solid state reaction and vacuum sintering. Influences of Tm3+ ion doping on the phase compositions, microstructure and magneto-optical characteristics of the prepared ceramics were investigated systematically. The results show that the increase in Tm3+ ion concentrations has no distinct effect on the crystal structure and average grain size of TAG ceramics. The undoped TAG transparent ceramic exhibits the best optical transmission and the optical transmittance decreases with the increase of Tm3+ doping concentrations due to the increased scattering centers. It is found that the Verdet constant of the samples increases with increasing the Tm3+ doping concentrations, which is benefit for improving the magnetic performance. The Verdet constant of 0.16 at% Tm3+-doped TAG ceramic is 189.5 rad T−1 m−1 at 633 nm wavelength, which is 41% higher than that of commercial TGG crystal. • Tm:TAG transparent ceramics were fabricated using solid state reaction and vacuum sintering. • Influences of Tm3+ doping on microstructure and magneto-optical properties were investigated. • The Verdet constant of TAG ceramics is significantly enhanced by doping Tm3+ ions. • The Verdet constant of 0.16 at% Tm:TAG at 633 nm is 41% higher than that TGG crystal. [ABSTRACT FROM AUTHOR]

TAG transparent ceramics with different Tb 4 O 7 additive contents were successfully fabricated using solid state reaction and vacuum sintering. The samples (T1-T5) added with 0-0.3 wt% Tb 4 O 7 exhibit high transparency in the visible and near infrared regions. It was found that adding 0.1–0.2 wt% Tb 4 O 7 was in favor of eliminating pores and optimizing magneto-optical properties and the ceramic added with 0.1 wt% Tb 4 O 7 (T2) possesses the highest transmittance, which reached 80.32% at 1064 nm. The TAP phase was detected by XRD and appeared in the microstructure of sample T7 with added 0.8 wt% Tb 4 O 7 content, which inhibited grain boundary migration and deteriorated the optical quality of TAG transparent ceramics. The Verdet constant increases slightly with a small increase in the amount of Tb 4 O 7 addition and the value of sample T5 added with 0.3 wt% Tb 4 O 7 is 177.5rad/(T·m), which is 32% higher than that of the commercially TGG crystal. • TAG transparent ceramics with different Tb 4 O 7 additive contents were successfully fabricated using solid state reaction and vacuum sintering. • We studied the effect of Tb 4 O 7 excess on the microstructure and magneto-optical properties of TAG transparent ceramic. • Adding 0.1–0.2 wt% Tb 4 O 7 was in favor of eliminating pores and optimizing magneto-optical properties. • The Verdet constant increases slightly with a small increase in the amount of Tb 4 O 7 addition and the value is 32% higher than that of the commercially TGG crystal. [ABSTRACT FROM AUTHOR]

We review the progress in the investigation of the Verdet constant of new magneto-active materials for the Faraday-effect-based devices used in high-power laser systems. A practical methodology for advanced characterization of the Verdet constant of these materials is presented, providing a useful tool for benchmarking the new materials. The experimental setup used for the characterization is a flexible and robust tool for evaluating the Faraday rotation angle induced in the magneto-active material, from which the Verdet constant is calculated based on the knowledge of the magnetic field and the material sample parameters. A general model for describing the measured Verdet constant data as a function of wavelength and temperature is given. In the final part of this review, we present a brief overview of several magneto-active materials, which have been to-date reported as promising candidates for utilization in the Faraday devices. This overview covers room-temperature investigations of the Verdet constant of several materials, which could be used for the ultraviolet, visible, near-infrared and mid-infrared wavelengths. [ABSTRACT FROM AUTHOR]

The long‐term temperature induced errors caused by fiber λ/4 wave plate and the Verdet constant of sensing fiber in the all fiber current transformer (FOCT) are theoretically analyzed. A temperature related response of fiber λ/4 wave plate is adopted to compensate for the change caused by temperature related Verdet constant through choosing appropriate initial phase retardation of the λ/4 wave plate. The experimental results show high temperature‐cycle accuracy in this kind of FOCT with relative error within 0.6%. [ABSTRACT FROM AUTHOR]

Abstract Transparent ceramics in the form of yttrium oxide (Y 2 O 3) doped with La and Nd and pure yttrium as a reference material were successfully prepared via modified EDTA gel process and hot isostatic pressure sintering. Their structure and microstructure were examined by means of scanning electron microscopy and X-ray diffraction, which revealed the high density and single-phase character of these materials. Their optical and magneto-optical properties were also analyzed. Emission spectra of Nd 0.1 La 0.1 Y 1.8 O 3 after excitation performed with a continuous 808 nm laser beam showed strong and sharp emission lines. The luminescence lifetime was also investigated. The doped material exhibited a high Verdet constant of over 1000 deg/T m. The figure of merit was calculated in the VIS spectrum. The investigated transparent oxide ceramics can be considered a promising material for application in lasers and magneto-optical devices. [ABSTRACT FROM AUTHOR]

Abstract In this paper, diamagnetic lead borate magneto-optical glasses with an improved Verdet constant, high glass-forming ability and good thermal stability were synthesized to meet the design requirements of fiber-optical current transducers (FOCTs). The structure and performance indexes of the glasses were characterized by Raman spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD). The Verdet constant of the glass samples can reach 0.1757 min/(G cm) at 633 nm, indicating excellent magnetic rotation properties. In practical applications, FOCTs are often used in complex industrial environments that require high temperature stability. To test the temperature dependence of the diamagnetic lead borate glasses, we constructed a dual-light-path variable-temperature magneto-optical modulation system. The experimental data show that the Verdet constant decreases slowly with increasing ambient temperature; thus, we theoretically analyzed the magneto-optical properties of the diamagnetic glass and the cause of its temperature dependence according to the discrepancy between the experimental results and the Becquerel formulas. We also obtained an empirical formula by fitting the Verdet–temperature curve, thereby providing an evaluation basis and a screening method for further development of FOCT materials. Highlights • Diamagnetic magneto-optical glasses suitable for the application of fiber-optical current transducer were prepared. • The structures of glasses were characterized by Raman and FT-IR spectroscopy and X-ray diffraction. • Using a dual-light-path modulation system to obtain the properties and temperature dependence data of diamagnetic glasses. • The temperature stability is influenced by the glass composition, and the diamagnetic property may be counteracted. [ABSTRACT FROM AUTHOR]