Magneto-optical Performance Research Articles

The effect of trace Fe3+ on the magneto-optical properties of Tb3+ doped B2O3-GeO2-Al2O3-ZnO-BaO glass

Magnetic particles of BaFe12O19 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 Tb2O3 (30 mol%) using a high-temperature melting method. The glasses are composed of B2O3-GeO2-Al2O3-ZnO-BaO-Tb2O3 (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.

Effect of Na2O on Verdet constant of Tb-doped magneto-optical glass

The terbium (Tb) ions doped magneto-optical glasses have attracted significant attention due to their high Verdet constant and excellent optical properties. In the Tb ions doped glass, +3 and + 4 valence states of Tb ions coexisted. However, only the +3 valence is favorable for magneto-optical performance. This study proposed a strategy to increase the concentration of Tb3+ ions (CTb3+) in the glass. The high optical basicity Na2O is beneficial for enhancing the Verdet constant. The lower melting temperature suppresses the oxidation of the Tb3+ to Tb4+, leading to the increase of CTb3+. As a result, the Verdet constant at 650 nm was achieved as high as 78.6 rad/(T·m), representing a 42.8 % improvement compared to glasses melted at 1450 °C. This approach avoids glass crystallization at high concentrations of Tb doping and provides a new solution for preparing high-performance magneto-optical glasses.

Recent advances of rare earth iron garnet magneto-optical single crystals

R3Fe5O12 (RIG) crystals are the most desirable elements for magneto-optical isolators in the near-infrared (NIR) to mid-infrared (MIR) region, with ever-growing demands for optical fiber communication and high-power laser system. Now, this system is the only commercialized Faraday rotator for optical isolators in 5G wireless communications. However, the growth of high-quality bulk RIG single crystals has been a big challenge for a long time, due to the typical incongruent melting characteristic and complex phase relationships. This work comprehensively summarizes the recent advances for the growth of RIG single crystals, including the proper choice of flux and innovative strategies on several growth techniques, like the flux-Bridgman, edge-defined film-fed growth (EFG) and top seeded solution growth (TSSG), etc. Effective modulation on the optical and magneto-optical performance is highlighted. Some ongoing perspectives are also proposed and discussed. It is anticipated that this work will provide deeper insight into the exploration of high-performance magneto-optical crystals for potential applications in NIR-MIR wavelength.

Enhancement in the magneto-optical effect induced by combining multiple modes in a gold film–supported hybrid periodic gold/magnetic nanorod array

In this study, the possibility of enhanced transverse magneto-optical Kerr effect (TMOKE) and performance monitoring of a hybrid nanostructure developed by sandwiching a ferromagnetic film within a gold layer and square periodic nanorod arrays, is theoretically investigated. Based on the findings, the TMOKE signal can be enhanced approximately 33 times when compared to the referenced planar film, which is elucidated by the hybrid of modes in the magnetic film region. In addition, a high level of environmental sensor performance is simultaneously achieved by recording the wavelength resonance positions with the variation of refractive index, which is compatible with gaseous medium from 1 to 1.01, indicating that the structure of the proposal will have applications in environmental monitoring.

Lattice engineering through Al-substitution leads to enhanced magneto-optical properties of Tb3(AlxGa1−x)5O12 single crystals

High-quality TAGG75 single crystals are obtained by the Czochralski method for the first time. They exhibit excellent magneto-optical performance beyond TGG.

Magneto-optical trap performance for high-bandwidth applications

Magneto-optical trap performance for high-bandwidth applications

Spectroscopic and magneto-optical properties of novel bifunctional Nd,Er:CeF3 crystal

In this study, we report a successful Bridgman growth of Nd3+ and Er3+ co-doped CeF3 (Nd,Er:CeF3) single crystal with a size of Ø25 mm × 30 mm. The absorption and fluorescence characteristics of the Nd,Er:CeF3 crystal were studied systematically. The results show that the fluorescence emission peaks were positioned at 547, 669, 1062.6, and 1542.6 nm, respectively. The fluorescence lifetimes centered at 1062.6 and 1542.6 nm for Nd3+ and Er3+ were 0.313 and 1.12 ms, respectively. Meanwhile, the spectroscopic properties of Nd,Er:CeF3 crystals were investigated based on the Judd–Ofelt theory. Notably, the magneto-optical performance of the Nd,Er:CeF3 crystal was investigated for the first time. The Verdet constants of the Nd,Er:CeF3 crystal at 532, 632.8, 1064, and 1310 nm are 220.3, 142.4, 40.7, and 23.1 rad T−1 m−1, respectively, which are significantly higher than those of undoped CeF3 and traditional Tb3Ga5O12. The results show that Nd,Er:CeF3 is a bifunctional crystal with potential applications in laser and magneto-optical fields.

Novel Nd3+ and Ho3+ co-doped multifunctional CeF3 crystal for laser and magneto-optical applications

In this study, a 1.5 at.% Nd3+ and 0.5 at.% Ho3+ co-doped CeF3 (Nd,Ho:CeF3) single crystal was successfully grown by the vertical Bridgman method. The absorption and fluorescence characteristics of the fabricated crystal were evaluated. The spectroscopic properties of the Nd,Ho:CeF3 crystal were investigated based on the Judd–Ofelt (J–O) theory. The parameters Ω2, Ω4, and Ω6 of Ho3+ were fitted as 0.338 × 10−20, 0.731 × 10−20, and 0.350 × 10−20 cm2, respectively. The fluorescence lifetimes centered at 1064 and 1970 nm for Nd3+ and Ho3+ were 261 and 47 μs, respectively. Notably, the magneto-optical performance of the Nd,Ho:CeF3 crystal was investigated for the first time. The measured Verdet constants of Nd,Ho:CeF3 at 532, 632.8, 1064, 1310, and 1550 nm were 228.0, 154.7, 42.4, 29.1, and 18.5 rad·T−1·m−1, respectively, which were significantly larger than those of pure CeF3 and traditional Tb3Ga5O12. The results demonstrated that Nd,Ho:CeF3 crystals can be applied in both lasers and magneto-optical devices.

Fabrication and performance optimization of novel (Tb0.9975R0.0025)3Sc2Al3O12 (R= Pr, Ho, Dy, Eu) magneto-optical transparent ceramics

Magneto-optical materials with high Verdet constants at high extinction ratios are desirable for the Faraday isolators. However, current terbium-based crystals have encountered several issues, such as low Verdet constants (TGG crystals), difficult growth (TSAG crystals), and low utilization of raw materials, which limit the development of the Faraday isolators. Here, R0.0025TSAG (R= Pr, Ho, Dy, Eu) transparent ceramics are prepared. The ceramics exhibit high optical transparency above 74.0% in the 525–1565 nm range and a high relative density of 98.9%. In particular, the transmittance of R0.0025TSAG ceramics at 1064 nm is approximately 81.6%, 81.6%, 79.8%, and 80.6%, respectively. The Verdet constants of R0.0025TSAG ceramics at the measurement wavelength are greater than those of the TSAG ceramic. The compelling magneto-optical performance of the Dy0.0025TSAG ceramic includes a high Verdet constant of 161.8 ± 3 rad·m−1·T−1 at 635 nm. The Verdet constant of the Dy0.0025TSAG ceramic is still superior to that of TSAG ceramic in the same temperature range. The extinction ratios of the R0.0025TSAG (R= Pr, Ho, Dy) ceramics exceed 40 dB. The figure of merit points out the superior characteristics of R0.0025TSAG ceramics. Moreover, R0.0025TSAG (R= Pr, Ho, Dy) ceramics with a thickness above the centimeter level are successfully prepared. This work indicates that the Dy0.0025TSAG ceramic can promote the miniaturization of magneto-optical isolators and can be applied in high-power lasers.

Epitaxy growth of pure phase CeFeO3 thin films with high magneto-optical performance and strong vertical magnetic anisotropy

The magneto-optical effects of rare earth ferrite can be greatly improved by doping Ce3+ ions. CeFeO3 with high Ce3+ concentration has excellent magneto-optical properties in theory. And due to its perovskite structure it is more suitable to be deposited on the substrates of optical devices compared with the commercial garnet ferrite. In this paper, the pure phase CexFe2–xO3 films were successfully obtained on the quartz glass and <100>-oriented SrTiO3 crystal substrates by radio frequency magnetron sputtering. The effects of substrate and Ce:Fe ratio on the epitaxial orientation, magnetism and magneto-optical performance of films were systematically studied. For the Ce1.0Fe1.0O3/STO film, its MCD ellipticity (ψF) intensity can reach up to 4750(°)/cm in the visible band and 14090(°)/cm in near ultraviolet band. And it also shows a strong vertical magnetic anisotropy, which makes it maintain a good thermal stability when the device size is reduced. These mean that the Ce1.0Fe1.0O3/STO film has a promising application in integrated optical communication devices.

Al2O3 triggered in-situ crystallization of Gd3Al2Ga3O12 in glass and enhancement in magnetic and Faraday rotating properties

Nanocrystals doped transparent glasses or glass ceramics have shown promising tunable magnetic and magneto-optical performance. In this study, the Al2O3-induced in-situ crystallization of Gd3Al2Ga3O12 in tellurite glass was reported. 10–20 nm-cubic Gd3Al2Ga3O12 (Ia3d space group) nanocrystals formed in tellurite glass with Al2O3 content ≤ 0.75 mol% by 400 °C-heat treatment. When Al2O3 content in glass was higher than 0.75 mol%, excessive Al2O3 triggered the crystallization of orthorhombic GdAlO3 (Pnma) in which the Gd and Al ions existed as octahedral GdO8 and AlO6 units at a temperature higher than 398 °C. The in-situ crystallization influenced the glass network structure, broke the linkage of tetrahedral TeO4, and BO4, and formed trigonal pyramids TeO3 and BO3 instead. At the same time, nuclear magnetic resonance spectra revealed the conversion of AlO4→ AlO6, GaO4→ GaO6, and the changes from bridging oxygen to non-bridging oxygen as well. From energy-dispersive X-Ray analysis, Gd3+ clusters were observed, leading to the ferromagnetism of glass. Electron paramagnetic resonance spectra witnessed an enhancement of the Zeeman effect which is the reason for the improvement of Faraday rotation. Tellurite glass with 0.75 mol% Al2O3 after 400 °C-annealing (A75) showed a giant Verdet constant of 93 rad/T.m at 633 nm which is superior to most of the values from the literature.

ABCs of Faraday Rotation in Organic Materials.

Faraday rotation is a magneto-optical effect central to a number of commercial technologies including optical isolation and magneto-optical imaging. Today, the performance needs of these technologies are met by inorganic materials containing paramagnetic heavy elements. However, organic thin films are increasingly being evaluated as replacement materials, promising higher magneto-optical performance and facile fabrication of structures that enable expanded applications. Despite being an object of research for more than 175 years, our understanding of the Faraday effect in solid-state organic materials remains incomplete, hindering our attempts to methodically improve magneto-optical performance. This Perspective aims to place several recent advances in the field of thin-film organic Faraday rotators within the well-established theoretical framework developed by solution-state magnetic circular dichroism spectroscopists: the Faraday A, B, and C terms. Through careful consideration of these quantum mechanical mechanisms in example molecules, an intuitive understanding of the impact of chemical structure in thin-film Faraday rotators can be achieved, including the critical roles of molecular symmetry, rigidity, absorptivity, and magnetism. Future work seeking to maximize the magneto-optical performance of organic thin films may more readily evaluate candidate chromophores based on the Faraday A, B, and C term framework presented herein.

Rapid and sensitive magnetic field sensor based on photonic crystal fiber with magnetic fluid infiltrated nanoholes

A fast response time (0.1 s) magnetic field sensor has been demonstrated utilizing a photonic crystal fiber with nano-size air holes infiltrated with polyethylene glycol based magnetic fluid. The effect of magnetic nanoparticles concentration in the fluid on the magneto-optical sensor performance and its dependence under varying magnetic-field loads was investigated in detail. In particular, the sensor response was analytically modelled with a Langevin function with a good fit (Rge 0.996). A threshold sensing point as low as 20 gauss was recorded and a detection range of 0–350 gauss was demonstrated by means of optical transmission measurements. The experimental results were validated by theory using a waveguide light transmission model fed by finite-element method simulations of the principal guided modes in the infiltrated fiber sensor. The simple interrogation scheme, high sensitivity and quick response time makes the proposed hybrid fiber-optic magneto-fluidic probe a promising platform for novel biochemical sensing applications.

Enhancement of magneto-optical performance of Tb2.85Er0.15Ga5O12 crystal with high transmittance

Magneto-optical materials based on Tb3Ga5O12 (TGG) crystals are providing promising opportunities for modern Faraday isolators (FIs). Tb2.85Er0.15Ga5O12 crystals with high transmittance were prepared using the Czochralski method (Cz). It is noted that as-prepared crystal presents an extremely low absorption coefficient of 1270 ppm/cm at 1064.0 nm and the Verdet constants of as-grown crystal at 405.0, 533.0, 632.0, 1064.0 nm were 588.0, 230.2, 152.3, and 51.7 rad m−1 T−1, respectively. The measured Verdet constant at 1064 nm was about 1.3 times higher than that of pure TGG crystal. Thus, it has the possibility to minimize the length and the magnet of faraday rotator in making FIs. The Excellent characteristic makes Tb2.85Er0.15Ga5O12 single crystal an attractive magneto-optical material.

(INVITED)Magneto-optical performance of (LuTb)3Al5O12 single crystal by SSCG method

High quality LuTAG [(Lu0.1Tb0.9)3Al5O12] single crystal was successfully synthesized by SSCG (Solid State Crystal Growth) method using <100>YAG (Y3Al5O12) seed crystals for the first time. The growth rate of the LuTAG single crystal is > 2 mm/h, and residual pores and birefringence cannot be detected inside the material. At a wavelength of 633 nm, a sample with a thickness of 7 mm has an inline transmittance of 81.5%, an optical loss of 0.06%/cm, and an extinction ratio of >35 dB, hence the optical quality is particularly excellent. The Verdet constant of this material at 1064 nm was 51 rad T−1m−1, which was 1.4 times that of the commercially available TGG (Tb3Ga5O12) single crystal.

Spectroscopic and magneto-optical characteristics of erbium doped cerium trifluoride crystal grown by the Bridgman method

In this study, a 2 at% erbium doped cerium trifluoride (Er:CeF3) single crystal was grown using the Bridgman method. The consequent absorption, infrared transmittance, and fluorescence spectra were recorded. The spectroscopic properties of Er:CeF3 crystals were intensively studied based on the Judd–Ofelt (J–O) theory. The Ω2, Ω4, and Ω6 parameters were fitted to be 5.206 × 10−20, 1.805 × 10−20, and 3.06 × 10−20 cm2, respectively. The emission cross-section centered at 1564.6 nm was calculated to be 1.053 × 10−20 cm2, and the corresponding fluorescence lifetime was measured to be 1.675 ms. Additionally, the magneto-optical (MO) performance of the Er:CeF3 crystal was investigated for the first time. The Verdet constants of Er:CeF3 at 532, 632.8, 1064, and 1310 nm are 231.0, 165.4, 43.4, and 24.4 rad·T−1·m−1, respectively, which are significantly higher than those of pure CeF3 and traditional Tb3Ga5O12. The results show that the Er:CeF3 crystal can be applied both to solid-state lasers and Faraday devices.

Study of magneto-optical properties of GeO2-B2O3-P2O5-ZnO-Tb2O3 glass doped with different rare-earth ions

Paramagnetic magneto-optical glasses doped with different rare-earth ions, 32GeO2–15B2O3–5P2O5–3ZnO-45Tb2O3-RE (RE = 0, 1Ho, 1Pr, 1Er, 1Nd, 1Dy, or 1Ce), referred to as GBPZ-T45-RE magneto-optical glasses, were prepared using a high-temperature melting technique. The effects of rare-earth ion doping on the structure, physical parameters, and magneto-optical properties of these GBPZ-T45-RE glasses and the effects of incident-light wavelength and temperature on the values of the Verdet constants were researched. The refractive indexes and theoretical optical basicities of the glasses were obtained by theoretical calculations. Notably, GBPZ-T45-RE glasses exhibited a large Verdet constant and superior magneto-optical performance; especially, Ho3+ and Pr3+ ions were the most effective in improving the magneto-optical properties. In addition, the Verdet constants were affected by temperature. The Verdet constants of GBPZ-T45-Ho and GBPZ-T45-Pr were determined to be −172.44 and −175.22 rad/(T·m), respectively, under 633 nm light at 298.15 K, values that are significantly greater than that the commercial terbium gallium garnet TGG crystal (−134 rad/(T·m)). The Verdet constants of GBPZ-T45-Ho and GBPZ-T45-Pr under 633 nm light increased to −254.93 and −255.92 rad/(T·m), respectively, at 273.15 K. The excellent magneto-optical properties of these glasses should enable their widespread application in optics, electricity, magnetism, information, communications, military operations, aviation, satellite measurement and control systems, and other fields.

Magneto-optical glass mixed with Tb3+ ions: High Verdet constant and luminescence properties

Compared with crystal and transparent ceramics, magneto-optical glass is an attractive choice for applications in communication and larger power laser systems. However, the presence of rare-earth ions in magneto-optical glass can cause devitrification of the glass and require a higher melting temperature. This study aims to address these issues. High-temperature melting quenching technology was used to prepare highly transparent Tb3+ ion-doped GeO2-PbO-B2O3–SiO2 (GPBS) magneto-optical glass. Through XRD, FT-IR, DSC, chemical corrosion resistance, density test, UV–vis, fluorescence test, and Faraday rotation test, the effects of different Tb3+ ion concentrations on the thermal performance, chemical stability, structure, luminescence performance and magneto-optical performance of heavy metal oxide magneto-optic glass were studied. Notably, these glass materials exhibit high density, refractive index, optical basicity value, good thermal properties (101 °C), strong water and alkali resistance, excellent Faraday effect. The Verdet constants at different wavelengths also had notably high values. It was found that such glass has a strong green light emission at 544 nm, which demonstrates that this type of magneto-optical glass has broader application prospects in the preparation of laser elements and optoelectronic functional devices.

Effects of different valence states of Mo and point vacancies on magneto-optical properties of ZnO

Experimental studies have been conducted to characterize the physical properties of Mo-doped ZnO. However, they have not considered the effects of different valence states and point vacancies on the magneto-optical performance of the system. The present study adopted the plane-wave ultrasoft pseudopotential + U method within the framework of spin density functional theory. The formation energy, electronic structure, and optical properties of ZnO systems with coexisting different valence states of Mo and point vacancies were calculated. Results showed that the formation energy of all doping systems was negative under Zn-rich and O-rich conditions, but the formation energy was relatively lower under O-rich conditions than under Zn-rich conditions. Compared with Mo6+ and Mo5+ when the concentration of O vacancies or Zn vacancies was the same, Mo6+-doped ZnO had the lowest formation energy, was the easiest to dope, and had the most stable system structure. Zn34Mo5+O36 and Zn34Mo6+O36 systems exhibited ferromagnetism, and their Curie temperature was above room temperature. The Zn34Mo6+O36 system had the largest magnetic moment, which is beneficial for designing and preparing new types of diluted magnetic semiconductors. The band gap widths of the Zn34Mo5+O36 (3.04 eV) and Zn34Mo6+O36 (2.92 eV) systems were both narrower than that of the pure ZnO system. By comparison, the band gap widths of the Zn35Mo5+O35 and Zn35Mo6+O35 systems were 4.07 and 3.94 eV, respectively. Although the band gap width widened, under light excitation conditions, the valence band electrons could absorb the photons of lower energy to transition to the impurity energy level, and then transition further from the impurity energy level to the conduction band. During the hierarchical transition, visible light and infrared light effects still occurred. The range of photon energy response of all doping systems expanded, and the absorption spectrum red-shifted in the light-absorption edge within the low-energy (0–3.2 eV) range. In particular, the Zn35Mo6+O35 system exhibited the strongest polarization ability, photoelectric field strength, and charge-binding ability in the low-energy region. Moreover, the dielectric and absorption peaks of the imaginary part of the dielectric function were relatively large, and the red-shift of the absorption spectrum was relatively substantial. Therefore, the Zn35Mo6+O35 system is useful in designing and preparing novel ZnO-based photocatalysts.

Thermal, nonlinear, magnetic and faraday rotation properties of sol-gel diamagnetic glass /NaYF4: Fe, Ho3+: Role of magnetic ions

Ho3+ owns the biggest magnetic moment, stark splitting of energy and low-symmetry D2 crystal field which make Ho3+ high polarizable and has been studied as dopant in several magnetic crystals. For the first time, Ho3+ doped sol-gel synthesized diamagnetic glass for nonlinear, magnetic and magneto optical study was reported. This paper reports the synthesis, structure, morphology and magnetization of hexagonal NaYF4:Fe, Ho nanorods and importantly, the influence of NaYF4:Fe, Ho to the thermal, nonlinear, magnetic and Faraday rotation of diamagnetic glasses through varies techniques such as X-ray diffraction, scanning electron microscopy, Raman spectra, Ultraviolet–visible spectra, different scanning calorimetry, thermal mechanical analysis, Z-scan, superconducting quantum interference device magnetometry and Verdet constant measurement. Experimental results discovered that the doping of Ho3+ and Fe3+ ions disturbed the self-assembly of NaYF4 while suppressed the length of nanorod. Due to its nanoscale, magnetization of NaYF4:Fe, Ho changed from diamagnetic to superparamagnetic. The doping of NaYF4:Fe, Ho increased the thermal stability and third nonlinearity. Glass with different amount of doping presented diamagnetism and paramagnetism due to the strongest magnetic moment, increased polarizability, electron transition of Ho3+ and d-d exchange of Fe3+ ions in glass matrix. Glass doped 2% of NaYF4:Fe, Ho glass showed the best magnetic, magneto optical performance and improved thermal stability and nonlinearity which can be ideal candidate for photonics, nonlinear and magneto optical applications.