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Currently, Faraday isolators and rotators for high‐power lasers are popular research topics; therefore, finding magneto‐optical materials with excellent Verdet constants and thermal properties is crucial. In this study, novel holmium scandium aluminum garnet (HoSAG) magneto‐optical ceramics were fabricated using vacuum sintering. This study improved the traditional ball milling method and pre‐synthesized powders with great sinterability after secondary ball milling and sieving. Different pre‐synthesis temperatures were found to have significant effects on the particle size and micromorphology of the synthesized powders. HoSAG ceramics with 0.05 wt% MgO sintering aid and held at 1700°C for 30 h reached a transmittance of 76.7% at 1550 nm. Meanwhile, HoSAG transparent ceramics maintain higher transmittance in the infrared region (>1500 nm) than terbium gallium garnet (TGG) crystals, indicating better application prospects. The Verdet constants of HoSAG magneto‐optical ceramics at 405, 532, 808, and 1064 nm were −421.5, −181.2, −65, and −32.3 rad T−1 m−1, respectively, which are slightly less than those of TGG magneto‐optical ceramics. Moreover, the thermal conductivity of HoSAG ceramics at 300.00 K was 4.89 W m−1 K−1, which is comparable to that of the TGG ceramics. [ABSTRACT FROM AUTHOR]

The current development direction of magneto-optical (MO) isolators involving miniaturisation and application in high-power lasers encounters difficulties in material application because preparing materials with excellent optical quality and a high Verdet constant remains a challenge. Herein, (Tb1−xCex)3Sc2Al3O12 (x = 0.001, 0.0025, 0.005, 0.01, 0.015, 0.02) MO ceramics with different doping concentrations were prepared by vacuum sintering. The phase structure, element distribution, microstructure, relative density, optical properties, surface properties and MO properties of the (Tb1−xCex)3Sc2Al3O12 ceramics were also characterised. Experimental characterisation reveals that the (Tb1−xCex)3Sc2Al3O12 ceramics have a pure Tb3Sc2Al3O12 (TSAG) phase and exhibit an excellent uniform element distribution. In addition, no secondary phase was detected in FESEM images with the increase in Ce concentration. However, a few small-sized residual pores, which remain entrapped in the Ce0.015TSAG and Ce0.02TSAG ceramics, can be observed. Moreover, all the obtained ceramics have good optical quality, and the in-line transmittances of the (Tb1−xCex)3Sc2Al3O12 ceramics at 1064 nm are 81.7%, 83.7%, 80.0%, 84.0%, 68.8% and 77.7%. The Verdet constant of the ceramics is optimised by Ce doping, and the Verdet constants of all the ceramics at the test wavelength are better than those of TSAG ceramic. The Verdet constant of the Ce0.01TSAG ceramic is still superior to that of the TSAG ceramic in the same temperature range. Finally, the extinction ratio values for the CexTSAG (x = 0.001, 0.0025, 0.005, 0.01) ceramics exceeded 40 dB. The Ce0.01TSAG ceramic shows the best optical transmittance, the highest magneto-optical FoM values and the highest Verdet constants. Thus, this ceramic can be used for a high-power laser in the visible and near-infrared regions in the future. [ABSTRACT FROM AUTHOR]

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]

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, R 0.0025 TSAG (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 R 0.0025 TSAG ceramics at 1064 nm is approximately 81.6%, 81.6%, 79.8%, and 80.6%, respectively. The Verdet constants of R 0.0025 TSAG ceramics at the measurement wavelength are greater than those of the TSAG ceramic. The compelling magneto-optical performance of the Dy 0.0025 TSAG ceramic includes a high Verdet constant of 161.8 ± 3 rad·m−1·T−1 at 635 nm. The Verdet constant of the Dy 0.0025 TSAG ceramic is still superior to that of TSAG ceramic in the same temperature range. The extinction ratios of the R 0.0025 TSAG (R= Pr, Ho, Dy) ceramics exceed 40 dB. The figure of merit points out the superior characteristics of R 0.0025 TSAG ceramics. Moreover, R 0.0025 TSAG (R= Pr, Ho, Dy) ceramics with a thickness above the centimeter level are successfully prepared. This work indicates that the Dy 0.0025 TSAG ceramic can promote the miniaturization of magneto-optical isolators and can be applied in high-power lasers. • (Tb 0.9975 R 0.0025) 3 Sc 2 Al 3 O 12 (R= Pr, Ho, Dy, Eu) transparent ceramics were synthesized and characterized. • The Verdet constants of R-TSAG ceramics at the measurement wavelength are greater than that of TSAG ceramic. • The values of extinction ratio for R-TSAG (R= Pr, Ho, Dy) ceramics exceed 40 dB. [ABSTRACT FROM AUTHOR]