In recent years, transparent terbium aluminum garnet (TAG) ceramics have attracted much attention for use in high-power Faraday isolators. Fine-grained ceramics usually possess better mechanical properties and accordingly better service performance. In this work, transparent TAG ceramics with fine grains were prepared using a two-step sintering procedure based on the low-temperature sintering process to suppress grain growth. The composition of TAG precursor and powders calcined at different temperatures was studied in detail. The microstructure and relative density of air pre-sintered TAG ceramics were studied to meet the requirements of hot isostatic pressing (HIP) post-treatment. Driven by the low pre-sintering temperature in air, the average grain sizes of the obtained TAG ceramics after HIP treatment are about 2.9–5.3 μm. The TAG ceramics (1.2 mm thick) pre-sintered at 1450 °C with HIP post-treatment at 1550 °C for 3 h under a 176 MPa Ar atmosphere possess the highest in-line transmittance of 80.3% at 1064 nm. The Verdet constant of the TAG ceramics at 632.8 nm is −180.5 rad·T−1·m−1 at room temperature, which is about 1.3 times larger than that of the commercial Tb3Ga5O12 single crystals.

In order to meet the increasing demand for high‐power laser diode lighting and displays, phosphor converters with high‐brightness and high‐directionality ought to be constructed to enhance the luminance and luminous efficacy. However, the pores formed during the sintering of phosphor ceramics affect the scattering effect and directionality of light. Therefore, porosity optimization and pore size regulation need to be explored. In this work, a series of Ce:YAG ceramics with various porosities and pore sizes were prepared. The influences of porosity and pore size on the microstructure, light confinement ability, and optical properties of Ce:YAG ceramics were studied. The ceramic phosphor with a porosity of 10 vol.% and a pore size of 3 μm exhibits a good spot confinement ability and shows a high luminous flux value of 3430 lm and a central luminance (1669 592 cd/m2) under blue laser excitation. The 10 vol.% Ce:YAG ceramic phosphor with a pore size of 5 μm has the highest emission intensity and gives a maximum luminous efficacy of 268 lm/W and a luminous flux of 4020 lm under 30 W/mm2 blue laser excitation. Thus, the porous Ce:YAG ceramics are expected to be a promising candidate for high‐brightness laser lighting and projection applications.