Highly transparent Tb₃Al₅O₁₂ ceramics for kilowatt-level Faraday isolator

Tb3Al5O12(TAG) ceramics with high optical quality were fabricated successfully by a solid-state reaction method combined with hot isostatic pressing (HIP) post-treatment. The microstructure, optical transmittance, Verdet constant, and thermo-optical properties were investigated. The obtained TAG ceramics showed a dense microstructure, and the in-line transmittance reached 82.8% at 1070 nm after laser-grade polishing. The Verdet constant of TAG ceramics was measured to be 50.9 rad center dot T-1 center dot m(-1) at 1070 nm, which is higher than that of commercial Tb3Al5O12 crystals. The Faraday isolator based on TAG ceramics can provide an isolation ratio of 30 dB with a laser power of more than 1 kW. With excellent optical quality, high Verdet constant, and maximum working power, TAG transparent ceramics are promising for applications of kilowatt-level Faraday isolators.