Transparent Cr4+‐Doped YAG Ceramics for Tunable Lasers

Abstract

Transparent Cr 4+ :YAG (Y 3 Al S O 12 ) ceramics doped with Ca and Mg as counterions and SiO 2 as a sintering aid were fabricated by a solid‐state reaction method using high‐purity powders of Al 2 O 3 , Y 2 O 3 , and Cr 2 O 3 . The mixed powder compacts were sintered at 1750°C for 10 h in oxygen, or 1750°C for 10 h under vacuum, and then annealed at 1400°C for 10 h in oxygen. Cr‐doped YAG ceramics sintered in oxygen had a brown color and characteristic absorption by Cr 4+ ions, whereas these YAG ceramics sintered under different conditions (vacuum + oxygen) had a green color and absorption at ∼590 and 430 nm by Cr 3+ ions. The absorption behavior of YAG ceramics sintered in oxygen was almost equivalent to that of Cr 4+ :YAG single crystals fabricated by the Czochralski method.