Decoloration of yttrium orthovanadate laser host crystals by annealing

Decoloration of a Czochralski-grown YVO4 laser host is studied by evaluation of the optical absorption and the photoluminescence spectrum before and after annealing under various atmospheres. Decoloration of yellow as-grown crystals, as a result of the decrease in the absorption near the absorption edge, occurs independently of the air, N2, and O2 annealing atmospheres. The most dramatic decrease in the absorption is seen in N2. Annealing in N2 atmosphere is suggested to be effective for obtaining the highly transparent crystals.