Optical Parameters of Nd-Doped Gadolinium Aluminium Tetraborate Crystals

Abstract

Nd-doped gadolinium aluminium tetraborate, Nd x Gd 1-x Al 3 (BO 3 ) 4 (NGAB), crystallizes with x = 0.1 in the trigonal system with point group 32, conforming space group R32. They were grown using flux method, of large sizes and good optical quality. The unit cell constants were a = 0.93057 (6) and c = 0.72481 (3) nm, and z = 1. The measured absorption of the NGAB is compared to Judd-Ofelt (JO) theory. When applied, the JO theory of parity-forbidden electric-dipole transitions of rare earth ions on noncentrosymmetric sites demonstrates good agreement. A measured band gap of the eigentransition was about 4.00 eV. The fitted intensity parameters Ω t (t = 2.4, and 6) were 2.446 × 10 -20 , 2.266 × 10 -20 and 2.598 × 10 -20 cm 2 . Both the emission properties of the sub-stable 4 F 3/2 state with the level lifetime of 506.20 μs and a fluorescence spectrum corresponding to the transition 4 F 32 → 4 I 11/2 were studied. The results indicate the pass band of laser for potential applications in practice.