Growth and properties of Pr3+-doped NaGd(MoO4)2 single crystal: A promising InGaN laser-diode pumped orange-red laser crystal

Abstract

Trivalent praseodymium (Pr3+) doped materials have received widely attentions due to their promising prospects for InGaN laser-diodes pumped visible lasers. In this work, a 2 at.% Pr3+ doped oxide crystal, Pr:NaGd(MoO4)2 crystal, was grown successfully by Czochralski method. The color of the crystal changes from black to green after annealing in air atmosphere. The structure of the crystal before and after annealing were characterized by powder X-ray diffraction. Then, Rietveld refinement method was performed to the X-ray diffraction data to determine the lattice parameters of the crystal. The structure of the crystal was further confirmed by Raman scattering spectrum. The spectroscopic properties of the crystal, including absorption and fluorescence spectra, were characterized and discussed. In visible range, the crystal has a strongest absorption band with center at 450 nm, which is well matched with the output wavelength of InGaN laser-diodes. The absorption cross-section at this wavelength was 1.07 × 10−20 cm2. Under the excitation at 450 nm, the strongest emission was detected at 652 nm, which corresponding to the 3P0→3F2 transition of Pr3+. The fluorescence decay time for the 3P0→3F2 transition of Pr3+ was fitted to be 4.01 μs. The results indicate that Pr:NaGd(MoO4)2 crystal is a potential candidate for InGaN-based LD pumped orange-red lasers.