Liquid phase epitaxy growth and visible emission of Tb³⁺,Gd³⁺:LiYF₄ layers

Abstract

Single-crystalline layers of 12 at.% Tb3+, 5 at.% Gd3+:LiYF4 were grown by the liquid phase epitaxy method on (001) oriented bulk undoped LiYF4 substrates using LiF as a solvent. The growth temperature was 737–740 °C, the growth duration was 15 - 25 min, and the layer thickness was 40–90 µm. The structural, morphological, vibronic and spectroscopic properties of the layers were studied. Tb3+ ions were uniformly distributed in the layers with no diffusion into the substrate. Polarized Raman spectroscopy confirmed the orientation of the layers (growth along the [001] direction). Under excitation in the blue, the layers exhibited intense green emission. For the 5D4 → 7F5 Tb3+ transition, the peak stimulated-emission cross-section is 1.28 × 10−21 cm2 at 542.0 nm for π-polarization. The luminescence lifetime of the 5D4 Tb3+ state is 5.05 ms at room temperature. The crystal-field splitting of Tb3+ multiplets was determined at low temperature. The developed epitaxies are promising for green and yellow waveguide lasers.