Liquid Phase Epitaxy Growth and Spectroscopy of Tb3+-Doped LiYF4 Crystalline Layers for Visible Waveguide Lasers

Trivalent terbium ions (Tb
³⁺
) present multi-color emissions in the visible due to the
${}^{5}\mathrm{D}_{4}\rightarrow {}^{7}\mathrm{F}_{\mathrm{J}}(J=0-6)$
transitions, with the most intense one at ~544 nm falling into the green spectral range (for
$J=5$
). Tb
³
+ ions are widely used in green phosphors and as probes in biochemistry. They are also suitable for directly generating visible (green and yellow) laser emission [1]. Currently, visible Tb lasers are based on bulk fluoride crystals, such as tetragonal Tb:LiYF4. In the present work, we report on the Liquid Phase Epitaxy growth and polarized spectroscopic properties of single-crystalline Tb
³⁺
, Gd
³⁺
-codoped LiYF4 crystalline layers suitable for the development of visible waveguide lasers.