Spectroscopic studies of KGd(WO4)2:Ho3+ single crystals

Research highlights: → Growth of KGd(WO4)2 crystals doped with Ho ions is reported. → Detailed studies of their absorption and luminescence spectra are described. → Judd-Ofelt analysis of the radiative properties of Ho ions was performed. → Optical transitions of Ho ions, suitable for laser generation, were identified. - Abstract: Single crystals of KGd(WO4)2 doped with Ho3+ ions were grown by the top seeded solution growth method. Polarized room temperature absorption spectra were analyzed by means of the conventional Judd-Ofelt theory taking into account strong dependence of the host refractive index on the wavelength. In addition to the intensity parameters Ω2, Ω4, Ω6, the branching ratios and radiative lifetimes were estimated for all possible transitions in the studied spectral region. The transitions predicted by the phenomenological model as potential transitions for laser applications are discussed. Emission spectra in the green, red, and near-infrared spectral regions were recorded for different excitation wavelengths. Comparison with spectroscopic properties of Ho3+ ion in other crystals is discussed.