Absorption and emission characteristics of Ho3+doped alkali chloroborophosphate glasses

Alkali chloroborophosphate glasses containing 1 mol% of HoCl3 were prepared and characterized. The optical absorption spectra of three glasses have been studied in the UV-VIS-NIR region. Ho3+ ion has several low lying meta stable levels, which can give rise to transitions at various wavelengths from infrared (IR) to ultraviolet (UV) regions. Racah (E1, E2, E3), spin-orbit (x4f), configuration interaction parameters (a,b) and hydrogenic ratios E1/E3 and E2/E3 are also obtained. Oscillator strengths (f) are measured from the absorption spectra and three intensity parameters Wl (2, 4 and 6) are calculated. Reasonable agreement between the measured and calculated f values has been found. For Ho3+ ion, 5I8à5G6 is the hypersensitive transition. Using Judd–Ofelt intensity parameters, electric dipole line strengths (Sed) and magnetic dipole line strengths (Smd) are calculated. From these, radiative lifetimes (τR), branching ratios (bR¬) and peak stimulated emission cross-sections (sp), radiative transition rates (A) are calculated. These results were used to predict the possible potential laser transitions.