Optical properties of alkali and alkaline-earth lead borate glasses doped with Nd3+ ions

Spectroscopic and physical properties of Nd3+ stop-doped alkali lead borate glasses of type 20R(2)O center dot 30PbO center dot 49.5B(2)O(3) center dot 0.5Nd(2)O(3) (R = Li and K) and alkaline-earth lead borate glasses 20RO center dot 30PbO center dot 49.5B(2)O(3) center dot 0.5Nd2O3 (R = Ca, Ba, and Pb) have been investigated. Optical absorption spectra have been used to determine the Slater-Condon (F-2, F-4, and F-6), spin orbit xi(4f), and Racah parameters (E-1, E-2, and E-3). The oscillator strengths and the intensity parameters Omega(2), Omega(4), and Omega(6) have been determined by the Judd-Ofelt theory, which, in turn, provide the radiative transition probability (A), total transition probability (A (T) ), radiative lifetime (tau(R) ), and branching ratio (beta(R), %) for the fluorescent levels. The lasing efficiency of the prepared glasses has been characterized by the spectroscopic quality factor (Omega(4)/Omega(6)), the value of which is in the range 0.2-1.5, typical of Nd3+ in different laser hosts. A red shift of the peak wavelength is observed upon addition of alkali or alkaline-earth oxides to the lead borate glass. A higher value of the W-2 parameter for potassium-doped glass indicates a higher covalency for this glass matrix. The relative intensity of the peaks I-4(9/2) -> F-4(7/2), S-4(3/2) has also been studied.