Spectroscopic investigations of Nd3+ doped flouro- and chloro-borate glasses

Spectroscopic and physical properties of Nd3+ doped sodium lead flouro- and chloro-borate glasses of the type 20NaX–30PbO–49.5B2O3–0.5Nd2O3 (X = F and Cl) have been investigated. Optical absorption spectra have been used to determine the Slater Condon (F2, F4, and F6), spin orbit ξ4f and Racah parameters (E1, E2, and E3). The oscillator strengths and the intensity parameters Ω2, Ω4 and Ω6 have been determined by the Judd–Ofelt theory, which in turn provide the radiative transition probability (A), total transition probability (AT), radiative lifetime (τR) and branching ratio (β) for the fluorescent level 4F3/2. The lasing efficiency of the prepared glasses has been characterized by the spectroscopic quality factor (Ω4/Ω6), the value of which is in the range of 0.2–1.5, typical for Nd3+ in different laser hosts. Nephelauxetic effect results in a red shift in the energy levels of Nd3+ for chloroborate glass. The radiative transition probability of the potential lasing transition 4F3/2 → 4I11/2 of Nd3+ ions is found to be higher for flouroborate as compared to chloroborate glass.