Observation of ⁴F_3/2 to ⁴I_15/2 radiative transition in Nd³⁺ ions in GaLaS glass using frequency-resolved PL spectroscopy

The photoluminescence (PL) emission band corresponding to 4F3/2 to 4I15/2 transition has been revealed using a double lock-in technique and quadrature frequency resolved spectroscopy (QFRS) at room temperature in Nd3+ in a GaLaS glass. The band is centred around 1840 nm and has a lifetime ~77µs, which seems to be the same for all four radiative transitions 4F3/2 to 4IJ (J = 9/2, 11/2, 13/2 and 15/2). The branching ratios β J of the four above transitions have been estimated from the PL data and agree well with the results of Judd-Ofelt (JO) analysis. In addition to the 1840 nm band, we have observed another PL band appearing around 1580 nm and having a dominant lifetime ~3.8 µs. This band may be identified with the radiative transition from the doublet (4F5/2, 2H9/2) to the 4I15/2 manifold. The short lifetime ~3.8 µs may be caused by effective multiphonon relaxation from the doublet to the 4F3/2 manifold