Spectroscopic and lasing properties of calcium niobium gallium garnet activated with Cr3+ and Nd3+

An investigation was made of the luminescence and lasing spectra of a calcium niobium gallium garnet crystal activated with Cr³⁺ and Nd³⁺ ions. An effective nonradiative energy transfer from the chromium to the neodymium ions was discovered. The probability of an elementary Cr→Nd interaction event was determined. A detailed study was made of the Stark structure of the ground (⁴I_9/2) and metastable (⁴F_3/2) levels of Nd³⁺. Selective laser excitation was used to identify four main optical Nd³⁺ centers for which the splitting schemes of the ⁴I_9/2 and ⁴F_3/2 levels were constructed. Lasing was observed at 300 K as a result of the ⁴F_3/2→⁴I_11/2 transition in crystals activated with Cr³⁺ and Nd³⁺.