Concentration Dependence of Fluorescence Lifetime of Nd3+-Doped Gd3Ga5O12 Lasers

The Nd³⁺ concentration dependence of the fluorescence lifetime in laser crystal Gd₃Ga₅O₁₂(GGG) for high power and high efficiency solid state laser is reported for the first time. The dominant mechanism of the concentration quenching in Nd³⁺: GGG rises from the electric dipole-dipole interaction between Nd³⁺ ions. The nonradiative transition probability of the ⁴F_3/2 state is found to be proportional to the Nd³⁺ concentration squared up to the Nd³⁺ concentration of 5× 10²⁰ cm^-3. The optimum Nd³⁺ concentration in Nd³⁺: GGG is estimated to be (3.4± 0.5)× 10²⁰ cm^-3 in pulsed laser operation.