Temperature and concentration dependence of spectroscopic properties of Nd3+-doped yttrium aluminum garnet crystal

The optical absorption spectra of yttrium aluminum garnet (YAG) crystals doped with Nd3+ ions with different concentrations (0.6 at%, 1.0 at%, 1.2 at%) at the temperature range from 300 K to 500 K have been measured. The calculated Judd-Ofelt (JO) parameters Ωt (t=2, 4, 6) based on the spectra have been used to predict the radiative transition probabilities, branching ratios and radiative lifetimes of the transitions from 4F3/2 level to the lower levels (4I13/2, 4I11/2, 4I9/2) at each concentration and temperature. The three JO parameters Ωt (t=2, 4, 6), according to the calculation, decrease with the increasing doped concentration at each temperature. The JO parameters Ω2 and Ω4 increase, while the parameter Ω6 decreases with the increasing temperature at each concentration. The branching ratios and radiative transition probabilities of the transitions from the 4F3/2 level to 4I13/2 and 4I11/2 levels decrease, while the transition from the 4F3/2 level to 4I9/2 level increases with the increasing temperature. The obtained results at each concentration and temperature are discussed.