Dynamic population of infrared radiation in dysprosium-doped different host materials

The dynamic population processes of infrared radiation in dysprosium-doped different host materials (LaF₃, Y₂O₃, YAlO₃ and silicate glass) are theoretically investigated. The radiation and non-radiation transition rates of each energy level are calculated using Judd-Ofelt (J-O) theory and according to "energy-gap law". It is demonstrated that the non-radiative transition rate increases significantly as the phonon energy increases, indicating that the choice of host materials has a great influence on the infrared transition processes. By solving the rate equations we establish, it is found that the population profiles of the same energy levels are almost the same, but the time to reach equilibrium population varies greatly among different materials. The population probability of ⁶H_9/2 and ⁶H_11/2 energy levels increases first and then decreases, whereas that of 6H13/2 and ⁶H_15/2 monotonically increases or decreases with time. The excited state ⁶H_13/2 has a quite long decay lifetime of 38.97 ms in dysprosium-doped LaF₃, which is a good metastable state for mid-infrared emission.. These results are helpful to the material selection and application of infrared lasers.