Simulation of the optical properties of Tm:ZBLAN glass

The optical properties of Tm:ZBLAN glass have been simulated. The simulated optical spectra agreed substantially with the observed spectra. The population of the energy levels of the Tm ³⁺ ion under dual-wavelength excitation for upconversion emission and amplification was evaluated by solving the rate equation with the simulated transition probabilities and spectral shapes of the transitions of which the initial levels were from the ³H ₆ to ³P ₂ levels. The large population of the ¹G ₄ level, which is the upper level for 480 nm laser oscillation, was estimated for the conditions of laser oscillation at room temperature. We also proposed new combinations of the excitation wavelengths for the amplification of the 1470 nm signal.