Luminescence Efficiency of Tm3+-Doped Crystals at 2.0 μm Under 793 nm Excitation

This study investigates the 2.0 μm luminescence efficiency of Tm3+-doped crystals under 793 nm excitation. An analytical model decomposing laser slope efficiency into the quantum defect, fluorescence quantum efficiency (ηq), and a mode matching factor was established, highlighting ηq optimization as key. Using a high-precision spectral system, the comparative study of Tm:YAG and Tm:YAP crystals revealed unprecedented ηq values of 184.8% and 190.6%, respectively. This breakthrough, corroborated by double-exponential decay kinetics, verifies the cross-relaxation-dominated quantum cutting mechanism. Superior performance of Tm:YAP crystal is attributed to its lower phonon energy, effectively suppressing non-radiative losses, providing a foundation for high-performance 2.0 μm lasers.