Co-Doped La 3+ Achieves Synergistic Regulation of Spectral Broadening and Energy Level Dynamics in Er 3+ :NaSrY(MoO 4 ) 3 Disordered Crystals

To address the narrow emission cross section of Er 3+ at 1.55 μm and its low luminescence efficiency at 2.6 μm due to the “self-quenching effect”, this work proposes a strategy of co-doping with non-optically active ion La 3+ to regulate the crystal structure and spectral properties. A series of disordered Er 3+:NaSrY 1– x La x (MoO 4 ) 3 ( x = 0.2, 0.5, and 0.8) crystals were successfully grown using the top-seeded solution growth (TSSG) method. Their structures, spectra, and laser properties were characterized in conjunction with first-principles calculations. Results indicate that La 3+ introduction significantly enhances crystal chemical disorder, inducing lattice expansion and phonon energy elevation. This broadens the Er 3+ emission spectrum at 1.55 μm from 68.2 to 102.1 nm (fwhm). Theoretical calculations further reveal La 3+ ’s regulatory effect on the host bandgap and electronic structure, providing microscopic insights into spectral broadening. Co-doping with La 3+ effectively modulated the energy level relaxation dynamics of Er 3+, alleviating the difficulty of population inversion in the 2.6 μm band. This work demonstrates the feasibility of achieving synergistic control over spectral broadening and energy level dynamics through La 3+ co-doping, offering a novel approach for developing high-performance, wide-tuning, multi-band laser gain media.