Effect of lanthanum on the spectroscopy and laser performance of Pr:Sr _{1- <i>x</i>} La _<i>x</i> Mg _<i>x</i> Al _{12- <i>x</i>} O ₁₉ hexaaluminates [Invited]

We report a systematic investigation of the effect of lanthanum incorporation on the polarization-resolved spectroscopic and laser properties of Pr 3+ -doped Sr 1- x La x Mg x Al 12- x O 19 (ASL) hexaaluminate solid-solution crystals, with reference to the parent SrAl 12 O 19 (SRA) compound. The addition induces inhomogeneous broadening of absorption and emission bands, while only weakly affecting the phonon spectra and radiative transition probabilities. In the red spectral region (the 3 P J → 3 F 2 transition), Pr 3+ :SRA exhibits a stimulated-emission cross section σ SE as high as 16.4 × 10 −20 cm 2 at 643.6 nm, with an emission bandwidth of 1.0 nm. For the La 0.47 composition, σ SE decreases to 6.1 × 10 −20 cm 2 at 645.8 nm, while the bandwidth is broadened to 4.1 nm. The luminescence lifetime remains nearly unchanged across the compositions, in the range of 36–38 µs. Under 465 nm GaN diode pumping, the optimized Pr 3+ :ASL (La 0.26 ) crystal delivers 164 mW at 644 nm, with a slope efficiency of 13.2% and a laser threshold of 0.30 W. Laser action in the deep red is also demonstrated. These results highlight the potential of La-substituted, Pr 3+ -doped hexaaluminates as broadly emitting visible laser gain media.