In-depth study of spectroscopic properties of new Pr3+-ion doped low-phonon sesquisulfide Lu2S3 material for mid-IR laser sources

Lu 2 S 3 material from the family of sesquisulfide hosts appears to be a promising low-phonon material for use as a laser gain medium allowing for a laser emission over a broad spectral range from ultraviolet to far mid-infrared wavelengths. In this paper, a praseodymium-ion doped Lu 2 S 3 single crystal grown by micro-pulling down technique is investigated with focus on its spectroscopic properties. The Raman, excitation, and luminescence spectra are presented. By selective excitation of the main energy levels of Pr 3+ -ions, 26 luminescence transitions of the Pr:Lu 2 S 3 crystal spanning the ∼0.49 − 5.5 μ m wavelength range have been identified. The correct assignment of the observed luminescence spectra to the respective Pr 3+ energy-level transitions was confirmed by the calculation of the optimized squared reduced-matrix elements for the tensor operators U ( k ) and L + g S . • New promising low-phonon Lu 2 S 3 material is investigated for its potential laser emission in the mid-infrared spectral region. • Lu 2 S 3 excels in non-hygroscopicity, satisfactory mechanical properties, and good acceptance for lanthanide group dopants. • Detailed spectroscopic properties of Pr:Lu 2 S 3 over a broad spectral range extending into the mid-infrared region are presented. • 26 luminescence transitions spanning the ∼0.49 − 5.5 μ m wavelength range were identified in the Pr:Lu 2 S 3 material.