Enhanced mid-infrared emission of Pr³⁺ ions in solids through a “3-for-1” excitation process – quantified

Abstract

Evidence is presented that a “three-for-one” process based on two cross-relaxations between Pr3+ ions efficiently populates the mid-infrared-emitting 3H5 manifold in a Pr3+-doped low-maximum-phonon-energy host. The concentration dependence of infrared fluorescence spectra and lifetimes of polycrystalline Pr:KPb2Cl5 initially excited to the 3F3,4 manifolds indicate that the 3500-5500-nm fluorescence becomes strongly favored over shorter-wavelength infrared emission bands in the higher-concentration sample. The strong concentration dependence of the 3F3 and 3H6 manifold lifetimes suggests that both of these decay by cross-relaxation processes, resulting in more than one ion excited to 3H5 for each ion initially excited to 3F3. Indeed, modeling and accounting for all possible decay paths indicate that, on average, about 2.3 ions are excited to 3H5 for each initially-excited ion. This confirms that the three-for-one excitation process must occur and contribute significantly to the total excitation efficiency. These results indicate that the two distinct cross-relaxation processes observed between Pr ions result in substantially higher excitation quantum efficiency, 230%, than any ever reported in rare-earth doped materials.

Rare-Earth-Doped Selenide Glasses as Laser Materials for the 5–6 μm Spectral Range

“…In this case, one absorbed pump photon corresponding to a wavelength of ~1.54 microns can generate up to three Pr 3+ ions at the upper-laser-level 3 H5. The efficiency of the proposed Pr 3+ pumping method was confirmed in [39] with the example of a KPb2Cl5 crystal.…”

Designing a W-type index praseodymium-doped chalcogenide fiber for strongly-efficient MIR Laser beyond 4 μm

“…Which yields to avoid the need of the cascade lasing approach and enhance the MIR emission. Finally, Pr 3+ has a strong cross relaxation process, leading to excite three ions to manifold 3 H 5 by de-excitation of one ion to 3 F 3 manifold [13]. However, it is prerequisite to use host materials with low phonon energy and optical loss to release an efficient MIR light source from a Pr 3+ -doped fiber and the promising candidate for this purpose is the chalcogenide glass [14].…”