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A comparative study was conducted to investigate the 3.9 µm mid-IR emission properties of Ho3+doped NaYF4and CsCdCl3crystals as well as Ho3+doped Ga2Ge5S13glass. Following optical excitation at ∼890 nm, all the studied materials exhibited broad mid-IR emissions centered at ∼3.9 µm at room temperature. The mid-IR emission at 3.9 µm, originating from the5I5→5I6transition, showed long emission lifetime values of ∼16.5 ms and ∼1.61 ms for Ho3+doped CsCdCl3crystal and Ga2Ge5S13glass, respectively. Conversely, the Ho3+doped NaYF4crystal exhibited a relatively short lifetime of ∼120 µs. Temperature dependent decay time measurements were performed for the5I5excited state for all three samples. The results showed that the emission lifetimes of Ho3+:CsCdCl3and Ho3+:Ga2Ge5S13were nearly temperature independent over the range studied, while significant emission quenching of the5I5level was observed in Ho3+:NaYF4. The temperature dependence of the multi-phonon relaxation rate for 3.9 µm mid-IR emission in Ho3+:NaYF4crystal was determined. The room temperature stimulated emission cross-sections for all three samples were calculated using the Füchtbauer-Landenburg equation. Furthermore, the results of Judd-Ofelt analysis are presented and discussed.
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Enhanced mid-infrared emission of Pr 3+ ions in solids through a “3-for-1” excitation process – quantified
Evidence is presented that a “three-for-one” process based on two cross-relaxations between Pr3+ions efficiently populates the mid-infrared-emitting3H5manifold in a Pr3+-doped low-maximum-phonon-energy host. The concentration dependence of infrared fluorescence spectra and lifetimes of polycrystalline Pr:KPb2Cl5initially excited to the3F3,4manifolds 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 the3F3and3H6manifold lifetimes suggests that both of these decay by cross-relaxation processes, resulting in more than one ion excited to3H5for each ion initially excited to3F3. Indeed, modeling and accounting for all possible decay paths indicate that, on average, about 2.3 ions are excited to3H5for 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.
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- Award ID(s):
- 1827820
- PAR ID:
- 10307774
- Publisher / Repository:
- Optical Society of America
- Date Published:
- Journal Name:
- Optics Express
- Volume:
- 29
- Issue:
- 24
- ISSN:
- 1094-4087; OPEXFF
- Format(s):
- Medium: X Size: Article No. 39001
- Size(s):
- Article No. 39001
- Sponsoring Org:
- National Science Foundation
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