In recent years, mid-IR (MIR) lasers operating around 3μm have attracted much attention for numerous applications in medical and sensing technologies because of the vibrational absorption band of water in this spectral region. Ho³⁺ is a well known ion with transitions in the IR region around 2.9 μm. However, the 2.9 μm emission cannot be obtained efficiently because the fluorescence lifetime of the upper ⁵I₆ level is considerably shorter than that of the lower level ⁵I₇. Co-doping of Pr³⁺ could be used as a feasible alternative to quench the lower level. LiLuF₄ (LLF) crystal has low multiphonon relaxation resulting in long radiative and fluorescence lifetimes of ⁵I₆ manifold, and the vibronic absorption bands appear in the MIR at a significantly higher wavelength. It has negative thermal dependence of refractive index, which leads to weak overall thermal lensing. In this poster session, Ho³⁺- and Ho³⁺, Pr³⁺-doped LLF crystals were successfully prepared. The use of Pr³⁺ co-doping for enhancement of the Ho³⁺:⁵I₆ → ⁵I₇ mid-IR emissions were investigated in the LLF crystal for the first time. It was found that Pr³⁺ greatly increased Ho³⁺ 2.9 μm emission by depopulating the Ho³⁺:⁵I₇ level while having little influence on the Ho³⁺:⁵I₆ level, leading to greater population inversion. The energy transfer efficiency from Ho³⁺:⁵I₇ to Pr³⁺:³F₂ is calculated to be 88%. Based on Judd–Ofelt theory, the 2.9 μm emission cross section is calculated to be 1.91 × 10⁻²⁰ cm², and the gain property of the Ho³⁺:⁵I₆ → ⁵I₇ transition is discussed. We propose that the Ho, Pr: LLF crystal may be a promising material for 2.9 μm laser applications.

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/29670 must be provided.

1. Crystal growth, spectroscopic characterization and laser performance of Yb-doped lead fluoride crystals
2. Direct Comparison of ZnO single crystal grown by the hydrothermal and Pressurized melt growth method
3. New type Anti-Stokes laser cooling materials: Yb:LiLuF₄ crystal