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A Ho³⁺-doped PbF₂ mid-IR laser crystal was successfully grown using the vertical Bridgman method. An intense 2.8 μm emission in Ho:PbF₂ crystal was observed for the first time. By analyzing the absorption and emission measurements of the Ho:PbF₂ crystal with the Judd-Ofelt theory, the intensity parameters Ω(2,4,6), exited state lifetimes, branching ratios, and emission cross-sections were calculated. It is found that the Ho:PbF₂ crystal has high fluorescence branching ratio (20.99%), large emission cross section (1.44×10⁻²⁰ cm²), long fluorescence lifetime (5.4 ms), and high quantum efficiency (88.4%) corresponding to the stimulated emission of Ho³⁺: ⁵I₆→⁵I₇ transition. The structure of Ho:PbF₂ crystal was also analyzed by the Raman spectrum, and it was found that the Ho:PbF₂ crystal possesses low phonon energy of 257 cm⁻¹. We propose that the Ho:PbF₂ crystal may be a promising material for 2.8 μm laser applications.

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Bi-layer structure has been widely adopted to improve the reliability of the conductive bridge random access memory (CBRAM). In this work, we proposed a convenient and economical solution to achieve a Ta 2 O 5 /TaO x bi-layer structure by using a low-temperature annealing process. The addition of a TaO x layer acted as an external resistance suppressing the overflow current during set programming, thus achieving the self-compliance switching. As a result, the distributions of high-resistance states and low-resistance states are improved due to the suppression of the overset phenomenon. In addition, the LRS retention of the CBRAM is obviously enhanced due to the recovery of defects in the switching film. This work provides a simple and economical method to improve the reliability of CBRAM.

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Nd,Mg:LiTaO 3 single crystal with high optical quality was grown by Czochralski technique. Absorption and fluorescence spectra were investigated. The peak absorption cross section at 806.5 nm and peak emission cross section at 1091 nm are 6.81×10 −20 and 3.28×10 −20 cm 2 , respectively. The fluorescence lifetime was measured to be 129 μs. With a laser-diode as the pump source, a maximum 375 mW continuous-wave laser output at 1083 nm has been obtained with a slope efficiency of 7.2% with respect to the pump power.

In order to meet the demands for applications of optical refrigerators in the fields of spaceflight, aviation, space science, and detection, a 2 wt. % Yb3+-doped LuLiF4 crystal, as a new laser cooling material, was prepared and demonstrated by using a 178 mW diode laser centered at 1015 nm and a resonant extra-cavity scheme with an enhancement factor of 12.8. Cooling efficiency of 1.27% and a temperature drop of 14.3 K/W are obtained with 79% of the incident laser power being absorbed. Based on our results, a sample with background absorption of α=4.2×10(-4)  cm(-1) can be potentially cooled down to ∼145 K. Our investigation shows that Yb3+-doped LuLiF4 crystal is potentially a promising candidate for solid-state refrigeration.