Fabrication,microstructures,and optical properties of Yb:Lu_(2)O_(3) laser ceramics from co-precipitated nano-powders

The Yb:Lu_(2)O_(3)precursor made up of spherical particles was synthesized through the co-precipitation method in the water/ethanol solvent.The 5 at% Yb:Lu_(2)O_(3)powder is in the cubic phase after calcination at 1100℃ for 4 h.The powder also consists of spherical nanoparticles with the average particle and grain sizes of 96 and 49 nm,respectively.The average grain size of the pre-sintered ceramic sample is 526 nm and that of the sample by hot isostatic pressing grows to 612 nm.The 1.0 mm-thick sample has an in-line transmittance of 81.6%(theoretical value of 82.2%)at 1100 nm.The largest absorption cross-section at 976 nm is 0.96×1^(0-20)cm^(2) with the emission cross-section at 1033 nm of 0.92×10^(-20)cm^(2) and the gain cross sections are calculated with the smallest population inversion parameter β of 0.059.The highest slope efficiency of 68.7% with the optical efficiency of 65.1% is obtained at 1033.3 nm in quasi-continuous wave(QCW)pumping.In the case of continuous wave(CW)pumping,the highest slope efficiency is 61.0% with the optical efficiency of 54.1%.The obtained laser performance indicates that Yb:Lu_(2)O_(3)ceramics have excellent resistance to thermal load stresses,which shows great potential in high-power solid-state laser applications.

Cold Hydrostatic Sintering:From shaping to 3D printing

We developed a novel consolidation technique,Cold Hydrostatic Sintering(CHS),which allows near full densification of silica.The technique is inspired by biosilicification and geological formation of siliceous rocks.Unlike established cold sintering method which is based on uniaxial pressure,CHS employs an isostatic pressure to enable room temperature consolidation of bulks having a complex threedimensional shape.The resulting material is transparent(in line transmittance exceeding 70% in the visible range)and amorphous.After drying,the Vickers hardness was as high 1.4 GPa which half of materials consolidated at 1200℃ and it is the highest among all materials processed at room temperature.The CHS method,because of its simplicity,might be suitable for broad range of applications including 3D printing,mould forming and preparation of multi-layered devices.Because of the absence of the firing step,CHS could be directly integrated in the manufacturing of a wide range of hybrid(organic/inorganic)materials for functional and biological applications.