V. A. Shitov

Laser ceramics with disordered crystalline structure

New ceramic materials based on yttrium oxide Y2O3 with isovalent (Yb2O3, Nd2 O3, and Lu2O3) and heterovalent (ZrO2 and HfO2) components are synthesized, and their spectroscopic properties are investigated. Possible channels of losses in the gain of stimulated radiation in the radiative transitions of Nd3+ and Yb3+ ions in ceramics with heterovalent additives are studied. The results of measurements of Y2O3 ceramics doped with zirconium and hafnium ions, the emission bandwidth and the lifetimes of the 4F3/2 and 2F5/2 levels of Nd3+ and Yb3+ ions, respectively, are presented. It is shown that the nonradiative population of the 4F3/2 levels of neodymium ions is due to their dipole-dipole interaction with Zr3+ and Hf3+ ions. Laser generation in [(Yb0.01Lu0.24Y0.75)2O3]0.88(ZrO2)0.12 ceramics with disordered crystalline structure was achieved at a wavelength of 1034 nm with a differential efficiency of 29%.

Synthesis of ceramic active Nd:YAG laser medium

The research results on the synthesis of highly transparent YAG ceramics and the generation of radiation in samples are reported. The possibilities of the synthesis of highly transparent ceramics from nanopowders in the garnet stoichiometry (Nd3+:Y3Al5O12) and a mixture of nanopowders (Nd3+:Y2O3, Al2O3) are studied. Data on phase transformations in compacts fabricated from both types of nanopowder obtained from results of calorimetric and X-ray analyses are presented. It is shown that a higher transparency (∼83%) is achieved in samples synthesized from a mixture of powders. According to the optical microscopy of the extinction centers in ceramics, it is established that a lower transparency compared to the theoretical one (83.8%) is caused by the dispersion by pores that appears near large agglomerates of particles. Experimental results on continuous lasing at the 1.064-μm wavelength with a power of 3.8 W and a slope efficiency of 19.1% in the ceramic sample with the best transparency are reported.

The energy structure of a neodymium ion in monoclinic yttria

We present an energy level diagram of a Nd3+ ion in monoclinic γ-phase of yttria reconstructed from transmission spectra of Y2O3:Nd3+ nanopowders.

Luminescent Response to the Phase Composition of Nd3+:Y2O3-Al2O3 System

The work demonstrates the luminescent method of identifying the phase composition of Nd3+:Y2O3-Al2O3 system by building calibration curves using standard samples.

Determining the phase composition of yttrium oxide nanopowders by means of luminescence

The possibility of developing a luminescence technique for phase composition analysis is demonstrated via the example of bi-phase yttria nanopowders doped with neodymium ions. The deviation from X-ray diffraction reference values is ±2%. It is found that the results depend on the inhomogeneity of the crystalline phase distribution within a sample’s bulk, rather than on the luminescence scattering by powder nanoparticles. A luminescence coefficient that determines the phase inhomogeneity in nanopowders is introduced.

Investigation of lasing characteristics of domestic Yb : YAG laser ceramics

We report on the synthesis and laser characteristics of Yb3+-doped yttrium aluminium garnet (Y3Al5O12) optical ceramics. The ceramics was produced by solid-phase reactive sintering of a mixture of Yb (5 at %) : Y2O3 and Al2O3 nanopowders synthesised by laser ablation, using additional calcination of the mixture before compaction. In a thin disk geometry, multiwatt laser oscillation was obtained at a wavelength of 1030 nm with a power of 5.2 W and a slope efficiency of 37.0% at a pump pulse period-toduration ratio of 5.72.

Nd:YAG/Cr:YAG composite laser ceramics

This work reports the synthesis of transparent composite ceramics consisting of Nd:YAG in the central part and Cr4+:YAG in the edge cladding. The central part of ceramics was shaped like 14-mm-diameter disk or 11-mm-side square and an outer diameter of the edge cladding was 18 mm or 23 mm, respectively. The central part of ceramics had an optical transmittance of ~84% at a wavelength of 1.06 µm. The concentration of Cr4+ in Cr4+:YAG ceramics of three different compositions was estimated from the transmission spectra measured and known absorption cross sections. The optimal composition of edge cladding was estimated to be 2.5 mol % Cr + 0.5 mol % Ca + 97 mol % YAG to avoid self-excitation in Nd:YAG.