Erbium ion implantation into LiNbO3, Al2O3, ZnO and diamond - measurement and modelling - an overview

The presented overview deals with the study of the luminescence properties of lanthanide ions incorporated into different dielectric crystalline materials for use in photonics and optoelectronics. From the crystalline materials, non-centrosymmetric hexagonal crystals of LiNbO₃, Al₂O₃ and ZnO, together with the centrosymmetric cubic crystal of diamond, were chosen. The above-mentioned materials represent a certain cross-section through various crystal structure geometries with different internal bonding of atoms which represent different crystal vicinity for the incorporated Er ions. During more than ten years of our research, each of the crystals was doped with erbium ions and the resulting structural and luminescence properties were studied in detail and compared between the mentioned crystalline materials to find similar behaviour for erbium ions in the different crystalline materials. To better understand the incorporation of erbium in the studied crystalline materials, theoretical simulations of different erbium-doped crystal models were carried out. In the calculations, cohesive energies of the structures and erbium defect-formation energies were compared in order to find the most favourable erbium positions in the crystals. Also, from the geometry optimization calculations, the optimal geometry arrangements in the vicinity of erbium ions in different crystals were studied and visualized. The results of the theoretical simulations confirmed the experimental results - i.e., from all the theoretical erbium-doped crystal models, the most stable structures contained erbium in the substitutional positions with octahedral oxygen coordination.

The structural and optical response of the Au nanoparticles embedded in YSZ modified using high-energetic ion irradiation

Gold nanoparticles (Au NPs) were synthesized in single-crystalline yttria-stabilized zirconia (YSZ) using a high-energetic gold ion implantation with the intention of subsequent modification by silicon ion irradiation. (100)-oriented YSZ samples were implanted with 1 MeV Au+ ions at room temperature and fluences of 1.5×1016 cm−2, 5.0×1016 cm−2 and 7.5×1016 cm−2 and subsequently annealed for 1 h at 1100 °C in air. Gold NPs modification was realized with irradiation by 10 MeV Si3+ with the fluence of 5.0×1014 cm−2. Au NPs distribution and subsequent YSZ structure modification were studied. YSZ samples as-implanted with Au ions, annealed and subsequently irradiated with Si ions were characterized using Rutherford backscattering spectrometry (RBS) and RBS in channelling mode (RBS-C). The RBS spectra show that the implanted Auions concentrate in the YSZ sub-surface layer in the depth of about 50-250 nm and shift to greater depth with increasing ion fluence. The Si3+ ions irradiation slightly increased Zr sub-lattice disorder. Optical absorbance shows an increase of absorption band at 550 nm after Au implantation only for the two highest ion fluences. After annealing and Si irradiation, optical absorbance increased at 530-580 nm with connection to ion implantation fluence of Au+ ions.

Microstructural modifications induced in Si+-implanted yttria-stabilised zirconia: a combined RBS-C, XRD and Raman investigation

The structural differences in (100)-, (110)- and (111)-oriented cubic yttria-stabilised zirconia (YSZ) single crystals after implantation with 2 MeV Si⁺ ions at the fluences of 5 × 10¹⁵, 1 × 10¹⁶ and 5 × 10¹⁶ cm^-2 were studied using Rutherford backscattering spectrometry in the channelling mode (RBS-C), X-ray diffraction (XRD) and Raman spectroscopy. The RBS-C results show that the damage accumulation in the 〈110〉 direction exhibits a lower level of disorder (<0.3) than the other orientations (<0.6) and it seems that the (110) crystallographic orientation is the most resistant to radiation damage. The experimental results from the RBS measurement were compared with the results from the XRD measurements. The XRD data were analysed using the standard two-beam dynamical X-ray diffraction theory and the pure isotropic strain was deduced from the fit for the fluence of 5 × 10¹⁵ cm^-2. It was shown that the maximum value of the isotropic strain does not depend on the surface orientation. The increase in signal intensity at ∼689 cm^-1 is probably related to an increase in implantation defects such as oxygen vacancies.

Creation of Gold Nanoparticles in ZnO by Ion Implantation-DFT and Experimental Studies

Three different crystallographic orientations of the wurtzite ZnO structure (labeled as c-plane, a-plane and m-plane) were implanted with Au⁺ ions using various energies and fluences to form gold nanoparticles (GNPs). The ion implantation process was followed by annealing at 600 °C in an oxygen atmosphere to decrease the number of unwanted defects and improve luminescence properties. With regard to our previous publications, the paper provides a summary of theoretical and experimental results, i.e., both DFT and FLUX simulations, as well as experimental results from TEM, HRTEM, RBS, RBS/C, Raman spectroscopy and photoluminescence. From the results, it follows that in the ZnO structure, implanted gold atoms are located in random interstitial positions -experimentally, the amount of interstitial gold atoms increased with increasing ion implantation fluence. During ion implantation and subsequent annealing, the metal clusters and nanoparticles with sizes from 2 to 20 nm were formed. The crystal structure of the resulting gold was not cubic (confirmed by diffraction patterns), but it had a hexagonal close-packed (hcp) arrangement. The ion implantation of gold leads to the creation of Zn and O interstitial defects and extended defects with distinct character in various crystallographic cuts of ZnO, where significant O-sublattice disordering occurred in m-plane ZnO.

Active Optical Fibers and Components for Fiber Lasers Emitting in the 2-μm Spectral Range

Laser sources emitting in the infrared range at around 2 µm are attracting great interest for a variety of applications like processing of transparent thermoplastic polymers in industry as well as plenty of applications in medicine, spectroscopy, gas sensing, nonlinear frequency conversion to the mid-infrared, to mention a few. Of late, fiber lasers compared to other kinds of lasers benefit from their all-fiber design, leading to a compact, robust, and well thermally manageable device. Particularly, thulium- and holmium-doped fiber lasers are the first choice in fiber lasers emitting light around 2 µm. In this paper, we give an overview of our recent results in the research on thulium- and holmium-doped optical fibers, fiber lasers, and related research topics in the 2-µm spectral range. In particular, we present, to our knowledge, the first results of improvement of pump absorption in double-clad fibers thanks to the fiber twist frozen during drawing. Finally, a brief demonstration of material processing by thulium all-fiber laser operating at 2 µm is presented.

Heavily Ce3+-doped Y3Al5O12 thin films deposited by a polymer sol–gel method for fast scintillation detectors

The performance of cerium-doped Y₃Al₅O₁₂ (Ce³⁺:YAG) often depends on cerium solubility achievable in a particular preparation technology.

Erbium Luminescence Centres in Single- and Nano-Crystalline Diamond-Effects of Ion Implantation Fluence and Thermal Annealing

We present a fundamental study of the erbium luminescence centres in single- and nano-crystalline (NCD) diamonds. Both diamond forms were doped with Er using ion implantation with the energy of 190 keV at fluences up to 5 × 1015 ions·cm-2, followed by annealing at controllable temperature in Ar atmosphere or vacuum to enhance the near infrared photoluminescence. The Rutherford Backscattering Spectrometry showed that Er concentration maximum determined for NCD films is slightly shifted to the depth with respect to the Stopping and Range of Ions in Matter simulation. The number of the displaced atoms per depth slightly increased with the fluence, but in fact the maximum reached the fully disordered target even in the lowest ion fluence used. The post-implantation annealing at 800 °C in vacuum had a further beneficial effect on erbium luminescence intensity at around 1.5 μm, especially for the Er-doped NCD films, which contain a higher amount of grain boundaries than single-crystalline diamond.

Erbium ion implantation into diamond – measurement and modelling of the crystal structure

Doping of diamond with erbium as an optically active centre.

All-fiber Ho-doped mode-locked oscillator based on a graphene saturable absorber

In this Letter, we demonstrate a graphene mode-locked, all-fiber Ho-doped fiber laser generating 1.3 nJ energy pulses directly from the oscillator. The graphene used as a saturable absorber was obtained via chemical vapor deposition on copper substrate and immersed in a poly(methyl methacrylate) support. The laser generated ultrashort soliton pulses at 2080 nm with bandwidth up to 6.1 nm. The influence of the output coupling ratio and the SA modulation depth on the mode-locking performance was also investigated.