Process design for the manufacturing of soft X-ray gratings in single-crystal diamond by high-energy heavy-ion irradiation

Artículo con 9 figurasThis paper describes in detail a novel manufacturing process for optical gratings suitable for use in the UV and soft X-ray regimes in a single-crystal diamond substrate based on highly focused swift heavy-ion irradiation. This type of grating is extensively used in light source facilities such as synchrotrons or free electron lasers, with ever-increasing demands in terms of thermal loads, depending on beamline operational parameters and architecture. The process proposed in this paper may be a future alternative to current manufacturing techniques, providing the advantage of being applicable to single-crystal diamond substrates, with their unique properties in terms of heat conductivity and radiation hardness. The paper summarizes the physical principle used for the grating patterns produced by swift heavy-ion irradiation and provides full details for the manufacturing process for a specific grating configuration, inspired in one of the beamlines at the ALBA synchrotron light source, while stressing the most challenging points for a potential implementation. Preliminary proof-of-concept experimental results are presented, showing the practical implementation of the methodology proposed herein.The authors acknowledge funding support by the following projects: PID2020-112770RB-C22 from the Spanish Ministry of Science and Innovation, TechnoFusión (III)-CM (S2018/EMT-4437) from Comunidad de Madrid (cofinanced by ERDF and ESF), agreement between Community of Madrid and Universidad Autónoma de Madrid (item “Excellence of University Professorate”). M.L.C. acknowledges financial support from the research project “Captacion de Talento UAM” Ref: #541D300 supervised by the Vice-Chancellor of Research of Universidad Autónoma de Madrid (UAM). LOREA beamline at ALBA is a project co-funded by the European Regional Development Fund (ERDF) within the Framework of the Smart Growth Operative Programme 2014-2020. The authors acknowledge the support from The Centro de Microanálisis de Materiales (CMAM)—Universidad Autónoma de Madrid, for the beam time proposal (demonstration of a grating profile for soft X-rays in diamond via ion lithography) with code IuB-005/21, and its technical staff for their contribution to the operation of the accelerator. We also acknowledge P. Olivero for very useful comments on the manuscript draf

Analysis and optimization of propagation losses in LiNbO3 optical waveguides produced by swift heavy-ion irradiation

The propagation losses (PL) of lithium niobate optical planar waveguides fabricated by swift heavy-ion irradiation (SHI), an alternative to conventional ion implantation, have been investigated and optimized. For waveguide fabrication, congruently melting LiNbO3 substrates were irradiated with F ions at 20 MeV or 30 MeV and fluences in the range 1013–1014 cm−2. The influence of the temperature and time of post-irradiation annealing treatments has been systematically studied. Optimum propagation losses lower than 0.5 dB/cm have been obtained for both TE and TM modes, after a two-stage annealing treatment at 350 and 375∘C. Possible loss mechanisms are discussed

Synergistic effects assessment between nuclear damage and electronic energy dissipation in LiTaO3 under heavy ion irradiation using optical waveguides properties and the irradiation angle of incidence

8 pags, 10 figs.High energy heavy ion irradiation has been performed in LiTaO in a broad set of experimental conditions to study the synergistic effects in the damage generation between the nuclear and the electronic energy loss mechanisms. Optical waveguides have been fabricated in LiTaO, using 20–25 MeV F and 40 MeV Si ions, and their refractive index profiles were used as a very accurate method for the in-depth damage profile determination and its correlation with the energy loss curves. In-situ optical reflectance of low energy irradiations (500 keV F and 300 keV Si ions) has been performed to estimate the nuclear damage kinetics of the buried regions of the high energy irradiations that are not optically accessible with the optical waveguide characterization in the fluence regime when the electronic damage is intense. The angle of incidence has been varied to enhance the damage and further ascertain the existence of a synergistic mechanism.his work has been supported by the Spanish Ministry of Economy and Competitiveness through the project MAT-2011-28379-C03-02, and by Madrid Community through the Program TECHNOFUSION(III)-CM (S2018/EMT-4437). We thank the Technical Staff of the CMAM-UAM center for their support with the irradiations

Raman characterization of phonon confinement and strain effects from latent ion tracks in α-quartz

8 pags., 5 figs.This study reports phonon confinement and strain effects in the Raman spectrum of ion-irradiated and subsequently etched α-quartz. Y- and Z-cut α-quartz single crystals were irradiated at room temperature with 20-MeV Ni and 40-MeV I ions. Latent ion tracks were produced with areal densities ranging from the isolated track regime to the overlapping track regime (nominal fluences of 1 × 10, 1 × 10, and 1 × 10 ions cm). Nanowell structures were revealed after vapor etching with hydrofluoric acid (HF) aqueous solutions. A phonon confinement model was invoked to explain the observed changes in the shape of the strong Raman peak located around 463 cm. Phonon coherence lengths of the irradiated samples were determined by fitting the confinement model to the experimental data. It was found that the phonon coherence lengths (L) decreased with increasing fluence (L ~ 66 nm for samples irradiated with 1 × 10 ions cm, L ~ 58 nm at 1 × 10 ions cm, and L ~ 45 nm at 1 × 10 ions cm), suggesting that ion tracks may confine optical phonons in quartz. An additional contribution to the upshift was observed at the highest fluence. This was attributed to a contribution from lattice strain when track separations are small and the overlapping strain fields around ion tracks extend through a large volume fraction of the crystal. Through an empirical correlation, the induced stress was estimated to be on the order of 100 MPa.Nuclear Regulatory Commission FacultyDevelopment Grant, Grant/AwardNumber: NRC-HQ-84-15-G-0044;TechnofusionIII, Grant/Award Number:S2018/EMT-4437; Missouri S&T;University of Tennesse

Anisotropic nanostructure formation by vapor etching of ion tracks in α-quartz

8 pags., 9 figs., 5 tabs.In this study, latent and etched ion tracks generated by high electronic excitation in alpha quartz (α-SiO) were characterized. Single crystals of Y- and Z-cut α-SiO were irradiated at room temperature with 20 MeV Ni ions and 40 MeV I ions. The track morphology depends on the energy of the incident ion and the stopping power on the target material. Subsequent chemical vapor-etching with hydrofluoric acid solutions was conducted with varying etching times and acid concentrations. The vapor etching process produced nanostructures whose dimensions increased with etching time and etchant concentrations. Y-cut samples etched more slowly than Z-cut samples and exhibited anisotropic track etching behavior. Production of nanowells with different aspect ratios was accomplished by altering the etching time and etchant concentration. The nanowells were characterized by Atomic Force Microscopy. The etched nanostructure templates could be used in the fabrication of novel nanodevices with unique optical, thermal, and electronic properties.This work was supported by the Nuclear Regulatory Commission Faculty Development Grant NRC-HQ-84-15-G-0044. M.L.C. acknowl- edges support from the University of Tennessee Governor’s Chair pro- gram. The authors acknowledge the support from The Centro de Microanalisis de Materiales (CMAM) - Universidad Autonoma de Madrid, for the beam time proposal (Fabrication of Ion Tracks in Quartz for use as Novel Plasmonic Substrates) with code IMP-020/19. Also, the authors want to thank the Materials Research Center (MRC) at Missouri S&T for its support and use of equipment. J. O. acknowledges the pro- jects TechnofusionIII (S2018/EMT-4437) from Comunidad de Madrid and EU COST Action CA17126

Photorefractive response and optical damage of LiNbO3 optical waveguides produced by swift heavy ion irradiation

The photorefractive behaviour of a novel type of optical waveguides fabricated in LiNbO3 by swift heavy ion irradiation is investigated. First, the electro-optic coefficient r 33 of these guides that is crucial in the photorefractive effect is measured. Second, two complementary aspects of the photorefractive response are studied: (i) recording and light-induced and dark erasure of holographic gratings; (ii) optical beam degradation in single-beam configuration. The main photorefractive parameters, recording and erasing time constants, maximum refractive-index change and optical damage thresholds are determined. © 2009 Springer-Verlag.This work was supported by the Ministerio de Educación y Ciencia (MEC) under grants MAT2005-06359-C03 and MAT2008-06794-C03. J. Villarroel acknowledges the financial support of the MEC through his FPI fellowship.Peer Reviewe

Assessment of swift-ion damage by RBS/C: Determination of the amorphization threshold

A theoretical strategy is developed to quantitatively assess the ion-beam damage as measured by Rutherford-backscattering spectrometry under channeling conditions (RBS/C) in LiNbO3 crystals. The approach is based on a recent exciton decay model to calculate the concentration of defects generated by the incoming ions as a function of their stopping power. To describe the channeled RBS yield the model takes into account the amorphous (core) as well as the defective halo contributions to the defect tracks caused by the ion impacts. It is concluded that the halo may significantly influence the assessed damage. © 2009 Elsevier B.V. All rights reserved.Peer Reviewe

Optimization of nanopores obtained by chemical etching on swift-ion irradiated lithium niobate

International audienceThe morphology of the nanopores obtained by chemical etching on ion-beam irradiated LiNbO3 has been investigated for a variety of ions (F, Br, Kr, Cu, Pb), energies (up to 2300 MeV), and stopping powers (up to 35 keV/nm) in the electronic energy loss regime. The role of etching time and etching agent on the pore morphology, diameter, depth, and shape has also been studied. The transversal and depth profiles of the pore have been found to be quite sensitive to both irradiation and etching parameters. Moreover, two etching regimes with different morphologies and etching rates have been identified

Thick optical waveguides in lithium niobate induced by swift heavy ions (~10 MeV/amu) at ultralow fluences

International audienceHeavy mass ions, Kr and Xe, having energies in the ~10 MeV/amu range have been used to produce thick planar optical waveguides at the surface of lithium niobate (LiNbO3). The waveguides have a thickness of 40-50 micrometers, depending on ion energy and fluence, smooth profiles and refractive index jumps up to 0.04 (λ = 633 nm). They propagate ordinary and extraordinary modes with low losses keeping a high nonlinear optical response (SHG) that makes them useful for many applications. Complementary RBS/C data provide consistent values for the partial amorphization and refractive index change at the surface. The proposed method is based on ion-induced damage caused by electronic excitation and essentially differs from the usual implantation technique using light ions (H and He) of MeV energies. It implies the generation of a buried low-index layer (acting as optical barrier), made up of amorphous nanotracks embedded into the crystalline lithium niobate crystal. An effective dielectric medium approach is developed to describe the index profiles of the waveguides. This first test demonstration could be extended to other crystalline materials and could be of great usefulness for midinfrared applications