P. Mazzoldi

Effect of low dose high energy O3+ implantation on refractive index and linear electro-optic properties in X-cut LiNbO3: Planar optical waveguide formation and characterization

X-cut LiNbO3 crystals were implanted at room temperature by 5.0 MeV O3+ ions with doses ranging from 1.0×1014 to 6.0×1014 O/cm2. Secondary ion mass spectrometry profiles of atomic species migration as well as damage profiles by the Rutherford backscattering channeling technique and refractive index variation were investigated as a function of dose and subsequent annealing conditions. Two different kinds of damage produced by oxygen implantation were seen: near-surface damage correlated to electronic stopping, which causes an increase of the extraordinary refractive index, and end-of-ion range damage generated by collision cascades, which decreases the extraordinary refractive index values. The different nature of the two kinds of damage is also seen by the different temperature conditions needed for recovery. Low loss planar optical waveguides were obtained and characterized by the prism coupling technique.

Silver nanocrystals in silica by sol-gel processing

Abstract Silver nanocrystal doped silica films were prepared by the sol-gel process. The sol was prepared from 1:0.12:12:0.2:6:7 molar ratios of Si(OC2H5)4:AgNO3:H2O:HNO3:C3nH7OH:C4iH9OH. The glassy, highly transparent film with high dopant concentration (silver/silicon atomic ratio = 0.12) was successfully prepared by the dip-coating method. After drying in air at 60°C for 30 min, samples were heat-treated, in air, at 300, 350, 400, 450, 500 and 550°C using 30–100 min soaking periods for each step in a cumulative heating procedure. Measurements on the films were made by ultraviolet-visible and infrared spectroscopy, X-ray photoelectron spectroscopy, Rutherford backscattering spectrometry and transmission electron microscopy. Mechanisms of silver colloid formation in the densified silica matrix with respect to the thermal treatment are discussed. To understand the formation of silver nanocrystals from the silver silicate network, the corresponding doped bulk gel samples were analyzed by X-ray diffraction and differential scanning calorimetry.

Metal Nanocluster Composite Glasses

Publisher Summary This chapter is concerned with metal nanocluster composites formed by transition metal clusters embedded in silicate glasses, in which cluster concentration is below percolation limit (dispersed clusters); in particular, the systems are in the condition of quasi-static regime, where cluster radius is much smaller than the wavelength of the light used to probe its response and–most of all–the light used in a MNCG-based optoelectronic device. Composite materials formed by transition metal clusters embedded in glass matrices exhibit peculiar optical properties. The development of the cluster-matter field assumed a strong impact owing to the experimentalavailability of selected cluster beams and time-of-flight mass spectrometry techniques. In general, the problem of the modelization of the cluster behavior has followed either atomistic (bottom-up) approaches, which exploits ab initio techniques of the quantum chemistry, or top-down approaches, describing the cluster as a mesoscopic piece of bulk to be treated in the solid-state or statistical physics framework. This work gives particular emphasis to the third-order nonlinear optical properties, because their technological implications as well as their peculiarity in MNCGs deserve this detailed treatment. One of the greatest challenges for optics is the development of computer systems based on all-optical photonic switching devices replacing electronic ones, that is, with short time and energy consumption per switch.

Formation of copper and silver nanometer dimension clusters in silica by the sol‐gel process

Ag and Cu (pure and/or mixture) nanoclusters doped silica films were prepared by the sol‐gel process. In the case of Ag and Cu codoped silica films, Cu/Ag molar ratio was 1, 2, and 3 at constant (Ag+Cu)/SiO2 molar ratio of 0.175. Separated Ag and Cu nanoclusters are formed in the silica matrix. The size of the clusters and their distribution are dependent on the film composition. Optical absorption was measured from 185 to 800 nm. Intensity‐dependent nonlinear refractive index was measured for pure Cu and Ag–Cu (1:1 molar ratio) samples using z‐scan technique in the wavelength range from 570 to 596 nm. The measured nonlinear refractive index is of the order of 10−13 m2/W at a pulse repetition rate of 15.2 MHz.

Copper in glazes of Renaissance luster pottery: Nanoparticles, ions, and local environment

Following the recent finding that luster decorations in glazes of historical pottery consist of copper and silver nanoparticles dispersed in a glassy medium, the glaze in-depth composition and distribution of copper nanoparticles, copper ions, and their local environment have been studied in original samples of gold and red luster. The study has been fully carried out by nondestructive techniques such as Rutherford backscattering spectrometry, ultraviolet and visible spectroscopy, x-ray fluorescence, and extended x-ray absorption fine structure (EXAFS). Elemental analyses indicate that gold decorations are characterized by silver and copper, while red decorations by copper only. The color is determined mainly by metal nanoparticles. Specifically, silver nanoparticles determine the gold color, while the red color is determined by nanoparticles of copper. EXAFS measurements, carried out at the Cu K edge, indicate that in both gold and red luster copper is mostly the oxidized form (Cu+ and Cu2+) with a large...

Peculiarities and application perspectives of metal-ion implants in glasses

Abstract Ion implantation in insulators causes modifications in the refractive index as a result of radiation damage, phase separation, or compound formation. As a consequence, light waveguides may be formed with interesting applications in the field of optoelectronics. recently implantation of metals ions (e.g. silver, copper, gold, lead, etc.) showed the possibility of small radii colloidal particles formation in a thin surface layer of the glass substrate. These particles exhibit an electron plasmon resonance which depends on the optical constants of the implanted metal and on the refractive index of the glass host. The non-linear optical properties of such colloids, in particular the enhancement of optical Kerr susceptibility, suggest that the ion implantation technique may play an important role for the production of all-optical switching devices. In this paper an analysis of the state-of-the-art of the research in this field will be presented in the framework of ion implantation in glass physics and chemistry.

Finite depth square well model : Applicability and limitations

An investigation of the finite depth square well model is presented in this article: model features and limitations, concerning size dependent band gap of semiconductor quantum structures, are presented and discussed. Model predictions are compared with large sets of experimental data for III–V, II–VI and lead salt semiconductor quantum dots and quantum wires. Matrix influence on the confinement is studied by modeling experimental results for colloidal CdS, CdSe, CdTe and InP quantum dots. The effect of quantum structure dimensionality is investigated and successfully simulated for colloidal CdSe and InP experimental data and Si first-principle calculations. Finally, model limitations for narrow band gap semiconductors are studied and discussed.

Damage effects produced in the near-surface region of x-cut LiNbO3 by low dose, high energy implantation of nitrogen, oxygen, and fluorine ions

The damage effects produced in the near-surface region of x-cut LiNbO3 by low dose, high energy implantation of carbon, nitrogen, oxygen, and fluorine ions are investigated as a function of the dose and substrate temperature during the implant process. The damage profiles were obtained by the Rutherford backscattering RBS-channeling technique, whereas the compositional profiles were performed by secondary ion mass spectrometry. The experimental results showed that the mechanisms governing the damage formation at the surface are strongly connected to the interaction of defects produced when the electronic energy loss exceeds a given threshold close to 220 eV/A. In particular, we observed a damage pileup compatible with a growth of three-dimensional defect clusters.

Interaction of high‐power laser light with silver nanocluster composite glasses

The size and size distribution of silver nanoclusters embedded in soda‐lime glasses (formed by ion irradiation of Ag+–Na+ ion‐exchanged waveguides) has been modified by high‐power laser irradiation. Optical transmittance in the visible range is found to increase above the energy threshold E*=0.3±0.1 J/cm2 for λ=532 nm and E*=5±1 J/cm2 for λ=1064 nm for pulse lengths of about 10 ns. Cluster size reduction has been observed. Small radii silver nanoclusters are also formed after laser irradiation of ion‐exchanged waveguides. The optical response of the composites has been determined by optical absorption spectroscopy. Transmission electron microscopy, x‐ray photoelectron and Auger electron spectroscopies, and Rutherford backscattering spectrometry have been used to characterize the composites.

Z-scan study on the nonlinear refractive index of copper nanocluster composite silica glass

We used the Z-scan technique for measuring the nonlinear refractive index n2 of a thin composite film formed by copper nanoparticles embedded in silica glass. By varying the number of pulses of the laser shot, we evidenced heating effects induced by the laser during measurements. We were able to estimate the nonthermal refractive-index value, n2=(3.0±0.3)×10−12 cm2/W.