Silver-sodium Ion Exchange Research Articles

Dark-field spectroscopy of plasmon resonance in metal nanoislands: effect of shape and light polarization

We present the experimental dark-field scattering studies and the simulation of plasmonic properties of isolated silver nanoislands. The nanoislands were fabricated on a soda- lime glass substrate using silver-sodium ion exchange, subsequent thermal poling and annealing of the processed glass substrate in hydrogen. The morphology of the nanoislands was characterized with atomic force microscopy and scanning electron microscopy; the dimensions were 100-180 nm in base and 80-160 nm in height. We measured and modeled dark-field scattering spectra of the silver hemiellipsoidal nanoparticles differing in size and shape. The SPR position varied from 450 nm to 730 nm depending on the particle shape and dimensions. Both experiments and simulation showed a red shift of the SPR for bigger nanoislands of the same shape. Losing the axial symmetry in nanoislands resulted in the resonance splitting, while their elongation led to an increase in the scattering of p-polarized light.

The effect of electron beam irradiation on silver–sodium ion exchange in silicate glasses

It is shown experimentally that electron irradiation of sodium–silicate glasses makes possible the control of the subsequent ion exchange Ag+↔Na+ process in a salt melt. The reason of this effect is the negatively charged regions formation in a glass volume during electron irradiation. The electric field, produced by these regions in glass volume, results in positive Na+ ions field migration into them. The spatial redistribution of Na+ ions results in the decrease of the ion exchange efficiency, or the ion exchange can be even blocked. This led to the decrease of the luminescence intensity of neutral silver molecular clusters in the irradiated zone, and effect on the silver nanoparticles formation during the subsequent thermal treatment. The observed effects can be used for the control of ion exchange processes during integrated optics devices fabrication, and for the electron-beam recording of optical information.

Custom Designed Fabrication

AbstractThe silver sodium ion exchange process is a versatile and flexible technique for realizing high quality refractive microoptical elements with a high degree of freedom in design. An accurate mask technique allows for implementing a huge variety of optical functions, such as micro lens arrays with 100 % filling factor, custom designed micro lenses with different optical parameters (i. e. focal length, Numerical Aperture, sphericity, etc.) within the same array or beam shaping elements such as vortex elements. The article shows actual results and applications of these elements.

Grazing incidence small angle X-ray scattering study of silver nanoparticles in ion-exchanged glasses

The size and distribution of silver nanoparticles in ion-exchanged silicate glass induced by thermal treatments in air at different temperatures were investigated by means of grazing incidence small angle X-ray scattering technique, X-ray diffraction and optical absorption spectra. Silver–sodium ion exchange of soda-lime silicate glasses was done at 350°C for 240min, then the samples were treated by thermal annealing in air at different temperatures 400, 500 and 550°C, respectively, for 1h. After the annealing treatment above 400°C for 1h, smaller Ag nanoparticles occurred, together with bigger ones. Both dissolution of smaller Ag nanoparticles and diffusion of larger ones are discussed in these stages of annealing in this contribution.

Effective enhancement of Bi near-infrared luminescence in silicogermanate glasses via silver–sodium ion exchange

The Ag ions were introduced into the Bi doped silicogermanate glasses by Ag+ for Na+ ion exchange method. After ion exchange, the X-ray photoelectron spectroscopy (XPS) spectrum implied the Ag ions were mainly in ionic form (Ag+) within the glasses. With the increase of the Ag+ concentration, more relaxation of local structure would be induced at the non-bridging oxygen (NBO), meaning that the network gave more negative sites. Bi3+ ions could be reduced to lower valence states of Bi containing Bi near infrared (NIR) active centers with the depolymerization of glass network, resulting in the enhancement of the Bi NIR luminescence. After heat treatment, the XPS, absorption spectra and transmission electron microscope (TEM) images revealed Ag nanoparticles (Ag NPs) formed in glasses. With the increase of the Ag NPs concentration, more NBOs released from Ag+, which led to reduce more Bi3+ ions to lower valence states of Bi containing Bi NIR active centers, resulting in further enhancement of the NIR luminescence. Our research may extend the understanding of structural modulation in Bi valence states and offer a valuable way to enhance the NIR luminescence of Bi in glasses.

Cross-sectional Raman micro-spectroscopy study of silver nanoparticles in soda–lime glasses

The growth and distribution of silver nanoparticles in ion exchanged glasses induced by thermal treatments in air at different temperatures were studied by means of cross-sectional Raman micro-spectroscopy analysis. Silver–sodium ion exchange of commercial soda–lime silicate glasses was done at 320°C for 20min, then the samples were treated by thermal annealing in air at temperatures in the range between 400 and 550°C for 1h. During the post-exchange thermal treatment, a further diffusion of silver from the surface toward the bulk occurred, together with the progressive formation of silver nanoparticles, whose fractional amount increased with an increase of the annealing temperature. Their average size and the related evolution as a function of the depth and of the treatment temperature were determined by Raman micro-spectroscopy analysis of the sample cross-section. Both aggregation of silver species and growth of silver nanoclusters are discussed on the basis of the theory of homogeneous nucleation in solids.

Formation and 2D-patterning of silver nanoisland film using thermal poling and out-diffusion from glass

We fabricated silver nanoisland films and patterned silver nanoisland films using out-diffusion of silver from glass in the course of the ion-exchanged glass substrate annealing in reducing hydrogen atmosphere. The choice of the annealing conditions allows to provide prevailing of silver nanoisland formation over the formation of silver nanoparticles in the bulk of the glass. The procedure of the patterned film formation includes (i) silver-sodium ion exchange in the glass, (ii) thermal poling of the ion-exchanged glass with a profiled anodic electrode, and (iii) annealing the glass in hydrogen. The formation of silver nanoislands in unpoled regions on the glass surface allowed us to avoid any post-processing of very fragile silver island film in formation of 2D-patterned nanoisland structures. Poling of the glass with properly profiled electrode was used for the formation of random chains and ordered arrays of separate silver nanoislands. Depending on processing parameters, a typical island size in the films and chains varied from several to tens of nanometers, and was down to 200 nm in the arrays.

Silver–Sodium Ion Exchange Dynamics in LTA Zeolite Membranes

Because of their high ion exchange capacity, silver exchanged LTA (Ag-LTA) zeolites can be incorporated in polymeric materials as antibacterial agents for various purposes such as preventing biofouling in water treatment membranes due to the formation of microorganisms like bacteria, algae. Ag-LTA can be prepared by exchanging extra-framework Na+ ions in an aqueous solution containing Ag+ ions. Since the release amount and rate of Ag+ ions from the zeolite are crucial factors determining the antibacterial efficiency of these materials, it is important to understand the ion-exchange dynamics to develop membranes featuring enhanced antibacterial activity. In this work, quantum mechanical calculations and molecular dynamics (MD) simulations were employed to elucidate the effects of several parameters on Ag+/Na+ ion exchange rates in LTA-type zeolites. Two different membrane systems in which Ag-LTA crystal in contact with Na+ containing electrolyte solution and Na-LTA crystal in contact with Ag+ containing el...

SERS-active silver nanoparticle aggregates produced in high-iron float glass by ion exchange process

Silver nanoparticles were produced in iron containing float glasses by silver–sodium ion exchange and post-annealing. In particular, the effect of the concentration and the oxidation state of iron in the host glass on the nanoparticle formation was studied. After the nanoparticle fabrication process, the samples were characterized by optical absorption measurements. The samples were etched to expose nanoparticle aggregates on the surface, which were studied by optical microscopy and scanning electron microscopy. The SERS-activity of these glass samples was demonstrated and compared using a dye molecule Rhodamine 6G (R6G) as an analyte. The importance of the iron oxidation level for reduction process is discussed. The glass with high concentration of Fe 2+ ions was found to be superior in SERS applications of silver nanoparticles. The optimal surface features in terms of SERS enhancement are also discussed.

Mass transfer in thermo-electric-field modification of glass-metal nanocomposites

Complex investigations of the elemental composition and optical characteristics of glass-metal nanocomposites modified by thermo-electric-field processing are carried out. The form of the silver distribution in the glass-metal nanocomposite obtained on the basis of soda-lime silicate glass using silver-sodium ion exchange followed by the reduction of silver during thermal treatment in hydrogen atmosphere is determined. Main transport processes occurring in the nanocomposite under thermo-electric-field treatment are identified.

Ion-exchange characteristics of sodium-calcium-silicate glass: Calculation from mode spectra

The characteristics of silver-sodium ion exchange in standard commercial sodium-calcium-silicate glass are investigated using mode spectroscopy. The activation energy of the process, the silver-sodium interdiffusion coefficient, and the dependence of the maximal modulation of the refractive index on the silver nitrate concentration in the experimental salt bath are determined. The data set presented here makes it possible to specify the conditions for the formation of ion-exchange optical structures with preset parameters based on the glasses studied here.

In situ fabrication of waveguide-compatible glass-embedded silver nanoparticle patterns by masked ion-exchange process

We report a study on the properties of silver nanoparticles formed in glass using a masked silver–sodium ion-exchange technique, a process that has been used to fabricate patterned optical waveguides. Characterizations reveal that spherical nanoparticles with a diameter of 5–10 nm are concentrated below the mask edge at a depth of 50–100 nm from the surface. The amount of nanoparticles and the wavelength of the associated localized surface plasmon resonance can be controlled by the spacing between adjacent mask openings. After gentle etching, the surface morphology of the sample shows well-defined nanoparticle patterns. These closely packed nanoparticles embedded in the glass surface have a potential to be used for high-sensitivity surface enhanced spectroscopy, in a glass waveguide device.

Hybrid Neodymium-doped passively Q-switched waveguide laser

In the mid 80s, the doping of optical fibers’ core with rare earth atoms has been a major breakthrough in the field of optical telecommunications since it allowed the realization of in line optical amplifiers. However, erbium-doped fiber amplifiers are a few meters long and a huge effort has been made in order to realize compact and efficient active devices based on rare-earth-doped waveguides. For this purpose the use of phosphate glasses instead of silicate ones has been investigated because they allow a better solubility of the inserted rare earths. In this paper we present the realization of a hybrid Neodymium-doped passively Q-switched waveguide laser made by an ion-exchange on a Schott IOG-1 phosphate laser glass combined with the deposition of a bis(4-dimethylaminodithiobenzil)nickel (BDN) saturable absorber diluted in a cellulose acetate polymer cladding. In a first step, we present the continuous wave (CW) operation of the laser with an undoped cladding. We show that for a 3.5 μm wide, 1.5 cm long waveguide realized by a silver–sodium ion-exchange, a 6 mW output has been achieved by creating a Fabry–Perot cavity with dielectric multilayers mirrors sticked to the chip facets. Then, the characterizations performed on the BDN-doped layers are presented. It is shown that a proper selection of the hybrid guiding condition and saturable absorber concentration entail a non-saturated excess absorption of 3.4 dB/cm. Finally, we present the results we obtained on the Q-switched behaviour of the laser. Indeed a repetition rate of 330 kHz is achieved for a pulse energy of 10 nJ and a peak power of 1 W.

Study of deeply buried waveguides: A way towards 3D integration

Ion-exchange on glass is now a mature integrated optics technology. Indeed, many devices such as wavelength multiplexers, splitters, optical amplifiers, lasers or sensors have been already realized. The challenge now is to integrate all these functions on a single chip. Two different paths can be used to achieve this goal: the first one consists of a reduction of the waveguides’ dimensions by an increase of the refractive index change, whereas the second one, which is addressed in this paper, is based on the realization of multilayered devices. Because ion-exchange on glass allows manufacturing either surface or buried waveguides, this technology is well adapted for 3D integration. However, to realize integrated optical devices with two different layers, it is mandatory to prevent any parasitic light transfer between them. This condition can be fulfilled if the top and bottom waveguides are sufficiently separated. In this article, we present the development of ion-exchanged waveguides deeply buried into a glass substrate and their application to 3D integrated devices. Deeply buried waveguides have been realized by means of a two steps silver–sodium ion-exchange on a dedicated custom made silicate glass. First, a thermal ion-exchange has been carried out at 330 °C during 2 min in a 0.8NaNO 3–0.2AgNO 3 molten salt in order to create the core of the waveguide. Then, this core has been buried into the glass substrate by applying an electric field of 450 kV/m during 1 h 30 min in a sodium nitrate solution at 260 °C. The obtained waveguide has been measured to be 22 μm under the glass surface. It is singlemode at λ = 1.55 μm. In order to prove the good isolation between this waveguide and the surface, a top layer has been added to the device by the realization of surface channel waveguides through a thermal ion-exchange performed in a 0.8NaNO 3–0.2AgNO 3 molten salt at 330 °C during 2 min. The near-field observation of the device output has shown no coupling between the top and bottom layers demonstrating therefore the feasibility of 3D integrated optical devices by means of ion-exchange on glass.

Realization of a 980-nm/1550-nm Pump-Signal (De)multiplexer Made by Ion-Exchange on Glass Using a Segmented Asymmetric Y-Junction

In this letter, the fabrication and characterization of a broadband 980-nm/1550-nm wavelength (de)multiplexer is described. This device is adapted for pump/signal multiplexing in erbium-doped waveguide amplifiers. The structure chosen is a segmented asymmetric Y-junction, which can be fabricated with one masking level using silver-sodium ion-exchange on a silicate glass substrate. The nonresonant behavior of the Y-junction allows a wideband multiplexing with isolations increasing from (9.7plusmn0.1) dB at 1500 nm to (15plusmn0.1) dB at 1630 nm and (26plusmn1) dB at 980 nm. The total insertion losses are (2.8plusmn0.1) dB at 980 nm and (3.3plusmn0.2) dB between 1500 and 1630 nm

UV-exposed Bragg gratings for laser applications in silver-sodium ion-exchanged phosphate glass waveguides

High reflectivity Bragg gratings have been written by ArF excimer laser through a phase mask into IOG-1 hybrid phosphate glass. After grating exposure, a waveguide was fabricated by silver-sodium ion-exchange. Reflectivities around 80% at a wavelength of ~ 1535 nm were measured from the waveguide for both quasi-TE and -TM polarizations. Waveguide laser operation with the photowritten waveguide grating as another mirror was demonstrated. Output power of 3.8 mW with a pump power of 199 mW could be extracted from the laser configuration.

Prism coupling characterization of planar optical waveguides made by silver ion exchange in glass

Laboratorio de Optica Integrada, Facultad de Ciencias, Universidad de Oviedo, Spain Received 11 October 2004, revised 6 May 2005, accepted 3 June 2005 Published online 29 July 2005 PACS 02.30.Zz, 07.05.Hd, 42.79.Gn, 78.20.Bh, 78.20.Ci, 82.39.Wj A modified dark-lines method of prism-coupling technique is utilized for the experimental determination of the effective index of propagating modes in a glass planar waveguide. We use to make the waveguides a silver-sodium ion exchange in a nitrate solution and sodalime glass as substrate (microscope slides). The measurements were accomplished by direct HeNe laser beam incidence and sensing the reflected light by a Thorlabs Dec110 optical detector linked to a Protek500 digital multimeter. A LabView virtual instru-ment was implemented for the automation of the measurement process. The effective indexes measured have been used to calculate the refractive index profile by IWKB method. A comparison with other results shows that our experimental setup is suitable for slab waveguide modes characterization.

Active waveguide devices by Ag–Na ion exchange on erbium–ytterbium doped phosphate glasses

Arrays of buried channel waveguide lasers and amplifiers were fabricated by silver–sodium ion exchange in erbium–ytterbium doped phosphate glass substrates. The fabrication process, consisting of a thermal diffusion from fused salt followed by a field-assisted burial step, is optimized to get single-mode channel arrays fully compatible with standard single-mode fibres and fibre ribbon cables. The active channels were successfully tested realizing both lasers and amplifiers in the C-band suitable for optical communications. Erbium waveguide lasers exhibit a maximum output power of ∼1.7 mW and erbium-doped waveguide amplifiers provide a maximum internal gain of ∼11.3 dB at 1534 nm.

Synthesis of silver clusters in silica-based glasses for optoelectronics applications

The techniques of silver–sodium ion exchange and Ag + ion implantation in glass have been successfully applied for producing silver clusters in soda-lime glass optical waveguides. Optical absorption spectroscopy, time and spectrally resolved photoluminescence, Rutherford backscattering spectrometry, X-ray photoelectron spectroscopy and transmission electron microscopy measurements were made. Structural changes of the Ag + environment were observed in ion-exchanged samples prepared in liquids with different Ag + concentrations. Heat treatments in air and in H 2 atmospheres induced cluster formation in ion-exchanged samples through different reduction–migration mechanisms, whereas clusters formation in ion-implanted samples is related to the defect concentrations induced by the radiation damage.

Ion exchange and the mixed mobile ion effect in micro-optics applications

Silver–sodium ion exchange in aluminosilicate glasses is reviewed in the context of micro-optics fabrication. The interdiffusion coefficient is more strongly concentration dependent in glasses with high non-bridging oxygen content. Radioactive tracer diffusion coefficients show unusual behavior in glasses devoid of nonbridging oxygen. The local environments of the silver and sodium ions are related to the changes in ion exchange behavior. The modified quasi-chemical (MQC) model links these structural details to the thermodynamic description of ion exchange. The MQC model accurately describes ion exchange behavior in silicate, aluminosilicate and aluminoborate glasses. Using this model, long experimental trials are no longer necessary, and fast identification of optimal glass types and process parameters results.