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Infrared-transparent 3 mol% tetragonal zirconia polycrystalline (3Y-TZP) ceramics with small grain size were fabricated by pre-sintering in an oxygen atmosphere and hot isostatic pressing (HIP). The microstructure, mechanical, optical, and elevated-temperature properties of the ceramics were investigated. Pre-sintering in an oxygen atmosphere suppressed the grain growth effectively, and the grain size reached approximately 138 nm. The small grain size led to an increased Vickers hardness of 13,790 MPa. The ceramics also exhibited a high transmittance of 76–78% in the range of 3–5 µm. The in-line transmittance remained stable with the temperature elevated to 400 °C. Overall, the results indicated that pre-sintering in an oxygen atmosphere and HIP was an effective method to prepare infrared-transparent 3Y-TZP ceramics with small grain size. [ABSTRACT FROM AUTHOR]

This Letter, reports the focused-femtosecond-laser induced dissolution of gold nanoparticles in an Au+-doped glass. Gold nanoparticles, pre-precipitated in the glass either by thermal treatment or by irradiation of a focused femtosecond laser and successive thermal treatment, are broken to dissolve when they are reirradiated by a focused femtosecond laser. It is suggested that the dissolution of gold nanoparticles is due to dramatically increasing in the temperature of gold nanoparticles, resulting from the energy absorbing from the femtosecond laser. A repeatable process of precipitation and dissolution of gold nanoparticles is also realized anywhere selected inside the glass, so does the control of the size of gold nanoparticles. [Copyright &y& Elsevier]

Highlights • A novel oxyfluorogallate glass with good mid-infrared property was provided. • Femtosecond surface damage characteristics of oxyfluorogallate glass are investigated. • Femtosecond nonlinear effect is studied to explain the damage mechanism. • Surface damage thresholds show an evident reduction as pulses number increasing. • No changes on the chemistry structure occur after femtosecond laser ablation. Abstract The femtosecond laser-induced damage characteristics of a novel oxyfluorogallate glass with good mid-infrared property are analyzed in detail and the surface-damage thresholds for single- and multi- pulses ablation are determined and an evident reduction trend is obtained. The nonlinear absorption coefficient measured through the femtosecond laser z-scan method is used to explain the damage mechanism according to the calculation of Keldysh parameter. The ablation characteristics of the oxyfluorogallate glass demonstrated a clear evidence of melting and the ablation rate decreased in the presence of the melting phenomenon. Based on subsequent X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy analyses, the chemistry of the mid-infrared oxyfluorogallate glass appeared to remain constant before and after femtosecond laser ablation. This work provides a reference to manufacture infrared optical devices and is useful in promoting the application of the mid-infrared glass material. [ABSTRACT FROM AUTHOR]

Abstract: Photoluminescence of undoped and B-doped ZnO in silicate glasses was investigated by varying the concentration of ZnO (35–50mol%) and B dopant (0–10mol%) in the glass matrices. The broad and intense near band edge emissions were observed while the visible light emission was very weak. UV luminescence in all samples was red-shifted relative to the exciton transition in bulk ZnO and enhanced by decreased ZnO concentration due to higher degree of structural integrity and the lower aggregation degree of ZnO. Donor B dopant played the double roles of filling conduction bands to broaden band gap when its concentration was lower than 5mol%, and emerging with conduction bands to narrow the gap when B dopant exceeded this value. [Copyright &y& Elsevier]

Abstract: The morphology of materials resulting from laser irradiation of the single-layer and the multilayer amorphous Ge2Sb2Te5 films using 120fs pulses at 800nm was observed using scanning electron microscopy and atomic force microscopy. For the single-layer film, the center of the irradiated spot is depression and the border is protrusion, however, for the multilayer film, the center morphology changes from a depression to a protrusion as the increase of the energy. The crystallization threshold fluence of the single-layer and the multilayer film is 22 and 23mJ/cm2, respectively. [Copyright &y& Elsevier]

Abstract: We report on space-selective co-precipitation of silver and gold nanoparticles in Ag+, Au3+ co-doped silicate glasses by irradiation of femtosecond laser pulses and subsequent annealing at high temperatures. The color of the irradiated area in the glass sample changed from yellow to red with the increase of the annealing temperature. The effects of average laser power and annealing temperature on precipitation of the nanoparticles were investigated. A reasonable mechanism was proposed to explain the observed phenomena. [Copyright &y& Elsevier]

Abstract: We report the space selective precipitation of Pd nanoparticles in Pd2+-doped silicate glass by ultrashort laser pulses irradiation and further annealing. Absorption spectra, transmission electron microscopy, refractive index measurement and Z-scan technique demonstrated that metallic Pd nanoparticles were precipitated in the glass sample after irradiation by an 800-nm femtosecond laser and subsequent annealing at 600°C. We discuss a refractive index change and nonlinear absorption that combines the precipitation of Pd nanoparticles. [Copyright &y& Elsevier]

Abstract: Crystallization is achieved in amorphous Ge2Sb2Te5 films upon irradiation with a single femtosecond laser pulse. Transmission electron microscopy images evidence the morphology of the crystallized spot which depends on the fluence of the femtosecond laser pulse. Fine crystalline grains are induced at low fluence, and the coarse crystalline grains are obtained at high fluence. At the damage fluence, ablation of the films occurs. [Copyright &y& Elsevier]

We report on precipitation of Ag nanoparticles in silicate glasses by a femtosecond laser irradiation and successive annealing. Effect of Al2O3 on the precipitation of Ag nanoparticles in glasses was investigated. Absorption spectra show that introducing a small amount of Al2O3 results in inhibition of color centers generation and an apparent increase of the annealing temperature for the precipitation of Ag nanoparticles. The mechanisms of the observed phenomena are discussed. [Copyright &y& Elsevier]

Nonlinear absorptions of Au nanoparticles precipitated silicate glasses by irradiation of a focused femtosecond pulsed laser were investigated using Z-scan technique with 8 ns pulses at 532 nm. Optical limiting (OL) effects in such glasses have been also measured. It is observed that the behaviors of transition from saturable absorption to reverse saturable absorption and the OL performances for different samples are significantly different, which depend drastically on the irradiation power density of the femtosecond laser used for the Au nanoparticles precipitation in the glass. Strong nonlinear absorptions in these samples are mainly attributed to the surface plasmon resonance (SPR) and free carrier absorptions of the precipitated Au nanoparticles. [Copyright &y& Elsevier]

Optical nonlinearities of Au nanoparticles precipitated inside glasses induced by irradiation of a focused femtosecond laser were investigated using Z-scan technique with 8 ns pulses at 532 nm. The transformation behaviors both from self-defocusing to self-focusing and from saturable absorption to reverse saturable absorption were observed in the glass samples, which depend drastically on the irradiation power density of the femtosecond laser used. The optical nonlinearities were analyzed in detail and proved numerically by the excited-state theory of conduction band electrons. [Copyright &y& Elsevier]

Abstract: We report on the precipitation of Si nanocrystals inside a borosilicate glass by using an 800nm, 250kHz femtosecond laser irradiation, which was confirmed with X-ray diffraction, Raman spectra and transmission electron microscopy analyses. Refractive index profile reveals that the refractive index of the Si nanocrystals precipitated region increased up to 8.7% in comparison with that of the unirradiated area, leading to a large diffraction efficiency of the fabricated dot structure. Furthermore, the third-order optical nonlinearity of the Si nanocrystals precipitated glass is greatly enhanced based on the Z-scan measurement. These results may find applications for the fabrication diffractive optical devices and optical switches. [Copyright &y& Elsevier]

Abstract: We report femtosecond laser induced valence state and refractive index change in transparent Sm3+-doped fluoroaluminate glass. The effect of annealing on the induced changes was studied and the thermal stability of these changes was discussed. The results show that the femtosecond laser induced valence state change is more stable than the induced refractive index change. The observed phenomenon could be applied to design the thermally erasable or stable storage medium. [Copyright &y& Elsevier]

Abstract: Broadband infrared luminescence is observed in various Bi-doped oxide glasses prepared by conventional melting-quenching technique. The absorption spectrum of the Bi-doped germanium oxide glass consists of five broad peaks at below 370, 500, 700, 800 and 1000nm. The fluorescence spectrum exhibits a broad peak at about 1300nm with full width at half maximum (FWHM) of more than 300nm when excited by an 808nm laser diode. The fluorescence lifetime at room temperature decreases with increasing Bi2O3 concentration. Influence of the glass composition and melting atmosphere on the fluorescence lifetime and luminescent intensity is investigated. The mechanism of the broadband infrared luminescence is suggested. The product of stimulated emission cross-section and lifetime of the Bi-doped aluminophosphate glass is about 5.0×10−24 cm2 s. The glasses might be promising for applications in broadband optical fiber amplifiers and tunable lasers. [Copyright &y& Elsevier]

Abstract: We report on three-dimensional precipitation of Au nanoparticles in gold ions-doped silicate glasses by a femtosecond laser irradiation and further annealing. Experimental results show that PbO addition plays the double roles of inhibiting hole-trapped centers generation and promoting formation and growth of gold nanoparticles. Additionally, glass containing PbO shows an increased non-linear absorption after femtosecond laser irradiation and annealing. The observed phenomena are significant for applications such as fabrications of three-dimensional multi-colored images inside transparent materials and three-dimensional optical memory, and integrated micro-optical switches. [Copyright &y& Elsevier]

Abstract: The doped Eu3+ ions can be partly reduced to Eu2+ in a series of MO–B2O3: Eu (M=Ba, Sr, Ca) glasses synthesized in air atmosphere, but not in the 12CaO–7Al2O3: Eu glass. The different redox-behavior of Eu ions in these two glass systems is attributed to the different host optical basicity. It is found that a lower valence state of Eu2+ is more favorable in acidic glasses, which have lower optical basicities. A notion of the critical value of optical basicity is introduced empirically, which can be used as a guide for the selection of glass composition suitable to incorporate Eu2+ for luminescence. [Copyright &y& Elsevier]

Abstract: We report a method for the selective introduction of fluorescent Ag nanoclusters in glass. Extinction and photoluminescence spectra show that a fraction of the Ag atoms are generated through femtosecond laser induced multiphoton reduction and then aggregate to form Ag nanoclusters after heat treatment. Red luminescence from the irradiated region is observed under blue or green laser excitation. The fluorescence can be attributed to interband transitions within Ag nanoclusters. This method provides a novel route to fabricate fluorescent nanomaterials in 3D transparent materials. [Copyright &y& Elsevier]

Abstract: We report transparent Ni2+-doped ZnO–Al2O3–SiO2 system glass-ceramics with broadband infrared luminescence. After heat-treatment, ZnAl2O4 crystallite was precipitated in the glasses, and its average size increased with increasing heat-treatment temperature. No infrared emission was detected in the as-prepared glass samples, while broadband infrared luminescence centered at 1310nm with full width at half maximum (FWHM) of about 300nm was observed from the glass-ceramics. The peak position of the infrared luminescence showed a blue-shift with increasing heat-treatment temperature, but a red-shift with an increase in NiO concentration. The mechanisms of the observed phenomena were discussed. These glass-ceramics are promising as materials for super broadband optical amplifier and tunable laser. [Copyright &y& Elsevier]

Abstract: We report ultrabroad infrared luminescence from Bi-doped aluminogermanate glasses. The infrared luminescence almost covers the whole low loss wavelength region (1200–1650 nm) of silica glass fiber when excited by a diode laser at 980 nm. The full width at half maximum (FWHM) of the luminescence is 510 nm. The luminescence peak can be divided into three Gaussian peaks, and the fluorescence lifetime of the three emissions are 297 μs, 470 μs and 1725 μs, respectively. These fluorescence properties indicate that the glasses are promising material for broadband optical amplifiers. [Copyright &y& Elsevier]

Abstract: Broadband infrared luminescence covering the optical telecommunication wavelength region of O, E and S bands was observed from bismuth-doped zinc aluminosilicate glasses and glass-ceramics. The spectroscopic properties of the glasses and glass-ceramics depend on the thermal-treatment history. With the appearance of gahnite (ZnAl2O4) crystalline phase, the fluorescent peak moves to longer wavelength, but the fluorescent intensity decreases. The ∼1300nm fluorescence with a FWHM larger than 250nm and a lifetime longer than 600μs possesses these optical materials with potential applications in laser devices and broadband amplifiers. The broad infrared luminescence from the bismuth-doped zinc aluminosilicate glasses and glass-ceramics might be from BiO or bismuth clusters rather than from Bi5+ and Bi3+. [Copyright &y& Elsevier]

Abstract: We report on the effect of various alkaline-earth metal oxides on the broadband infrared luminescence covering 1000–1600 nm wavelength region from bismuth-doped silicate glasses. The full width at half maximum (FWHM) of the infrared luminescence and the fluorescent lifetime is more than 200 nm and 400 μs, respectively. The fluorescent intensity decreases with increasing basicity of host glasses. Besides the broadband infrared luminescence, luminescence centered at 640 nm was also observed, which should be ascribed to Bi2+ rather than to the familiar Bi3+. We suggest that the infrared luminescence should be assigned to the transition of BiO molecules dispersed in the host glasses. [Copyright &y& Elsevier]

Abstract: The structure of the titanate glass is destroyed during irradiation by the femtosecond laser pulses, and (TiO6)8− and (TiO4)4− anion units are exsolved from the network of the titanate glass. These anion units are rearranged to form some crystals such as anatase and Ba2TiO4 crystals. By Raman spectroscopy, it is found that these crystals have a strong dependence on the intensity of the femtosecond laser pulses. The relation between the generation of these crystals and space distribution of the femtosecond laser power intensity is qualitatively explained. [Copyright &y& Elsevier]

Abstract: The broadband luminescence covering 1.2–1.6μm was observed from bismuth and aluminum co-doped germanium oxide glasses pumped by 808nm laser at room temperature. The spectroscopic properties of GeO2:Bi,Al glasses strongly depend on the glass compositions and the pumping sources. To a certain extent, the Al3+ ions play as dispersing reagent for the infrared-emission centers in the GeO2:Bi,Al glasses. The broad infrared luminescence with a full width at half maximum larger than 200nm and a lifetime longer than 200μs possesses these glasses with the potential applications in broadly tunable laser sources and ultra-broadband fiber amplifiers in optical communication field. [Copyright &y& Elsevier]

Abstract: Crystallization in amorphous Ge2Sb2Te5 films by irradiation with femtosecond laser was investigated. The reflectivity and X-ray diffraction measurements confirmed that the crystalline state has been achieved in amorphous Ge2Sb2Te5 films under the irradiation of femtosecond laser with an average power of 65 mW at a frequency of 1000 Hz and a pulsed width of 120 fs. The surface morphology before and after femtosecond laser irradiation was studied by scanning electron microscope; results showed that the surface of films with irradiation of femtosecond laser was composed of some the crystallized micro-region. [Copyright &y& Elsevier]

Zinc borosilicate glass is studied as a scintillating material. Glass samples with zinc oxide concentrations as high as 60 mol% were prepared successfully without deteriorating the glass-forming ability. Different post-preparation thermal treatments were carried out on the samples in the temperature range of 300–700°C and for 3–8 h duration. A dominant emission band was observed near 400 nm in the luminescence spectra with the excitation peak near 260 nm. Photoluminescence decay kinetics shows dominant decay times of about 7–10 and 170–200 ns with a weak tail down to several tens of microseconds. Thermal treatment was found to enhance the 400 nm emission intensity several times with respect to an as-prepared sample and X-ray diffraction analysis confirmed the presence of ZnO crystallized phase in heavily annealed glass samples. [Copyright &y& Elsevier]

Abstract: Luminescences from bismuth-doped lime silicate glasses were investigated. Luminescences centered at about 400, 650, and 1300nm were observed, excited at 280, 532 and 808nm, respectively. These three luminescence bands arise from three different kinds of bismuth ions in the glasses. The visible luminescences centered at 400 and 650nm arise from Bi3+, and Bi2+, respectively. The infrared luminescences cover the wavelength range from 1000 to 1600nm when exited by an 808nm laser diode. The full width at half maximum (FWHM) of the infrared luminescences is more than 205nm. The intensity of the infrared luminescence decreases with the increment in CaO content. We suggest that the infrared luminescences might arise from Bi+. Such broadband luminescences indicate that the glasses may be potential candidate material for broadband fiber amplifiers and tunable lasers. [Copyright &y& Elsevier]

Abstract: In an attempt to form space-selective color centers in LiF crystal, photon-induced color centers were continuously created by focusing an ultra-fast intense laser through a microscope objective and translating the LiF crystal sample perpendicular to the axis of the laser beam. The resulting stable color centers region was induced inside the LiF crystal along the path traversed with the focal point of the laser. The measured absorption spectra of color center regions express that it is possible to form space-selective lasing color centers in LiF crystal by the irradiation of ultra-fast intense laser. [Copyright &y& Elsevier]