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Using conventional melt-quenching and subsequent thermal treatment, Er(3+) doped CaF(2) transparent glass ceramic (GC) was prepared. X-ray diffraction and high-resolution transmission electron microscopy confirmed the formation and microstructure of CaF(2) nanocrystals in glass. An energy-dispersive spectrometer was used to investigate the distribution of Er(3+) ions and CaF(2) nanocrystals in glass. It was found that Er(3+) ions prefer to concentrate in the CaF(2) nanocrystals rather than in a glass matrix, and the amount of Er(3+) ions plays a key role in the formation of CaF(2) nanocrystals in a glass matrix with the Er(3+) ions as nucleating agent. An intense 2.7 μm emission due to Er(3+): I(11/2)4 → I(13/2)4 was achieved upon excitation at 980 nm with a laser diode, while the 2.7 μm emission can be neglected in the as-prepared glass counterpart, which confirmed the incorporation of Er(3+) ions into CaF(2) nanocrystals. An obvious enhancement of 2.7 μm emerged in the GC doped with 3% Er(3+) and heat-treated at 620 °C.

Yttrium fluoride YF3:Er(3+) and yttrium oxyfluoride YOF:Er(3+) submicron-crystals with mid-infrared fluorescent emissions were synthesized for the first time. The rhombohedral phase YOF submicron-crystals were synthesized by the crystalline phase transformation from pure orthorhombic YF3 submicron-crystals, which were prepared by co-precipitation method. The composition and morphology were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM), which showed that submicron-crystals were quasi-spherical with the particle size of ~400 nm. A novel formation mechanism of YOF submicron-crystals was proposed. Photoluminescence (PL) spectra indicated the 2.7 μm emission of Er(3+) has remarkably enhanced with the increase of Er(3+) doping concentration, and a novel dynamic circulatory energy transfer mechanism was proposed. Fourier transform infrared spectra (FTIR) were used to demonstrate the change of hydroxyl content. These oxyfluoride submicron-crystals provide a new material for nano/submicron-crystals-glass composites, and open a brand new field for the realization of mid-infrared micro/nano-lasers.

We report the synthesis of silicon nanocrystals via a one-step route, namely, femtosecond laser ablation in 1-hexene under ambient conditions. The size of these silicon nanocrystals is 2.37 ± 0.56 nm as determined by transmission electron microscopy. Fourier transform infrared spectra and X-ray photoelectron spectra indicate that the surface of the silicon nanocrystals is passivated by organic molecules and is also partially oxidized by O(2) and H(2)O dissolved in the solution. These silicon nanocrystals emit stable and bright blue photoluminescence. We suggest that the photoluminescence originates from the radiative recombination of electron-hole pairs through the oxide-related centers on the surface of the silicon nanocrystals. The decay rate of the oxide-related surface recombination can be comparable to that of the direct band gap transition. In the excitation and emission spectra, a vibrational structure with nearly constant spacings (0.18 eV) is observed. We propose that the strong electron-phonon coupling between excitons and the longitudinal optical (LO) phonons of the Si-C vibration is responsible for this vibrational structure. The fluctuations in the peak resolution, about ±0.01 eV, are ascribed to the size distribution and presence of Si-O vibrations. These silicon nanocrystals offer stable luminescence and are synthesized through a "green" and simple route. They may find important applications in many fields, such as bioimaging and environmental science.

A facile strategy based on the reaction of urea and boric acid is developed for the synthesis of toxicity-free BCNO nanocrystals containing carbon impurities and which exhibit efficient multi-color fluorescence under both single-photon and two-photon excitation.

Lanthanide doped nanoparticles (NPs) exhibit tunable X‐ray‐excited optical luminescence and X‐ray‐excited persistent luminescence (XEPL), holding broad prospects for applications in display/anti‐counterfeiting and X‐ray imaging. The development of effective strategies for multi‐dimensional applications based on lanthanide‐doped fluoride NPs are a constant challenge. Here, core–shell structured fluoride NPs, in which the heavy metal fluoride shell effectively suppresses the non‐radiative relaxation and simultaneously improve the X‐ray absorption of the shell are designed and fabricated. Under X‐ray irradiation, the developed NPs exhibit an increased number of secondary electrons which migrate to Er3+ centers at the interface and greatly improve the XEPL intensity. Additionally, the introduction of Mn2+ further enhances the XEPL intensity and offers an effective route to control the red‐green ratio of the upconversion spectrum. The NPs co‐doped with Mn2+ exhibit a bright green XEPL under X‐ray irradiation and a red emission under 1532 nm laser excitation. It is further validated that these NPs can be utilized for advanced anti‐counterfeiting and high‐resolution delayed imaging based on a film containing NPs as a scintillation screen. These findings suggest a new strategy of designing Er3+ doped NPs for multi‐dimensional applications. [ABSTRACT FROM AUTHOR]

Efficient light sources with emission spanning from visible to infrared range are of central importance for applications including precision spectroscopy and sensing. Under irradiation with constant‐wave (CW) lasers, here, the generation and modulation of incandescence‐like ultra‐broad emission (600–4000 nm) from random aggregates of metal oxide nanoparticles are demonstrated by judicious doping of free carriers, that of any existing photoluminescence process and commercial broadband light sources. It is revealed that this emission is associated with a dominant thermal origin and it is characterized by a pump‐dependent nonlinear response with the maximum order of nonlinearity exceeding 8, which is benefited from the intensified light‐matter interaction mediated by the high density of hot spots in the random plasmonic nanostructures. Moreover, by leveraging the prominent plasmon response, the emission spectra and intensity can be tuned by the Drude terms of the oxide nanoparticles. the use of this broadband infrared (IR) emission is exploited further as the light source for the demonstration of IR spectrometry, exemplified by the examination of organic molecules. The method for producing strong and continuum IR emission based on engineered plasmonic oxide can stimulate further exploitation of miniaturized IR light sources for applications including imaging and sensing. [ABSTRACT FROM AUTHOR]

Rare-earth ion-doped upconversion (UC) micro/nanoparticles (UCM/NPs) could enable the conversion of near-infrared photons to high-energy emissions in the visible and ultraviolet regions. This unique property makes UCM/NPs highly attractive for applications in diverse fields, including materials science, photophysics, and biomedicine. However, ensemble spectroscopy ignores the heterogeneity in terms of size, shape, defects, surface groups, and charges of single UCM/NPs. Recently, the rapid development of single-particle spectroscopic techniques results in a gradual shift in the investigation of UC materials to heterogeneous nanoscale structures, unique photophysical phenomena, and advanced applications of single UCM/NPs, and the optical performance of a single UCM/NP has become a central topic in the community of UC materials. In this Perspective paper, we outline the characterization methods of a single UCM/NP and provide an overview of recent and on-going progress in investigations on single UCM/NPs, with a focus on their spectroscopic properties and applications in the polarization, waveguide, micro/nano-laser, super-resolution nanoscopy, and nanobarcode. Finally, current challenges and perspectives in this field are highlighted for future research. [ABSTRACT FROM AUTHOR]

The availability of laser pulses with femtosecond duration allows materials to be subjected to higher light intensity than ever before, opening the door to the study of laser/material interactions in a new regime. Various microstructures induced by femtosecond laser have been reported, such as color centers, voids, and refractive index change. In this article, we review our recent research findings on the femtosecond laser induced microstructures in glasses, which are not only helpful for understanding the interaction process between the ultrafast laser and the glassy materials, but also valuable for the fabrication of integrated optical elements. [ABSTRACT FROM AUTHOR]

Abstract: Precipitation behaviors of metallic nanoparticles inside silicate glasses by femtosecond laser irradiation are studied in this work. Laser irradiation results easily in precipitation of metallic nanoparticles where colors depend in part on their sizes and quantities. Laser irradiation induced precipitation of metallic nanoparticles displays the different behaviors from that in the unirradiated area inside glasses and their mechanisms are investigated. [Copyright &y& Elsevier]

Abstract: In the past decades, femtosecond laser has been widely used to study the interaction between light and matter, and dynamic processes of various reactions. In this article, we review femtosecond laser-induced microfeatures in glasses and their promising applications in micro-optics and optoelectronics. Various highly localized microstructures, e.g. color center defects, refractive index change, micro-void and micro-crack, have been observed in the glasses after the femtosecond laser irradiation. The mechanisms of the observed phenomena are discussed. We also demonstrate the fabrication of various micro-optical components, e.g. three-dimensional optical memory, optical waveguide, micro-grating, micro-lens and fiber attenuator, by using the femtosecond laser-induced structures. [Copyright &y& Elsevier]

Gold nanoparticles were precipitated inside gold ion-doped glasses after irradiation by a femtosecond laser, a nanosecond laser or X-ray and successive annealing. Experimental results show that the irradiation resulted in decrease of minimum annealing temperature and critical size for the precipitation of gold nanoparticles. The observed phenomenon has promising applications for the fabrication of multi-colored images inside transparent materials, optical memory and integrated micro-optical switches. [Copyright &y& Elsevier]

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]

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]

Plasmonic spectral properties of silver nanoblocks fabricated by electron beam lithography are investigated. The extinction spectra of silver nanoblocks showed a red shift, broadening, and damping with the passage of storage time. In contrast, silver nanoblocks with titanium coating on the top did not show apparent spectral change even after storage for two months. Morphological change of the silver nanoblocks was characterized by scanning electron microscope. The present work clearly demonstrates that coating titanium on the top of the silver nanostructures is an effective way to prevent them from chemical corrosion and stabilize their plasmonic spectral properties. [ABSTRACT FROM PUBLISHER]

We report on the precipitation control of Au nanoparticles in periodic arrays in silicate glass. Au[sub 2]O-doped glass samples were first irradiated by two 800 nm interfered femtosecond laser pulses at room temperature and then heat treated at 550 °C for the Au nanoparticle precipitation in the laser irradiation areas. One-dimensional periodic arrays of the Au nanoparticles were controlled by changing the pulse energy and the incident angle between the interfered laser pulses. The smallest dimension in the obtained arrays was a width of 300 nm. The mechanism of the metal nanoparticle precipitation by this technique was discussed. Only two pulses are required to encode these periodic microstructures, which are applicable to emerging nanostructure devices such as optical memory with ultrahigh storage density, micrograting with high diffractive efficiency and integrative micro-optical switches. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We report the precipitation and control of metal nanoparticles inside transparent glasses. An Ag[sup +]-doped silicate glass sample was first irradiated by using an 800 nm femtosecond laser at room temperature and then annealed at 550 °C. The area near the focal point of the laser beam became gray after laser irradiation and yellow after further annealing at 550 °C for 10 min. Absorption and electron spin resonance spectra of the glass sample showed that a portion of silver ions near the focused part of the laser beam inside the glass were reduced to silver atoms after the laser irradiation. These silver atoms aggregated to form nanoparticles after further annealing at temperatures above 500 °C. A mechanism is suggested that consists of multiphoton reduction, which is induced by the fundamental light of the laser beam and supercontinuum white light, and diffusion of silver atoms driven by heat energy to form nanoparticles. The observed phenomenon may have promising applications for the fabrication of three-dimensional multicolored images inside a transparent material and for integrative micro-optical switches. [ABSTRACT FROM AUTHOR]

Transparent inorganic‐organic nanocomposite film (Y2O3: Eu‐PMMA)W is fabricated for solar blind UV light photo‐voltage response at room temperature. In suggested design, Y2O3: Eu nanoparticales with efficient visible luminescence excited under solar blind UV light is incorporated into an Y2O3: Eu‐PMMA nanocomposite film coated onto a glass substrate, which converts solar blind UV light to visible light that is absorbed by the Si‐detector. Photo‐voltage response from the thin film Si‐APD detector attached with the inorganic‐organic nanocomposite film demonstrates a prospective application for solar blind UV light detection. Y2O3: Eu‐PMMA film is fabricated for solar blind UV light photo‐voltage response. Y2O3: Eu nanoparticales with efficient visible luminescence excited under solar blind UV light is incorporated into an Y2O3: Eu‐PMMA nanocomposite film coated onto a glass substrate, which converts solar blind UV light to visible light that is absorbed by the Si‐detector for Photo‐voltage response. [ABSTRACT FROM AUTHOR]

Multimodal luminescence has emerged as a promising solution in the realm of anti-counterfeiting techniques, which have gained global attention due to their association with information and data security. The conventional approach to achieving multimodal luminescence typically involves combining upconversion and downshifting luminescence, which necessitates the use of external excitation sources and costly detection equipment. Herein, we develop an anti-counterfeiting strategy based on the afterglow performance of NaLuF 4 : Gd, Tm nanoparticles after X-ray excitation. The X-ray-induced Frenkel defects-base traps ensnare electrons with low kinetic energy, resulting in the creation of persistent photon traps that are responsible for the temperature-dependent afterglow intensity. The dual-band and thermo-enhanced afterglow emission can encrypt information well according to our proof-of-concept experiment and the visible light signal can be successfully captured by a smartphone camera. These unique features of NaLuF 4 : Gd, Tm nanoparticles render them highly appealing for multilevel anti-counterfeiting applications. [ABSTRACT FROM AUTHOR]

Material composition engineering and device fabrication of perovskite nanocrystals (PNCs) in solution can introduce organic contamination and entail several synthetic, processing, and stabilization steps. We report three-dimensional (3D) direct lithography of PNCs with tunable composition and bandgap in glass. The halide ion distribution was controlled at the nanoscale with ultrafast laser–induced liquid nanophase separation. The PNCs exhibit notable stability against ultraviolet irradiation, organic solution, and high temperatures (up to 250°C). Printed 3D structures in glass were used for optical storage, micro–light emitting diodes, and holographic displays. The proposed mechanisms of both PNC formation and composition tunability were verified. [ABSTRACT FROM AUTHOR]

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: Silver nanoparticles were prepared by a focused femtosecond laser irradiation in a 5mM AgNO3 solution in the presence of TiO2 sol. TEM analysis revealed that the size of silver nanoparticles was less than 20nm. A mechanism for the precipitation of silver nanoparticles was proposed. Nonlinear absorptions and optical limiting properties of silver nanoparticles contained solution were also measured. It is observed that the composite material showed strong self-focused effect and significant optical limiting property. [Copyright &y& Elsevier]

Nanocrystals with combined properties of magnetic and fluorescence are considered as “multifunctional materials” or “smart materials” which have promising biological applications including dual-modal imaging, biological research, targeted drug delivery, clinical diagnostics and therapeutics. Utilizing a green hydrothermal method, magnetic nanocrystals Ni-doped ZnAl 2 O 4 with broadband emission at ∼1200 nm have been developed as a new type of multifunctional material. The obtained ultrasmall nanocrystals in sub-10 nm range are more easily for body clearance and less toxicity in theory. Ni ions are demonstrated distribute homogeneously in +2 valance state, which provides ferromagnetism in the diamagnetic matrix of ZnAl 2 O 4 . Under the excitation of 670 nm, the whole broad emission band centered at 1200 nm fully covers the second near-infrared window (1.1–1.4 μm). These ultrasmall Ni-doped ZnAl 2 O 4 nanocrystals with magnetic-fluorescent multifunctionality open a door to more efficient and safer biological probes. [ABSTRACT FROM AUTHOR]

High energy X-rays have been widely employed in biological and medical fields because of its unlimited penetration depth in biological tissues and near-infrared (NIR) emission is considered as a preferred signal in bioimaging and biosensing. However, it remains a big challenge for nanoparticles to emit high intensity NIR light upon X-ray radiation due to the presence of defects and material's intrinsic low X-ray absorption ability. In this work, we prepare NaLuF 4 : Gd, Tm nanoparticles with different doping levels of Gd3+ and Tm3+ ions and systematically study the NIR emission properties under X-ray irradiation. NaLuF 4 : 20Gd, 1 Tm nanoparticles exhibits ∼3.5 times stronger radioluminescence at 800 nm as compared to solely Tm3+ doped nanoparticles. When X-ray induced electrons and holes recombine, Gd3+ ions serve as energy absorber and transfer the optical energy to Tm3+ ions. Excessive amount of Gd3+ ions will result in efficient energy flow to defects and apparent decreased NIR emission which can be confirmed by the lifetime curves of 3H 4 states of Tm3+ ion. We further examine the X-ray-induced afterglow intensity of nanoparticles at 800 nm and demonstrate conceptually bioimaging with a deep penetration depth using the developed nanoparticles. The clear picture taken by a NIR camera indicates the NaLuF 4 : 20Gd, 1 Tm nanoparticles can be used a promising probe for X-ray luminescence optical imaging. • NaLuF 4 : Gd, Tm nanoparticles containing different amount of Gd3+ and Tm3+ ions were prepared. • Mechanism of enhanced near-infrared emission of Gd3+-doped fluoride nanoparticles upon X-ray excitation was clarified. • A clear deep penetration bioimaging was achieved by utilizing the X-ray-induced afterglow at 800 nm. [ABSTRACT FROM AUTHOR]

In order to increase metallic state of surface and elevate dispersion of Bi 2 Te 3 nanoparticles, we synthesized nanoscaled Bi 2 Te 3 with a size of 91.4±2.2 nm via a hydrothermal method. Bi 2 Te 3 nanoparticles exhibit narrow distribution in size and uniform dispersion in several solvents, such as ethanol and polymethyl methacrylate (PMMA) solution. A Bi 2 Te 3 /PMMA flexible composite film was fabricated to further guarantee the uniformity of dispersion during the application. An open-aperture Z-scan technique was utilized to verify saturable absorption response of the Bi 2 Te 3 /PMMA composite film under 130 fs pulse at a wavelength of 800 nm. The nonlinear absorption coefficient β was fitted to be ~ 10 − 11 m / W , and the value of β slightly increased as the incident laser strengthened. A modulation depth of 15.1% and a saturation intensity of 18.9 GW/cm 2 for the composite film were also calculated. Our investigation suggests that the nanoscaled Bi 2 Te 3 /PMMA composite film could potentially be applied in large-energy laser pulses due to its high saturable intensity, and which might enlarge the application range of topological insulator (TI) materials. [ABSTRACT FROM AUTHOR]

We report on microstructure modification and local luminescence change in oxyfluoride tellurite glasses induced by a 1030 nm, 500 kHz femtosecond laser. Tellurium nanoparticles are precipitated in the laser-modified region based on X-ray diffraction analysis and transmission electron microscopy observation. Micro-Raman spectra and energy dispersive spectroscopy show that migration of ions (Te 4 + , Zn 2 + and O 2− ) and coordination state transformation of Te 4 + ions occurred after the irradiation. The luminescence property of Er 3 + -doped glass also changes in the irradiated zone. The mechanisms of above phenomena are interpreted. During the 500 kHz femtosecond laser irradiation, photo-ionization process plays a significant role in the precipitation of Te crystalline phase. The creation of sharp temperature gradient results in modification of element distribution, which leads to the coordination change of Te 4 + ions and luminescence change of Er 3 + ions. These results are of reference value to fabricate integrated optical waveguide amplifiers and lasers in oxyfluoride tellurite glasses. [ABSTRACT FROM AUTHOR]

Abstract: Upconversion, converting two or more photons into a higher energy photon, has attracted tremendous interest for the wide applications ranging from science to engineering, yet always suffered from the shortcoming of low efficiency. We propose and demonstrate an approach to improve the upconversion efficiency by multi-wavelength excitation in Er3+ doped NaYF4 nanoparticles. Compared to the sum of emission intensities excited by two single-wavelength (790nm and 1520nm) separately, the green and red emissions from NaYF4: 1%Er nanoparticles excited by two-wavelength simultaneously are enhanced by a factor of 3.05 and 1.53, respectively. Ground state absorption and excited state absorption are considered to be the microscopic mechanism of the observed phenomenon. Our conception of improving the upconversion luminescence with multi-wavelength excitation might be a potential solution for the efficient ulilization of near infrared light by solar cells. [Copyright &y& Elsevier]

Up-conversionluminescence in rare earth ions (REs) doped nanoparticles has attractedconsiderable research attention for the promising applications insolid-state lasers, three-dimensional displays, solar cells, biologicalimaging, and so forth. However, there have been no reports on REsdoped nanoparticles to investigate their polarized energy transferup-conversion, especially for single particle. Herein, the polarizedenergy transfer up-conversion from REs doped fluoride nanorods isdemonstrated in a single particle spectroscopy mode for the firsttime. Unique luminescent phenomena, for example,sharpenergy level split and singlet-to-triplet transitions at room temperature,multiple discrete luminescence intensity periodic variation with polarizationdirection, are observed upon excitation with 980 nm linearly polarizedlaser. Furthermore, nanorods with the controllable aspect ratio andsymmetry are fabricated for analysis of the mechanism of polarizationanisotropy. The comparative experiments suggest that intraions transitionproperties and crystal local symmetry dominate the polarization anisotropy,which is also confirmed by density functional theory calculations.Taking advantage of the REs based up-conversion, potential applicationin polarized microscopic multi-information transportation is suggestedfor the polarization anisotropy from REs doped fluoride single nanorodor nanorod array. [ABSTRACT FROM AUTHOR]

Abstract: Transparent glasses containing copper nanoparticles are promising materials for ultrafast all-optical switches in the THz region due to their wide range of resonant absorption frequencies, ultrafast time response, as well as large third-order nonlinear optical coefficients associated with the surface plasmon resonance (SPR) in the visible region. In this paper, three dimension controllable precipitation of copper nanoparticles inside a borosilicate glass by irradiation of femtosecond laser pulses is studied. According to the designed program, different patterns made up of copper nanoparticles can be induced inside the glass sample. Absorption spectra are used to confirm the precipitation of copper nanoparticles. The precipitated nanoparticles can be space-selectively “dissolved” by the second time femtosecond laser irradiation. The involved mechanisms are discussed. [Copyright &y& Elsevier]

Abstract: Transparent glass samples doped with bismuth nanoparticles are prepared by heat treatment of as-made glass samples. According to the results of X-ray diffraction, transmission electron microscopy, and energy-dispersive X-ray spectra, Bi nanoparticles are well distributed inside glasses after heat treatment. The average size of Bi nanoparticles increases with the increasing of heat treatment temperature. Because of the size effect and multiple scattering of nanoparticles, the fundamental absorption edge shows a red-shift behavior with the increasing of heat treatment temperature. Nonlinear optical properties of Bi nanoparticles doped glasses are investigated by using Z-scan technique. The maximum value of χ (3) of the glasses is estimated to be 2.49×10−7 esu at 800nm. These results indicate that Bi nanoparticles doped glasses may be promising as material for optical switching. [Copyright &y& Elsevier]

Abstract: We report on highly localized precipitation of copper nanoparticles in borate glasses by irradiation with femtosecond laser pulses. The area in the vicinity of the laser focal point of an 800nm femtosecond laser inside the glass sample became red due to the precipitation of copper nanoparticles after the femtosecond laser irradiation. The precipitation of copper nanoparticles was confirmed by transmission electron microscopy images, electron energy-loss spectra and absorption spectra. The average power of the femtosecond laser and the irradiation time are two important factors related to the formation of the precipitates. The mechanism of the precipitation of copper nanoparticles is discussed. [Copyright &y& Elsevier]

Abstract: This paper reports the measurements of the bulk plasmon of Bi nanoparticles supported by a SiO2 matrix using electron energy-loss spectroscopy. The blue shifts of plasmon peak in small particles were observed. However, the degree of shift was much smaller than the previous study in the literature and cannot be interpreted by the quantum confinement. [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 obtain Au and Ag nanoparticles precipitated in glasses by irradiation of focused femtosecond pulses, and investigate the nonlinear absorptions of the glasses by using Z-scan technique with ns pulses at 532nm. We observe the saturable absorption behavior for Au nanoparticles precipitated glasses and the reverse saturable ones for Ag ones. We also obtain, by fitting to the experimental results in the light of the local field effect near and away from the surface plasmon resonance, and 5.9×10−8 esu for the imaginary parts of the third-order susceptibilities for Au and Ag nanoparticles, respectively. The nonlinear response of Au nanoparticles in the glass samples arises mainly from the hot-electron contribution and the saturation of the interband transitions near the surface plasmon resonance, whereas that of Ag nanoparticles in the glass samples from the interband transitions. These show that the obtained glasses can be used as optoelectronic devices suiting for different demands. [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]

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]

A Cr4+ activated NIR-NIR multi-mode luminescent nanothermometer was achieved for temperature sensing of double biological windows. The demonstration for sensing occurring in tissue overcomes the limitations of current materials, such as lanthanide-doped nanoparticles. • Employing transition metal, Cr4+ as the emitters for optical nanothermometers. • Synthesizing Cr4+-doped aluminosilicate Ca 2 Al 2 SiO 7 : Cr4+ nanoparticle. • Being excited in first biological window and emit in second biological window. • Allowing for a multi-mode temperature thermal sensing within a single probe. • Demonstrating its sensitivity superiority in NIR deep tissue imaging. Remote temperature sensing in biological media is used to monitor intracellular evolutionary process reliably, and is potentially applied in the field of diagnostics and therapeutics. Ideally, such nanothermometers should be functional in biological optical transparency windows across a wide range of broad absorption and emission bands, strong luminescence and larger Stokes shift. Here, this is achieved via using NIR-to-NIR transition metal (Cr4+)-doped aluminosilicate nanoparticles as multiparametric thermal sensing probes. They can be excited in first biological window and emitted in second biological window, allowing for large optical penetration into tissues while maintaining high-spatial resolution. We also demonstrate that the phenomena of temperature-induced population redistribution and temperature-induced spectral red-shift (maximum thermal sensitivity is 0.61% °C−1, superior to the most of the current materials), essentially allow for a multi-mode thermal sensing within a single probe towards to a very different optical response. We believe that these findings can be expanded a wide range of promising applications using transition metal-activated luminescent nanoparticles as nanothermometers in deep tissue temperature measurements of biological and biochemical. [ABSTRACT FROM AUTHOR]

Abstract: We have investigated the space selective precipitation of silver nanoparticles inside Er3+ and Ag+ co-doped silicate glasses by focused femtosecond laser irradiation. Local heating effect of erbium resulted in direct precipitation of silver nanoparticles. We suggest that the local heating effect of Er3+ ions be also helpful to directly fabricate functional nanoparticles other than silver nanoparticles in transparent glasses. [Copyright &y& Elsevier]

Abstract: α-Bi2O3 nanoparticles have been produced by femtosecond laser ablation in ethanol at room temperature. Their crystal structure, crystal phase, shape and size distribution, and photophysical property are investigated using X-ray diffraction, Raman, transmission electron microscopy (TEM), high-resolution TEM and UV–vis spectroscopy. The α-Bi2O3 nanoparticles produced by laser ablation with two particle size population distributions having the mean particle size of ∼10 and ∼60nm exhibited a good photocatalytic activity on the photodegradation of indigo carmine under 365nm light emitting diode irradiation. [ABSTRACT FROM AUTHOR]