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1.
Two-dimensional crystal curved lines consisting of the nonlinear optical SmxBi1−xBO3 phase are fabricated at the surface of 8Sm2O3·37Bi2O3·55B2O3 glass by continuous wave Nd:YAG laser (wavelength: 1064 nm) irradiation (samarium atom heat processing) with a power of ∼0.9 W and a laser scanning speed of 5 μm/s. The curved lines with bending angles of 0-90° or with sine-shapes are written by just changing the laser scanning direction. The polarized micro-Raman scattering spectra for the line after bending are the same as those for the line before bending, indicating that the crystal plane of SmxBi1−xBO3 crystals to the crystal growth direction might be maintained even after the change in the laser scanning direction. It is found from laser scanning microscope observations that the crystal lines at the surface are swelled out smoothly, giving a height of about 10 μm.  相似文献   

2.
Zinc oxide (ZnO) thin films were deposited on the gallium nitride (GaN) and sapphire (Al2O3) substrates by pulsed laser deposition (PLD) without using any metal catalyst. The experiment was carried out at three different laser wavelengths of Nd:YAG laser (λ = 1064 nm, λ = 532 nm) and KrF excimer laser (λ = 248 nm). The ZnO films grown at λ = 532 nm revealed the presence of ZnO nanorods and microrods. The diameter of the rods varies from 250 nm to 2 μm and the length varies between 9 and 22 μm. The scanning electron microscopy (SEM) images of the rods revealed the absence of frozen balls at the tip of the ZnO rods. The growth of ZnO rods has been explained by vapor-solid (V-S) mechanism. The origin of growth of ZnO rods has been attributed to the ejection of micrometric and sub-micrometric sized particulates from the ZnO target. The ZnO films grown at λ = 1064 nm and λ = 248 nm do not show the rod like morphology. X-ray photoelectron spectroscopy (XPS) has not shown the presence of any impurity except zinc and oxygen.  相似文献   

3.
We report on the femtosecond laser micromachining of photo-induced embedded diffraction grating in flexible Poly (Dimethly Siloxane) (PDMS) plates using a high-intensity femtosecond (130 fs) Ti: sapphire laser (λp = 800 nm). The refractive index modifications with diameters ranging from 2 μm to 5 μm were photo-induced after the irradiation with peak intensities of more than 1 × 1011 W/cm2. The graded refractive index profile was fabricated to be a symmetric around from the center of the point at which femtosecond laser was focused. The maximum refractive index change (Δn) was estimated to be 2 × 10−3. By the X-Y-Z scanning of sample, the embedded diffraction grating in PDMS plate was fabricated successfully using a femtosecond laser.  相似文献   

4.
Single crystals of glycine nitrate [(C2H6NO2)+ · (NO3)] were grown using submerged seed solution method. The crystals were characterized by using single crystal X-ray diffraction and density measurements. Spectroscopic, thermal and optical studies were carried out for analyzing the presence of the functional groups, thermal stability, decomposition and transparency of the sample. These studies showed that the crystals are thermally stable upto 145 °C and transparent for the fundamental and second harmonic generation of Nd:YAG (λ = 1064 nm) laser. Second harmonic generation (SHG) conversion efficiency was investigated to explore the NLO characteristics of this material. Microhardness and dielectric studies were also carried out.  相似文献   

5.
The 96GeO-(3-χ)Al2O3-χNa2O-1NaBiO3 (χ = 0, 0.5, 1.5 molar percent designated as A1, A2 and A3) and 96GeO-(3.5-ψ)Al2O3-ψNa2O-0.5Bi2O3 (ψ = 0.5, 1, 2 molar percent designated as B1, B2 and B3) glasses were prepared by conventional melting method with the measurement of their DTA curve, fluorescence decay curve, transmission, absorption and emission spectra. The near infrared superbroadband emission characteristics of the A1, A2, B1 and B2 glasses peak at ∼1220 nm were observed when pumped by an 800 nm laser diode. The stimulated emission cross section (σp) was obtained from the emission spectra. The result indicated that the introduction of Bi5+ in NaBiO3 into raw materials could increase the emission intensity of the obtained glasses by 5.6 times than that of Bi3+ in Bi2O3, and the FWHM (Δλ) and emission lifetime (τ) at 1220 nm increased from 195 nm to 275 nm, and 280 μs to 434 μs. Meanwhile, it was found that the absorption edges were blue-shifted from 486 to 447 nm by comparing those of A1 and B1. The absorption edges were considered to be ascribed to the charge transfer from Bi3+ 6s2 to Bi5+ 6s0. Therefore we could conclude that the content of Bi5+ ions in A1 was more than that in B1 glasses. It could be deduced from the emission and absorption spectra that the stronger emission intensity and wider FWHM were due to the higher concentration of Bi5+ ion in glass. In particular, the increase of Na2O content was in proportion to the thermal stability and the value of σp × τ and σp × Δλ of glasses.  相似文献   

6.
Laser irradiation of glass materials has drawn much attention because this technique can offer a new processing method for spatially selected structural modification and/or crystallization in glass. Crystallized line and dot patterns at the micrometer scale were fabricated on the surface of Sm-doped sodium borate (Na2O-B2O3) glass by irradiation of a continuous-wave Nd:YAG laser at λ = 1064 nm. The pattern sizes could be controlled by adjusting such parameters as scan rate, exposure time, and laser power. Analyses by Raman spectroscopy and X-ray diffraction revealed that the crystalline phase is Na3Sm2(BO3)3.  相似文献   

7.
Semiconductor nanostructures with narrow band gap were synthesized by means of laser chemical vapor deposition (LCVD) of elements from iron carbonyl vapors [Fe(CO)5] under the action of Ar+ laser radiation (λL = 488 nm) on the Si substrate surface. The temperature dependence of the specific conductivity of these nanostructures in the form of thin films demonstrated typical semiconductor tendency and gave the possibility to calculate the band gap for intrinsic conductivity (Eg) and the band gap assigned for impurities (Ei), which were depended upon film thickness and applied electrical field. Analysis of deposited films with scanning electron microscopy (SEM) and atomic force microscopy (AFM) demonstrated their cluster structure with average size not more than 100 nm. Semiconductor properties of deposited nanostructures were stipulated with iron oxides in different oxidized phases according to X-ray photoelectron spectroscopy (XPS) analysis.These deposited nanostructures were irradiated with Q-switched YAG laser (λL = 1064 nm) at power density about 6 × 107 W/cm2. This irradiation resulted in the crystallization process of deposited films on the Si substrate surface. The crystallization process resulted in the synthesis of iron carbide-silicide (FeSi2−xCx) layer with semiconductor properties too. The width of the band gap Eg of the synthesized layer of iron carbide-silicide was less than for deposited films based on iron oxides Fe2O3−x (0 ≤ x ≤ 1).  相似文献   

8.
The synthesis by pulsed laser deposition technique of zinc oxide thin films suitable for gas sensing applications is herein reported. The ZnO targets were irradiated by an UV KrF* (λ = 248 nm, τFWHM ∼7 ns) excimer laser source, operated at 2.8 J/cm2 incident fluence value, whilst the substrates consisted of SiO2(0 0 1) wafers heated at 150 °C during the thin films growth process. The experiments were performed in an oxygen dynamic pressure of 10 Pa. Structural and optical properties of the thin films were investigated. The obtained results have demonstrated that the films are c-axis oriented. Their average transmission in the visible-infrared spectral region was found to be about 85%. The equivalent refractive indexes and extinction coefficients were very close to those of the tabulated reference values. Doping with 0.5% Au and coating with 100 pulses of Au clusters caused but a very slight decrease (with a few percent) of both transmission and refractive index values. The coatings with the most appropriate optical properties as waveguides have been selected and their behavior was tested for butane sensing.  相似文献   

9.
Thin nano-structured carbon films have been deposited in vacuum by pulsed laser ablation, from a rotating polycrystalline graphite target, on Si 〈1 0 0〉 substrates, kept at temperatures ranging from RT to 800 °C. The laser ablation was performed by a Nd:YAG laser, operating in the near IR (λ = 1064 nm).X-ray diffraction analysis, performed at grazing incidence angle, both in-plane (ip-gid) and out-of-plane (op-gid), has shown the growth of oriented nano-sized graphene particles, characterised by high inter-planar stacking distance (d? ∼ 0.39 nm), compared to graphite. The film structure and texturing are strongly related both to laser wavelength and substrate temperature: the low energy associated to the IR laser radiation (1.17 eV) generates activated carbon species of large dimensions that, also at low T (∼400 °C), easy evolve toward more stable sp2 aromatic bonds, in the plume direction. Increasing temperature the nano-structure formation increases, causing a further aggregation of aromatic planes, voids formation, and a related density (by X-ray reflectivity) drop to very low values. SEM and STM show for these samples a strongly increased macroscopic roughness. The whole process, mainly at higher temperatures, is characterised by a fast kinetic mode, far from equilibrium and without any structural or spatial rearrangement.  相似文献   

10.
Nanoscale surface modification of silicate glasses was examined by applying nanoimprint technique using a nanostriped NiO thin film mold. The mold had the pattern composed of regularly arranged straight nanogrooves, which was formed by high-temperature annealing of the Li-doped NiO epitaxial thin film deposited on the atomically stepped sapphire (α-Al2O3 single crystal) substrate. The glass imprint was proceeded through the simple steps of heating (∼600 °C), pressing (∼1 kPa) and then cooling in air. The nanoimprinted glass surface transferred reversely from the mold exhibited the multi nanowire array having an interval of ∼80 nm, wire width of ∼70 nm, and wire height of ∼20 nm.  相似文献   

11.
Zinc oxide doped with Al (AZO) thin films were prepared on borosilicate glass substrates by dip and dry technique using sodium zincate bath. Effects of doping on the structural and optical properties of ZnO film were investigated by XRD, EPMA, AFM, optical transmittance, PL and Raman spectroscopy. The band gap for ZnO:Al (5.0 at. wt.%) film was found to be 3.29 eV compared with 3.25 eV band gap for pure ZnO film. Doping with Al introduces aggregation of crystallites to form micro-size clusters affecting the smoothness of the film surface. Al3+ ion was found to promote chemisorption of oxygen into the film, which in turn affects the roughness of the sample. Six photoluminescence bands were observed at 390, 419, 449, 480, 525 and 574 nm in the emission spectra. Excitation spectra of ZnO film showed bands at 200, 217, 232 and 328 nm, whereas bands at 200, 235, 257 and 267 nm were observed for ZnO:Al film. On the basis of transitions from conduction band or deep donors (CB, Zni or VOZni) to valence band and/or deep acceptor states (VB, VZn or Oi or OZn), a tentative model has been proposed to explain the PL spectra. Doping with Al3+ ions reduced the polar character of the film. This has been confirmed from laser Raman studies.  相似文献   

12.
Glasses with compositions 25Li2O-(75−x)Bi2O3-x B2O3, with 0?x?30 mol%, have been prepared using the melt quenching technique. The density and the molar volume have been determined. IR spectroscopy is used as a structural probe of the nearest neighbor environment in the glass network. The optical transmittance and reflectance spectrum of the glasses have been recorded in the wavelength range 400-1100 nm. The values of the optical band gap Egopt for indirect transition and refractive index have been determined for 0?x?30 mol%. The average electronic polarizability of the oxide ion αo2− and the optical basicity have been estimated from the calculated values of the refractive indices. Variations in the different physical parameters such as the density, molar volume, optical band gap, refractive index, average electronic polarizability of the oxide ion and optical basicity with B2O3 content have been analyzed and discussed in terms of the changes in the glass structure.  相似文献   

13.
Anatase phase TiO2 films have been grown on fused silica substrate by pulsed laser deposition technique at substrate temperature of 750 °C under the oxygen pressure of 5 Pa. From the transmission spectra, the optical band gap and linear refractive index of the TiO2 films were determined. The third-order optical nonlinearities of the films were measured by Z-scan method using a femtosecond laser (50 fs) at the wavelength of 800 nm. The real and imaginary parts of third-order nonlinear susceptibility χ(3) were determined to be −7.1 × 10−11esu and −4.42 × 10−12esu, respectively. The figure of merit, T, defined by T=βλ/n2, was calculated to be 0.8, which meets the requirement of all-optical switching devices. The results show that the anatase TiO2 films have great potential applications for nonlinear optical devices.  相似文献   

14.
Investigation of the process of nanohole formation on silicon surface mediated with near electromagnetic field enhancement in vicinity of gold particles is described. Gold nanospheres with diameters of 40, 80 and 200 nm are used. Irradiation of the samples with laser pulse at fluences below the ablation threshold for native Si surface, results in a nanosized surface modification. The nanostructure formation is investigated for the fundamental (λ = 800 nm, 100 fs) and the second harmonic (λ = 400 nm, 250 fs) of the laser radiation generated by ultrashort Ti:sapphire laser system. The near electric field distribution is analyzed by an Finite Difference Time Domain (FDTD) simulation code. The properties of the produced morphological changes on the Si surface are found to depend strongly on the polarization and the wavelength of the laser irradiation. When the laser pulse is linearly polarized the produced nanohole shape is elongated in the E-direction of the polarization. The shape of the hole becomes symmetrical when the laser radiation is circularly polarized. The size of the ablated holes depends on the size of the gold particles, as the smallest holes are produced with the smallest particles. The variation of the laser fluence and the particle size gives possibility of fabricating structures with lateral dimensions ranging from 200 nm to below 40 nm. Explanation of the obtained results is given on the basis simulations of the near field properties using FDTD model and Mie's theory.  相似文献   

15.
Time-resolved photography was employed to study plasma dynamics and particle ejection of laser-irradiated iron oxide materials. Nano-particle powder, pressed powder pellets and sintered ceramics were ablated in air and Ar gas background by means of short laser pulses (Nd:YAG laser wavelength λ = 1064 nm and pulse duration τL ≈ 6 ns; KrF laser λ = 248 nm and τL ≈ 20 ns). Plasma plume dynamics significantly depended on sample morphology. The ejection of non-luminous particles up to several hundreds of microseconds after the laser pulse was observed for powder and pressed powder target materials. Laser-induced breakdown spectroscopy (LIBS) was employed for element analysis of iron oxide powders, pressed pellets and sintered ceramics. LIBS spectra of the different targets were comparable to each other and qualitatively independent of target morphology.  相似文献   

16.
Nonlinear optical β-BaB2O4 (β-BBO) crystal straight lines are written in 10Sm2O3·40BaO·50B2O3 glass by irradiation of a continuous wave Nd:YAG laser operating at 1064 nm. The linearly polarized micro-Raman scattering spectra for β-BBO crystal lines are consistent with those for commercially available y-cut β-BBO bulk single-crystals, supporting that β-BBO crystal straight lines with the c-axis orientation along the YAG laser scanning direction might be single-crystals. The photoluminescence spectra with large intensities and Stark splitting are observed for β-BBO crystal lines, and it is concluded that some amounts of Sm3+ ions in the glass are incorporated into β-BBO crystal lines. Two-dimensional β-BBO crystal curved lines with a bending angle of 30° are successfully written in 10Sm2O3·42BaO·48B2O3 glass.  相似文献   

17.
Subwavelength ripples (<λ/4) are obtained by scanning a tightly focused beam (∼1 μm) of femtosecond laser radiation (λ = 800 nm, tp = 100 fs) over the surface of either bulk fused silica and silicon and Er:BaTiO3. The ripple pattern extends coherently over many overlapping laser pulses parallel and perpendicular to the polarisation. Investigated are the dependence of the ripple spacing on the spacing of successive pulses, the direction of polarisation and the material. The evolution of the ripples is investigated by applying pulse bursts with N = 1 to 20 pulses. The conditions under which these phenomena occur are specified, and some possible mechanisms of ripple growth are discussed. Potential applications are presented.  相似文献   

18.
A simulation of erbium-doped glass systems, which provides population density for the excited states involved in the 1.5 μm and also for 2.7 μm emissions when pumped around 980 nm, is presented. To describe the diode pump laser processes, a theoretical model based in a coupled system of differential rate equations was developed. The approach used and the obtained spectroscopic parameters are discussed. The materials under study are two oxide glasses, lead fluoroborate (PbO-PbF2-B2O3), and heavy metal oxide (Bi2O3-PbO-Ga2O3) and a fluoride glass (ZrF4-BaF2-LaF3-AlF3-NaF), all of them doped with Er3+.  相似文献   

19.
The objective of this study was to identify a material suitable to absorb radiation at the wavelength of neodymium-doped Yttrium Aluminum Garnet (Y3Al5O12:YAG), 1064 nm. M-(M= Sm3+, Co2+, Co3+, Cr3+, and Cr4+) doped highly transparent YAG ceramics were fabricated, and their absorption spectra were measured. Unlike Co2+ and Cr3+-doped ceramic samples, Co3+ and Cr4+ and Sm3+-doped:YAG ceramics were found to have significant absorption at 1064 nm. However, the Sm3+-doped YAG clearly emerged as the best candidate because it is also transparent at 808 nm, the pumping wavelength laser diode (LD), and also at most absorption bands used for flash-lamp pumping.  相似文献   

20.
A laser-induced forward transfer technique has been applied for the maskless patterning of amorphous V2O5 thin films. A sheet beam of a frequency doubled (SHG) Q-switched Nd:YAG laser was irradiated on a transparent glass substrate (donor), the rear surface of which was pre-coated with a vacuum-deposited V2O5 180 nm thick film was either in direct contact with a second glass substrate (receiver) or a 0.14 mm air-gap was maintained between the donor film and the receiving substrate. Clear, regular stripe pattern of the laser-induced transferred film was obtained on the receiver. The pattern was characterized using X-ray diffraction (XRD), optical absorption spectroscopy, scanning electron microscopy (SEM), energy dispersive analysis of X-ray (EDAX), atomic force microscopy (AFM), etc.  相似文献   

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