Photoluminescence of a silver-doped glass

The absorption, emission and excitation spectra of Ag⁺ ions in a soda lime glass doped with two different concentration of silver are investigated. Absorption spectra exhibit a main broad band peaked at about 260 nm (4.77 eV) with a shoulder at about 227 nm (5.46 eV). The relative height of the shoulder depends on silver concentration in the glass. Emission spectra of Ag⁺ are dominated by an ultraviolet broad band at about 330 nm (3.76 eV). The excitation spectra for this emission show a preponderant broad band peaked at about 227 nm (5.46 eV) which coincides with peak position of the shoulder displayed in the optical absorption spectra. A weak broad featureless emission band centred at about 550 nm (2.25 eV) with an excitation peak at about 242 nm (5.12 eV) is tentatively related to an impurity from the host silica glass rather than originated in silver-type centres. Comparison of the luminescence decay curves for both emissions show substantial differences between them. Consequently, the emissions in the time-resolved spectra can easily be discriminated.     

Evolution of the optical properties of a silver-doped phosphate glass during thermal treatment

The optical properties of a silver-doped phosphate glass have been monitored during thermal processing at several fixed temperatures by in situ optical microspectroscopy. Silver nanoparticle (NP) formation and growth processes were assessed by analysis of surface plasmon resonance spectral features. Nucleation and growth processes were distinguished, which appeared temperature and time dependent. While nucleation was favored at low temperatures, relatively high temperatures promoted NP growth by silver diffusion. Photoluminescence spectra acquired along with optical absorption data indicated a continuous reduction of Ag⁺-Ag⁰ pairs concomitant with NP precipitation, suggesting their role as nucleation centers. The work of Ag NP formation and the activation energy for silver diffusion were estimated.     

Optical anisotropy and photostability of polarizing films dyed with Brilliant Yellow

We obtained polyvinyl alcohol films dyed with Brilliant Yellow (BY) and have determined their spectral and polarizing characteristics in the short-wavelength region of the visible spectrum (400–430 nm). We have shown that BY imparts a polarizing power of ≥99% to the film. We measured the orientational parameters characterizing the degree of ordering of the polymer chains and the dye molecules for different BY content in the film. An increase in BY concentration above 0.3 wt.% is accompanied by a decrease in its orientational parameter, which is connected with aggregation of dye molecules and a change in the distribution of the molecular axes relative to the film orientation axis. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 3, pp. 466–472, May–June, 2009.     

梯度介质光学常数的反射起偏法测量

本实验将弱信号检测放大技术应用于反射起偏法,使其成为折射的高精度测量方法,为梯度介质光学常数测量提供了一个简捷准确的途径,但仍属破坏法.     

冰洲石-玻璃组合e光超高透偏光棱镜

为了既节省稀有昂贵的冰洲石晶体材料，又尽量提高偏光棱镜的透射比，设计了一种冰洲石晶体与光学玻璃组合的方法。叙述以布儒斯特角入射来提高偏光棱镜e光透射比的设计方案。该棱镜可用甘油或有机硅胶将FK 2玻璃与冰洲石晶体胶合而成。理论分析和实验测试表明，该棱镜的透射比高于96％，消光比优于10-5，在一定情况下可以取代纯冰洲石晶体材料的偏光棱镜。     

偏光棱镜长度孔径比与材料特性的关系

为了掌握激光偏光棱镜的长度孔径比情况,根据激光的特点和不同晶体材料特性,利用光在各向异性晶体中的传播规律,分析了长度孔径比受材料双折射率、胶合剂折射率等因素的影响。研究显示,同一材料中两个主折射率的较大者决定了长度孔径比的最小值,而较小者决定了长度孔径比的最大值;有较大主折射率的材料,相应器件长度孔径比也小;选用低折射率的胶合剂,有利于缩小器件长度孔径比。此结果也可以作为多波长使用情况下的偏光器件的设计参考。     

亚波长介质偏振分束光栅的衍射特性

 采用严格耦合波理论并结合矩阵LU分解法,分析了亚波长介质光栅的刻槽深度、占空比、入射角、入射波长等参数对TE偏振和TM偏振0级衍射效率的影响。结果表明:在1 550 nm波长处,出现瑞利反常现象。由此提出利用瑞利反常现象设计工作波长为1 550 nm的偏振分束光栅,通过优化设计确定了最佳设计参数,即光栅周期为l0/2,瑞利入射角为30°,刻槽深为0.9l0,占空比为0.5。结果表明,参数优化后的偏振分束光栅可以使TE偏振0级反射波和TM偏振0级透射波同时达到近100%的衍射效率。     

The defect structure of silver-doped CdS

High-temperature Hall effect measurements are carried out on CdS doped with 2·5 × 10¹⁷?2·3 × 10²⁰ Ag cm^?3 under various cadmium and sulfur pressures. At high p_cd and low silver concentrations, Ag acts as a donor. At higher concentrations self compensation occurs. An anomalous variation of the Hall coefficient with p_s2 indicates that the electron concentration increases with increasing p_s2. This is attributed to the formation of anti structure defects S_cd. A complete defect model is proposed, and published solubility and diffusion data for Ag in CdS in equilibrium with (Ag, Cd) alloys are reinterpreted on the basis of this model.     

Optical fiber splicing using low-melting-point glass solder

A new splicing technique is described that uses a low-melting-point glass solder as the connecting material. Losses between 0.2 and 0.4dB have been obtained for a fiber with a 45-μm core diameter. The measured breaking strength of the splices was in the range of 3 to 5N.     

Modified polarizing prism

We accomplish the production of linearly polarized light by modifying our earlier design of a non-deviating dispersion prism for three cases by setting, (i) the angle of incidence equal to the inverse of the cotangent of the refractive index (n), (ii) twice the angle of incidence equal to the angle of refraction plus the inverse of the cotangent of the refractive index (n), and (iii) the angle of incidence equal to the difference of twice the inverse of the cotangent of the refractive index (n), and the angle of refraction. Finally, we present a design for an achromatic polarizer using a penta prism. These designs and their salient features are discussed in the light of Cervantes’ review and other polarizers. Some possible applications are given.     

Biomedical properties of laser prepared silver-doped hydroxyapatite

Thin films of hydroxyapatite (HA) and silver-doped HA were synthesized using KrF excimer laser deposition. Material was ablated from one target composed from silver and HA segments. Layers properties as silver content, structure, color, FTIR spectra and antibacterial properties (Gram-positive Bacillus subtilis) were measured. Silver concentration in HA layers of 0.06, 0.3, 1.2, 4.4, 8.3, and 13.7 at % was detected. The antibacterial efficacy changed with silver dopation from 71.0 to 99.9%. The focus is on investigation of minimum Ag concentration needed to reach a high antibacterial efficacy.     

Optical waveguide spectrometer based on thin-film glass plates

Commercially available thin-film glass plates have been successfully used for optical waveguide spectroscopy of chemical and biological films adsorbed upon the plates' surfaces. A 50-mum -thick glass plate was placed in contact with two parallel strips of silicone rubber supported on a slide glass. The plate area between the rubber strips served as the waveguiding region, eliminating the negative effect of the substrate on absorbance sensitivity. We coupled white light into the waveguide by focusing the light from a xenon lamp onto one end of a glass fiber and then inserting the other end into a glycerol drop overlaid upon the plate's surface. With a CCD detector, light at wavelengths as short as 360 nm was found to transmit out of the plate's end face. The propagation loss of the waveguide was measured to be 相似文献   

Reflecting polarizing beam splitter

We propose and experimentally demonstrate the use of metal-covered lamellar relief gratings as a polarizing beam splitter operating at a single wavelength near Littrow incidence. We report the characteristics of a grating produced by holography and reactive ion etching that was calculated for operation as beam splitter at lambda = 633 nm (for a He-Ne laser).     

Optical absorption and track studies of gamma-irradiated ZnP glass

The optical absorption spectra of a specially prepared zinc phosphate glass (ZnP) were studied as a function of gamma dose. The optical absorption spectra in the wavelength region of 200–800 nm were recorded for pristine ZnP glass sample and a number of samples exposed to different γ-doses in the range 10⁰–10⁶ Gy. The optical energy gap (E_g) was determined using Tauc's plot. It was found to be independent of γ-irradiation up to the dose of 10³ Gy followed by a slow decrease of E_g up to 10⁵ Gy. However, a sharp decrease in optical energy band gap was observed at 10⁶ Gy. The bulk-etch rates for different γ-doses were also determined and found to be constant up to the dose of 10⁵ Gy. On the other hand, there is a 12% increase in the bulk-etch rate for the dose of 10⁶ Gy.     

Optical properties of wavelength-tunable green-emitting color conversion glass ceramics

Color conversion glass ceramics are prepared by cosintering borosilicate glass frits and green 0.06Ce:Y_2.94(Al_1-xGa_x)₅O₁₂ phosphors. The crystal structures, the influence of Ga concentration on the photoluminescence (PL), and reliability properties of the color conversion glass ceramics are investigated. The PL emission wavelengths of 0.06Ce:Y_2.94(Al_1-xGa_x)₅O₁₂ glass ceramics show blue shift from 545 nm to 525 nm with increasing Ga content (x value) under excited at 460 nm. Reliability test results show that the quantum yield (QY) of 0.06Ce:Y_2.94(Al_1-xGa_x)₅O₁₂ glass ceramics decreases from 70.60% to 59.06% with x value increasing from 0.15 to 0.35 under the ambient condition of 85℃/RH85% for the exposure time of 168 h. And the quantum yield (QY) of 0.06Ce:Y_2.94(Al_1-xGa_x)₅O₁₂ glass ceramics decreases from 65.13% to 52.23% after being soaked into boiled water for 4 h. The finding reveals that the addition of Ga can deteriorate the reliability of the color conversion glass ceramics.