Search

Discusses the measurement by Z-scan technique of third-order optical nonlinear susceptibilities of Bi2O3 nanoparticles coated by a layer of stearic acid in toluene sol and bare in hydrosol. Determination of the figures of merit related to linear loss and two-photon absorption; Suitability in all-optical switching applications.

The aggregation-induced emission (AIE) of a 1,2-diphenyl-1,2-di(p-tolyl)ethene (TPE) was explored as a novel fluorescence method for probing the assembling/disassembling of amphiphilic molecules. The fluorescence intensity was able to monitor the formation of micelles and determine the critical micelle concentration (CMC) of surfactants. The temperature-dependent micellization of the pharmaceutically important PEO–PPO–PEO copolymer, Pluronic F127, was further studied by using the TPE fluorescence spectrum intensity. Our results showed good agreement with those reported in the literature by using other methods. The special advantage of the AIE probe method was further explored to determine the assembling/disassembling process of the colored amphiphilic molecule, 1-[4-(3-phenylazophenoxy)butyl]triethylamine bromide (AzoC4), whose CMC value has not previously been described. Since the TPE fluorescence signal mainly comes from the aqueous phase, not from the inside of hydrophobic core, it provides a possible platform to study the CMC of those colored surfactants. Based on the novel fluorescence properties of TPE in the aggregated and dispersed states, one can conclude that the TPE method is a promising method for the determination of the CMC and critical micellization temperature (CMT), particularly having a special advantage to determine the assembling/disassembling process of colored amphiphilic molecules. [ABSTRACT FROM AUTHOR]

Au colloids were prepared by irradiation with a Nd:YAG laser. Au nanoparticles were characterized by absorption spectra, transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. It is found that the wavelength of the laser has no effect on the size but the number of the Au nanoparticles. By irradiating a transparent silica gel doped with gold ions with the focused laser in the gel and subsequent exposing in air, a space-selective pattern of letter “P” consisting of Au nanoparticles was observed inside the silica gel. [ABSTRACT FROM AUTHOR]

A nonlinear system capable of expanding pulse with spectral narrowing, an analogy to a spatial beam expander in linear optics, is studied theoretically and experimentally. The system, with features of high efficiency and maintaining near Fourier-transform limit (FTL), is constructed by using quadratic nonlinear processes with chirped pulses. The spectral and temporal characteristics of such a pulse expander are investigated analytically and computationally. It shows that group-velocity mismatch of nonlinear crystal plays a detrimental role, which leads to a deviate operation of pulse expander from its ideal case, e.g., temporal shortening, spectral broadening, and a deviation from the FTL of the expanded pulses. The criteria for designing a near aberration-free pulse expander are given based on these analyses. As a demonstration, we experimentally expand broadband 70-fs pulses from a Ti:sapphire regenerative amplifier to narrowband 60-ps longer pulses. The conversion efficiency from pump to idler of the nonlinear pulse expander is currently limited to a few percent and can be practically improved to 10% to 20%. [ABSTRACT FROM PUBLISHER]

Presents a study which investigated the presence of space-selective precipitation of gold nanoparticles in silicate glasses. Potential applications of gold nanoparticles; Considerations on the mechanism of the precipitation of gold nanoparticles; Factor which make possible to space-selectively induce the precipitation of gold nanoparticles.

Presents a study that examined photoinduced formation of colloidal silver by a near-infrared femtosecond laser. Experimental methods; Results of the study; Conclusions.

Presents a study which investigated the long-lasting phosphorescence and photostimulated long-lasting phosphorescence phenomena in laser-irradiated manganese-doped alumino-phosphofluoride glasses. Review of related literature; Methodology; Results and discussion.

Transparent Li2O–Ga2O3–SiO2 glass ceramics containing Cr3+/Ni2+ codoped LiGa5O8 nanocrystals were synthesized. The steady state emission spectra indicated that the near-infrared emission intensity of Ni2+ at 1300 nm in Cr3+/Ni2+ codoped glass ceramics was enhanced up to about 7.3 times compared with that in Ni2+ single-doped glass ceramics with 532 nm excitation. This enhancement in emission intensity was due to efficient energy transfer from Cr3+ to Ni2+, which was confirmed by time-resolved emission spectra. The energy transfer efficiency was estimated to be 85% and the energy transfer mechanism was discussed. [ABSTRACT FROM AUTHOR]

This letter reports the ultrabroadband infrared luminescence from 1000- to 1700-nm wavelength range and demonstrate optical amplification at the second optical communication window in a novel bismuth-doped germanosilicate glass. The full-width at half-maximum of the luminescence is about 300 nm and the optical gain is larger than 1.37 within the wavelength region from 1272 to 1348 nm with pump power 0.97 W. This material could be useful to fabricate ultrabroadband optical fiber amplifiers. [ABSTRACT FROM PUBLISHER]

Silver nanowires in large quantities can be obtained through a simple method in the absence of a surfactant or polymer and without addition of external seeding nanocrystallites. A plausible mechanism was proposed to elucidate the formation mechanism of silver nanowires based on TEM studies. [ABSTRACT FROM AUTHOR]

Tb&sup3+;-doped glass sample emits bright and long-lasting phosphorescence after irradiation by an 800-nm femtosecond pulsed laser. Long-lasting phosphorescence is observed once again after further excitation by 365-nm UV light when the femtosecond laser-induced long-lasting phosphorescence cannot be detected. [ABSTRACT FROM AUTHOR]

Studies the preparation of colloidal gold by a femtosecond laser. Preparation of gold ion solution; Details on the experiments; Results of the experiments.

Broadband near-infrared (IR) luminescence in transparent alkali gallium silicate glass-ceramics containing Ni2+-doped β-Ga2O3 nanocrystals was observed. This broadband emission could be attributed to the 3T2g (3F) ? 3A2g (3F) transition of octahedral Ni2+ ions in glass-ceramics. The full width at half-maximum (FWHM) of the near-IR luminescence and fluorescent lifetime of the glass-ceramic doped with 0.10 mol% NiO were 260 nm and ~1220 µs, respectively. It is expected that transparent Ni2+-doped β-Ga2O3 glass-ceramics with this broad near-IR emission and long fluorescent lifetime have potential applications as super-broadband optical amplification media. [ABSTRACT FROM AUTHOR]

Infrared (IR) luminescence covering 1.1 to ∼1.6 üm wavelength region was observed from bismuth-doped barium silicate glasses, excited by a laser diode at 808 nm wavelength region, at room temperature. The peak of the IR luminescence appears at 1325 nm. A full width half-maximum (FWHM) and the lifetime of the fluorescence is more than 200 nm and 400 µs, respectively. The fluorescence intensity increases with Al2O3 content, but decreases with BaO content. We suggest that the IR luminescence should be ascribed to the low valence state of bismuth Bi2+ or Bi+, and Al3+ ions play an indirect dispersing role for the infrared luminescent centers. [ABSTRACT FROM AUTHOR]