Spectral properties and mechanism of instability of nanoengineered silver blocks.

The instability of silver nanoblocks under atmospheric conditions is investigated. The localized surface plasmon resonance band of the silver nanoblocks shows a red shift, broadening, and damping with increasing storage time under atmospheric conditions. The change in spectral properties of silver nanoblocks is considered to be due to sulfidation of silver and structural breakage of silver nanoblock based on scanning electron microscope observation and numerical simulation. The effect of aspect ratio of silver nanoblocks on the change in spectral properties of the nanoengineered silver blocks is also discussed.

Intense near-infrared emission from ZnO-LiYbO(2) hybrid phosphors through efficient energy transfer from ZnO to Yb(3+).

The ZnO-LiYbO(2) hybrid phosphors were sintered by the solid-state reaction method, in which the intense near-infrared emission around 1000 nm due to Yb(3+ 2)F(5/2)-->(2)F(7/2) transition was obtained due to the efficient energy transfer from ZnO to Yb(3+) ions. The growth of the LiYbO(2) crystal and the formation of the diffusion layer between LiYbO(2) and ZnO were confirmed by XRD, SEM and EDX studies. The high efficient energy transfer is benefited from the inter-diffusion of Li(+), Yb(3+) and Zn(2+) in the diffusion region. The spectroscopy results clearly indicated that the ZnO-LiYbO(2) hybrid phosphors can harvest the energy from near-UV photons in a broad wavelength region and effectively convert them into Yb(3+) near-infrared emission.

Near infrared broadband emission of bismuth-doped aluminophosphate glass.

Near infrared broadband emission characteristics of bismuth-doped aluminophosphate glass have been investigated. Broad infrared emissions peaking at 1210nm, 1173nm and 1300nm were observed when the glass was pumped by 405nm laser diode (LD), 514nm Ar+ laser and 808nm LD, respectively. The full widths at half maximum (FWHMs) are 235nm, 207nm and 300nm for the emissions at 1210nm, 1173nm and 1300nm, respectively. Based on the energy matching conditions, it is suggested that the infrared emission may be ascribed to 3P1? 3P0 transition of Bi+. The broadband infrared luminescent characteristics of the glasses indicate that they are promising for broadband optical fiber amplifiers and tunable lasers.

Infrared broadband emission of bismuth-doped barium-aluminum-borate glasses.

We report near infrared broadband emission of bismuth-doped barium-aluminum-borate glasses. The broadband emission covers 1.3microm window in optical telecommunication systems. And it possesses wide full width at half maximum (FWHM) of ~200nm and long lifetime as long as 350micros. The luminescent properties are quite sensitive to glass compositions and excitation wavelengths. Based on energy matching conditions, we suggest that the infrared emission may be ascribed to 3P1? 3P0 transition of Bi+. The broad infrared emission characteristics of this material indicate that it might be a promising candidate for broadband optical fiber amplifiers and tunable lasers.

Direct writing computer-generated holograms on metal film by an infrared femtosecond laser.

Writing computer-generated holograms have been achieved by using a near infrared femtosecond laser selective ablation of metal film deposited on glass substrate. The diffraction features with data reconstruction of the fabricated computer-generated holograms were evaluated. Both transmission and reflection holograms can be fabricated in a single process. The process requires no mask, no pre- or post-treatment of the substrate.

Optical transfer of periodic microstructures by interfering femtosecond laser beams.

We report on an optical interference method for transferring periodic microstructures of metal film from a supporting substrate to a receiving substrate by means of five-beam interference of femtosecond laser pulses. Scanning electron microscopy and optical microscopy revealed microstructures with micrometer-order were transferred to the receiving substrate. In the meanwhile, a negative copy of the transferred structures was induced in the metal film on the supporting substrate. The diffraction characteristics of the transferred structures were also evaluated. The present technique allows one-step realization of functional optoelectronic devices.

[Clinical observation on treatment of gastro-esophageal reflux with modified zhizhu pill].

OBJECTIVE: To observe the therapeutic effect of modified Zhizhu pill (ZZP) in treating gastro-esophageal reflux disease (GERD) and to explore its mechanism. METHODS: Sixty-three GERD patients were randomly divided into the treated group (n = 30) and the control group (n = 33). The treated group was treated with ZZP 100 ml, twice daily by orally taking half an hour before meal. The control group was treated with Ranitidine 0.15 g, twice daily and Cisapride 10 mg, three times a day by orally taking before meal. The therapeutic course for both groups was 8 weeks. The changes of symptom scoring, endoscopic examination, esophageal pressure, 24 hrs monitoring on pH and blood level of motilin in the two groups were recorded and compared. RESULTS: After treatment, the symptom scoring, esophageal pressure, 24 hrs monitoring on pH and blood motilin level were improved in both groups (P < 0.05), and the improvement in the treated group was more significant than that in the control group (P < 0.05). CONCLUSION: ZZP has good effect in treating GERD.

Fabrication of internal diffraction gratings in calcium fluoride crystals by a focused femtosecond laser.

We report the fabrication of internal diffraction gratings in calcium fluoride crystals by a focused near-IR 800 nm femtosecond laser. The diffraction efficiency and refractive index change were evaluated after femtosecond laser irradiation and subsequent annealing. The maximum refractive index change was estimated to be 3.57x10(-4). Optical absorption spectra, measured for the crystals before and after the laser irradiation and subsequent annealing, indicate that the absorbance increase after femtosecond laser irradiation and decrease with increasing annealing temperature. The mechanisms of refractive index change are proposed. The results may be useful for fabrication of three-dimensional integrated optics devices in the crystals.

Controllable precipitation and dissolution of silver nanoparticles in ultrafast laser pulses irradiated Ag+-doped phosphate glass.

We report a controllable process of recipitation and dissolution of silver nanoparticles in ultrashort laser pulses irradiated Ag+-doped phosphate glass. Absorption spectra, transmission electron microscopy and refractive index measurement revealed that metallic silver nanoparticles were precipitated in the glass sample after irradiation by an 800-nm femtosecond laser and subsequent annealing at 300 degrees C, and dissolved after further annealing at 450 degrees C. We discuss a mechanism that combines the formation and decoloration of color centers, precipitation and dissolution of silver nanoparticles.