A tunable luminescence from red to blue in Eu-doped mesoporous AlPO4 glass is achieved by adjusting the annealing temperature. With increasing annealing temperature, the increased Eu3+ ions reduction changes the luminescence of the obtained glass. The abnormal reduction of Eu3+ to Eu2+ occurs in AlPO4 mesoporous glass at relative low annealed temperatures from 600 to 800 oC in air. The presence of Eu2+ ions, which are reduced from Eu3+ by hole-electron pairs, is revealed by XPS spectra. Our results indicate the mesoporous AlPO4 glass is a suitable matrix to incorporate Eu ions as the tunable luminescent light sources or LEDs.

A new silica antireflective coating with improved hydrophobicity and optical stability in a vacuum is obtained by a two-step route. Firstly, silica sols are prepared with a sol-gel process, in which tetraethyl orthosilicate is utilized as a precursor. And by introduction of fluorine containing glycol into the sols, the porosity of silica particles and surface polarity of the coatings are decreased. Afterward, coatings are constructed with low surface roughness by modification of PMBA-PMMA. The coatings retain transmission of up to 99.6%, and laser damage threshold of about 50 J/cm2 at a wavelength of 532 nm (1-on-1, 10 ns).

The preparation and characterization of in-plane polarized lead zirconate titanate (PZT) piezoelectric diaphragms for sensors and actuators applications are demonstrated in this letter. The single phase PZT films can be obtained on SiO2-passivated silicon substrates via sol-gel technique, in which PbTiO3 (PT) films are used as seed layers. Al reflective layer is deposited and patterned into concentric interdigitated top electrode by lithographic process, subsequently. The diaphragms are released using orientation-dependent wet etching (ODE) method. The size of the diaphragms is 5 mm in diameter and the outer interdigitated (IDT) electrode diameter (4.25 mm) is fixed at 85% of the diaphragm diameter. The three-dimensional (3D) profiles results indicate that the measured maximum central deflection at 15 V is approximately 9 \mu m. Sensing measurements show that the capacitance continually decreases with an increase of applied force, while the case of induced charge exhibits a reverse tendency.

A sol-gel method for the preparation of silica coating that varied in refractive index is developed. Silicon dioxide sol is obtained by hydrolysis and co-condensation reactions occurred in acid-catalyzed system. Surface morphology, refractive index, and transmission spectrum of the samples are studied. The results of transmission spectra of single-sided coatings show that the average transmittance of the samples increases about 4% compared with the uncoated one in the spectra range from 400 to 1 200 nm in the case of vertical incidence. For the double-sided coating the maximum transmittance is 99% at the wavelength of 840 nm.

Two series of Yb3+-doped silica glasses (YA and YAP) are fabricated using the sol-gel method, and their spectroscopic properties are investigated. The longest fluorescence lifetime of 0.96 ms is obtained in YAP2 and YAP3 glasses. The emission cross-section (emi) and emi × of Yb3+ in the YAP1 glass are 1.00 pm2 and 0.94 pm2·ms, respectively. Co-doping with Al and P decreases the hydroxyl group content in the glasses because of the reduction in non-bridging oxygen content. The lowest OH content in the YAP3 glass is 9.6 ppm.

AlPO4 mesoporous glass doped with perylene orange (PO) is prepared using two steps. The effects of dipping time and PO concentration on the fluorescent properties and molecular formation are investigated through absorption spectra, excitation spectra, and emission spectra. A slight increase in the intensity of excitation bands formed at 499 and 468 nm is ascribed to PO J-dimers aggregates as the dipping time increased from 2 to 24 h at high PO concentration (4×10^-3 mol/L). This is also the reason behind the concentration increase from 4×10^-6 to 4×10^-3 mol/L for the 16 h dipping. The excitation spectra, and the emission spectra of samples doped with PO show a slight red shift as the dipping time and the PO concentration increase. AlPO4 mesoporous glass is suitable to host the PO at high concentration.

SiO2-TiO2 sol-gel films are deposited on SiO2/Si by dip-coating technique. The SiO2-TiO2 strips are fabricated by laser direct writing using an ytterbium fiber laser and followed by chemical etching. Surface structures, morphologies and roughness of the films and strips are characterized. The experimental results demonstrate that the SiO2-TiO2 sol-gel film is loose in structure and a shrinkage concave groove forms if the film is irradiated by laser beam. The surface roughness of both non-irradiated and laser irradiated areas increases with the chemical etching time. But the roughness of laser irradiated area increases more than that of non-irradiated area under the same etching time. After being etched for 28 s, the surface roughness value of the laser irradiated area increases from 0.3 nm to 3.1 nm.

A novel fiber Bragg grating (FBG) based chemical sensor using hydrogel, a swellable polymer, as sensitive element is demonstrated. The sensing mechanism relies on the shift of Bragg wavelength due to the stress resulted from volume change of sensitive swellable hydrogel responding to the change of external environment. A polyacrylamide hydrogel fiber grating chemical sensor is made, and the experiments on its sensitivity to the salinity are performed. The sensitivity is low due to the less stress from the shrinking or swelling of hydrogels. Reducing the cross diameter of the grating through etching with hydrofluoric acid can greatly improve the sensitivity of the sensor.