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Conformal multilayer TiO2/SiO2/TiO2 coatings were deposited on the surface of ∼27 μm spherical soda lime glass (SLG) particles using fluidized bed chemical vapor deposition at atmospheric pressure. Cost-effective precursors of titanium and silicon chlorides together with water were employed to deposit titania and silica films at 300 °C and room temperature, respectively. Focused ion beam cross-sectional transmission electron microscopy, scanning electron microscopy, energy-dispersive spectroscopy, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller surface area analysis, and X-ray diffraction were used to characterize the multilayer-coated particles. The results revealed a pinhole-free and uniform multilayer of anatase TiO2 and amorphous SiO2 with a thickness of ∼110 and 20 nm. Moreover, the photodegradation performance of the coated particles was examined by the degradation of methylene blue as the model reaction. It was found that a multilayer thin film of titania and silica can effectively prevent sodium ion diffusion from the SLG microsphere substrates, thus improving the photocatalytic performance of such system.

MetaModeTM reactive sputtering was employed to produce optical quality aluminum oxide films at rates an order of magnitude higher than those possible with conventional reactive magnetron sputtering. System pressure, reactive-to-nonreactive gas flow ratio, and ion-source current density were varied to investigate their effects on rate, process stability, and film properties. It was found that the coatings deposited at a reduced pressure (0.27 Pa) produced dense, water-free coatings without compromising optical quality or deposition rate.

Two new approaches are described for epi-down die bonding of diode lasers. The first approach, based on an acetic acid vapor flux, eliminates complications associated with the use of liquid flux in optoelectronic packaging. Based on this approach, InGaAsP/InP laser arrays were soldered onto silicon substrates. These laser arrays, which were passively aligned to single-mode optical fibers on the silicon substrate, had thermal impedances comparable to those obtained using conventional liquid flux. The second approach, called bridged die bonding, is proposed as a technique for reducing stress associated with epi-down bonding of diode lasers with hard solders. Bridged die bonding seeks to minimize bonding stress by avoiding contact of the laser active region with the hard solder. Thermal modeling indicates that the bridged die bonding approach, which uses a solder pattern with an air gap, can provide a thermal impedance comparable to conventional soldering techniques.