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Astudy of the droplet transport characteristics in the two-phase boundary layer using a phase Doppler particle analyzer in a vertical downward duct reveals that the velocity profile and turbulence intensities of the flow are influenced by the drops present in the boundary layer. Droplet transport mechanisms such as the spreading of droplets to the boundary-layer region from the freestream regulate the flow characteristics. The dispersion coefficients have a slope of 22.66 for large drops and 15.75 for the smaller ones.

Measurements of the droplet behavior near the wall in a vertical rectangular duct were conducted by a phase Doppler particle analyzer (PDPA). The test Reynolds number and drop size range is from 18,500 to 89,300 and from 5 [[micro]meter] to 110 [[micro]meter], respectively. Results show that the negative slip-velocity of the drops near the free-stream region normally results in the reversed slip-velocity phenomenon in the boundary layer region. No negative slip-velocity of all drops are discovered for Reynolds number less than 38,300. This indicates no reversed slip-velocity phenomenon for the test drop size range under low Reynolds number conditions. However, when the Reynolds number is over 38,300, the free-stream slip-velocity of the bigger drops becomes negative. It is found that the negative slip-velocity and, hence, the reversed slip-velocity phenomenon may take place for drop size larger than 52 [[micro]meter] to 90 [[micro]meter] depending on the flow Reynolds number.

Substrate wave propagation and Bragg diffraction by multiplexed holographic gratings have been used to demonstrate a new 1-to-30 fanout optical interconnect having an overall diffraction efficiency of 87.8% at 514.5 nm and an individual channel efficiency of 3.0 [+ or -] 0.8%. The device configuration utilizes the large multiplexing capability of dichromated gelatin polymer films and substrate total internal reflection to realize large channel fanouts within the plane of a soda-lime glass substrate. A simplified theoretical formulation is presented to treat the corresponding three-dimensional holographic diffraction problem in the Bragg regime for slanted phase gratings. Results are compared with experimentally measured quantities for singly exposed phase gratings in different polarization conditions and incident angle orientations. The limitations of using multiplexed holograms in multiplanar substrate interconnection applications are also discussed. Key words: Optical interconnect, fanout, holographic grating, planar integration.

Carbon doped silicon oxide SiO(C, H) low k thin films (k∼2.9) deposited by the plasma enhanced chemical vapor deposition technique from trimethylsilane (3MS) and oxygen (O2) have been studied. Two types of chemical vapor deposition process recipes, namely CVD1 and CVD2 were applied for film deposition. CVD1 is an initial recipe that resulted in films with a uniform deposition rate irrespective of film thickness and a low dielectric constant of about 2.9. However, it suffers from extraordinarily high post particle counts. CVD2 is a modified recipe adopted to address this issue. The main difference between the two recipes is that a pump down step immediately before the film deposition has been omitted in recipe CVD2, and this has successfully reduced the particle counts to a satisfactory level. However when using recipe CVD2, the deposition rate is nonuniform and the dielectric constant is slightly above 3.0, attributed to the residual oxygen in the process step prior to film deposition. In this study we investigate the effects of oxygen incorporation on the properties of SiO(C, H) films. Surface defects and their element composition, film thickness, refractive index, dielectric constant, and chemical bonding analysis of the films have been carried out. The chemical composition and structure of films deposited by recipes CVD1 and CVD2 show very slight differences, and are also slightly nonuniform along the film depth. Although the nonuniformity does not have much effect on the dielectric constants of the SiO(C, H) films, it may pose a potential challenge for these low k films in terms of advanced integration. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In this paper, high-speed optical ribbon couplers for card-to-backplane interconnect applications are presented. The ribbon couplers are based on evanescent coupling between flexible multimode waveguide arrays. A soft lithographic technique is utilized to fabricate the ribbons. A flexible nonterminating optical data bus has been developed. Using BeamPROP software, we simulated the evanescent light coupling between two closely spaced ribbon waveguides to study the effects of waveguides separation, interaction length, and misalignment on coupling efficiency. Further experimental analysis and tests have been performed to quantify these effects. To investigate data transmission performance, a 12-channel optical interconnect link has been assembled. Experimental results demonstrated successful evanescent coupling; facilitating auto alignment coupling between card and backplane ribbon waveguides at data speeds as high as 10 Gb/s per channel. The evident high-speed interconnect performance and rapid ribbon prototyping approach can result in overall lower cost coupler fabrication for prospective optical interconnect applications. [ABSTRACT FROM PUBLISHER]

We report on a novel vacuum-assisted microfluidic (VAM) technique for guided wave device fabrication. Ultraviolet curable resins were used to demonstrate the effective VAM waveguide fabrication. Comparisons to a conventional soft molding technique demonstrate that the VAM approach results in lower propagation losses, lower crosstalk, and improved waveguide structures. More importantly, microscope analysis portrays improved device formation, sidewall edges, and the elimination of the polymer background residue inherent to traditional soft molding fabrication techniques. As a low-cost rapid prototyping technique, the VAM soft lithographic method allows guided wave devices to be implemented rapidly and inexpensively. [ABSTRACT FROM PUBLISHER]

We report a 1 times 4 wavelength reconfigurable photonic switch based on thermally tuned microring resonators (MRs) fabricated on a silicon-on-insulator substrate. The high refractive index of silicon facilitates the formation of highly confined optical waveguides and MRs. With a fabricated ring diameter of about 10 mum, the MRs support 18-nm free-spectral range and 0.15-nm resonant spectral linewidth. Many wavelength channels can be selected through local thermal tuning of resonators for reconfigurable switching and wavelength-division multiplexing/demultiplexing. The switch response time is about 1 ms. The results suggest the feasibility of high port-count photonic circuitry with dynamic wavelength reconfiguration capability for the development of large-scale integrated photonics. [ABSTRACT FROM PUBLISHER]