Implementation and Performance Evaluation of a Bivariate Cut-HDMR Metamodel for Semiconductor Packaging Design Problems with a Large Number of Input Variables.

A metamodeling technique based on Bivariate Cut High Dimensional Model Representation (Bivariate Cut HDMR) is implemented for a semiconductor packaging design problem with 10 design variables. Bivariate Cut-HDMR constructs a metamodel by considering only up to second-order interactions. The implementation uses three uniformly distributed sample points ( = 3) with quadratic spline interpolation to construct the component functions of Bivariate Cut-HDMR, which can be used to make a direct comparison with a metamodel based on Central Composite Design (CCD).

Deconvolution of spectral power distribution of high-power laser diode arrays.

A novel method is proposed to predict the spectral power distributions (SPDs) of individual emitters in a high-power laser diode (LD) array. The proposed method deconvolutes the SPD of an LD array by taking into account the thermal cross-talk effect as well as the current competition effect. A complete analytical expression to deconvolute the SPD of an LD array is described.

Method for predicting junction temperature distribution in a high-power laser diode bar.

A hybrid experimental/numerical method is proposed for predicting the junction temperature distribution in a high-power laser diode (LD) bar with multiple emitters. A commercial water-cooled LD bar with multiple emitters is used to illustrate and validate the proposed method. A unique experimental setup is developed and implemented first to measure the average junction temperatures of the LD bar emitters.

Spectral power distribution deconvolution scheme for phosphor-converted white light-emitting diode using multiple Gaussian functions.

We propose a procedure to deconvolute the spectral power distribution (SPD) of phosphor-converted LEDs (pc-LEDs). The procedure involves a two-step process using multiple Gaussian functions. The first step is a preliminary process to deconvolute an SPD using a pair of Gaussian functions.

Numerical study on the mixing performance of a ring-type electroosmotic micromixer with different obstacle configurations.

A new type of electrokinetic micromixer with a ring-type channel is introduced for fast mixing. The proposed mixer takes two fluids from different inlets and combines them in a ring-type mixing chamber. The fluids enter two different inlets (inner radius: 25 microm and outer radius: 50 microm), respectively.

Measurements of true leak rates of MEMS packages.

Gas transport mechanisms that characterize the hermetic behavior of MEMS packages are fundamentally different depending upon which sealing materials are used in the packages. In metallic seals, gas transport occurs through a few nanoscale leak channels (gas conduction) that are produced randomly during the solder reflow process, while gas transport in polymeric seals occurs through the bulk material (gas diffusion). In this review article, the techniques to measure true leak rates of MEMS packages with the two sealing materials are described and discussed: a Helium mass spectrometer based technique for metallic sealing and a gas diffusion based model for polymeric sealing.

Thermal-structural modeling of polymer Bragg grating waveguides illuminated by a light emitting diode.

This study reports both analytical and numerical thermal-structural models of polymer Bragg grating (PBG) waveguides illuminated by a light emitting diode (LED). A polymethyl methacrylate (PMMA) Bragg grating (BG) waveguide is chosen as an analysis vehicle to explore parametric effects of incident optical powers and substrate materials on the thermal-structural behavior of the BG. Analytical models are verified by comparing analytically predicted average excess temperatures, and thermally induced axial strains and stresses with numerical predictions.

Modified coupled-mode model for thermally chirped polymer Bragg gratings.

A modified coupled-mode (CM) model is proposed for the optical behavior of thermally chirped Bragg gratings. The model accounts for the axial gradient in the modulation wavenumber, which has been ignored in the classical CM model. The model is used to characterize the optical behavior of a polymethyl methacrylate-based polymer Bragg grating subjected to nonisothermal conditions.

Analytical and molecular simulation study of water condensation behavior in mesopores with closed ends.

Mesopores present in inorganic barrier films have a unique structure since the bottom sides are blocked by underlying polymer substrates. Characterization of pore blockage by water condensation is important in understanding gas transport mechanisms because the pore blockage changes the transmission behavior of water vapor itself as well as other gases. In this study a water condensation behavior inside mesopores is investigated analytically and numerically.

Phase-shifting in achromatic moiré interferometry system.

Phase-shifting in an achromatic configuration of moiré interferometry is explained. The rigorous diffraction theory defines the phase of diffracted beams in terms of the pitch and the relative position of a compensator grating. A numerical analysis proceeds to determine the total phase change between two diffracted beams that produce moiré fringes.

Thermo-optical modeling of an intrinsically heated polymer fiber Bragg grating.

A fully concatenated thermo-optical model is presented to predict the thermo-optical behavior of an intrinsically heated polymer fiber Bragg grating (PFBG). Coupled-mode theory and heat-conduction theory are first used to determine the axial heat generation and temperature distribution of a PFBG and the transfer matrix method (TMM) is subsequently employed to predict its thermo-optical behavior. The validity of the TMM is corroborated experimentally using an externally heated glass fiber Bragg grating (FBG) with an axially decaying temperature field.

Error analysis of the phase-shifting technique when applied to shadow moiré.

An exact solution for the intensity distribution of shadow moiré fringes produced by a broad spectrum light is presented. A mathematical study quantifies errors in fractional fringe orders determined by the phase-shifting technique, and its validity is corroborated experimentally. The errors vary cyclically as the distance between the reference grating and the specimen increases.

Advanced iterative algorithm for phase extraction of randomly phase-shifted interferograms.

An advanced random phase-shifting algorithm to extract phase distributions from randomly phase-shifted interferograms is proposed. The algorithm is based on a least-squares iterative procedure, but it copes with the limitation of the existing iterative algorithms by separating a frame-to-frame iteration from a pixel-to-pixel iteration. The algorithm provides stable convergence and accurate phase extraction with as few as three interferograms, even when the phase shifts are completely random.