Coupling Limitations Of Asymmetric Multimode Couplers

Characterization of the ground states of a simplified CuO2 model in strong- and weak-coupling regions

Recent advances in immersion lithography have created the need for a small field microstepper to carry out the early learning necessary for next generation device application. Combined with fluid immersion, multiple-beam lithography can provide an opportunity to explore lithographic imaging at oblique propagation angles and extreme NA imaging. Using the phase preserving properties of Smith Talbot interferometry, the Amphibian XIS immersion lithography microstepper has been created for research and development applications directed toward sub-90nm patterning. The system has been designed for use at ArF and KrF excimer laser wavelengths, based on a fused silica or sapphire prism lens with numerical aperture values up to 1.60. Combined with a chromeless phase grating mask, two and four beam imaging is made possible for feature resolution to 35nm. The approach is combined with X-Y staging to provide immersion imaging on a microstepper platform for substrates ranging up to 300mm. The Amphibian system consists of single or dual wavelength sources (193nm and 248nm), a 2mm exposure field size, stage accuracy better than 1 um, polarization control over a full range from linear polarization to unpolarized illumination, full control of exposure dose and demodulation (to synthesize defocus), and the ability to image both line patterns as well as contact features. A fluid control system allows use of water or alternative fluids, with the ability to change fluids rapidly between wafers. The Amphibian system is fully enclosed in a HEPA and amine controlled environment for use in fab or research environments.

In this study we evaluate the focus budget of an i-line stepper, examining the sources of focus erosion for a 0.40 micrometers process. The analysis first examines the best focus of the system as predicted by the several common tools currently used in the industry. Using the overlay focus- monitor, we then determine the value of lens aberrations such as astigmatism and field curvature. The results of lens heating examined for the lens using these common techniques. A model describing the focus aberrations is then developed and applied to the data. This model uses data derived from the focus monitor to determine lens errors such as coma, astigmatism and field curvature. Using this model, data gathered over various numerical aperture and partial coherence values are evaluated to determine the variation of lens aberrations over their range and the depth of focus. Finally, data consisting of critical dimension information gathered using an commercial, automated SEM is used to validate the predictions of the focus model.

Study on electrochemical lithiation stress model of graphite-carbon fiber bilayer electrode

Methanol (CH₃OH) is a volatile, transparent, and toxic substance widely used in chemical substrates, antifreeze, and industrial applications. Ethanol (C₂H₅OH), in contrast, is commonly used in alcoholic beverages, as a fuel additive, and as an antiseptic. Differentiating between methanol and ethanol is critical due to the severe health risks associated with methanol ingestion, while ethanol is safe for consumption in moderation. To tackle this challenge, we present a highly sensitive and accurate Photonic Crystal Fiber (PCF) sensor designed for the detection of both methanol and ethanol. The proposed sensor demonstrates impressive performance, with maximum relative sensitivities (RS) of 95.72% for methanol and 97.55% for ethanol, while operating within the 2.2 to 3.2THz range. Additionally, it achieves low Effective Material Loss (EML) values of 0.0066cm⁻1 for ethanol and 0.0044cm⁻1 for methanol, with Numerical Aperture (NA) values of 0.257 and 0.270, respectively. The key advantages of this sensor include its exceptional precision, high sensitivity, and low material loss, making it a reliable solution for accurately distinguishing between methanol and ethanol in various industrial and commercial applications. By providing enhanced detection capability in the THz range, this sensor improves safety monitoring and quality control processes in sectors where these substances are frequently used.

Mueller matrix imaging contains abundant microstructural information of the sample and provides quantitative characterization of anisotropic structures. In contrast to non-polarized microscopic imaging, Mueller matrix imaging can obtain basic structural information of the sample, such as fiber orientation and density, from polarization parameter images at low resolution. To analyze the combined effect of imaging resolution on Mueller matrix polarization properties, we first measured Mueller matrix images of unstained collagen fiber-rich rat dorsal skin sections using a range of objective magnification or numerical aperture (NA) values. Quantitative analysis of first-order moments and image texture parameters were then compared in conjunction with polarimetry basis parameters images. The results show that the polarimetry basis parameter images preserve most of the structural information of the sample and can provide fast imaging speed. This study provides a criterion to determine which structural information can be accurately and rapidly obtained by transmission Mueller matrix microscopy with low NA targets to aid in pathological diagnosis and other applications.

Raman spectroscopic study of concentration dynamics in glycine crystallization achieved by optical trapping

We present a coupled-mode theory of fiber-optic add-drop filters, which involve directional coupling between two fibers combined with fiber Bragg gratings defined inside the coupling region. The analysis self-consistently accounts for both the directional and the reflection coupling, and the propagation constants and structure of the supermodes of the combined structure are derived. We present a detailed analysis of a filter design based on identical fibers. The calculated device parameters satisfy the requirements for dense wavelength-division multiplexing applications.

The fabrication and performance of a stable single-mode transmissive 8×8 star coupler is described. The device exhibits very low excess loss (0.13 dB), good coupling uniformity (0.73 dB) and low near-end crosstalk (>64 dB). The star coupler is fabricated from eight lengths of single-mode fibre, by forming 3 dB fused coupling regions between appropriate fibre pairs. A Table of insertion loss measurements is presented, together with graphs showing the wavelength response between 1.2 and 1.7 μm.

This study simulated the Scoring process and the Can opening process of Easy Open End by finite element method. A FEM model was developed to predict the limitation of the scoring depth and the opening force at the End of steel Can using ABAQUS. In spite of a complex 3D structure, the shape of the Can End was simplified 2D axisymmetric model and analyses were focused on the change of materials and score shapes. Adaptive meshing was applied to the region of the score in the scoring process in order to suppress large deformation of elements. The critical depth of the scoring was observed because necking occurred at the panel during the scoring process. Necking could be restrained by changing the shape of the score punch. For the opening simulation, the shear failure model was utilized. The opening force was predicted with various materials, residual thickness, panel thickness (thickness ratio) and score shapes. The influence of these factors changed with the thickness ratio. Synthetically, the score condition of the steel Can End that the opening force is similar to the aluminum End was proposed.

Numerical analysis of high-strength centrifugal precast RC hollow pipe columns using grouted corrugated duct connection: Confinement effect and ductility evaluation

Frequency selective directional couplers consisting of two polished single-mode fibers can be fabricated as low loss components applicable to wavelength division multiplexing in optical transmission systems. Symmetrical couplers made of two identical fibers are well known.1 To obtain narrow channel spacings, long interaction lengths are necessary and the alignment tolerances become very stringent. The best published values for the 3-dB bandwidth of the measured power transfer characteristics (PTCs) are ~40 nm.

The study of the dynamic response of the plasma is a valuable tool for investigating transport processes in a tokamak. A deductive approach is adopted, in order to make the best use of this experimental information. A system identification method is developed to estimate the transfer function of the system from the time evolution of its parameters to any excitation. The form of the identified transfer function is linked with a representation of the transport in terms of poles (eigenvalues) and eigenmodes. These are directly deduced from the raw data, with no restriction on the underlying processes, and there is consequently no need to adjust any simplified transport model to the experimental data. This method is illustrated by analysing the injection of pellets on Tore Supra. The density and the temperature transfer functions were observed to share the same poles, with the corresponding eigenmodes grouped in pairs with identical profiles. This implies the presence of a coupling between the particle flow and the heat flow. A criterion based on compatibility with the observed transfer function is developed to select among several possible coupling mechanisms. The selection suggests a particle diffusion coefficient depending on the density and the temperature gradient

We present our analysis and optimization of slot ring resonators by investigating the slotted coupler properties in order to achieve high Q ring resonators. Firstly, different ring resonators loaded by conventional straight bus ring resonator couplers with different gaps were fabricated with a cavity length of 828 µm and a bending radius of 50 µm. They were measured with an average Q-factor around 85,000 and proved to present large intrinsic coupler losses. We then proposed a new symmetric racetrack ring resonator coupler to reduce coupler loss thanks to a smoothed transition in coupling region between the coupled supermodes and achieved Q factor above 120,000 with total intrinsic loss around 2.2 dB/cm in a 50 µm radius ring resonator with total cavity length 326 µm by this approach. These optimized slot ring resonators could bring a new progress towards low loss silicon slot waveguiding structures for hybrid Si photonics including on-chip nonlinear optics and sensing in future.

In this report, effect of MgO and Y2O3 additives on modifying the dielectric constant-temperature (K-T curve) properties of the BaTiO3 materials for multilayer ceramic capacitors (MLCC), using base metals (Cu and Ni) as electrode materials was systematically studied. Low temperature coefficient of capacitance (TCC), which meets X7R specification, has been obtained. Microstructural examinations using transmission electron microscopy (TEM) indicate that small TCC of thus obtained materials is attributed to microstructural control of materials. Simulation using simplified microstructure model indicates that the effective dielectric constant of core-shell structured materials significantly not only with the dielectric properties of cores and shells, but also with the shell-to-core thickness ratio, which results in a K-T behavior extremely sensitive with the processing parameters. In contrast, the X7R type K-T properties for BaTiO3 materials can be obtained in a much wider processing window by forming duplexed structure. Simulation also indicated that the effective dielectric constant of such a duplexed material is relatively insensitive to the fluctuation of K-T properties of each component.