Modeling, Design, and Fabrication of Plasmonic Coupling to a Silicon Nitride Waveguide-Photodetector

This paper reports an evanescent coupling to silicon nitride-Germanium (SiN-Ge) photodetectors using surface plasmon polaritons (SPPs). Modeling, design, and fabrication of plasmonic coupling to Al nanoscale metal and light detection are included. Since 10 % of light coupled with surface plasmons is detected from poly-Si waveguides using lens fiber, Ge-photodetectors and SiN waveguides are utilized to detect light around 1550 nm wavelength with less insertion loss. Two plasmonic configurations with either Ag or Al nanoscale metal are simulated and analyzed using Lumerical FDTD simulation. Difficulty during fabricating SiN-Ge photodetectors are mentioned, and the best design and fabrication are suggested. The results in this paper can be applied to the design and fabrication of plasmonic systems with SiN-Ge photodetectors

An alternative IIB embedding of F(4) gauged supergravity

Through the construction of a complete non-linear Kaluza-Klein reduction ansatz from type IIB supergravity to Romans' F(4) gauged supergravity, we identify a recently discovered supersymmetric AdS_6 solution as the IIB uplift of the supersymmetric vacuum of Romans' theory. We present new IIB uplifts of a number of known solutions of Romans' theory and comment on supersymmetry in higher-dimensions where it is expected.Comment: 39 pages, 1 figure, typos corrected, footnote added, references updated, to appear in JHE

Thermodynamic Volume and the Extended Smarr Relation

We continue to explore the scaling transformation in the reduced action formalism of gravity models. As an extension of our construction, we consider the extended forms of the Smarr relation for various black holes, adopting the cosmological constant as the bulk pressure as in some literatures on black holes. Firstly, by using the quasi-local formalism for charges, we show that, in a general theory of gravity, the volume in the black hole thermodynamics could be defined as the thermodynamic conjugate variable to the bulk pressure in such a way that the first law can be extended consistently. This, so called, thermodynamic volume can be expressed explicitly in terms of the metric and field variables. Then, by using the scaling transformation allowed in the reduced action formulation, we obtain the extended Smarr relation involving the bulk pressure and the thermodynamic volume. In our approach, we do not resort to Euler's homogeneous scaling of charges while incorporating the would-be hairy contribution without any difficulty.Comment: 1+21 pages, plain LaTeX; v2 typo fixed and references adde

Analytical time domain electromagnetic field propagators and closed-form solutions for transmission lines

An analytical solution for the coupled telegrapher’s equations in terms of the voltage and current on a homogeneous lossy transmission line and multiconductor transmission line is presented. The resulting telegrapher’s equation solution is obtained in the form of an exact time domain propagator operating on the line voltage and current. It is shown that the analytical equations lead to a stable numerical method that can be used in the analysis of both homogeneous and inhomogeneous transmission lines. A numerical dispersion relation is derived proving that this method has no numerical dispersion down to the two points per wavelength Nyquist limit. Examples are presented showing that exceptionally accurate results are obtained for lossy single and multiconductor transmission lines. The method is extended to represent the general solution to Maxwell’s differential equations in vector matrix form. It is shown that, given the electromagnetic field and boundary conditions at a given instant in time, the free space time domain propagator and corresponding dyadic Green’s functions in 1-, 2-, and 3-dimensions can be used to calculate the field at all subsequent times

The Study of Chemically Cross-Linked Ion Gels for Electronic Devices

This thesis presents the development of new chemically cross-linked (CC) ion gels and their application in electronic devices. The CC ion gels are synthesized by a hitherto unreported and novel method using self-assembled gelation; this method allows for a straightforward synthesis without complicated procedures. The CC ion gels have excellent ionic conductivities and can exhibit high capacitances through the formation of electric double layers. These CC ion gels are applied to electrolyte-gated transistors (EGTs) in the field of printed electronics. In particular, they are applied as gate insulators, which separate the semiconducting channel from the gate electrode. They simultaneously act as mediating materials for electric double layer formation, to switch the channel on and off upon an applied bias potential between source and gate electrode. Two different ion gels are utilized for the fabrication of gate insulators, making use of a self-assembled gelation of a CC ion gel, combined with ink-jet printing, which is an effective technique to fabricate gate insulators of EGTs. The ink-jet printing process involves the development of an ink-jet printable ink to prevent nozzle clogging. The optimized amount of solvent in that ink plays an essential role in inhibiting the gelation before printing. The self-assembled gelation starts upon solvent evaporation after printing, and the CC ion gel is spontaneously synthesized on the semiconductor. In a subsequent approach, adhesive properties are added to the CC ion gel to enable hand laminating of electrodes or semiconductors. The CC ion gels fabricated by both methods exhibit remarkable gating performances in EGTs. In particular, they mitigate the drawback of the major humidity sensitivity of the common composite solid polymer electrolytes (CSPE), and show stable transfer curves in the range of 20 % to 90 % relative humidity. The presented results enable for the first time ink-jet printing of CC ion gels. Moreover, the presented CC ion gels demonstrate great potential as gate insulators for EGTs. New findings about synthesis, analysis, and utilization of the CC ion gel suggest new directions for the development and application of advanced CC ion gels in the future

Implementing Engineering Based STEM Programs in High School Classrooms in the Republic of Korea

In 2022, South Korea announced new national curriculum that implement it from 2023. High school curriculum is about to fully implement the high school credit system, which allows students to choose subjects that suit their needs and career paths. In South Korea, technology education in middle school is a common compulsory subject, but high school technology education is a selective subject and has the name of technology and home-economics. High school technology education experiences difficulties that are not selected in many schools due to the confusion of identity of subject names and social negative perception of technology. The purpose of this is to develop an engineering education program that can be used in high school technology education and to verify its effect on students. To achieve the purpose of this study, an engineering education program was developed and students’ changes through the program were measured. This study was based on a single-group pre-post test design and was conducted with 96 10th grade students. As a result of this study, students’ engineering interest, engineering self-efficacy, and engineering career awareness were statistically significantly improved through the developed engineering education program. This study provides great implications for actively including and utilizing engineering in technology education. In addition, it will give great implication for the direction and program development of high school technology education