Hiremath, Kirankumar R

For detecting skin cancer, a silicon nitride based ring resonator refractive index sensor is modelled using coupled mode theory. This device has a high sensitivity of 249nm/RIU and Q factor of 1310.

We investigated the effect of Au nanoparticles in Zinc o xide semiconductor matrix for enhanced absorption. Apart from ZnO optical absorption at 360 n m, the matrix also shows plasmonic absorption at 560 nm.

The work presents an inventive, simple and implementable design approach to enhance the bandwidth of conventional Salisbury Screen Microwave Absorber (SSMA). Theoretically, the maximum fractional bandwidth of SSMA for FR4 substrate with an optimum sheet resistivity of 308 Ω/sq for –10 dB reflection is nearly 42.1%. In comparison, the bandwidth for square patch based SSMA is 59.7% with the same thickness. The design comprises square patches of SSMA placed periodically on a metal sheet. The square patches consist of an FR4 substrate and a 200 Ω/sq resistive sheet. A single reflection null is observed in the SSMA due to λ/4 resonance whereas in the proposed absorber an additional resonant mode is introduced due to coupling between the nearby patches. The simultaneous overlapping of the λ/4 mode and the additional coupling mode results in bandwidth extension. The close agreement between the simulation and measurement data is observed.

Keynesian theory focuses on identifying the money supply as a constant. But recent trends show that post-Keynesian theory emphasizes the endogeneity of the money supply. Thus, we will be considering the money supply as an endogenous variable i.e., not a constant. Taking in account the business cycle Investment Savings-liquidity preference Money supply (IS-LM) model, we incorporated dual time delays in the capital accumulation equation. Thus, the model we propose is a four-dimensional system with dual delay inspired from new Keynesian theory. In order to keep the model simple yet approachable we have considered a linear model. While scrutinizing the system, we evaluate equilibrium points and then consider three separate cases according to the delays viz., when both delays are absent, only one delay is absent and no delay is absent. Linear Stability analysis is done around the equilibrium point. Delays have been observed to cause stability switches in the dynamic behavior of the system. Our system thus experiences switches in stability and undergoes Hopf bifurcation when the parameter time delay crosses a critical value. The delay dependent stability regions are identified. Lastly, numerical simulations are executed to validate our analyses

Nonlocal hydrodynamic Drude model overcomes the limitations of the conventional Drude model in describing light-matter interactions in nanoplasmonic structures. Here we present a weak formulation based rigorous numerical method for it, which avoids spurious resonances as in the case of the curl-free approximation setting. The simulated results agree with Mie results, and the method is capable of handling arbitrarily shaped scatterers.

In this paper, a simple design strategy is presented for designing broadband, polarization insensitive metasurface for radar cross section (RCS) reduction. Two different unit cell structures, circular patch, and loop are chosen to enhance the phase bandwidth. Different phase gradient supercells are designed by positioning these unit cells in a specific phase gradient direction. The eight supercells are then randomly distributed in a checkerboard pattern for further diffusing the incident wave. The proposed metasurface significantly reduce the RCS and demonstrate features such as polarization insensitivity and wideband operational bandwidth.

We carried out a detailed balance calculation of quantum dot sensitized solar cell based on widely used TiO2 as electron transport material and polysulfide electrolyte as hole transport material, considering the finite electrochemical potential level for these layers. The findings suggest that detailed balance efficiency decreases much faster for higher band gap quantum dots absorber as compared to that of ideal electron and hole transport layers. The detailed balance efficiency values are close to 20% without carrier multiplication for Eg near exciplex quantum dots, closer to experimental observation with finite Ediff limitation and without considering carrier multiplication, much smaller than the ideal case, which is close to 30% for ideal open circuit voltage. Thus, the present study shows the impact of limited/finite electron and hole transport material energy levels in designing QDSSCs, towards more realistic photovoltaic efficiency values.

We synthesized zinc titanate nanopowder in different crystal structures by varying calcination temperature and time and phase evolution is qualitatively investigated using reference intensity ratio (RIR) approach. The electronic properties showed 2.9 eV as indirect band transition, and 3.59 ± 0.02 eV as direct band transition for the highest temperature annealed rhombohedral ZnTiO3 and cubic spinel Zn2TiO4 zinc titanate materials. The intermediate temperature annealed (∼850 °C) material consists of ZnTiO3, Zn2TiO4, and Zn2Ti3O8 zinc titanate nanopowder, showing similar two electronic transitions. Zinc titanate with dominant rhombohedral phase ZnTiO3 (900 °C annealed) and dominant Zn2Ti3O8 phase (750 °C annealed) are used to synthesize mesoporous electrodes for integrating the ZnS passivated CdS quantum dots. Finally, Cu2S counter electrode is integrated with polysulfide electrolyte to realize 1 cm2 area quantum dot sensitized solar cells (QDSSCs). QDSSCs with dominant ZnTiO3 phase are showing lower photovoltaic performance (short circuit current 0.76 mA/cm2, open circuit voltage 0.55 V) with respect to that of dominant Zn2Ti3O8 phase with 2.2 mA/cm2 short circuit current and 0.69 V open circuit voltage, respectively. The observed difference is attributed to differences in electronic and morphological properties of the synthesized zinc titanate powders.

In this paper, the absorption properties of resonant patch absorbers are analyzed using the quality factor approach. The total quality factor contributing from both the dissipative quality factor and radiative quality factor is deduced. The resonant circular patch absorbers are studied under the influence of position randomness with increasing filling factor. It is observed that by introducing position disorder, it is possible to enhance the absorption bandwidth of the otherwise periodic circular patch resonant absorbers. This enhancement in absorption bandwidth is obtained due to the coupling among neighboring resonators, which results in broadening of collective resonances. The designed disordered resonant patch absorbers also exhibit polarization insensitivity for oblique incidences for both polarizations. In addition, square patch absorbers are also investigated under the periodic and disordered setting. It is found that the enhancement in the bandwidth of the disordered absorber structures is independent of the shape of the patch resonators, and depends solely on the coupling among the neighboring resonators.

We present the design and fabrication of a bandwidth enhanced metamaterial absorber, based on multiple wires printed on metal backed lossy dielectric substrate. The proposed structure is fabricated using screen printing technique. In the proposed structure, broadband absorption is achieved by overlapping the absorption peaks of individual wires. Results show that bandwidth of proposed absorber corresponding to 10dB return loss, is 0.5 GHz. The simulated bandwidth of proposed absorber is independent of the variation in incidence angle from 0 to 30°.