Broadband Vibration Attenuation Achieved by 2D Elasto-Acoustic Metamaterial Plates with Rainbow Stepped Resonators

This paper investigates the influences of nonperiodic rainbow resonators on the vibration attenuation of two-dimensional metamaterial plates. Rainbow metamaterial plates composed of thin host plates and nonperiodic stepped resonators are considered and compared with periodic metamaterial plates. The metamaterial plates are modelled with the finite element modelling method and verified by the plane wave expansion method. It was found that the rainbow metamaterial plates with spatially varying resonators possess broader vibration attenuation bands than the periodic metamaterial plate with the same host plates and total mass. The extension of attenuation bands was found not to be attributed to the extended bandgaps for the two-dimensional metamaterial plates, as is generally believed for a one-dimensional metamaterial beam. The complete local resonance bandgap of the metamaterial plates is separated to discrete bandgaps by the modes of nonperiodic resonators. Although the additional modes stop the formation of integrated bandgaps, the vibration of the plate is much smaller than that of resonators at these modal frequencies, the rainbow metamaterial plates could have a distinct vibration attenuation at these modal frequencies and achieve broader integrated attenuation bands as a result. The present paper could offer a new idea for the development of plate structures with broadband vibration attenuation by introducing non-periodicity.

Realization of Twenty Monochromatic Beams using Photonic Structure via Principle of Filtering

The current work employs silicon-based one dimensional photonic structure which delivers ‘20’ different types of monochromatic beams (wavelengths) via filtering action. The I/P signals are essentially varies from visible to short infrared range to justify the work. Though similar type of works related to filtering application are found in the literature, the present research deals with an output signal which could be deployed in different purposes vis-à-vis dentistry, dermatology, spectroscopy, printing, holography, barcode scanning etc. The physicality of this work incorporates 68 layers of silicon monoxide and silicon based one-dimensional optical waveguide along with their configuration where the plane wave expansion method does fulfill the nitty-gritty of required mathematics to solve out electromagnetic wave equations. Reflectance and transmittance characteristics along with the absorbance are the critical parameters that substantiate the said application.

Binary-Like Topology Optimization of Piezoelectric Metamaterial Plate with Interface Circuits Using Extended Plane Wave Expansion Method

Piezoelectric metamaterial plate (PMP) is being investigated for structural vibration energy harvesting (SVEH), in which an interface circuit is often used. Thus, it is a challenge to perform bandgap optimization of such an elastic–electro–mechanical coupling system. This paper presents a binary-like topology optimization scheme by dividing the unit cell into identical pieces, where a {0, 1} matrix is optimized to indicate material distribution. Firstly, a unified motion equation is derived for the elastic plate and the piezoelectric patch, and an electromechanical coupling model is built for a self-powered synchronized charge extraction circuit. Then, an extended plane wave expansion method is presented to model the bandgap character of the PMP with interface circuits (PMPICs), and the numerical solution of the dispersion curves is derived based on the Bloch theorem. Next, an extended genetic algorithm is applied for the topology optimization of the PMPIC. In the end, numerical and finite element simulations are performed to validate the proposed method. The results demonstrate that both the structure and the circuit can be optimized simultaneously to obtain the maximum first-order bandgap at a given central frequency. Therefore, the proposed method should provide an effective solution for the topology optimization of a PMPIC for broadband SVEH.

Patterned PCF Containing Disordered Suspended Particles in Hollow Core–An Innovative Platform for Optofluidic Sensing

The unique and striking characteristics of the photonic crystal fiber (PCF) with patterned dielectric rods have been reported for last decades, providing applications in the field of prototype sensors and more recently in optofluidic sensing. The proposed PCF sensor contains an empty core injected with disordered suspended particles (such as Cs2, CCl4, C6H6) surrounded by n-type solid semiconductor material (P2O5-doped silicate) and suspended plasma dielectric rods. The effect of intensity of field and concentration of doped semiconductor material on band structure has been analyzed, respectively, by using the plane wave expansion method. The sensitivity of PCF towards various analytes has been measured by the change in the band structure. The results reported in this work are very useful for constructing an optoelectronic device, useful in medical science and ultrahigh-band width signal processing.

Stochastic Modeling of 2D Photonic Crystals

Due to the fabrication processes, inaccurate manufacturing of the photonic crystals (PCs) might occur which affect their performance. In this paper, we examine the effects of tolerance variations of the radii of the rods and the permittivity of the material of the two-dimensional PCs on their performance. The presented stochastic analysis relies on plane wave expansion method and Mote Carlo simulations. We focus on two structures, namely Si-Rods PCs and Air-Holes PCs. Numerical results show – for both structures – that uncertainties in the dimensions of the PCs have higher impact on its photonic gap than do the uncertainties in the permittivity of the Si material. In addition, Air-Holes PCs could be a good candidate with least alteration in the photonic gap considering deviations that might occur in the permittivity of Si due to impurities up to 5%.