Gotowa bibliografia na temat „2D nanoresonators”

Abstract Nowadays the volume of transmitted information exponentially grows and requires the development of new telecommunication systems. Dielectric nanoresonators can be considered as a basic part of such systems to control the emission of the nanoscale source. Here we numerically investigated resonant dielectric nanoresonators for emission enhancements of 2D nanomaterials. We show that the radiative Purcell factor can achieve the value of up to 21 and 12 for the magnetic quadrupole and dipole responses, respectively. Also, we compare the directivity patterns for magnetic dipole and quadrupole resonances. The results obtained in this work can be applied in the development of optical chips and interfaces.

Abstract All-dielectric nanophotonics is a rapidly developing and practical alternative to plasmonics for nanoscale optics. The electric and magnetic Mie resonances in high-index low-loss dielectric nanoresonators can be engineered to exhibit unique scattering responses. Recently, nanophotonic structures satisfying parity-time (PT) symmetry have been shown to exhibit novel scattering responses beyond what can be achieved from the conventional nanoresonators. The complex interference of the magnetic and electric Mie resonances and lattice modes excited in PT-symmetric nanoantenna arrays give rise to a scattering anomaly called lasing spectral singularity (SS), where the scattering coefficients tend to infinity. In our previous work (Tapar, Kishen and Emani 2020 Opt. Lett. 45 5185), we demonstrated the existence of lasing SSs in vertically stacked two-dimensional (2D) GaInP PT-symmetric metasurface. In this paper, we analyse the direction-sensitive scattering response of the PT-symmetric GaInP metasurface by decomposing the total scattered field into the electric and magnetic multipoles. The far-field scattering response at the singularity is highly asymmetric for incidence from either the gain or loss side and can be tuned by changing the geometry. By analysing the phase of even- and odd-parity higher-order multipoles, we explain the observed scattering response over a broad parameter space in terms of the generalized Kerker effect. The interference between the direction-dependent excitation of different order multipoles and the overall 2D-lattice resonance opens a route towards designing a special class of tunable sources exhibiting direction-sensitive emission properties.

Nonlinear plasmonic effects in perspective 2D materials containing low-dimensional quantum emitters can be a basis of a novel technological platform for the fabrication of fast all-plasmonic triggers, transistors, and sensors. This article considers the conditions for achieving a strong coupling between the surface plasmon–polariton (SPP) and quantum emitter taking into account the modification of local density of optical states in graphene waveguide. In the condition of strong coupling, nonlinear interaction between two SPP modes propagating along the graphene waveguide integrated with a stub nanoresonator loaded with core–shell semiconductor nanowires (NWs) was investigated. Using the 2D full-wave electromagnetic simulation, we studied the different transmittance regimes of the stub with NW for both the strong pump SPP and weak signal SPP tuned to interband and intraband transition in NW, respectively. We solved the practical problem of parameters optimization of graphene waveguide and semiconductor nanostructures and found such a regime of NW–SPP interaction that corresponds to the destructive interference with the signal SPP transmittance through the stub less than 7 % in the case for pump SPP to be turned off. In contrast, the turning on the pump SPP leads to a transition to constructive interference in the stub and enhancement of signal SPP transmittance to 93 % . In our model, the effect of plasmonic switching occurs with a rate of 50 GHz at wavelength 8 µ m for signal SPP localized inside 20 nm graphene stub loaded with core–shell InAs/ZnS NW.

AbstractThermoelastic damping (TED) represents the lower limit of material damping in flexural mode micro- and nanoresonators. Current predictive models of TED calculate damping due to thermoelastic temperature gradients along the beam thickness only. In this work, we develop a two dimensional (2D) model by considering temperature gradients along the thickness and the length of the beam. The Green's function approach is shown to be a robust means of solving the coupled heat conduction equation in one and two dimensions. In the 1D model, curvature information is lost and, hence, the effects of structural boundary conditions and mode shapes on TED are not captured. In contrast, the 2D model retains curvature information in the expression for TED and can account for beam end conditions and higher order modes. The differences between the 1D and 2D models are systematically explored over a range of beam aspect ratios, frequencies, boundary conditions, and flexural mode shapes.

2D material-based nanoelectromechanical systems have emerged as excellent tools for force measurement with extreme sensitivity levels. Most sensing methods with 2D nanoelectromechanical (2D NEMS) systems utilize frequency tuning of the resonant mode in response to external stimuli. However, the interaction of the harsh external stimulus with the delicate 2D NEMS limited these devices’ utility only in the research labs. We propose a fabrication and packaging method for 2D NEMS devices to extend their application outside the research labs. Under the proposed scheme, the 2D NEMS is coupled to the external stimulus through substrate strain. The substrate acts as a protective barrier between the NEMS and the environment. At the same time, the substrate also influences the strain on the 2D NEMS. The external stimulus changes the strain on the substrate and hence on the 2D NEMS device. The strain change on 2D NEMS changes the frequency of vibration modes. 2D materials such as graphene have a high Young’s modulus. High Young’s modulus allows the strain to frequency transductions with high accuracy and sensitivity. We report the most straightforward application of this scheme for pressure sensing with a responsivity of 20Hz/Pa. Using the proposed scheme, we also demonstrate the ability to utilize duffing nonlinear response of the graphene resonator for pressure sensing. The resonant response of the 2D nanoresonators becomes nonlinear, even at very small excitation voltages. The nonlinear response of the 2D nanoresonators shows sharp amplitude jumps at the bifurcation points and hysteresis. We utilize the sharp amplitude jumps to realize the bifurcation amplifier for pressure sensing. While the hysteresis in the frequency response is used to demonstrate basic logic operations such as OR, AND, and XOR with pressure pulse as input and vibration amplitude as output. The external stimulus can also have a dynamic variation that can excite the substrate’s vibration modes. In this case, the frequency tuning of the 2D NEMS is also dynamic as it follows the strain on the substrate. Utilizing this principle, we report the ability of the 2D NEMS to track the dynamic stimulus with a frequency component as high as 40kHz. Characterizing time-varying stimuli is crucial for accelerometers, acoustic sensors, and vibrometers. We demonstrate the use of highly responsive 2D nanoresonators for such dynamic sensing. Since the proposed 2D NEMS package allows external stimulus to couple to the 2D NEMS efficiently, the 2D NEMS is also susceptible to various environmental noise sources. We use the Allan Deviation of the frequency fluctuations to study the performance of these devices against noise. The measurements reveal that the primary cause of the frequency fluctuations of the 2D NEMS is the temperature of the surrounding air. These measurements provide crucial insights into designing a sensor with the required sensitivity, bandwidth and noise isolation. The barrier-substrate design can be changed according to specific applications to achieve the intended transduction. This concept can be extended easily for sensing inertial forces, biological stimuli, and temperature.