Rectangle Aperture Research Articles

Numerical Investigation of an AlN-Based Resonant Detector with a Plasmon Aperture Absorber for Dual-Band IR Sensing

An aluminum nitride (AlN) piezoelectric resonant infrared (IR) detector based on a Lame-wave resonator (LWR) and plasmon apertures was designed for dual-band sensing, and was investigated by using the finite element method (FEM) and finite difference time domain (FDTD) simulations. A plasmon structure with the apertures was designed on the surface of the detector in order to maintain electrical performance and to obtain ultrahigh dual-band IR absorption. The electrical performance of the LWR with the plasmon apertures was comparable to that of the LWR with floating electrodes, which was found to be superior to that of the LWRs with plasmon particles or open electrodes. Both of the rectangle aperture and cross-shaped aperture absorbers can achieve ultrahigh dual-band absorptions of up to 97%, and the cross-shaped aperture absorber is insensitive to the polarization angle. Moreover, a detailed optimization analysis for the thermal properties of the detector was conducted to obtain favorable responsivity and response speed. The calculated results demonstrate that the proposed resonant detector has great potential applications in IR detection.

Graphene aperture-based metalens for dynamic focusing of terahertz waves.

We theoretically study a tunable reflective focusing lens, based on graphene metasurface, which consists of rectangle aperture array. Dynamic control of either the focal intensity or focal length for terahertz circular polarized waves can be achieved by uniformly tuning the graphene Fermi energy. We demonstrate the graphene apertures with the same geometry; however, spatially varying orientations can only control the focal intensity. To change the focal length, the spatially varying aperture lengths are also required. A comparative study between the metalenses, which generate only geometric or both gradient and geometric phase changes, has shown that the apertures' spatially varying length distribution is the key factor for determining the modulation level, rather than the focal length's modulation range. This kind of metalens provides tunable, high-efficiency, broadband, and wide-angle off-axis focusing, thereby offering great application potential in lightweight and integrated terahertz devices.

Color holographic system without undesirable light based on area sampling of digital lens

AbstractIn this paper, we demonstrate a color holographic system without undesirable light based on area sampling of a digital lens. This system, which improves the quality of the reconstructed color image, is fundamentally realized by using three spatial light modulators and a rectangle aperture. By altering the sampling area of the digital lens on the spatial light modulator panels, we can control the offset position of the reconstructed image. Thus, the zero‐order diffraction light as the undesirable light and the reconstructed images are separated, and the chromatic aberration can be corrected. In addition, a rectangle aperture is used to eliminate the zero‐order diffraction light. The final reconstructed image with improved quality can be observed, which verifies the effectiveness of our proposed system.

Transmission Control Property of a Nano-optical System Made by an Antenna over a Bowtie Aperture

In this paper, we report a characteristic transmission control property of a nano-optical system by introducing an antenna over the input opening of a bowtie aperture. The transmission process through the system is investigated quantitatively by the coupling and transmission efficiencies, and an optical switch effect is found as the antenna length varies. To understand the physical mechanism, we then investigate the electrical field distribution of the antenna over a rectangle aperture as a simplified model. It is discovered that the "on" state of the system is due to Fabry–Perot resonances in the horizontal cavity formed by antenna, dielectric layer, and metal film. On the other hand, a cutoff occurs for the characteristic rectangle length shorter than the diffraction limit to turn the device to the "off" state. Such a phenomenon can thus provide a promising candidate for application in manipulating light in large-scale optoelectronic device integration.

Numerical Simulation of Transient Gauss pulse Coupling through Small Apertures

Transient electromagnetic pulse (EMP) can easily couple into equipments through small apertures in its shells. To study the coupling effects of transient Gauss pulse to a cubic cavity with openings, coupling course is simulated using sub-gridding finite difference in time domain (FDTD) algorithm in this paper. A new grid partition approach is provided to simulate each kind of apertures with complex shapes. With this approach, the whole calculation space is modeled, and six kinds of aperture with different shapes are simulated. Coupling course is simulate in the whole time domain using sub-gridding FDTD approach. Selecting apertures with dimension of several millimeters to research, coupled electric field waveform, power density and coupling coefficient are calculated. The affect on coupling effects by varied incident angle and varied pulse width are also analyzed. The main conclusion includes interior resonance phenomenon, increase effect around rectangle aperture and several distributing rules of coupled electric field in the cavity. The correctness of these results is validated by comparing with other scholars' results. These numerical results can help us to understand coupling mechanism of the transient Gauss pulse.

Study correlation vortices in the near-field of partially coherent vortex beams diffracted by an aperture

We have derived the analytical expression of the electric cross-spectral density in the near- field of partially coherent vortex beams diffracted by an aperture. Taking the Gaussian Schell-model vortex beam as a typical example of partially coherent vortex beams, the spatial correlation properties and correlation vortices in the near-field of partially coherent vortex beams diffracted by a rectangle aperture are studied. It is shown that the off-axis displacement, spatial degree of coherence parameter, propagation distance, and the opening factor of the aperture affect the spectral degree of coherence and positions of correlation vortices. With the optimization algorithm, we obtain the symmetric distributing coherent vortex.

Wideband and Dual-Band Design of a Printed Dipole Antenna

A wideband and dual-band dipole antenna with an integrated balun feed is given. First, the antenna structure is optimized and a 41.5% bandwidth is obtained where voltage standing wave ratio (VSWR) is less than 2. In order to further get a larger bandwidth and dual-band capabilities of this antenna, some rectangle apertures are etched onto the antenna surface, and a better dipole antenna is fabricated. Through investigating rectangle aperture with different sizes, a 47.8% bandwidth is obtained at L-band, and a 15.1% bandwidth comes true at S-band. Agreement between calculations and measurements is very good. The result indicates that the novel design not only may obtain better wideband characteristic but also can let the dipole antenna work at L- and S-bands.