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A novel antenna array with improved radiation characteristics using a series-feed technique is presented in this article. The antenna array has a size of 132 × 80 μm and is developed using Polytetrafluoroethylene (PTFE) with graphene as conductive material. The proposed antenna comprises a central microstrip line loaded with short slant radiating stubs. The bandwidth characteristics of the antenna are enhanced by loading the slant stubs with octagonal ring elements. The number of radiating stubs is increased to enhance the overall radiation characteristics. The proposed THz antenna operates from 3.8 THz to 5.3 THz offering a fractional bandwidth of 31 % with reference |S₁₁| ≤ −10 dB. In addition, a 1 × 2 antenna array with differential feeding is explored to improve the overall directionality of the antenna making it a viable solution for directional IoT systems. The estimated theoretical directivity is above 11 dBi and the total efficiency is greater than 75 % throughout the operating bandwidth. Furthermore, the multiple input and multiple output (MIMO) performance of the THz antenna is discussed. The proposed two-element has an intrinsic isolation of more than 40 dB. Owing to the enhanced bandwidth and radiation property, the proposed THz antenna is suitable for high data-rate 6 G Internet-of-things (IoT) communications.

An investigation for electronic, magnetic, and optical properties of Mn-doped ${\mathrm{ZnSnAs}}_2$ compound performed using advanced computational methods. Using spin-polarized density functional theory (DFT) calculations with local orbital linearized augmented plane wave (lo-LAPW) method and Tran–Blaha’s modified Becke–Johnson (TB-mBJ) functional, Mn-doped n-type chalcopyrite semiconductor ${\mathrm{ZnMn}}_x{\mathrm{Sn}}_{(1-x)}{\mathrm{As}}_2$, studied within varying Mn doping concentration range $0\le x\le 0.5$. Doping of Mn to Sn site in pure ${\mathrm{ZnSnAs}}_2$ creates a strong spin effect, which makes it useful spintronic materials. We observed with increase the Mn concentration in ${\mathrm{ZnSnAs}}_2$, energy bandgap changes while the magnetic strength of the unit cell remains unchanged, showing stability of system’s magnetism. Optical properties of the Mn doped ${\mathrm{ZnSnAs}}_2$ compounds analysed in term of dielectric function, absorption spectra, and refractive index. Optical properties show, compound is optically low active in the Infrared (IR) region and more active in visible and ultraviolet (UV) region. The electronic and optical properties of Mn-doped ${\mathrm{ZnSnAs}}_2$, offer potential technological advancements in semiconductor device design technology and engineering.

A background noise removal method based on averaging fractional Fourier domains is presented. The method is applied to Digital Lensless Holographic Microscopy (DLHM) intensity reconstructions, where the background is perturbed by the weak yet detrimental presence of information of the twin image. A set of fractional Fourier domains of a DLHM intensity reconstruction is computed and thereafter averaged leading to a sensible reduction of the background noise and, therefore, an increase in the overall contrast of the resulting image. The maximum reach of the fractional rotations used in the method is determined by measuring the spatial resolution in a regular star test target such that the spatial resolution is kept within the span of interest for a given application. The set of images to be averaged is composed of fractional rotations of the original intensity reconstruction that are smaller than the previously determined maximum reach. The number of fractional rotations that are finally averaged is determined by the sought increase in the contrast of the resulting image. Experimental samples of micrometer-sized objects and an intricate biological specimen have been used to validate the proposal.

Image super-resolution (SR) is the task of inferring a high resolution (HR) image from one/multiple single low resolution (LR) input(s). Traditional networks are evaluated by pixel-level metrics such as Peak-Signal-to-Noise Ratio (PSNR) etc., which do not always align with human perception of image quality. They often produce excessively smooth images that lack high-frequency texture and appear unnatural. Therefore, in this paper, we propose a lightweight adaptive residual dense attention generative adversarial network (SRARDA) for image SR. Firstly, our generator adopts the residual in residual (RIR) structure but redesigns the basic module. By using dynamic residual connection (ARC) to dynamically adjust the importance of residual and main paths, we design a novel adaptive residual dense attention block (ARDAB) that enhances the feature extraction capability of the generator. In addition, we build a high-frequency filtering unit (HFU) to extract more high-frequency features from the LR space. Finally, to fully utilize the discriminator, we use WGAN to compute the difference between the HR image and the reconstructed image. Experiments demonstrate that SRARDA effectively addresses the issue of excessive smoothing in reconstructed images, while also enhancing visual quality.

Given that circular symmetric Airy vortex beam (CSAVB) was found to possess a stable central cavity and an opposing transport process to circular Airy vortex beam, it has been recognized as a potentially powerful tool for particle trapping and optical communication. In order to facilitate broader application scenarios, this paper presents a novel approach to the generation of multiple CASVBs based on a single metasurface. In the proposed method, three independent CSAVBs carrying different new kinds of power-exponent-phase vortices (NPEPVs) can be obtained under two orthogonal circularly polarized or an arbitrary linear polarized incident, respectively. Each of these vortex structures is characterized by a distinct orbital angular momentum, which is jointly determined by two parameters of the NPEPVs. This indicates that the CSAVB and the device have greater freedom than the canonical optical vortex beams and the previous vortex beam generators in controlling the optical vortex. These results have the potential to advance the development of vortex beams and enhance their applications in micromanipulation, optical communication and imaging.

Deep learning gained great popularity in the task of object detection. This paper proposes a printed circuit board (PCB) defect detection algorithm based on deep learning, which can improve product quality and avoid potential failures and accidents in the electronics manufacturing industry. In this paper, the YOLOv7 model is selected as the original model for PCB defect detection. Firstly, the K-means++ clustering algorithm is used to calculate the target anchor parameters which can enhance the dataset. Secondly, the receptive field enhancement (RFE) module is added to the head layer of the network to take full advantage of the receptive field in the feature map. Thirdly, the loss function CIoU of the YOLOv7 model is changed to WIoUv2. Fourthly, add the Triplet attention mechanism to the CBS and SPPCSPC modules. Finally, the detection accuracy of the improved YOLOv7 model is compared with that of Faster R-CNN, SSD, YOLOv3-tiny, YOLOv5s, and YOLOv7 models. The experimental results show that the detection accuracy and detection speed of the improved YOLOv7 model are enhanced compared with the original YOLOv7 model.

This study explores the effectiveness of an amorphous buffer layer, specifically Indium Zinc Magnesium Oxide (IZMO), as an alternative buffer in Copper Indium Gallium Sulfide Selenide (CIGSSe) solar cells. The findings reveal a significant impact on efficiency through precise adjustment of the Mg/(In+Zn+Mg) ratio (MIZM) from 0 to 0.23. The bandgap exhibits a consistent increase with an ascending Mg/(In+Zn+Mg) ratio, transitioning from 3.42 eV to 3.63 eV for IZMO prepared with Ar and from 3.18 eV to 3.53 eV for IZMO prepared with an Ar+O₂ gas mixture, respectively. This rise is attributed to the augmentation of the conduction band minimum (E_C) of IZMO resulting from the addition of MgO. Moreover, an increase in the Mg/(In+Zn+Mg) ratio correlates with improved conversion efficiency, escalating from 6.31 % to 9.19 %. Notably, the open-circuit voltage experiences a rise from 0.430 V to 0.520 V. This is attributed to the heightened E_C of IZMO due to MgO addition, which mitigates recombination between the light-absorbing layer and the buffer layer, consequently elevating the open circuit voltage. The addition of MgO also enhances the resistance of the buffer layer, contributing to an increase in shunt resistance and a subsequent decrease in leakage current. Conversely, IZMO introduced with O₂ exhibits inferior performance akin to IZO, attributable to substantial sputter damage induced by O₂ introduction.

The color centers in diamonds are promising candidates in the context of quantum information science, quantum computation, and spin-based quantum sensors due to their spin-dependent optical transitions. The manipulation and optical readout of electronic spin state is measured using a technique known as optically detected magnetic resonance (ODMR). Here, we discuss the indigenous development of ODMR setup to coherently manipulate and precise readout of spin state of nitrogen-vacancy centers (NV) in nanodiamond at room-temperature. The study involves the confocal mapping of an ensemble of NV centers to measure spin state-dependent optical transition by applying an optical excitation and microwave field simultaneously. The spin state control appears as a dip at 2.87 GHz in the measured emission intensity spectra as a function of microwave frequency. An ODMR contrast of 3.4 % is achieved at the NV center emission maximum of 660 nm and an inhomogeneous dephasing time of 0.03 microseconds. We find an inherent small split in the ODMR dip which is induced by local strain in nanodiamonds. The split becomes stronger while applying an external magnetic field, which forms the basis of NV center-based magnetometry. The results are useful for spin-based microwave-optical quantum transducers, quantum sensing, and quantum memory devices.

Magnesium oxide (MgO) thin films, both pure and zinc (Zn) doped, were fabricated on soda lime glass substrates using ultrasonic spray pyrolysis. Zn was introduced at concentrations of 0.5 %, 1 %, 2 %, 4 %, and 8 %. The effects of these doping levels on the films' structural, morphological, optical, and H2 gas sensing properties were studied using XRD, SEM, EDAX, UV–vis spectroscopy, PL spectroscopy, gas sensing measurements, and XPS. The films showed a cubic crystal structure without secondary phases, and grain sizes generally decreased with doping. Morphological changes in nanocrystal shapes were noted due to impurities. Optimal doping enhanced MgO's absorbance, with a slight increase in bandgap. The PL spectra showed increased luminescent emissions with higher doping, due to defects from Zn ions. Pure films were responsive to H2 gas, while Zn-doped samples showed weaker responses. The XPS confirmed the expected chemical compositions.