Future Communication Applications Research Articles

A Compact Linear Microstrip Patch Beamformer Antenna Array for Millimeter-Wave Future Communication.

5/6G is anticipated to address challenges such as low data speed and high latency in current cellular networks, particularly as the number of users overwhelms 4G and LTE capabilities. This paper proposes a microstrip patch antenna array comprising six radiating patches and utilizing a microstrip line feeding technique to facilitate the compact design crucial for 5G implementation. ROGER 3003, chosen for its advanced and environmentally friendly features, serves as the dielectric material, ensuring suitability for 5G and B5G applications. The designed antenna, evaluated at a resonating frequency of 28.8 GHz with a -10 dB impedance bandwidth of 1 GHz, offers a high gain of 9.19 dBi. Its compact array, cost-effectiveness, and broad impedance and radiation coverage position it as a viable candidate for 5G and future communication applications.

Design of a novel compact low specific absorption rate multiple input multiple output antenna for 5G sub-6 GHz terminals

This investigation presents a new design and analysis of a fourteen elements massive multiple input multiple output (MIMO) compact low specific absorption rate (SAR) antenna system for 5G and beyond terminals. The MIMO antennas are realized for sub-6 GHz LTE-band 46 (5.1-5.8 GHz) long-term evolution 5G wireless communication services. The proposed antenna system is designed on an FR-4 dielectric constant 4.3 substrate consisting of the main board and four sideboards. The radiating elements are developed on the sideboards consisting of a monopole antenna and two metamaterial unit cells, as well as the feed line is designed on the principal board. The overall volume of the proposed structure is 150×80×7.5 mm. Through the use of the metamaterial unit cells, the proposed antennas have been arranged in close proximity without developing a strong mutual coupling. The results obtained were very important in terms of impedance matching, isolation among the antennas, and good gain. Even, the SAR analysis at the operating frequency band of 5.5 GHz proves that the proposed MIMO antenna system satisfies safety standards set for human exposure at the international level. Therefore, the proposed massive MIMO antenna structure is a potential solution for future communication applications.

Liquid Crystal Metasurface for On‐Demand Terahertz Beam Forming Over 110° Field‐Of‐View

AbstractThe terahertz spectral region, which bridges between electronics and optics, is poised to play an important role in the development of transformative wireless communication and imaging systems with unprecedented functionality. Currently, a major challenge in terahertz technology is to develop high‐performance terahertz beam‐forming devices that can dynamically shape the terahertz radiation in a flexible manner. Existing terahertz beam‐forming devices have limited coding bits, field‐of‐view, and beam gain. Here, a reconfigurable liquid crystal‐integrated terahertz metasurface is experimentally demonstrated, with each metasurface unit cell being independently addressable. The metasurface has a 260° continuous phase tuning range with a liquid crystal layer thickness of only 1% of the free‐space wavelength. The terahertz wave diffracted from the metasurface can be steered toward a wide range of directions is shown, covering a record‐large 110° field‐of‐view with a peak gain of 25 dBi. The metasurface also features a low power consumption and sub‐second switching time. Furthermore, the formation of multiple terahertz beams is demonstrated, with the direction of each beam and the power ratio between beams adjustable on demand. The proposed liquid crystal metasurface possesses compelling prospects for future terahertz communication and imaging applications.

Adsorption of N, He and Ne on CGe nanoribbons for sensing and optoelectronic applications.

Research into nanomaterials yields numerous exceptional applications in contemporary science and technology. The subject of this investigation is a one-dimensional nanostructure, six atoms wide, featuring hydrogen-functionalized edges. The theoretical foundation of this study relies on Density Functional Theory (DFT) and is executed through the utilization of the Vienna Ab initio Simulation Package (VASP). The outcomes demonstrate the stability of adsorption configurations, along with the preservation of a hexagonal honeycomb lattice. The pristine configuration, characterized by a wide bandgap, is well-suited for optoelectronic applications, whereas adsorption configurations find their application in gas sensing. Nitrogen (N) adsorption transforms the semiconducting system into a semimetallic one, with the spin-up state showing semiconductor characteristics and the spin-down state exhibiting metallic attributes. The intricate multi-orbital hybridization is explored through the analysis of partial states. While the pristine system remains non-magnetic, N adsorption introduces a magnetic moment of 0.588 μB. The examination of charge density differences indicates a significant charge transfer from N to the CGe substrate surface. Optical properties are systematically investigated, encompassing the dielectric function, absorption coefficient and electron-hole density. Notably, the real part of the dielectric function exhibits negative values, a result that holds promise for future communication applications.

Terahertz imaging through emissivity control

Electromagnetic radiation in the terahertz (THz) frequency band has unique potential for future communication and imaging applications. However, the adoption of THz technologies is hindered by the lack of cost-effective THz sources. Here we demonstrate a way to generate and control THz radiation, via spatio-temporal emissivity modulation. By patterning the optical photoexcitation of a surface-passivated silicon wafer, we locally control the free-electron density, and thereby pattern the wafer’s emissivity in the THz part of the electromagnetic spectrum. We show how this unconventional source of controllable THz radiation enables a form of incoherent computational THz imaging. We use it to image various concealed objects, demonstrating that this scheme has the penetrating capability of other THz imaging approaches, without the requirement of femtosecond pulsed laser sources. Furthermore, the incoherent nature of thermal radiation also ensures the obtained images are free of interference artifacts. Our spatio-temporal emissivity control could enable a family of long-wavelength structured illumination, imaging, and spectroscopy systems.

Design of Orbital Angular Momentum Antenna Array for Generating High-Order OAM Modes

Orbital angular momentum (OAM) modes can offer high density and high-capacity communication. The traditional phased array antenna can only produce a limited number of OAM beam modes l, usually less than half of the number of array elements (N): −N/2 < lmax < N/2. An OAM antenna array for generating high-order OAM modes is proposed in this letter. The proposed antenna array consists of a ring patch antenna that can generate vortex waves with OAM mode l = 1 or −1 and a phase-shifting feeding network. By adding different feed excitation signals to each element, the generated beam carries a higher-order mode: l = N or −N, breaking the previous limitations. Near-field measurements were conducted on antenna arrays composed of 3, 4, and 5 elements, revealing a high degree of correspondence between their phase distribution and radiation patterns with numerical simulation results. This alignment further substantiates the practical efficacy of this approach in significantly enhancing the generation of high-order OAM modes within antenna arrays. This advancement improves component utilization efficiency, reduces system complexity, and meets the high demands for spectral resources and channel capacity in future communication applications.

Observing Er3+ Sites in Si With an In Situ Single-Photon Detector

We studied the optical properties of a resonantly excited trivalent Er ensemble in Si accessed via in situ single photon detection. A novel approach which avoids nanofabrication on the sample is introduced, resulting in a highly efficient detection of 70 excitation frequencies, of which 63 resonances have not been observed in literature. The center frequencies and optical lifetimes of all resonances have been extracted, showing that 5% of the resonances are within 1 GHz of our electrically detected resonances and that the optical lifetimes range from 0.5 ms up to 1.5 ms. We observed inhomogeneous broadening of less than 400 MHz and an upper bound on the homogeneous linewidth of 1.4 MHz and 0.75 MHz for two separate resonances, which is a reduction of more than an order of magnitude observed to date. These narrow optical transition properties show that Er in Si is an excellent candidate for future quantum information and communication applications.

High-speed uni-traveling-carrier photodiodes on silicon nitride

Integrated photonics is an emerging technology for many existing and future telecommunication and data communication applications. One platform of particular interest is silicon nitride (SiN), thanks to—among others—its very low-loss waveguides. However, it lacks active devices, such as lasers, amplifiers, and photodiodes. For this, hybrid or heterogeneous integration is needed. Here, we bring high-speed uni-traveling-carrier photodiodes to a low-loss SiN-platform by means of micro-transfer-printing. This versatile technology for heterogeneous integration not only allows very dense and material-efficient III–V integration but also eases the fabrication, yielding high-performance detectors. The waveguide-coupled photodiodes feature a responsivity of 0.3 A/W at 1550 nm, a dark current of 10 nA, and a bandwidth of 155 GHz at a low bias. At zero bias, a record bandwidth of 135 GHz is achieved. We further demonstrate that this integrated detector can be used for direct photomixing at terahertz frequencies. A back-to-back communication link with a carrier frequency of around 300 GHz is set up, and data rates up to 160 Gbit/s with a low error vector magnitude are shown, showcasing a near-identical performance at zero bias.

Scaling waveguide-integrated superconducting nanowire single-photon detector solutions to large numbers of independent optical channels.

Superconducting nanowire single-photon detectors are an enabling technology for modern quantum information science and are gaining attractiveness for the most demanding photon counting tasks in other fields. Embedding such detectors in photonic integrated circuits enables additional counting capabilities through nanophotonic functionalization. Here, we show how a scalable number of waveguide-integrated superconducting nanowire single-photon detectors can be interfaced with independent fiber optic channels on the same chip. Our plug-and-play detector package is hosted inside a compact and portable closed-cycle cryostat providing cryogenic signal amplification for up to 64 channels. We demonstrate state-of-the-art multi-channel photon counting performance with average system detection efficiency of (40.5 ± 9.4)% and dark count rate of (123 ± 34) Hz for 32 individually addressable detectors at minimal noise-equivalent power of (5.1 ± 1.2) · 10-18 W/Hz. Our detectors achieve timing jitter as low as 26ps, which increases to (114 ± 17) ps for high-speed multi-channel operation using dedicated time-correlated single photon counting electronics. Our multi-channel single photon receiver offers exciting measurement capabilities for future quantum communication, remote sensing, and imaging applications.

Generation and Superposition of Perfect Vortex Beams in Terahertz Region via Single-Layer All-Dielectric Metasurface.

Terahertz (THz) orbital angular momentum (OAM) technology provides promising applications in future wireless communication with large bandwidth and high capacity. However, the ring radius of the conventional THz vortex beam is related to the topological charge, limiting the co-propagation of multiple OAM modes in the THz communication systems. Although the perfect vortex beam (PVB) based on traditional methods can solve this problem, they are usually bulky and unstable. Here, we demonstrate two PVB generators based on a single all-dielectric metasurface to obtain polarization-independent PVB and spin multiplexed PVB, respectively. The former regulates the propagation phase by using isotropic unit cells; the latter simultaneously manipulates the propagation and geometric phase to achieve the spin-decoupled phase control by arranging anisotropic unit cells. In addition, we also demonstrate the stable generation of a perfect Poincaré beam with arbitrary polarization and phase distribution on a hybrid-order Poincaré Sphere via a spin-decoupled metasurface, which is achieved by the linear superposition of two PVBs with orthogonal circular polarizations. The proposed scheme provides a compact and efficient platform for the generation and superposition of PVBs in THz region, and will speed up the progress of THz communication systems, complex light field generation, and quantum information sciences.

Toward high-bandwidth yellow-green micro-LEDs utilizing nanoporous distributed Bragg reflectors for visible light communication

In this study, high − 3 dB bandwidth yellow-green InGaN/GaN micro-LEDs grown on polar c-plane GaN substrates are realized by using nanoporous distributed Bragg reflectors, which can increase light extraction efficiency and serve as strain-relaxed buffers to mitigate the quantum-confined Stark effect, resulting in improved external quantum efficiency. Moreover, atomic layer deposition technology is introduced for surface defect passivation, thereby reducing the leakage current. As a result, the device exhibits the highest − 3 dB bandwidth up to 442 MHz and a data transmission rate of 800 Mbit/s at a current density of 2.5 kA / cm 2 with on–off keying modulation, and holds great promise for future high-speed visible light communication applications.

A (CH3)2CNHCH3PbBr3/CH3NH3PbBr3 core-shell heterostructure fabricated by an in situ a-site reaction for fast response 1D perovskite photodetectors.

Benefitting from their long carrier diffusion lengths, low trap densities and high carrier mobilities, metal halide perovskites are of great value in the field of energy and optical communications. Herein, we propose a reversible organic cation reaction for (CH3)2CNHCH3PbBr3/CH3NH3PbBr3 core-shell microwires (MWs), in which (CH3)2CNHCH3PbBr3 grow on bulk CH3NH3PbBr3 in acetone and then convert back to CH3NH3PbBr3 on the surface with the action of water. The core-shell MWs present excellent stability for more than 454 days with over 80% humidity. Moreover, the employed core-shell heterostructure significantly increases the photoluminescence lifetime and improves the rise/recovery response. The (CH3)2CNHCH3PbBr3/CH3NH3PbBr3 core-shell heterostructure demonstrates excellent stability and fast response (2.8 ms/0.8 ms), which is anticipated to find comprehensive applications in future optical communication of one-dimensional devices.

On-chip all-optical quantizer based on the cross polarization modulation effect in a double-ridge a-Si:H-Si3N4 waveguide.

The on-chip all-optical quantizer is a key functional module to realize all-optical analog-to-digital conversion. It has important applications in future optical communication and ultrafast all-optical signal processing systems. To the best of our knowledge, a novel all-optical quantization scheme based on the cross-polarization modulation effect in a double-ridge a-Si:H-Si3N4 waveguide is proposed. For the optimized waveguide, the maximum nonlinear coefficient and transmission loss at the probe wavelength are 2680.5m-1W-1 and 2.246 dB/cm, respectively. The simulation results of the proposed all-optical quantizer show that a nonlinear phase shift of 8 can be generated in the 8.79 mm long waveguide when the peak pump light power is 0.8 W. A 16-level quantization and a 4-bit quantization resolution are obtained. The effective number of bits is 3.79-bit, which is only 0.21-bit away from the ideal resolution.

Active Terahertz Modulator and Slow Light Metamaterial Devices with Hybrid Graphene-Superconductor Photonic Integrated Circuits.

Metamaterial photonic integrated circuits with arrays of hybrid graphene–superconductor coupled split-ring resonators (SRR) capable of modulating and slowing down terahertz (THz) light are introduced and proposed. The hybrid device’s optical responses, such as electromagnetic-induced transparency (EIT) and group delay, can be modulated in several ways. First, it is modulated electrically by changing the conductivity and carrier concentrations in graphene. Alternatively, the optical response can be modified by acting on the device temperature sensitivity by switching Nb from a lossy normal phase to a low-loss quantum mechanical phase below the transition temperature (Tc) of Nb. Maximum modulation depths of 57.3% and 97.61% are achieved for EIT and group delay at the THz transmission window, respectively. A comparison is carried out between the Nb-graphene-Nb coupled SRR-based devices with those of Au-graphene-Au SRRs, and significant enhancements of the THz transmission, group delay, and EIT responses are observed when Nb is in the quantum mechanical phase. Such hybrid devices with their reasonably large and tunable slow light bandwidth pave the way for the realization of active optoelectronic modulators, filters, phase shifters, and slow light devices for applications in chip-scale future communication and computation systems.

System demonstrations of Ka‐band 5‐Gbps data transmission for satellite applications

SummarySatellite‐ground‐link high‐rate high‐efficiency data transmission technique is one of the key supports for the development of high‐resolution low‐earth‐orbit (LEO) earth observation satellite systems. Ka‐band, frequency ranging from 24.6 to 40 GHz, shares a wide available bandwidth, high frequency reuse rate, and strong ability of anti‐jamming. Satellite operators have utilized the Ka‐band for satellite‐earth data transmission, which requires higher traffic capacity, and even have planned to launch new satellites with Ka‐band capacity. In this paper, we propose and experimentally demonstrate a 5‐Gbps uncoded data rate (corresponding to the channel rate of 6 Gbps) of Ka‐band data‐transmission system with dual‐circular polarization and frequency reuse for satellite‐earth applications. The objective of the experiment is gathering experimental data to validate the performance of the proposed four channel systems, including bit error ratio (BER) and link budget. Our work could support future satellite communication applications and meet the imperative demands of high rate transmission to earth.

Analysis of THz space communication link based on STK

The characteristics of terahertz communication technology, such as large capacity, high speed and high security, make it stand out among many wireless communication technologies. For future space communication application scenarios, the link performance and beam pointing accuracy of the terahertz communication system were analyzed. The beam adjustment angular acceleration index were analyzed through STK.

Feasibility of quantum key distribution from high altitude platforms

This paper presents the feasibility study of deploying quantum key distribution (QKD) from high altitude platforms (HAPs), as a way of securing future communications applications and services. The paper provides a thorough review of the state of the art HAP technologies and summarises the benefits that HAPs can bring to the QKD services. A detailed link budget analysis is presented in the paper to evaluate the feasibility of delivering QKD from stratospheric HAPs flying at 20 km altitude. The results show a generous link budget under most operating conditions which brings the possibility of using diverged beams, thereby simplifying the pointing, acquisition and tracking of the optical system on the HAPs and ground, potentially widening the range of future use cases where QKD could be a viable solution.

IR emission of Er3+ ion-doped fluoroborotellurite glass for communication application

We have successfully synthesized Er3+ ion-doped TeO2-B2O3-ZnF2-BaO using conventional melt and quenching technique to explore their possible future application. The physical properties were determined by their density and molar volume, while the structural properties were observed by FTIR spectra. The optical absorption spectra and emission spectra were measured to study their optical and photoluminescence properties. The optical absorption spectra were measured between 400 to 1800 nm. It shows the hypersensitive transition at 521 nm due to the 4I15/2→2H11/2 transition. The intense emission was shown in the peak of 1541 nm excited by 521 nm due to 4I13/2 to 4I15/ 2 transition. From the analysis of Judd-Ofelt theory, it is found that 1.5 mol% Er2O3 in the glass system possesses JO trendline Ω2 > Ω4 > Ω6 and 2.94 × 10−21 cm2 stimulated emission cross-section with the long radiative lifetime around 12.19 ms. The gain cross-section of prepared glass calculated using the Mc Cumber theory reveals the inversion population of prepared glass at γ≥0.4. It could be concluded from all results that 1.5 mol% Er2O3 doped fluoroborotellurite glass have a high potential for future communication application such as IR optical amplifier, IR laser, and WDM network system in C and L communication band.

Entanglement of a Nanowires System with Rashba Interaction

We propose a scheme to investigate the behavior of a ballistic nanowire system with Rashba interaction within a perpendicular magnetic field. The quantum entanglement of a nanowire system is discussed via the negativity. When the strong and weak magnetic fields are applied, we discuss the influence of the spin-orbit interaction and the initial states on the population inversion and the negativity. Our results show that the degree of entanglement for the nanowire system mainly depends on the effect of the spin-orbit interaction and the initial states of the system. This opens up new avenues for designing nanowire systems for future quantum computation and communication applications.

Organic photovoltaics for simultaneous energy harvesting and high-speed MIMO optical wireless communications

We show that organic photovoltaics (OPVs) are suitable for high-speed optical wireless data receivers that can also harvest power. In addition, these OPVs are of particular interest for indoor applications, as their bandgap is larger than that of silicon, leading to better matching to the spectrum of artificial light. By selecting a suitable combination of a narrow bandgap donor polymer and a nonfullerene acceptor, stable OPVs are fabricated with a power conversion efficiency of 8.8% under 1 Sun and 14% under indoor lighting conditions. In an optical wireless communication experiment, a data rate of 363 Mb/s and a simultaneous harvested power of 10.9 mW are achieved in a 4-by-4 multiple-input multiple-output (MIMO) setup that consists of four laser diodes, each transmitting 56 mW optical power and four OPV cells on a single panel as receivers at a distance of 40 cm. This result is the highest reported data rate using OPVs as data receivers and energy harvesters. This finding may be relevant to future mobile communication applications because it enables enhanced wireless data communication performance while prolonging the battery life in a mobile device.