Optical Antenna Research Articles

Fluorescent Fiber-Based Optical Antenna for Visible Light Communication Applications

Fluorescent Fiber-Based Optical Antenna for Visible Light Communication Applications

Study of optical antenna image quality under high-power laser irradiation

Study of optical antenna image quality under high-power laser irradiation

Graphene-based plasmonic nanoantenna with trapezoidal structure in THz band

Mainly manipulating emitted waves via plasmonic resonance is a fundamental characteristic of optical antennas. Plasmonic nanoantennas are used for terahertz (THz) radiation caused by optical interaction with surface resonance. The designed nanoantenna is such that the plasmonic resonance of the nanoantenna changes by controlling the graphene chemical potential (μc) from 0 eV to 0.2 eV. Although a dielectric layer separates the trapezoidal graphene sheets, an essential difference in the scattering parameters and the radiation pattern is observed since an external direct current bias changed the graphene surface impedance to about 860 Ω, which is the optimal value for reducing return loss in nano-systems. In other words, the plasmonic resonance frequencies can be tuned by the effect of a localised electrostatic field. Also, the trapezoidal graphene-based plasmonic nanoantenna has a high quality factor (Q-factor) from 2.35 to 5.71. Therefore, dynamic control, enhancing the input impedance and stable efficiency of graphene-based plasmonic nanoantennas, improves performance and matching at THz nano-systems for many applications of optoelectronic devices.

A Quasi-Bound States in the Continuum Dielectric Metasurface-Based Antenna-Reactor Photocatalyst.

Metasurfaces are a class of two-dimensional artificial resonators, creating new opportunities for strong light-matter interactions. One type of nonradiative optical metasurface that enables substantial light concentration is based on quasi-Bound States in the Continuum (quasi-BIC). Here we report the design and fabrication of a quasi-BIC dielectric metasurface that serves as an optical frequency antenna for photocatalysis. By depositing Ni nanoparticle reactors onto the metasurface, we create an antenna-reactor photocatalyst, where the virtually lossless metasurface funnels light to drive a chemical reaction. This quasi-BIC-Ni antenna-reactor drives H2 dissociation under resonant illumination, showing strong polarization, wavelength, and optical power dependencies. Both E-field-induced electronic and photothermal heating effects drive the reaction, supported by load-dependent reactivity studies and our theoretical model. This study unlocks new opportunities for photocatalysis that employ dielectric metasurfaces for light harvesting in an antenna-reactor format.

Plasmonic Nanocone Scanning Antenna: Fabrication and Optical Properties

Optical antennas are nanostructures that introduce unprecedented possibilities for light–matter interaction at the nanoscale. An appropriately tailored plasmonic antenna can enhance the total radiative decay rate and modify the angular radiation pattern of a single‐quantum emitter through controlled near‐field coupling. Despite their ability to surpass the fundamental diffraction limit and confine the electromagnetic field to a tiny mode volume, fabricating 3D sharp scanning nanoscale plasmonic structures with desired aspect ratio is yet an ambitious goal. The fabrication of nanocones by gold evaporation on commercial atomic force microscopy probes followed by a focused ion beam milling technique is presented. The method is versatile and allows the fabrication of nanocones with desired dimensions around 100 nm along with an aspect ratio of ≈1. Their optical properties are studied and it is shown how the variation in the refractive index of the dielectric substrate affects the localized surface plasmon resonance of the nanocones, the decay rate enhancement, and the quantum yield of an emitter relevant for fluorescence/Raman scanning experiments. Theoretical studies using finite‐difference time‐domain calculations have guided the fabrication process and are consistent with experimental results.

Design of a compact off-axis two-mirror freeform optical antenna for shaping and transmitting an elliptical beam emitted by laser diode.

Elliptical Gaussian beams generated by laser diodes (LDs) often exhibit asymmetrical divergence angle distribution, which limits their practical applications. In this study, we propose what we believe is a novel approach to shape and collimate the elliptical output beam from a LD. The design process involves the construction of two freeform reflective surfaces on a reference circle using a three-dimensional point-by-point iterative method, based on the law of conservation of energy, the vector reflection theory, and Fermat's principle. The output beam's maximum divergence angle is effectively compressed to 3.1579mrad. The design is compact with a folded optical path and antenna size of 368.8c m 3. This paper presents a comprehensive design and optimization process, along with an in-depth analysis of the system's performance, thereby offering novel insights for emerging optical design practitioners.

Designing high-speed GEO-to-Moon optical wireless communication links

Moon exploration and colonization will strongly rely upon high-speed optical wireless communications over a huge distance (around 400,000 km). Here, we introduce a holistic model, including the propagation issues as well as the realistic communication limitations and the expected practical limitations. We focus on the communication issues in a link connecting a GEO satellite to a fixed Moon optical station: here, we consider the challenging 10 Gbit/s transmission rate, and we assume an optical pre-amplified receiver, which is today the only option for high speed; we then select three different modulation formats, with corresponding implementations and increasing complexity and performance. Under these assumptions, we estimate the common operating conditions at the forward error correction threshold and point out the role of the transmitter and receiver telescopes: for practical size (e.g., 1 m), relevant limitations arise, which we combine with the typical photons-per-bit sensitivity values in an optical link. We find that all considered modulation formats can be used at 10 Gbit/s, although with different margins and hardware requirements, particularly considering the size of the optical antennas. We then extend the analysis to higher rates, up to 40 Gbit/s. This work can open the way to the realization of optical wireless communication systems to/from the future Moon Village.

Research on the localized lightfield features of metallic nano-cone-tip optical antenna via investigating near-field lightwave and correlated net-charge distribution

In this paper, the near-field lightwave characteristics of an arrayed silicon nano-cone-tip optical antenna (NOA) covered by a common metal film, which can be viewed as a featured quasi quantum dot (QD), are carefully investigated. A dipole net-charge distribution closely correlated with the surface lightwaves excited over the antennas by incident lasers with a central wavelength of 633 nm, is clearly observed. An obvious Coulomb-like blockade from the apex apparently influencing the net-charge converging over the surface of NOA, is verified, which can also be predicted by the simulations according to surface standing waves across the apex node. The antinodes of the surface net-charge instantaneous distribution are already pushed away from the normal location owing to the apex Coulomb-like blockade, so as to present a distorted waveform different from traditional standing wave modes. The tip proximity effect leading to a relatively weak net-charge converging over surrounding planar facet and adjacent NOAs, is also discovered.

Design of high-efficiency and large-field silicon-based transceiver integrated optical phased array

With the rapid development of photonic integrated circuits, optical phased array (OPA) technology has attracted much attention in recent years because it can turn quickly without mechanical structure, and has been widely studied in the fields of light detection and ranging (LiDAR). However, the two-dimensional optical phased array antenna is still limited by the antenna spacing, and it is difficult to expand the scanning range. We propose a two-dimensional silicon-based optical phased array (OPA) transceiver with high efficiency and a large field of view. The structure adjusts the phase of the two dimensions of the antenna through the external waveguide phase shifter of the antenna array and further scans the two dimensions of the far field. We take an 8 × 8 array as an example, reasonably design the array structure, and optimize the performance of some functional devices. Finally, the scanning range of 14.9°×11.2° can be achieved. At the same time, we can realize the free switching of the OPA receiving and transmitting functions through an optical switch.

Excitation Wavelength‐Dependent Fluorescence of a Lanthanide Organic Metal Halide Cluster for Anti‐Counterfeiting Applications

AbstractThe achievement of significant photoluminescence (PL) in lanthanide ions (Ln3+) has primarily relied on host sensitization, where energy is transferred from the excited host material to the Ln3+ ions. However, this luminous mechanism involves only one optical antenna, namely the host material, which limits the accessibility of excitation wavelength‐dependent (Ex‐De) PL. Consequently, the wider application of Ln3+ ions in light‐emitting devices is hindered. In this study, we present an organic–inorganic compound, (DMA)4LnCl7 (DMA+=[CH3NH2CH3]+, Ln3+=Ce3+, Tb3+), which serves as an independent host lattice material for efficient Ex‐De emission by doping it with trivalent antimony (Sb3+). The pristine (DMA)4LnCl7 compounds exhibit high luminescence, maintaining the characteristic sharp emission bands of Ln3+ and demonstrating a high PL quantum yield of 90–100 %. Upon Sb3+ doping, the compound exhibits noticeable Ex‐De emission with switchable colors. Through a detailed spectral study, we observe that the prominent energy transfer process observed in traditional host‐sensitized systems is absent in these materials. Instead, they exhibit two independent emission centers from Ln3+ and Sb3+, each displaying distinct features in luminous color and radiative lifetime. These findings open up new possibilities for designing Ex‐De emitters based on Ln3+ ions.

Tunable Kerker Scattering in a Self‐Coupled Polaritonic Metasurface

AbstractThe strong coupling between electronic transitions and resonant cavity modes, facilitated by coherent energy transfer, presents unprecedented opportunities for tailoring the photoelectronic properties of constituent components. Here, the concept of Kerker effect is leveraged to demonstrate the dynamic control of scattering directionality in dielectric nanostructures by tuning the exciton‐photon coupling. First, theoretical evidence for a significant modification of the scattering directionality of a dielectric metastructure engineered by excitonic polaritons is provided. As a proof of concept, self‐coupled metasurfaces composed of bulk MoS2, which exhibit a forward/backward scattering ratio up to 20, are constructed. Importantly, tunable directionality is achieved by thermally controlling the excitonic coupling to the Mie modes. The simulated results are in good agreement with the experimental measurements, and the subsequent multipole decompositions effectively elucidate the underlying mechanism, attributed to the interplay between electric and magnetic dipole modes that are modified by excitons. The findings shed light on the control of light flow in the far field through coherent light–matter interactions, thereby opening up numerous possibilities for active optical antennas and quantum emitters on a nanoscale.

Optical Vivaldi Antenna Array for Solar Energy Harvesting

In this paper, we try to find the best solution for our energy harvesting application by designing an efficient optical antenna which receives the solar radiation and converts it from AC to DC by integrating a rectifier. This work consists of designing a Vivaldi optical antenna with a maximum electric field captured in its gap. We also examine the use the optical array(double, four and eight) in order to increase the captured electric field concentrated in the common gap, compared to the single structure . Feeding lines are used to ride the captured electric field from the gap of each single antenna to a common gap. These innovative systems are small electronic devices often consisting of a low-power computer, wireless sensors, an antenna and capable of communicate with their environment. These devices also have an on-board energy source in the form of cells or batteries that require maintenance operations. periodic replacement or recharging, which can hinder the mobility and deployment of these communicating systems for the greatest number. This is the reason why we Today, we also note the very strong interest in improving energy autonomy and even the complete independence of these systems with respect to on-board sources.

Optical Antenna with Controlled Radiation Pattern for Application in Atmospheric Communication Channels

A mathematical model of a new optical (1550 nm) antenna with an electrically controlled radiation pattern is presented. The working principle is considered, and the main parameters are calculated. As distinct from existing solutions, the antenna does not require convergence of beams at a distance of one half of wavelength. In the framework of the model, an electro-optical switch based on lithium niobate is calculated. Such antenna elements as a phase shifter and deflector are presented and calculated

Optical nano patch antenna for terahertz applications with graphene

Nano optical crescent patch antenna for Terahertz applications using Graphene is designed in this paper. The antenna is designed at 7.28 THZ with several substrates material as PTFE (²r = 2.1), polymide (²r = 3.5), RO3003 (²r = 3), RO4003 (²r = 3.4) and Arlon AD (²r = 2.5). Graphene is the material patch used with different properties such as chemical potential µc = 0.2 eV, relaxation time τ = 1 ps and thickness of 60 nm to achieve a high gain and bandwidth. We obtained a very good performance of crescent antenna at 7.28 THZ with −37.962 dB, 7.124 dBi, 1.767 THZ of return loss, gain and bandwidth respectively which is very satisfactory for terahertz transmission between [0.1-10] THZ.

Optical Antenna with Controlled Radiation Pattern for Application in Atmospheric Communication Channels

Optical Antenna with Controlled Radiation Pattern for Application in Atmospheric Communication Channels

Silicon Photonic Optical Phased Array with Integrated Phase Monitors

The optical phased array (OPA) is an emerging non-mechanical device that enables high-speed beam steering by emitting precisely phase-controlled lightwaves from numerous optical antennas. In practice, however, it is challenging to drive all phase shifters on an OPA in a deterministic manner due to the inevitable fabrication-induced phase errors and crosstalk between the phase shifters. In this work, we fabricate a 16-element silicon photonic non-redundant OPA chip with integrated phase monitors and experimentally demonstrate accurate monitoring of the relative phases of light from each optical antenna. Under the beam steering condition, the optical phase retrieved from the on-chip phase monitors varies linearly with the steering angle, as theoretically expected.

Non-imaging metasurface design for collimated beam shaping.

Non-imaging optical lenses can shape the light intensity from incoherent sources to a desired target intensity profile, which is important for applications in lighting, solar light concentration, and optical beam shaping. Their surface curvatures are designed to ensure optimal transfer of energy from the light source to the target. The performance of such lenses is directly linked to their asymmetric freeform surface curvature, which is challenging to manufacture. Metasurfaces can mimic any surface curvature without additional fabrication difficulty by imparting a spatially-dependent phase delay using optical antennas. As a result, metasurfaces are uniquely suited to realize non-imaging optics, but non-imaging design principles have not yet been established for metasurfaces. Here, we take an important step in connecting non-imaging optics and metasurface optics, by presenting a phase-design method for beam shaping based on the concept of optimal transport. We establish a theoretical framework that enables a collimated beam to be redistributed by a metasurface to a desired output intensity profile. The optimal transport formulation leads to metasurface phase profiles that transmit all energy from the incident beam to the output beam, resulting in an efficient beam shaping process. Through a variety of examples, we show that our approach accommodates a diverse range of different input and output intensity profiles. Last but not least, a full field simulation of a metasurface has been done to verify our phase-design framework.

Multi-wavelength unidirectional forward scattering properties of the arrow-shaped galliumphosphide nanoantenna.

An arrow-shaped gallium phosphide nanoantenna exhibits both near-field electric field enhancement and far-field unidirectional scattering, and the interference conditions involve electric and magnetic quadrupoles as well as toroidal dipoles. By using long-wavelength approximation and exact multipole decomposition, the interference conditions required for far-field unidirectional transverse light scattering and backward near-zero scattering at multiple wavelengths are determined. The near-field properties are excellent, as exemplified by large Purcell factors of 4.5×109 for electric dipole source excitation, 464.68 for magnetic dipole source excitation, and 700V/m for the field enhancement factor. The degree of enhancement of unidirectional scattering is affected by structural parameters such as the angle and thickness of the nanoantenna. The arrow-shaped nanoantenna is an efficient platform to enhance the electric field and achieve high directionality of light scattering. Moreover, the nanostructure enables flexible manipulation of light waves and materials, giving rise to superior near-field and far-field performances, which are of great importance pertaining to the practicability and application potential of optical antennas in applications such as spectroscopy, sensing, displays, and optoelectronic devices.

A review on design, development and characterization of plasmonic nano-antenna for photonic applications

Abstract This article provides an overview of plasmonic nano-antennas for photonic applications. This paper delves into the theoretical analysis of nano/optical antennas, including optical antenna impedance, near and far field characteristics, and directivity. The materials used for manufacturing optical antennas are discussed in the context of terahertz communication. The comparative analysis of different types of fabrication techniques on the nanoscale is presented as a requirement for the implementation of nano-antennas. The testing mechanism of the nano-antenna using microscopy techniques is also presented. A detailed review of the different shapes of the nano-antennas that are used for applications in the field of photonics is discussed. According to this review article, graphene, gold, and silver are the most promising materials. It is also noticed that pen-dip and direct growth are fast and inexpensive techniques for nano-antenna fabrication.

Design and Optical Performance of a Single-Junction GaAs Nanowire-Ge Solar Cell

Solar cells are one of the most effective methods available for energy harvesting and are constructed from a variety of materials. In recent years, the use of novel materials for low-cost, high-efficiency photovoltaics has been one of the most exciting breakthroughs. This study conducted an in-depth investigation into the optical characteristics of GaAs nanowires on a Ge bottom cell. Geometric optimization of nanowires is necessary to increase solar cell performance metrics. The absorption efficiency per unit volume was considerably boosted over its traditional bulk and thin-film counterparts as a result of inherent antireflection, intensive stimulation of resonant modes, and optical antenna effects. A 3D FDTD framework was used to acquire optical properties and incorporate numerical values. Under typical AM 1.5G illumination, the diameter of GaAs nanowires was optimized to 170 nm.