Optical Array Antenna Research Articles

Optical Transparent Antenna Array Integrated With Solar Cell

This letter presents an optical transparent antenna array integrated with solar cell. Metal-meshed structure is used in the transparent antenna array, which achieves a balance between radiation efficiency and optical transparency. The meshed patches have equidistant distribution in the array and are fed by coaxial probes. A meshed ground, which has the same grid size as the meshed patch, is introduced and aligned with the patch. Cheap coating technology is utilized in printing silver-meshed patch and ground on the two surfaces of a glass substrate. A commercial monocrystalline silicon solar cell is closely assembled under the transparent antenna array. The proposed antenna array operates from 8.51 to 9.10 GHz (VSWR $\leq 2$ ) with low cross-polarization levels, and obtains an 88% optical transparency. The transparent antenna array achieves a good radiation performance with little effect on solar photovoltaic generation.

Metasurfaces: Subwavelength nanostructure arrays for ultrathin flat optics and photonics

Abstract

Review of Photonic Integrated Optical Phased Arrays for Space Optical Communication

A review of photonic integrated optical phased array (OPA) for space optical communication is presented. We review and summarize the typical works of the photonic integrated OPAs with one-dimensional and two-dimensional optical antenna array in recent years. The basic components of the photonic integrated OPA are introduced separately, including optical coupler, optical power division network, phase shifter, and optical antenna. In addition, the configuration of the optical antenna array and the control circuit are introduced for OPA beam steering. The basic principle and experiment setup for testing the radiation properties of the OPA are presented. A proof-of-concept nonuniform silicon integrated OPA with 64 antennas is designed and a one-dimensional beam steering range of 28° is achieved with beam width of about 0.25°. The challenges and development trends of large-scale integrated OPA chip applied in space optical communication are also discussed.

Physical foundation of optical smart antenna based on metamaterial and lithium niobate

In this work we present the main physical foundations of optical antenna array. This antenna array is based on the mirror system and lens system. To provide the necessary phase shift we propose two kind of structures: based on litium neobate and on ferrite-garnet. The main analytical expressions describing system behaviour are found for the first time. The results of calculation of the lens system parameters in the program ZEMAX are presented also.

ФИЗИЧЕСКИЕ ОСНОВЫ ПОСТРОЕНИЯ УПРАВЛЯЕМОЙ ОПТИЧЕСКОЙ АНТЕННЫ НА ОСНОВЕ НИОБАТА ЛИТИЯ

The article highlights a promising direction for high-speed signal transmission in wireless optical communication systems, namely, the use of optical antennas. Unlike fiber-optic systems which are sufficiently advanced today, today only one patent and one work are performed to describe the optical antenna array, which describes the optical antenna array for transmitting the optical signal in telecommunication networks. An important task in creating the antenna is selecting intelligent material to control the radiation pattern. The main physical foundations of optical antenna array have been described. The antenna array is based on the mirror system and lens system. To provide the necessary phase shift, two kinds of structures are proposed: of lithium niobate and of ferrite-garnet. The main analytical expressions describing system behavior are found for the first time.

Optical Adaptive Antenna Array for Multiuser Mobile Optical Communication

In this paper, an optical adaptive antenna array system for multi-user optical mobile communication is studied. A coherent signal source is embedded in a spherical optical phased cell array with an external spherical lens system. The system can predict the signal power of the receiving end according to the channel transfer matrix and perform power compensation when transmitting the signal. Correspondingly, a pure phase lossless desired light field recovery algorithm is proposed and used for space division multiple access and free power allocation of antenna array systems. A small-scale optical adaptive antenna array experimental system is built and tested with good performance and consistent with the expected results.

Negative permittivity and permeability of gold nanostructured thin films in UV–vis region

In this article, we report the growth of gold nanorods on glass substrates and copper nanoparticle thin films by cylindrical direct current magnetron sputtering (CDCMS) at room temperature. The grown gold nanorods have short lengths of < 20nm and show negative optical parameters in UV-Vis region. So far negative permittivity and permeability were only shown for complex artificial structures. In a case of simple structures like gold nanorods, the negative optical parameters were only predicted by simulation methods and considering ideal structures and they were not yet reported by experimental groups, who has grown or synthesis gold nanorods by physical or chemical methods. The small size of gold nanorods and thickness of our samples compare to other experimental groups could be the reason of negative permittivity and permeability in our case. Low loss metamaterials with simultaneously negative permittivity and permeability are desired for practical applications in many optical devices such as optical switching, waveguides, modulators, and plasmonic antenna arrays. The optical properties of the grown gold nanorods were defined by ultraviolet- visible (UV-Vis) spectroscopy and their quality was assessed through multi-technique characterization using transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and energy dispersed X-ray (EDX).

Material platforms for optical metasurfaces

AbstractOptical metasurfaces are judicously engineered electromagnetic interfaces that can control and manipulate many of light’s quintessential properties, such as amplitude, phase, and polarization. These artificial surfaces are composed of subwavelength arrays of optical antennas that experience resonant light-matter interaction with incoming electromagnetic radiation. Their ability to arbitrarily engineer optical interactions has generated considerable excitement and interest in recent years and is a promising methodology for miniaturizing optical components for applications in optical communication systems, imaging, sensing, and optical manipulation. However, development of optical metasurfaces requires progress and solutions to inherent challenges, namely large losses often associated with the resonant structures; large-scale, complementary metal-oxide-semiconductor-compatible nanofabrication techniques; and incorporation of active control elements. Furthermore, practical metasurface devices require robust operation in high-temperature environments, caustic chemicals, and intense electromagnetic fields. Although these challenges are substantial, optical metasurfaces remain in their infancy, and novel material platforms that offer resilient, low-loss, and tunable metasurface designs are driving new and promising routes for overcoming these hurdles. In this review, we discuss the different material platforms in the literature for various applications of metasurfaces, including refractory plasmonic materials, epitaxial noble metal, silicon, graphene, phase change materials, and metal oxides. We identify the key advantages of each material platform and review the breakthrough devices that were made possible with each material. Finally, we provide an outlook for emerging metasurface devices and the new material platforms that are enabling such devices.

Nanocrescent Optical Antennas for Ultrafast Photonic PCR

Ultrafast photonic polymerase chain reaction (PCR), which thermal cycling utilizing rapid plasmonic conversion of the light to heat drastically reduced time-consuming thermal cycling step. However, to enable rapid precision medicine in the point-of-care (POC), quantitative and multiplexed realtime PCR is necessary. Here we present a hexagonally packed nanocrescent optical antenna array for realtime ultrafast photonic PCR. We theoretically demonstrated that each nanocrescent antennae have an internal cavity with ∼ 0.1 fL volume and liquid within the cavity is heated up from 25 °C to 95 °C in nanosecond scale. We also experimentally demonstrated that hexagonally packed nanocrescent cavity heater array exhibited fast heating in the macroscale (22.4 ± 3.1 °C). In order to demonstrate real-time PCR on the chip, we integrated hexagonally packed nanocrescent array to the microfluidic chip. We believe that this hexagonally packed nanocrescent optical antenna impact both life science and ultrafast precision molecular diagnostics.

Metasurface-assisted phase-matching-free second harmonic generation in lithium niobate waveguides

The phase-matching condition is a key aspect in nonlinear wavelength conversion processes, which requires the momenta of the photons involved in the processes to be conserved. Conventionally, nonlinear phase matching is achieved using either birefringent or periodically poled nonlinear crystals, which requires careful dispersion engineering and is usually narrowband. In recent years, metasurfaces consisting of densely packed arrays of optical antennas have been demonstrated to provide an effective optical momentum to bend light in arbitrary ways. Here, we demonstrate that gradient metasurface structures consisting of phased array antennas are able to circumvent the phase-matching requirement in on-chip nonlinear wavelength conversion. We experimentally demonstrate phase-matching-free second harmonic generation over many coherent lengths in thin film lithium niobate waveguides patterned with the gradient metasurfaces. Efficient second harmonic generation in the metasurface-based devices is observed over a wide range of pump wavelengths (λ = 1580–1650 nm).

A back side configured pointed dipole plasmonic optical antenna array enhanced quantum dot infrared photodetector

In this paper, we report a back side configured pointed dipole optical antenna array enhanced quantum dot infrared photodetector (QDIP). In this configuration, the light illumination is from the substrate side (i.e. back side illumination), goes through the QDIP and then reaches the optical antenna array. The near-field electric fields (E-fields) are simulated for both top and back side illuminations. The back side configured pointed dipole antenna array gives stronger E-fields than the top side configuration. The physical mechanism for the difference is analyzed. A longwave infrared QDIP with the back side configured pointed dipole optical antenna array was fabricated and tested. The measurements agree well with the simulation. Compared with the top side configured optical antenna array, the back side configured optical antenna array allows easier fabrication of large format (e.g. 640 × 512 or 1024 × 1024) focal plane arrays and provides higher plasmonic enhancement.

Analysis of mutual couplings in a concentric circular ring plasmonic optical antenna array

In this paper, we report the analysis of a concentric circular ring plasmonic optical antenna (POA) array using a simple lumped coupled circuit (LCC) model. The currents in the circular rings of the POA array and their mutual couplings are analyzed using the LCC model. The results agree well with the numerical simulation using CST’s Microwave Studio®. The LCC model reveals the mutual couplings between the antenna rings. It is found that the mutual couplings are not only between the adjacent antenna rings, but also involve their second (2nd) nearest or farther neighbors. Since the near-fields of the optical antennas are related to the currents in the optical antennas, the LCC model provides a useful tool for the analysis of the near-field and their mutual interactions in the circular ring POA array.

Performance evaluation of optical beamforming-based wideband antenna array (Invited Paper)

A wideband-generalized pattern multiplication approach to evaluate the performance of an optical beamforming-based wideband antenna array is proposed and experimentally demonstrated, which enables the far-field measurement of a large wideband array with a small anechoic chamber. Because the optimum reception of a wideband microwave signal is highly related to the time-domain distortions of the beamforming system, a correlation-receiver-based radiation pattern is applied to take the fidelity of the wideband signals into account. A four-element optical beamforming system is built to verify the feasibility of the proposed method. The results achieved by the proposed method agree well with the conventional direct measurements.

Yagi–Uda optical antenna array collimated laser based on surface plasmons

The divergence and directivity of a laser with a periodic Yagi–Uda optical antenna array modulated surface are investigated by finite element method. The nanoparticle optical antenna arrays are optimized to achieve the high directivity and the small divergence by using of Helmholtz's reciprocity theorem. When the nanoparticle antenna replaced by a Yagi–Uda antenna with same size, the directivity and the signal-to-noise ratio of the modulated laser beam are notably enhanced. The main reason is that the directors of the Yagi–Uda antennas induce more energy to propagate towards the antenna transmitting direction. The results can provide valuable guidelines in designing collimated laser, which can be widely applied in the field of biologic detection, spatial optical communication and optical measurement.

Resonance spectra of diabolo optical antenna arrays

A complete set of diabolo optical antenna arrays with different waist widths and periods was fabricated on a sapphire substrate by using a standard e-beam lithography and lift-off process. Fabricated diabolo optical antenna arrays were characterized by measuring the transmittance and reflectance with a microscope-coupled FTIR spectrometer. It was found experimentally that reducing the waist width significantly shifts the resonance to longer wavelength and narrowing the waist of the antennas is more effective than increasing the period of the array for tuning the resonance wavelength. Also it is found that the magnetic field enhancement near the antenna waist is correlated to the shift of the resonance wavelength.

Nanoimprinted thrombin aptasensor with picomolar sensitivity based on plasmon excited quantum dots

To achieve sensitive biomolecular detection, a gold nanohole array sensing chip was designed by plasmonic simulation and fabricated by high fidelity nanoimprinting technology. The gold nanohole array on a glass substrate serves as an optical antenna array, to produce localized surface plasmon resonance (LSPR) of 10–100 times stronger than the illumination light for quantum dot (QD) excitation. In this work, a robust sandwich bioassay of primary aptamer/thrombin/secondary aptamer with QD655 was established on the chip, to detect thrombin at a limit of detection (LOD) of 1ng/ml (27pM), with low non-specific binding even at the presence of 1000 times more concentrated bovine serum albumin (BSA). The conformation and QD enhancement mechanism of the sandwich assay were characterized by atom force microscopy (AFM) and dual polarization interferometry (DPI). This is the first time that DNA is surface functionalized on gold nanostructures for protein detection by plasmon enhanced QD emission. Considering the low-cost, easy regeneration and long shelf-life of the capturing aptamer, low non-specific binding and high sensitivity of the bioassay, as well as the inexpensive mass fabrication of the high quality chips, this novel aptasensor platform is particularly useful for a point-of-care system on medical diagnostics.

Large-Scale Arrays of Bowtie Nanoaperture Antennas for Nanoscale Dynamics in Living Cell Membranes.

We present a novel blurring-free stencil lithography patterning technique for high-throughput fabrication of large-scale arrays of nanoaperture optical antennas. The approach relies on dry etching through nanostencils to achieve reproducible and uniform control of nanoantenna geometries at the nanoscale, over millimeter-sizes in a thin aluminum film. We demonstrate the fabrication of over 400 000 bowtie nanoaperture (BNA) antennas on biocompatible substrates, having gap sizes ranging from (80 ± 5) nm down to (20 ± 10) nm. To validate their applicability on live cell research, we used the antenna substrates as hotspots of localized illumination to excite fluorescently labeled lipids on living cell membranes. The high signal-to-background afforded by the BNA arrays allowed the recording of single fluorescent bursts corresponding to the passage of freely diffusing individual lipids through hotspot excitation regions as small as 20 nm. Statistical analysis of burst length and intensity together with simulations demonstrate that the measured signals arise from the ultraconfined excitation region of the antennas. Because these inexpensive antenna arrays are fully biocompatible and amenable to their integration in most fluorescence microscopes, we foresee a large number of applications including the investigation of the plasma membrane of living cells with nanoscale resolution at endogenous expression levels.

Optical phased array radiating optical vortex with manipulated topological charges.

Optical antennas are key elements in quantum optics emitting and sensing, and behave wide range applications in optical domain. However, integration of optical antenna radiating orbital angular momentum is still a challenge in nano-scale. We theoretically demonstrate a sub-wavelength phased optical antenna array, which manipulates the distribution of the orbital angular momentum in the near field. Orbital angular momentum with topological charge of 4 can be obtained by controlling the phase distribution of the fundamental mode orbital angular momentum in each antenna element. Our results indicate this phased array may be utilized in high integrated optical communication systems.

Spectroscopic studies of resonant coupling of silver optical antenna arrays to a near-surface quantum well

The coupling of radiation emitted on semiconductor inter-band transitions to resonant optical-antenna arrays allows for enhanced light–matter interaction via the Purcell effect. Semiconductor optical gain also potentially allows for loss reduction in metamaterials. Here we extend our previous work on optically pumped individual near-surface InGaAs quantum wells coupled to silver split-ring-resonator arrays to wire and square-antenna arrays. By comparing the transient pump-probe experimental results with the predictions of a simple model, we find that the effective coupling is strongest for the split rings, even though the split rings have the weakest dipole moment. The effect of the latter must thus be overcompensated by a smaller effective mode volume of the split rings. Furthermore, we also present a systematic variation of the pump-pulse energy, which was fixed in our previous experiments.

Phase change material based tunable reflectarray for free-space optical inter/intra chip interconnects.

The concept of phase change material (PCM) based optical antennas and antenna arrays is proposed for dynamic beam shaping and steering utilized in free-space optical inter/intra chip interconnects. The essence of this concept lies in the fact that the behaviour of PCM based optical antennas will change due to the different optical properties of the amorphous and crystalline state of the PCM. By engineering optical antennas or antenna arrays, it is feasible to design dynamic optical links in a desired manner. In order to illustrate this concept, a PCM based tunable reflectarray is proposed for a scenario of a dynamic optical link between a source and two receivers. The designed reflectarray is able to switch the optical link between two receivers by switching the two states of the PCM. Two types of antennas are employed in the proposed tunable reflectarray to achieve full control of the wavefront of the reflected beam. Numerical studies show the expected binary beam steering at the optical communication wavelength of 1.55 μm. This study suggests a new research area of PCM based optical antennas and antenna arrays for dynamic optical switching and routing.