Beam Steering Control Research Articles

Tunable and plasmon-enhanced four-wave mixing on an aluminum grating

We report on wavelength-tunable and plasmon-enhanced four-wave mixing (4WM) on an Al grating. When surface plasmons (SPs) are excited at the first and second pump wavelengths, the electromagnetic fields near the grating surface are dramatically enhanced and the corresponding 4WM signals are enhanced by factors of 177 and 42 compared with off resonant conditions. The maximum output power of the 4WM signal is as high as 25 nW. Moreover, by fixing the first pump beam to the SP excitation angle and tuning the second pump beam from 1200 to 1550 nm, we obtain a tunable and enhanced 4WM output from 539 to 600 nm. This setup can potentially be applied to frequency conversion, beam steering and dispersion control.

Monolithic Patch-Antenna THz Lasers with Extremely Low Beam Divergence and Polarization Control

Arrays of patch antennas have impacted modern telecommunications in the RF range significantly, owing to their versatility in tailoring the properties of the emitted radiation such as beam width and polarization, along with their ease of fabrication. At higher frequencies, in the terahertz (THz) range, there is a pressing need for a similar monolithic platform to realize and enable the advanced functionalities available in the RF technology. This platform would benefit a wide variety of fields such as astronomy, spectroscopy, wireless communications, and imaging. Here, we demonstrate THz lasers made of arrays of 10 × 10 patch antenna microcavities that provide up to 25 mW output power with robust single mode frequency and spatial mode. This device architecture leads to an unprecedented beam divergence, better than 2° × 2°, which depends only on the number of resonators. This allows to functionalize the device while preserving a high quality far-field pattern. By interconnecting the symmetric square microcavities with narrow plasmonic wires along one direction, we introduce an asymmetry into the originally degenerate and cross-polarized TM01 and TM10 modes, leading to a precise control of the resonant frequency detuning between the TM modes. This feature allows devices to be designed that radiate with any coherent polarization states from linear to circular. Large-scale full-wave simulations of the emission from entire arrays support our experimental results. Our platform provides a solution to finally achieve monolithic terahertz emitters with advanced integrated functionalities such as active beam steering and polarization control.

Experimental demonstration of a microwave photonic link using an optically phased antenna array for a millimeter wave band.

We present a hybrid radiofrequency and microwave photonic link at 25 GHz using the chromatic dispersion of an optical fiber to steer the beam of a three-element planar dipole-based phased antenna array (PAA). Our team has designed and developed an in-house built PAA, experimentally verified its parameters, and successfully demonstrated optically controlled beam steering as measured in an anechoic chamber. Moreover, a detailed analysis of the optically based beam steering in the proposed microwave photonics system has been carried out, with data transmission achieving an error vector magnitude as low as 5.6% for the frequency of 25 GHz and 20 MHz bandwidth.

Simulation of beam steering control in arrayed liquid prisms system based on electrowetting-on-dielectric

In this paper, an arrayed liquid prisms system based on electrowetting-on-dielectric (EWOD) is proposed to modulate the three-dimensional beam steering control. The relationships between beam steering control range, electrowetting contact angle, and liquid refractive index are derived. COMSOL is employed to demonstrate the beam steering control properties of the electrowetting-based arrayed liquid prisms when bias voltages are applied. The influence of contact angle, liquid refractive index, and interval between adjacent prisms are discussed. The results show that the beam steering control performance of the system will be greatly improved, and the range of beam steering angle is −20° to 20° by selecting optimum combinations of liquids and rational interval between adjacent prisms. The arrayed liquid prisms system can succeed to achieve continuous control of beam steering in a conical region with an apex angle of 40°, and the vertex of the circular cone is located at the 15.02 mm in the z-axis. The proposed system will promote the development of non-mechanical beam steering technology and have a wide range of applications.

Ultrafast Topological Engineering in Metamaterials.

Transient optical heating provides an efficient way to trigger phase transitions in naturally occurring media through ultrashort laser pulse irradiation. A similar approach could be used to induce topological transitions in the photonic response of suitably engineered artificial structures known as metamaterials. Here, we predict a topological transition in the isofrequency dispersion contours of a layered graphene metamaterial under optical pumping. We show that the contour topology transforms from elliptic to hyperbolic within a subpicosecond timescale by exploiting the extraordinary photothermal properties of graphene. This new phenomenon allows us to theoretically demonstrate applications in engineering the decay rate of proximal optical emitters, ultrafast beam steering, and dynamical far-field subwavelength imaging. Our study opens a disruptive approach toward ultrafast control of light emission, beam steering, and optical image processing.

Nonmechanical three-dimensional beam steering using electrowetting-based liquid lens and liquid prism.

In this paper, we present a system for nonmechanical three-dimensional beam steering using an electrowetting based liquid lens and liquid prism. The optical design of the presented system was modeled with Zemax and three-dimensional beam steering was simulated by changing the ROC of the lens and the apex angle of the prism. The liquid lens from Corning-Varioptic was used and the liquid prism was fabricated and these were combined. The liquid lens and liquid prism were filled with two immiscible liquids whose densities are the same. The liquid lens provides variable focal lengths as the applied voltage is changed. The diopter range of the liquid lens is from -3.9 D to 14.5 D. Beam steering on the x-axis, y-axis, and xy-axis was achieved by applying different voltages to four sidewalls of the liquid prism. The liquid prism has a beam steering angle of up to 11.6 °, 12 °, and 11.8 ° on x-axis, y-axis, and xy-axis, respectively. By combining the electrowetting actuated liquid lens and liquid prism, three-dimensional beam steering control including the z-axis direction was demonstrated.

Design of Area Efficient Beam Steering Control System for Phased Array Radar

Phased array radar architecture consists of the multiple antenna elements that are controlled by the active electronic circuits called T/R modules. Transmit/Receive modules (T/R modules) plays vital role in the modern phased array radar system for different radar applications. The problem asserted with electrically scanned phased array radar suffers from two main limitations. First one is the high hardware cost in terms of area and second one is the design complexity. To overcome the above issues, architecture has been developed by implementing single control unit, distributive memory elements and data control logic to design an area efficient control system. The entire system is implemented on Artix-7 FPGA.

Design and Implementation of Scalable Beam Steering Control System for Phased Array Radar

Transmit/Receive (T/R) modules plays important role in advanced phased array radar system consists of array of antenna elements. In order to produce beam pattern for multiple radiating elements, the phase angle for each T/R module should be assigned with calculated value. When phase gradient is sent to T/R unit, phase values are calculated for array of elements associated with them. The paper presents a beam steering control system architecture consists of Graphical user interface, group controller with scalable T/R control unit (TRCU) having two hexa decagon T/R module controllers (HTRMCs) and control logic unit for parallel data flow. Calculation of 6 bit phase value from the phase gradient carried out using FPGA. Also, use of logic core and quantization of phase values are discussed. The paper also reports the area factor for the proposed architecture.

Tunable Beam Steering, Focusing and Generating of Orbital Angular Momentum Vortex Beams Using High-Order Patch Array

In this paper, a tunable patch array based on high-order is proposed at the frequency of 300 GHz, achieving active controllable beam steering, focusing and generation of orbital angular momentum vortex beams. It has been demonstrated that the patch array can achieve wide beam scanning angle by controlling the phase of array elements with tunable phase shifters. Meanwhile, beam focusing on the specified position can also be realized by phase modulation of array elements based on the focusing theory. In addition, we also designed a patch array to generate vortex beams with multiple topological charges by high-order modes. The performances show that the patch antenna array we designed has a good application prospect.

Ultra-compact electrically controlled beam steering chip based on coherently coupled VCSEL array directly integrated with optical phased array.

Beam steering devices have wide applications in both military and civil fields. The ultimate goal for such devices is to reduce their size, weight, and power consumption. However, the laser source in these devices is spatially separate from the phase shifter, resulting in large size, complex packaging, and low coupling efficiency. To solve these problems, a novel electrically controlled beam steering chip based on coherently coupled vertical cavity surface emitting laser (VCSEL) array directly integrated with liquid crystal optical phased array (LCOPA) is proposed in this paper. Implant-defined in-phase coherently coupled VCSEL arrays (CCVAs) with uniform near-field are designed and fabricated first to act as the coherent laser source for the chip. Then, taking advantage of the CCVA planar structure, the LCOPA is integrated directly on the CCVA by conventional process. The coherent light generated by the in-phase CCVA is uniformly and normally incident into the LCOPA and is electrically steered by the LCOPA. One-dimensional beam steering is achieved by two proof-of-concept integrated chips. The chips based on a 4 × 4 square CCVA and a 16-element hexagonal CCVA offer a field of view of 2.21° and 6.06°, respectively. Independent control of the CCVA and LCOPA guarantees a relatively high wavelength stability and power stability. Theoretical calculations are also performed, which are consistent with the experiments.

介电润湿液体棱镜阵列的三维空间光束指向控制

介电润湿液体棱镜阵列的三维空间光束指向控制

Space-time-coding digital metasurfaces

The recently proposed digital coding metasurfaces make it possible to control electromagnetic (EM) waves in real time, and allow the implementation of many different functionalities in a programmable way. However, current configurations are only space-encoded, and do not exploit the temporal dimension. Here, we propose a general theory of space-time modulated digital coding metasurfaces to obtain simultaneous manipulations of EM waves in both space and frequency domains, i.e., to control the propagation direction and harmonic power distribution simultaneously. As proof-of-principle application examples, we consider harmonic beam steering, beam shaping, and scattering-signature control. For validation, we realize a prototype controlled by a field-programmable gate array, which implements the harmonic beam steering via an optimized space-time coding sequence. Numerical and experimental results, in good agreement, demonstrate good performance of the proposed approach, with potential applications to diverse fields such as wireless communications, cognitive radars, adaptive beamforming, holographic imaging.

Electrically controlled beam steering with wide deflection angles in liquid crystal photonic crystals

Electrically controlled beam steering behaviors in a 2D square photonic crystal (PC) composed of Si cylinders surrounded by nematic liquid crystal are studied. The results show that by applying an external saturated electric field, the structure becomes anisotropic and results in remarkable change of band structure to produce a single band from 0.3105 to 0.3245(c/a) accordingly. This special single band is high anisotropic and only allows one mode with negative refraction to be excited in the ГM direction. Further studies show that as the external saturated electric field rotates from 0° to 90°, the equifrequency contours of the single band deform continuously from rectangle-like to parallelogram-like shapes, and then recover to rectangle-like shapes but with the long-side rotated by 90°. Moreover, we demonstrate continuous tunable beam steering behaviors with wide deflection angles from −38° to +38° at normal incidence by finite-difference time-domain simulations. These results have the potential for designing various tunable PC devices.

Beam Steering Controller Architectures for an Active Electrically Scanned Array Antenna: Comparison and a Cost Effective Implementation

Beam Steering Controller Architectures for an Active Electrically Scanned Array Antenna: Comparison and a Cost Effective Implementation

Integrated Full-Hemisphere Space-to-Frequency Mapping Antenna With CRLH Stripline Feed Network

A planar 2-D antenna array capable of mapping a full-hemisphere space to frequencies around 6 GHz is presented. It was designed using composite right-/left-handed transmission lines for the series feed network as well as for the radiating elements, thus achieving size reduction and beam steering control simplification compared to other approaches. Stripline fabrication technology is utilized to eliminate the undesired feed network radiation. A via-less unit cell reduces sensitivity to via misplacement. The result is an antenna that can be used for radar or imaging applications with the appropriate transmit/receive circuitry. Validation is provided by pattern measurements and successful detection of reflective targets.

A 28-GHz 32-Element TRX Phased-Array IC With Concurrent Dual-Polarized Operation and Orthogonal Phase and Gain Control for 5G Communications

This paper presents the first reported 28-GHz phased-array IC for 5G communications. Implemented in 130-nm SiGe BiCMOS, the IC includes 32 TRX elements and features concurrent independent beams in two polarizations in either TX or RX operation. Circuit techniques to enable precise beam steering, orthogonal phase and amplitude control at each front end, and independent tapering and beam steering at the array level are presented. A TX/RX switch design is introduced which minimizes TX path loss resulting in 13.5 dBm/16 dBm Op1dB/Psat per front end with >20% peak power added efficiency of the power amplifier (including switch and off-mode LNA) while maintaining a 6 dB noise figure in the low noise amplifier (including switch and off-mode PA). Comprehensive on-wafer measurement results for the IC across multiple samples and temperature variation are presented. A package with four ICs and 64 dual-polarized antennas provides eight 16-element or two 64-element concurrent beams with 1.4°/step beam steering (<0.6° rms error) across a ±50° steering range without requiring calibration. A maximum saturated effective isotropic radiated power of 54 dBm is measured in the broadside direction for each polarization. Tapering control without requiring calibration achieves up to 20-dB sidelobe rejection without affecting the main lobe direction.

Terahertz Focusing and Polarization Control in Large-Area Bias-Free Semiconductor Emitters

We show that, when large-area multiplex terahertz semiconductor emitters, that work on diffusion currents and Schottky potentials, are illuminated by ultrashort optical pulses they can radiate a directional electromagnetic terahertz pulse which is controlled by the angular spectrum of the incident optical beam. Using the lens that focuses the incident near-infrared pulse, we have demonstrated THz emission focusing in free space, at the same point where the optical radiation would focus. We investigated the beam waist and Gouy phase shift of the THz emission as a function of frequency. We also show that the polarization profile of the emitted THz can be tailored by the metallic patterning on the semiconductor, demonstrating radial polarization when a circular emitter design is used. Our techniques can be used for fast THz beam steering and mode control for efficiently coupling to waveguides without the need for THz lenses or parabolic mirrors.

基于正解过程的Risley棱镜光束指向控制精度分析

基于正解过程的Risley棱镜光束指向控制精度分析

Liquid crystal based non-mechanical beam tracking technology

The simulation and experimental testing of a non-mechanical beam tracking technology was investigated, in which a liquid crystal spatial light modulator (LCSLM) was used as a beam steering control device. The LCSLM was capable of steering the beam from −2.8947 to 2.8947° with a resolution of approximately 0.0226°. The LCSLM-based tracking system was simulated by MATLAB, and the Bode diagram indicated that the tracking performance was better than −17dB when the disturbance frequency was 1Hz. The tracking experiment was also executed to test the actual performance. The experimental data revealed that the tracking error (1σ) ranged from 0.024θmax to 0.225θmax when the disturbance frequency ranged from 0.2 to 2.0Hz with an amplitude of θmax=2.4873°. Simulation and experimental testing demonstrated the feasibility of the non-mechanical beam tracking technology that employs liquid crystals.

Optically Powered and Controlled Beam Steering System for Radio-Over-Fiber Networks

This study presents an optically powered and controlled beam steering system for radio-over-fiber networks. The beam steering technique is based on optical multicasting and true-time delay among the multicast signals for a remote antenna unit. The power required for driving the entire remote antenna unit is delivered from a central office to the remote antenna unit by power-over-fiber technique using double-clad fibers, which consist of a single-mode core and an inner-cladding that surrounds the single-mode core. In the fiber link, an optical data signal is transmitted into the single-mode core without limiting the signal bandwidth because of modal dispersion, whereas high-power feed light for optical powering is transmitted into the inner-cladding with a core effective area that is much larger than the single-mode core. To show the feasibility of the beam steering system, we have experimentally evaluated the signal performance of beam steering for a 60-W power-over-fiber feed using a 300-m double-clad fiber link in terms of error-vector magnitude measurements. We have successfully achieved good signal performances for various beam angles estimated using true-time delay settings for multicast signals.