Beam Steering Device Research Articles

Feasibility assessment of parallelized helical drilling

With the average power of commercial ultrafast lasers reaching the kW-level, process parallelization is required to avoid detrimental quality issues, such as caused by heat accumulation. This is especially relevant in the case of helical drilling, as the processing strategy is only employed when precise geometry, high-quality surface finish, tight tolerances, and high reproducibility are a priority. We illustrate that parallelization by means of a multipass process is conceptually attractive for pulsed drilling processes, but also challenging due to limitations imposed by the properties of appropriate beam-steering devices. While paraxial beam propagation methods applied to the suggested setup predict no aberrations, deviations from the idealized solution are a concern. Our experimental proof-of-principle investigations show that parallelization by means of a deflector preceding the helical drilling optics is possible while ensuring nearly identical processing parameters for all parallelly processed boreholes.

Highly angle-sensitive and efficient optical metasurfaces with broken mirror symmetry

Abstract Optical metasurfaces have great potential to overcome the functional limitations of conventional optical devices. In addition to polarization- or wavelength-multiplexed metasurfaces, angle-multiplexed metasurfaces can provide new degrees of freedom, enabling previously unrealized complex functionality in diverse applications such as LiDAR, augmented reality glasses, and imaging. However, there have been fundamental trade-offs in transmission efficiency and angular sensitivity for practically important paraxial rays. In this paper, we overcome this limitation by breaking mirror symmetries of single-layer metasurface structures. Based on an effective medium theory, we intuitively explain which material parameters affect the sensitivity and efficiency and prove that high sensitivity and high efficiency can be achieved simultaneously by breaking the mirror symmetry. Based on this, we propose optimized metasurfaces for two applications: an angle-multiplexed beam-steering device with up to 93% relative efficiency and an angle-multiplexed metalens array that can break the fundamental resolution–density trade-off of microlens arrays with high efficiency. The proposed angle-selective designs could pave the way for the development of new classes of compact optical devices with novel functions.

Conformal Volumetric Grayscale Metamaterials.

Conformal artificial electromagnetic media that feature tailorable responses as a function of incidence wavelength and angle represent universal components for optical engineering. Conformal grayscale metamaterials are introduced as a new class of volumetric electromagnetic media capable of supporting highly multiplexed responses and arbitrary, curvilinear form factors. Subwavelength-scale voxels based on irregular shapes are designed to accommodate a continuum of dielectric values, enabling the freeform design process to reliably converge to exceptionally high figures of merit (FOMs) for a given multi-objective design problem. Through additive manufacturing of ceramic-polymer composites, microwave metamaterials, designed for the radio-frequency range of 8-12GHz, are experimentally fabricated and devices with extreme dispersion profiles, an airfoil-shaped beam-steering device, and a broadband, broad-angle conformal carpet cloak, are demonstrated. It is anticipated that conformal volumetric metamaterials will lead to new classes of compact and multifunctional imaging, sensing, and communications systems.

An electro-optic continuous laser beam steering device based on an SBN75 crystal

The performance of electro-optics (EO) beam steering systems relies on the EO effect exhibited by certain crystals which is a refractive index change with an applied electric field. The very high EO coefficient and transparency, high optical damage limit, low conductivity, and comparatively low Curie temperature of SrxBa1-xNb2O6 (SBN) make this EO crystal very attractive for EO beam steering applications. In this study, an EO laser beam steering device based on a bulk Sr0.75Ba0.25Nb2O6 (SBN75) crystal grown at Teledyne Scientific was designed 1 . The SBN beam steerer was tested under different scenarios and the first and second EO effects and all linear EO coefficients of the SBN75 ( ) were measured based on the laser beam’s deflection angles and compared with the values reported in the literature. The results showed that Teledyne’s SBN75 crystal exhibited a primary EO effect of about 4 to 6% more than the value reported in the literature at the room temperature, the share of the secondary EO effect is less than 8% and the linear EO effect disappeared at 58 °C.

On the Fabrication Improvements of Liquid Crystal Beam Steering Device for LFVR System

On the Fabrication Improvements of Liquid Crystal Beam Steering Device for LFVR System

Grating-like Terahertz Metasurface for Large-Deflection-Angle Beam Manipulations

Multifunctional terahertz beam manipulations have attracted much attention because of the potential for wide-scale applications in terahertz imaging, communications, etc. In this work, a grating-like terahertz reflective-type metasurface is designed for terahertz beam manipulations on the basis of a frequency-scanning mechanism. The theoretical calculation based on the grating principle has predicted that the metasurface grating can steer the deflected beam from 59.5° to 47.3° as the frequency of the perpendicularly incident terahertz wave changes between 0.87 and 1.02 THz. The large-deflection-angle frequency-scanning performance is validated by both numerical simulations and experimental tests. The metasurface grating developed in this work possesses the potential for applications in terahertz beam steering and beam-splitting devices.

Programmable Wavefront Control in the Visible Spectrum Using Low-Loss Chalcogenide Phase-Change Metasurfaces.

All-dielectric metasurfaces provide unique solutions for advanced wavefront manipulation of light with complete control of amplitude and phase at sub-wavelength scales. One limitation, however, for most of these devices is the lack of any post-fabrication tunability of their response. To break this limit, a promising approach is employing phase-change materials (PCMs), which provide fast, low energy, and non-volatile means to endow metasurfaces with a switching mechanism. In this regard, great advancements have been done in the mid-infrared and near-infrared spectrum using different chalcogenides. In the visible spectral range, however, very few devices have demonstrated full phase manipulation, high efficiencies, and reversible optical modulation. In this work, a programmable all-dielectric Huygens' metasurface made of antimony sulfide (Sb2 S3 ) PCM is experimentally demonstrated, a low loss and high-index material in the visible spectral range with a large contrast (≈0.5) between its amorphous and crystalline states. ≈2π phase modulation is shown with high associated transmittance and it is used to create programmable beam-steering devices. These novel chalcogenide PCM metasurfaces have the potential to emerge as a platform for next-generation spatial light modulators and to impact application areas such as programmable and adaptive flat optics, light detection and ranging (LiDAR), and many more.

Electrically controlled continuous laser beam steering in a liquid crystal based electro-optic waveguide

Non-mechanical and continuous beam steering devices are highly desirable in recent laser scanning applications and telecommunication advancements. We report a liquid crystal (LC) core waveguide-based electrically controlled, non-mechanical, and continuous laser beam steering device. The waveguide uses nematic 5CB (4-cyano-4′-pentylbiphenyl) LC as a propagation medium surrounded by PVA (polyvinyl alcohol) polymer cladding, which is realized on ITO coated glass substrates. A pattern of five triangular electrodes is transferred on the substrate using photolithography to create prisms of tunable refractive index in the LC core of the waveguide. The beam steering for transverse electric (TE) and transverse magnetic (TM) polarization is theoretically studied and experimentally characterized using a He-Ne laser of λ = 633 nm. A steering angle of −5.4° and +5.7° at 7 Vpp is obtained for TE and TM polarization, respectively, in a waveguide with the prism’s apex angle of 13°. Similarly, a higher steering angle up to 7.3° for TM polarization is demonstrated in the waveguide with an apex angle of 22°. The device is developed using ease of fabrication process and cost-effective materials that operate at relatively low voltages.

Beam steering at the nanosecond time scale with an atomically thin reflector

Techniques to mold the flow of light on subwavelength scales enable fundamentally new optical systems and device applications. The realization of programmable, active optical systems with fast, tunable components is among the outstanding challenges in the field. Here, we experimentally demonstrate a few-pixel beam steering device based on electrostatic gate control of excitons in an atomically thin semiconductor with strong light-matter interactions. By combining the high reflectivity of a MoSe2 monolayer with a graphene split-gate geometry, we shape the wavefront phase profile to achieve continuously tunable beam deflection with a range of 10°, two-dimensional beam steering, and switching times down to 1.6 nanoseconds. Our approach opens the door for a new class of atomically thin optical systems, such as rapidly switchable beam arrays and quantum metasurfaces operating at their fundamental thickness limit.

Metasurface-based Fourier lens fed by compact plasmonic optical antennas for wide-angle beam steering

A Fourier lens can perform the Fourier transform of an incident wavefront at the focal plane. This paper reports a metasurface-based Fourier lens fed by compact plasmonic optical antennas for wide-angle beam steering. The metasurface, composed of six elements with different configurations covering the 2π phase range, features a large field-of-view (FOV) of ±50°. A novel plasmonic optical antenna for broadside radiation is then designed as the feed source of the metasurface. The proposed antenna has ultra-compact size of 0.77λ × 1.4λ, and achieves a high directivity of 9.6 dB and radiation efficiency of over 80% at the wavelength of 1550 nm. Full-wave simulations are carried out to evaluate the performances of the designed metasurface-assisted beam steering device. The results show that this device can achieve a maximum directivity of 21.5 dB at broadside radiation. Compared to conventional Yagi-Uda antenna feed, a directivity enhancement of about 2.7 dB can be obtained, exhibiting a great superiority of the proposed feed antenna. In addition, a large beam steering range of ±50° can be achieved with an acceptable gain drop of 2.83 dB. With the advantages of wide beam steering range, good radiation characteristics, small footprint, and ease of integration, the proposed metasurface-assisted beam steering device would be a promising candidate for integrated photonic applications, including wireless optical communications, light detection and ranging, and augmented reality.

Are phase change materials ideal for programmable photonics?: opinion

The objective of this Opinion is to stimulate new research into materials that can meet the needs of tomorrow’s programmable photonics components. Herein, we argue that the inherent property portfolios of the common telluride phase change materials, which have been successfully applied in data storage technologies, are unsuitable for most emerging programmable photonics applications. We believe that newer PCMs with wider bandgaps, such as Sb2S3, Sb2Se3, and Ge2Sb2Se4Te (GSST), can be optimized to meet the demands of holographic displays, optical neural network memories, and beam steering devices.

Optimization of Optical Phase Profile in Beam Deflector with Advanced Simulation Method for High Diffraction Efficiency.

Controlling the phase of light with a high efficiency and precision is essential for applications in imaging, tunable devices, and optical systems. Spatial light modulators (SLMs) based on liquid crystals (LCs) have been regarded as one of the best choices for the generation of phase profiles for the steering of light. The upper glass substrate has an unpatterned electrode for a common electrode, while the lower glass substrate has one-dimensional micro-patterned electrodes for controlling the single pixel level by the applied voltages. By applying different voltages to each electrode to create a sawtooth-shaped phase profile, the collimated input beam is deflected to the desired angle. To maximize the diffraction efficiency (DE) values, an advanced simulation method has been developed to find the optimized phase profile through the analysis of LC director distributions. The resulting diffraction patterns are investigated both computationally and experimentally, with a good agreement between the results obtained. Finally, the beam deflector (BD) system with an advanced driving algorithm has a high 1st order DE, about 60%, 37%, and 7.5% at 1°, 2.5°, and a maximum steering angle of 7.5°, respectively. The LC director distributions in relation to various diffraction angles are simulated and an experimental success in realizing enhanced DE for the beam steering device is presented.

Flexible Terahertz Beam Manipulations Based on Liquid-Crystal-Integrated Programmable Metasurfaces

Terahertz wave manipulations, especially the phase manipulations, through metasurfaces has attracted considerable interests. Here, we develop a terahertz beam steering device using the liquid-crystal (LC)-integrated programmable metasurface. Specifically, a reflective-type 1 bit metasurface element is designed by employing a multilayer structure composed of metallic back plate-LC-complementary split ring resonator (CSRR). Numerical simulations show that, at the optimized operation frequency of 0.675 THz, the developed metasurface element has a nearly 180° phase difference between unbiased and biased states with close reflection amplitudes. Furthermore, a one-dimensional programmable metasurface array with 32 independently controlled subarrays is designed and fabricated using the lithography technology. Both simulated and measured far-field scattering patterns of the metasurface certify the anomalous beam reflection and wide-angle beam steering performances. Nevertheless, the optimal frequency red shifts to 0.645 THz in the experiment. This work may advance the application of metasurfaces in terahertz beam manipulation devices.

Finite element analysis and design of beam steering devices with global control

PurposeThis paper aims to design metaguide- or metasurface-based compact inexpensive beam-steering devices, which play an important role in modern cellular networks, radar imaging and satellite communication.Design/methodology/approachThis paper uses finite element analysis to study, design and optimize arrays of resonating elements as beam steering devices. The first set of such devices involves metamaterial-based apertures fed by a waveguide, tunable via the permittivity of the host material. In the second approach, dynamic beam steering is effected by alternating between two or more waveguide feeds.FindingsParticular examples show how the direction of the main lobe of the radiated beam can be reliably switched by approximately 30° in one of the quadrants by changing a single global control parameter within a very reasonable range.Research limitations/implicationsThe findings pave the way for the design and fabrication of inexpensive compact beam steering devices. This study anticipates that the proposed designs can be further improved and fine-tuned using “heavy duty” optimization packages.Originality/valueIn many published designs of similar beam-steering devices, the radiation pattern of an array of resonating elements is controlled by complex circuitry, so that each radiating element is tuned separately. In contrast with these existing approaches, the designs rely just on a simple global control parameter.

High-Precision Beam Angle Expander Based on Polymeric Liquid Crystal Polarization Lenses for LiDAR Applications

A novel beam steering angle expander is demonstrated by cascading two polymeric liquid crystal polarization lenses with different diopters. The lens module performs as a planar telescope, which has features such as a light weight, low cost, and high precision. The magnifier offers wide-angle, continuous steering when integrated with an active fine-angle beam steering device. The potential application for LiDAR is emphasized.

Solid-state FMCW LiDAR with in-fiber beam scanner.

The beam scanner is a predominant part in the light detection and ranging (LiDAR) system to achieve three-dimensional (3D) imaging. The solid-state beam-steering device has emerged as a promising candidate technology for a beam scanner with the advantages of robustness, stability, and high scanning speed. Here we propose a frequency modulated continuous wave (FMCW) LiDAR system with an in-fiber solid-state beam scanner. A 45° tilted fiber grating (TFG) is first employed to achieve in-fiber solid-state spectral scanning in the LiDAR system. A maximum output efficiency of 93.7% is achieved with proper polarization control. A single-mode fiber is then used to fabricate a 2-cm 45° TFG, which significantly reduces the size and the cost of the beam scanner in the LiDAR system. We experimentally realize 3D imaging of targets placed at a distance of 1.2 m based on our proposed LiDAR system. In addition, the system can achieve a detection distance of 6 m with a ranging precision of 24 mm.

Achromatic doublet electrowetting prism array for beam steering device in foveated display.

A foveated display is a technology that can solve the problem of insufficient angular resolution (relative to the human eye) for near-eye display. In a high-resolution foveated display, a beam steering element is required to track the human gaze. An electrowetting prism array is a transmissive non-mechanical beam steering device, that allows a light and compact optical system to be configured and a large aperture possible. However, the view is obstructed by the sidewall of the prism array. When the size of the cell prism is 7mm, the prism array has an 87% fill-factor. To push the fill-factor to 100%, the cell prisms were magnified using a lens array. Image processing was performed such that the image produced by the lens array was identical to the original. Beam steering by refraction is accompanied by chromatic dispersion, which causes chromatic aberration, making colors appear blurry. The refractive index condition to reduce chromatic dispersion was obtained using the doublet structure of the electrowetting prism. The chromatic dispersion was reduced by 70% on average.

A Beamforming Technique Using Rotman Lens Antenna for Wireless Relay燦etworks

Rotman lens, which is a radio frequency beam-former that consists of multiple input and multiple output beam ports, can be used in industrial, scientific, and medical applications as a beam steering device. The input ports collect the signals to be propagated through the lens cavity toward the output ports before being transmitted by the antenna arrays to the destination in order to enhance the error performance by optimizing the overall signal to noise ratio (SNR). In this article, a low-cost Rotman lens antenna is designed and deployed to enhance the overall performance of the conventional cooperative communication systems without needing any additional power, extra time or frequency slots. In the suggested system, the smart Rotman lens antennas generate a beam steering in the direction of the destination to maximize the received SNR at the destination by applying the proposed optimal beamforming technique. The suggested optimal beamforming technique enjoys high diversity, as well as, low encoding and decoding complexity. Furthermore, we proved the advantages of our suggested strategy through both theoretical results and simulations using Monte Carlo runs. The Monte Carlo simulations show that the suggested strategy enjoys better error performance compared to the current state-of-the-art distributed multi-antenna strategies. In addition, the bit error rate (BER) curves drawn from the analytical results are closely matching to those drawn from our conducted Monte Carlo simulations.

Mass-Manufactured Beam-Steering Metasurfaces for High-Speed Full-Duplex Optical Wireless-Broadcasting Communications.

Beam-steering devices, which are at the heart of optical wireless-broadcasting communication links, play an important role in data allocation and exchange. An ideal beam-steering device features large steering angles, arbitrary channel numbers, reconfigurability, and ultracompactness. However, these criteria have been achieved only partially with conventional beam-steering devices based on waveguides, micro-electricalmechanical systems, spatial light modulators, and gratings, which will substantially limit the application of optical wireless-broadcasting communication techniques. In this study, an ultracompact full-duplex metabroadcasting communication system is designed and experimentally demonstrated, which exhibits beam steering angles up to ±40°, 14 broadcasting channels with capacity for downstream and upstream links up to 100 and 10Gbps for each user channel, three operating modes for flexible signal switching, and metadevice dimensions as small as 2mm×2mm. In particular, the beam-steering metadevices are mass-manufactured by a complementary metal-oxide-semiconductor (CMOS) processing platform, which shows their potential for large-scale commercial applications. The demonstrated metabroadcasting communication system merges optical wireless-broadcasting communications and metasurfaces, which reduces the complexity of beam-steering devices while significantly increasing their performance, opening up a new avenue for high-quality optical wireless-broadcasting communications.

Non-redundant optical phased array

Optical phased arrays (OPAs) are promising beam-steering devices for various applications such as light detection and ranging, optical projection, free-space optical communication, and optical switching. However, previously reported OPAs suffer from either an insufficient number of resolvable points, or complicated control requirements due to an extremely large number of phase shifters. To solve this issue, we introduce the non-redundant array (NRA) concept to the OPA devices. Based on this design, we can realize high-resolution OPAs whose number of resolvable points scales quadratically with the number of antennas N . In contrast, that of traditional OPAs scales only linearly with N . Thus, a significant reduction in the number of required phase shifters can be attained without sacrificing the number of resolvable points. We first investigate the impact of employing the NRA theoretically by considering the autocorrelation function of the array layout. We then develop a Costas-array-based silicon OPA and experimentally demonstrate 2D beam steering with ∼ 19 , 000 resolvable points using only 127 phase shifters. To the best of our knowledge, this corresponds to the largest number of resolvable points achieved by an OPA without sweeping the wavelength.