Beam Steering Device Research Articles

Highly Directive Hybrid Plasmonic Leaky-Wave Optical Antenna With Controlled Side-Lobe Level

Various configurations are proposed to engineer the pattern of optical leaky-wave antennas with the goal of achieving a desired side-lobe level (SLL). By the aid of the proposed algorithm, two types of hybrid plasmonic optical traveling wave antennas with controlled SLL are designed and numerically analyzed. The antennas are designed to operate at the standard telecommunication wavelength of 1550 nm, and have a wide bandwidth that completely cover the standard optical communication bands of E, S, and C. The first configuration in which the tapering is applied to the width of slots results in a broad bandwidth of 28 THz, a high directivity of 14.6 dBi, an efficiency of 73%, and a low SLL of $-$ 19.4 dB. The second configuration, in which wall tapering is applied, exhibits a bandwidth greater than 30 THz, a high directivity of 13.6 dBi, an efficiency of 79%, and an excellent SLL of $-$ 25 dB. Thanks to the high gain and low SLL, these devices can have applications in integrated optical interconnects, highly integrated optical beam-steering devices, such as active LIDARs and solar cells with high efficiency.

Rationally Designed Dynamic Superstructures Enabled by Photoaligning Cholesteric Liquid Crystals

a proper electric fi eld, simple grating with parallel stripes are produced in uniformly aligned cells. [ 14 ] Unfortunately, the defects induced by conventional mechanical rubbing technique signifi cantly interrupt the continuity of helical axis, thus it is diffi cult to get orderly arranged stripes with a uniform periodicity (Figure S1, Supporting Information). That is why the so-called “fi ngerprint” nonuniform textures are usually reported. [ 15 ] Moreover, the capability to manipulate the in-plane helical axes to realize more complex stripe pattern remains highly restricted. Based on the CLC in-plane aligned helical axis structure, diffraction gratings [ 16 ] and lithography mask [ 17 ] have been demonstrated. Moreover, the variation of the period of CLC grating [ 14,18 ] and its rotation [ 19 ] make it an excellent candidate for nonmechanical beam steering devices. Thus, the capability of generating high-quality CLC superstructures with ordered orientation and reliable periodicity is crucial for above applications. However, as mentioned above, the low quality and poor controllability of the self-assembled CLCs make the task very formidable. Furthermore, the present mechanical aligning technique is only suitable to produce 1D [ 14,20 ] or 2D gratings. [ 21 ]

High-Efficiency All-Dielectric Metasurfaces for Ultracompact Beam Manipulation in Transmission Mode.

Metasurfaces are two-dimensional structures enabling complete control on light amplitude, phase, and polarization. Unlike plasmonic metasurfaces, silicon structures facilitate high transmission, low losses, and compatibility with existing semiconductor technologies. We experimentally demonstrate two examples of high-efficiency polarization-sensitive dielectric metasurfaces with 2π phase control in transmission mode (45% transmission efficiency for the vortex converter and 36% transmission efficiency for the beam steering device) at telecommunication wavelengths. Silicon metasurfaces are poised to enable a versatile platform for the realization of all-optical circuitry on a chip.

Reliability of Liquid Crystals in Space Photonics

Passive liquid crystal (LC) devices are becoming an interesting alternative for the manufacturing of photonic devices in spatial applications. These devices feature a number of advantages in this environment, the lack of movable parts, and of exposed electronics being among the most outstanding ones. Nevertheless, the LC material itself must demonstrate its endurance under the harsh conditions of space missions, including launch and, perhaps, landing. In this paper, we present the environmental testing of an LC device for space applications. A number of LC based beam steering devices were manufactured, characterized, and tested in a series of destructive and nondestructive tests defined by the European Space Agency (ESA). The purpose was to evaluate the behavior and possible degradation of the LC response in simulated space environments. Device fabrication and testing was done within an ESA-funded project, whose purpose was the design, manufacturing, and characterization of adaptive optical elements, as well as the execution of qualification tests on the devices in space-simulated conditions.

Active acoustic metamaterials reconfigurable in real time

A major limitation of current acoustic metamaterials is that their acoustic properties are either locked into place once fabricated or are only modestly tunable, tying them to the particular application for which they are designed. We present a design approach that yields active metamaterials whose physical structure is fixed, yet their local acoustic response can be changed almost arbitrarily and in real time by configuring the digital electronics that control the metamaterial acoustic properties. We demonstrate this approach experimentally by designing a metamaterial slab configured to act as a very thin acoustic lens that manipulates differently three identical, consecutive pulses incident on the lens. Moreover, we show that the slab can be configured to simultaneously implement various roles, such as that of a lens and a beam steering device. Finally, we show that the metamaterial slab is suitable for efficient second harmonic acoustic imaging devices capable of overcoming the diffraction limit of linear lenses. These advantages demonstrate the versatility of this active metamaterial and highlight its broad applicability, in particular, to acoustic imaging.

Reflected wavefronts modulation with acoustic metasurface based on double-split hollow sphere

Metasurfaces with sub-wavelength thickness and planar profile have exhibited abnormal manipulation to waves that could not be realized by traditional materials. Here, we present an acoustic metasurface (AMS) model composed of double-split hollow sphere (DSHS) resonator arrays with the functionality of modulating reflected wavefronts at will. By tailoring the split-hole diameter of DSHS, the AMS can be designed to cover 2π phase shifts with a step of π/4. The acoustic waves perpendicularly and obliquely incident on the AMS can be reflected at any angle, including anomalous reflection and negative reflection. These anomalous manipulations of the reflected wave are simulated to fulfill the generalized Snell’s law by projecting suitable phase gradient. Such AMS provides another path to acoustic applications such as acoustic imaging, cloaking, beam steering devices.

Simulation of two-dimensional target motion based on a liquid crystal beam steering method

A simulation platform is established for target motion using a liquid crystal (LC) spatial light modulator as a nonmechanical beam steering control device. By controlling the period and orientation of the phase grating generated by the spatial light modulator, the platform realizes two-dimensional (2-D) beam steering using a single LC device. The zenith and azimuth angle range from 0 deg to 2.89 deg and from 0 deg to 360 deg, respectively, with control resolution of 0.0226 deg and 0.0300 deg, respectively. The response time of the beam steering is always less than 0.04 s, irrespective of steering angle. Three typical aircraft tracks are imitated to evaluate the performance of the simulation platform. The correlation coefficients between the theoretical and simulated motions are larger than 0.9822. Results show that it is highly feasible to realize 2-D target motion simulation using the LC spatial light modulator.

Electrical Switching of Infrared Light Using Graphene Integration with Plasmonic Fano Resonant Metasurfaces

Graphene has emerged as a promising optoelectronic material because its optical properties can be rapidly and dramatically changed using electric gating. Graphene’s weak optical response, especially in the infrared part of the spectrum, remains the key challenge to developing practical graphene-based optical devices such as modulators, infrared detectors, and tunable reflect-arrays. Here it is experimentally and theoretically demonstrated that a plasmonic metasurface with two Fano resonances can dramatically enhance the interaction of infrared light with single layer graphene. Graphene’s plasmonic response in the Pauli blocking regime is shown to cause strong spectral shifts of the Fano resonances without inducing additional nonradiative losses. It is shown that such electrically controllable spectral shift, combined with the narrow spectral width of the metasurface’s Fano resonances, enables reflectivity modulation by nearly an order of magnitude. We also demonstrate that metasurface-based enhancement of the interaction between graphene and infrared light can be utilized to extract one of the key optical parameters of graphene: the free carrier scattering rate. Numerical simulations demonstrate the possibility of strong active modulation of the phase of the reflected light while keeping the reflectivity nearly constant, thereby paving the way to tunable infrared lenses and beam steering devices based on electrically controlled graphene integrated with resonant metasurfaces.

Highly sensitive beam steering with plasmonic antenna.

In this work, we design and study a highly sensitive beam steering device that integrates a spiral plasmonic antenna with a subwavelength metallic waveguide. The short effective wavelength of the surface plasmon polaritons (SPPs) mode supported by the metallic waveguide is exploited to dramatically miniaturize the device and improve the sensitivity of the beam steering. Through introducing a tiny displacement of feed point with respect to the geometrical center of the spiral plasmonic antenna, the direction of the radiation can be steered at considerably high angles. Simulation results show that steering angles of 8°, 17° and 34° are obtainable for a displacement of 50 nm, 100 nm and 200 nm, respectively. Benefiting from the reduced device size and the shorter SPP wavelength, the beam steering sensitivity of the beam steering is improved by 10-fold compared with the case reported previously. This miniature plasmonic beam steering device may find many potential applications in quantum optical information processing and integrated photonic circuits.

62.1: Distinguished Paper: Multi‐View Three‐Dimensional Display System by Using Arrayed Beam Steering Devices

AbstractMulti‐view three‐dimensional (3D) display using beam steering optical array is proposed. For the beam steering optics we fabricated an electrowetting micro prism array. The steering angle and the profiles are measured. Based on the results, we modeled the beam steering devices and simulate the performance for 3D display. Realistic view profiles are obtained by integrating the experimental beam profile data. Below the crosstalk 200%, the distance between views is 3 mm and the number of views is 90, which shows the possibility of the quasi continuous viewpoint with high resolution 3D display.

Beam steering with graded index photonic crystal lens and liquid crystal

In this numerical study, a new compact and tunable beam-steering device composed of graded index photonic crystal lens and liquid crystal material has been presented and demonstrated. The beam-steering device can work in two modes: First, incident single wavelength beam steers by tuning the refractive index of the liquid crystal material. Second, by fixing the refractive index of the liquid crystal material, incident multi-wavelength beam steers with different off-axis angles for each wavelength. The numerical simulations with finite-difference time-domain method reveal that wide-angle, ± 28.4°, beam steering can be achieved when the length of the liquid crystal layer equals 5.17 μm. Moreover, the wavelengths over λ = 1.518-1.553 μm or λ = 1.487-1.518 μm can be steered to different angles. A special characteristic of the presented structure gives an opportunity to be used as an efficient element in a high integrated optical device for miniaturisation and tuning purposes.

Beam Steering, Beam Shaping, and Intensity Modulation Based on VCSEL Photonics

A beam-steering device has been a key element for various sensing and imaging applications. We proposed a beam-steering device based on a vertical-cavity surface-emitting laser (VCSEL)-based waveguide structure. We show a giant steering angle and ultrahigh steering resolution at the same time by increasing the length of a device. In this paper, we present our high-resolution beam-steering concept based on VCSEL photonics. A steering angle of over 60° and a number of resolution points over 1000 are demonstrated for millimeter-scale devices, which is the highest in nonmechanical beam-steering devices. We also demonstrate the on-chip integration of a beam-steering function with a VCSEL. In addition, we demonstrate additional functionalities including the creation of vortex beams and low-voltage amplitude modulation with beam steering.

2D Electro-Optic Scanner

In this paper, we present the design and fabrication of a 2D beam steering device using cascaded prism and grating deflectors. The device, based on a single prism with a maximum deflection angle of 5.6{degree sign}, is able to achieve a maximum deflection angle of 29.2o for the cascaded three-prism stage design in the horizontal direction, a 4.6o deflection angle from the grating stage in the vertical direction, and a collimated 4µm beam diameter profile.

Dynamic characterization and modelling of a dual-axis beam steering device for performance understanding, optimization and control design

This paper presents a lumped thermal model of a dual-axis laser micromirror device for beam steering in a free-space optical (FSO) communication system, designed for fractionated spacecraft. An FSO communication system provides several advantages, such as larger bandwidth, smaller size and weight of the communication payload and less power consumption. A dual-axis mirror device is designed and realized using microelectromechanical systems technology. The fabrication is based on a double-sided, bulk micromachining process, where the mirror actuates thermally by joints consisting of v-grooves filled with the SU-8 polymer. The size of the device, consisting of a mirror, which is deflectable versus its frame in one direction, and through deflection of the frame in the other, is 15.4 × 10.4 × 0.3 mm3. In order to further characterize and understand the micromirror device, a Simulink state-space model of the actuator is set up using thermal and mechanical properties from a realized actuator. A deviation of less than 2% between the modelled and measured devices was obtained in an actuating temperature range of 20–200 °C. The model of the physical device was examined by evaluating its performance in vacuum, and by changing physical parameters, such as thickness and material composition. By this, design parameters were evaluated for performance gain and usability. For example, the crosstalk between the two actuators deflecting the mirror along its two axes in atmospheric pressure is projected to go down from 97% to 6% when changing the frame material from silicon to silicon dioxide. A feedback control system was also designed around the model in order to examine the possibility to make a robust control system for the physical device. In conclusion, the model of the actuator presented in this paper can be used for further understanding and development of the actuator system.

Rotatable diffractive gratings based on hybrid-aligned cholesteric liquid crystals

This work proposes a thermally rotatable grating that is based on hybrid-aligned cholesteric liquid crystals (HBA-cholesteric LCs). Experiments reveal that the HBA-cholesteric texture has a uniformly striped domain, which forms a grating, when the ratio of the cell gap to the helical pitch (d/p) is in the range of 2≤d/p≤3. The stripe direction of the HBA-cholesteric grating is predicted by the proposed vertically aligned LC layer model. The stripe direction of the HBA-cholesteric grating rotates continuously under thermal and electrical effects. Furthermore, the HBA-cholesteric grating has a larger rotational angle under the thermal effect (~101°) than under the electrical effect (~48°). Potential applications of the proposed thermally rotatable cholesteric grating for beam steering devices are emphasized.

Polymeric waveguide electro-optic beam-steering device with DNA biopolymer conductive cladding layers

A polymer electro-optic (EO) waveguide beam-steering device with deoxyribonucleic acid (DNA) biopolymer conductive cladding layers and a core layer of the commercially available EO polymer SEO100 is demonstrated with 100% relative poling efficiency. This demonstration device exhibits a deflection efficiency of 99 mrad/kV with a corresponding in-device EO coefficient r33 of 124 pm/V at 1550 nm. When the DNA biopolymer bottom cladding layer is replaced by the commonly used cladding polymer UV15, the deflection efficiency and in-device r33 drop to 34 mrad/kV and 43 pm/V, respectively.

Miniature Nonmechanical Beam Deflector Based on Bragg Reflector Waveguide With a Number of Resolution Points Larger Than 1000

A compact and super-high-resolution beam steering device is demonstrated using a Bragg reflector waveguide. For 37-nm tuning in input wavelengths, we obtained a continuous beam steering angle of 60°. In addition, a divergence angle as small as 0.025 ° is recorded. The maximum divergence angle and steering range in the entire wavelength range of 958-986 nm are 0.040° and 41°, respectively. These data indicate a number of resolution points larger than 1000, which is the highest number for nonmechanical beam deflectors ever reported.

Beam manipulating by graded photonic crystal slab made of dielectric elastomer actuators

The focusing lens and beam-steering device are implemented using two-dimensional graded photonic crystals with dielectric elastomer tube array embedded in air background. The gradient refractive index could be adjusted by varying the applied voltage on the dielectric elastomer tube so that the tube radius would change accordingly, which consequently alters the filling factor of the constituent material in photonic crystals, and the photonic dispersion band can be modulated. The finite element method is employed to simulate the electromagnetic wave propagation inside the designed device and analyze both the tunable focusing properties and beam-deflecting behavior. The implementation of the proposed device is validated within the lowest band. It is concluded that the proposed innovative device could easily accomplished the applications of focusing and steering electromagnetic fields with nonuniform applied voltage profiles.

Electrical beam steering with metal-anisotropic-metal structure

In this numerical study, we present and demonstrate a compact, electrical plasmonic beam-steering device composed of anisotropic material. The splitting angle can be modulated by the external electric or magnetic field. The physical principle of this phenomenon is evaluated from the phase of surface plasmon polaritons and Fabry-Perot (F-P) resonance in slits. Our numerical simulations with finite-difference time-domain (FDTD) technique reveals that wide-angle (±27°) beam steering can be achieved. Moreover, the efficiency increases when increasing the steering angle. A special characteristic of the presented structure gives an opportunity to be used as an efficient element in a high integrated optical device for miniaturization and tuning purposes.

Electro-Thermal Beam Steering Using Bragg Reflector Waveguide Amplifier

We demonstrate the electro-thermal beam steering taking advantage of the large angular dispersion of a Bragg Reflector waveguide amplifier. It is realized by changing the waveguide refractive index with injection current in the amplifier. Both theoretical calculations and experimental demonstration are presented. Output light rotates over 6° with an injection current of 400 mA. The divergence angle is smaller than 1°. The result reveals a possibility of electro-thermal tuning in our proposed beam steering device.