Beam Steering Device Research Articles

Observation of Goos-Hänchen shift in plasmon-induced transparency

We observed positive and negative Goos–Hänchen (GH) shifts in plasmon-induced transparency (PIT) in a metal–insulator–metal (MIM) multi-layer structure based on the attenuated total reflection response. Here, the MIM waveguide (WG) mode and the surface plasmon polariton (SPP) resonance act as low- and high-Q resonances, respectively. SPP also induced the transparency window in otherwise opaque wavenumber (k) regions. The observed GH shifts were caused by the relevant k-domain dispersion in PIT, which is controllable through the adjustment of the coupling strength between the MIM WG and SPP resonances. This effect, thus, can be recognized as a rigorous counterpart of slow light in electromagnetically induced transparency and other related phenomena in the frequency domain. The tunable GH shift in PIT in a MIM structure would enable applications in beam steering devices and high-sensitivity sensors.

Controlling On-chip Optical Radiation with All-Dielectric Antennas: Reconfigurable Interconnects and Lab-on-achip Devices

Aimed to improve the flexibility of optical network-on-a-chip topologies, unguided optical interconnects using plasmonic nanoantennas or dielectric phased arrays have been proposed. However, the bulky footprints of the latter, and both the low directivity figures and high losses of the former, together with complicated excitation schemes, limit their use for on-chip optical interconnects. Here, we introduce a novel concept of on-chip CMOS-compatible wireless optical system based on the use of smartly-engineered broadband easily-fed antennas, which not only overcomes the aforementioned drawbacks but also opens a wide range of applications in several fields. To illustrate its potential, several unprecedented on-chip wireless applications are outlined and experimentally demonstrated. This includes the verification of broadband highly-directive wireless data transmission at speeds as high as 160 Gbit·s−1 over mm-scale links, the realization of fully-reconfigurable wireless beam steering device and the validation of an ultra-compact integrated contactless microflow cytometer.

Fan-beam steering device using a photonic crystal slow-light waveguide with surface diffraction grating.

Compact non-mechanical beam steering devices are desired not only for current common applications, but also for advanced applications such as light detection and ranging. We use a Si photonic crystal slow-light waveguide with a diffraction grating, which radiates the guided mode to free space and steers a fan beam by sweeping the wavelength. Due to its large angular dispersion, slow light enhances the steering range without degrading the beam quality, resulting in more resolution points. We fabricated 600μm devices and observed a 23° steering range and a beam divergence of 0.23°, which resulted in 100 resolution points.

Impact of pitch angle fluctuations on airborne lidar forward sensing along the flight direction

Abstract. Airborne lidar forward sensing along the flight direction can serve for notification of clear air turbulence (CAT) and help to prevent injuries or fatal air accidents. The validation of this concept was presented in the framework of the DELICAT (DEmonstration of LIdar-based CAT detection) project. However, the strong variations in signal level, which were observed during the DELICAT measurements but not explained, sometimes indicated the need of a better understanding the observational errors due to geometrical factors. In this paper, we discuss possible error sources pertinent to this technique, related to fluctuations of the flight parameters, which may lead to strong signal variations caused by the random deviations of the sensing beam from the forward flight trajectory. We analyze the variations in backscattered lidar signal caused by fluctuations of the most important forward-sensing flight parameter, the pitch angle. The fluctuation values considered in the paper correspond to the error limits of the compensational gyro platform used in civil aviation. The part of the pitch angle fluctuations not compensated for by the beam-steering device in the presence of aerosol concentration variations can lead to noticeable signal variations that can be mistakenly attributed to wind shear, turbulence, or fast evolution of the aerosol layer. We formulate the criteria that allow the recognition of signal variations caused by pitch angle fluctuations. Influence of these fluctuations is shown to be stronger for aerosol variations on smaller vertical scales. An example of DELICAT observations indicating a noticeable pitch angle fluctuation impact is presented.

Two-dimensional switchable blue phase gratings manufactured by nanosphere lithography.

Switchable two dimensional liquid crystal diffraction gratings are promising candidates in beam steering devices, multiplexers and holographic displays. For these areas of applications a high degree of integration in optical systems is much sought-after. In the context of diffraction gratings this means that the angle of diffraction should be rather high, which typically poses a problem as the fabrication of small grating periods is challenging. In this paper, we propose the use of nanosphere lithography (NSL) for the fabrication of two-dimensionally structured electrodes with a periodicity of a few micrometers. NSL is based on the self-assembly of micro- or nanometer sized spheres into monolayers. It allows for easy substrate structuring on wafer scale. The manufactured electrode is combined with a liquid crystalline polymer-stabilized blue phase, which facilitates sub-millisecond electrical switching of the diffraction efficiency at a diffraction angle of 21.4°.

Investigation of Kerr effect in a blue phase liquid crystal using wedge-cell technique

In this work an alternative method for refractive index measurement of blue phase liquid crystal in the Kerr effect has been described. The proposed wedge method uses simple goniometric setup, allowing for direct index measurements for any wavelengths and index values. This is significant advantage comparing to other methods, usually having limitations of the measurement range as well as necessity complicated calculation to obtain refractive indices values. The results are reliable and agree well with the subject literature. Full Text: PDF ReferencesW. Cao et al., "Lasing in a three-dimensional photonic crystal of the liquid crystal blue phase II", Nat. Mater. 1, 111-113 (2002). CrossRef S. Meiboom, M. Sammon, W.F. Brinkman, "Lattice of disclinations: The structure of the blue phases of cholesteric liquid crystals", Phys. Rev. A. 27, 438 (1983). CrossRef S. Tanaka et al., "Double-twist cylinders in liquid crystalline cholesteric blue phases observed by transmission electron microscopy", Sci. Rep. 5, 16180 (2015). CrossRef Y. Li and S.-T. Wu, "Polarization independent adaptive microlens with a blue-phase liquid crystal", Opt. Express 19(9), 8045-8050 (2011). CrossRef N. Rong et al., "Polymer-Stabilized Blue-Phase Liquid Crystal Fresnel Lens Cured With Patterned Light Using a Spatial Light Modulator", J. of Disp. Technol. 12(10), 1008-1012 (2016). CrossRef J.-D. Lin et al., "Spatially tunable photonic bandgap of wide spectral range and lasing emission based on a blue phase wedge cell", Opt. Express 22(24), 29479-29492 (2014). CrossRef P. Joshi et al., "Tunable light beam steering device using polymer stabilized blue phase liquid crystals", Photon. Lett. Poland 9(1), 11-13 (2017). CrossRef Ch.-W. Chen et al., "Temperature dependence of refractive index in blue phase liquid crystals", Opt. Mater. Express 3(5), 527-532 (2013). CrossRef Y.-H. Lin et al., "Measuring electric-field-induced birefringence in polymer stabilized blue-phase liquid crystals based on phase shift measurements", J. Appl. Phys. 109, 104503 (2011). CrossRef J. Yan et al., "Direct measurement of electric-field-induced birefringence in a polymer-stabilized blue-phase liquid crystal composite", Opt. Express 18(11), 11450-11455 (2010). CrossRef K.A. Rutkowska, K. Orzechowski, M. Sierakowski, "Wedge-cell technique as a simple and effective method for chromatic dispersion determination of liquid crystals", Photon. Lett. Poland 8(2), 51-53 (2016). CrossRef O. Chojnowska et al., "Electro-optical properties of photochemically stable polymer-stabilized blue-phase material", J. Appl. Phys. 116, 213505 (2014). CrossRef J. Yan et al., "Extended Kerr effect of polymer-stabilized blue-phase liquid crystals", Appl. Phys. Lett. 96, 071105 (2010). CrossRef M. Chen et al., "Electrically assisting crystal growth of blue phase liquid crystals", Opt. Mater. Express 4(5), 953-959 (2014). CrossRef J. Kerr, Philos. Mag. 50, 337 (1875).

Polarization analysis of the beam-steering device of quantum optical systems

Polarization analysis of the laser radiation of quantum optical systems intended for pulsed laser ranging of satellites orbiting the Earth is conducted. The polarization states of laser radiation at the output of a laser rangefinder for different azimuth and elevation angles of satellites are determined. Problems related to controlling polarization losses upon reflection from the dielectric mirrors of the quantum optical system and reduction of error of laser ranging by using circularly polarized laser radiation are analyzed. It is confirmed that it is effective to use circularly polarized laser radiation for laser ranging of satellites orbiting the Earth.

Color-Selective and Versatile Light Steering with up-Scalable Subwavelength Planar Optics

Resonant waveguide gratings (RWGs) are subwavelength structures of great interest for biosensors, optical filters and optical security applications. We demonstrate and characterize a beam steering device, where the in-coupling and out-coupling processes make use of different RWGs that share the same ultrathin dielectric waveguide. This device enables selective color-filtering and redirection of a white light source (such as a white LED). Furthermore, this structure is compatible with up-scalable fabrication processes such as roll-to-roll replication, and is relevant for high-volume production. Because of its color selectivity and its use in low coherence illumination conditions, such a beam steering device could be implemented in a variety of optical applications such as optical security, multifocal or monochromatic lenses, biosensors, and see-through optical combiners for near-eye displays.

Experimental Demonstration of >230° Phase Modulation in Gate-Tunable Graphene–Gold Reconfigurable Mid-Infrared Metasurfaces

Metasurfaces offer significant potential to control far-field light propagation through the engineering of the amplitude, polarization, and phase at an interface. We report here the phase modulation of an electronically reconfigurable metasurface and demonstrate its utility for mid-infrared beam steering. Using a gate-tunable graphene-gold resonator geometry, we demonstrate highly tunable reflected phase at multiple wavelengths and show up to 237° phase modulation range at an operating wavelength of 8.50 μm. We observe a smooth monotonic modulation of phase with applied voltage from 0° to 206° at a wavelength of 8.70 μm. Based on these experimental data, we demonstrate with antenna array calculations an average beam steering efficiency of 23% for reflected light for angles up to 30° for this range of phases, confirming the suitability of this geometry for reconfigurable mid-infrared beam steering devices. By incorporating all nonidealities of the device into the antenna array calculations including absorption losses which could be mitigated, 1% absolute efficiency is achievable up to 30°.

High-efficiency large-angle Pancharatnam phase deflector based on dual-twist design

We have previously shown through simulation that an optical beam deflector based on the Pancharatnam (geometric) phase can provide high efficiency with up to 80° deflection using a dual-twist structure for polarization-state control [Appl. Opt.54, 10035 (2015)]. In this report, we demonstrate that its optical performance is as predicted and far beyond what could be expected for a conventional diffractive optical device. We provide details about construction and characterization of a ± 40° beam-steering device with 90% diffraction efficiency based on our dual-twist design at a 633nm wavelength.

Unified Architecture of an Integrated SDM-WSS Employing a PLC-Based Spatial Beam Transformer Array for Various Types of SDM Fibers

There is no doubt that wavelength-division multiplexing will continuously play an important role in future space-division multiplexing (SDM) capable optical networks. In this paper, we propose a unified architecture for integrated wavelength selective switches (WSSs) that can be applied to various types of SDM fibers and reconfigurable optical add/drop multiplexer switching types. A recently reported planar lightwave circuit (PLC)-based spatial beam transformer (SBT) array is anticipated to be used as a key enabler for the architecture to integrate multiple WSSs on a single liquid crystal on silicon beam steering device. The architecture enables individual switching and power adjustment functionality of an SDM-WSS that supports an uncoupled single-mode multicore fiber (SM-MCF) in an economical manner. The same architecture provides fractional joint wavelength switching functionality in an SDM-WSS for a few-mode MCF (FM-MCF) and a grouped-coupled-core MCF (GCC-MCF) as well as joint wavelength switching in an SDM-WSS for multiple few-mode fibers with almost no additional hardware complexity. Preliminary scalability evaluation shows that a 1×24 individual switching SDM-WSS for a single-mode eight-core uncoupled MCF or a 1×7 fractional joint wavelength switching SDM-WSS for a three-mode eight-core FM-MCF or a three-coupled-core × eight-group GCC-MCF is feasible using the SBT array design reported in the literature. The evaluation also shows that compared to the traditional approach based on conventional WSSs, the proposed architecture is anticipated to reduce the hardware footprint requirement by parallelism factor mC, where m and C indicate the number of modes per core and the number of cores per fiber, respectively.

Optimization of liquid crystal devices based on weakly conductive layers for lensing and beam steering

Liquid crystals are mostly known for their use in displays, but over the past decade these materials have been applied in a number of other devices such as tunable lenses or beam steering devices. A common technique to realize a gradual electric field profile as is required to obtain a gradual refractive index profile in these applications is the use of weakly conductive materials. The weakly conductive layers are able to spread the voltage profile which is applied through well-conductive electrodes at the side of the weakly conductive layer. The simulation and design of such structures is not trivial because two or three dimensional quasi-static electric field profiles need to be calculated. This is due to the fact that the resistivity of the conductive layers and the dielectric properties of the liquid crystal are coupled. An exact solution requires solving a number of coupled differential equations. In this paper, we develop a model to simulate the RC-effects with an approximate model.

X-band SAR imaging with a liquid-crystal-based dynamic metasurface antenna

Synthetic aperture radar (SAR) synthesizes a large effective aperture via coherent processing of multiple measurements taken from a moving platform. We present an approach for SAR imaging using an X-band (10–13.7 GHz) dynamic metasurface antenna (MSA). This newly developed antenna has over 6000 liquid-crystal-switched radiating elements that cover a circular area with an approximate diameter of 0.45 m. The MSA’s main beam can be steered electronically to spherical angles of up to ±70°. To the best of our knowledge, we present the first-reported laboratory-scale imaging experiments with a liquid-crystal-switched MSA. We leverage the beam-steering capabilities of the MSA in a spotlight SAR mode to achieve a measured cross-range resolution of 1.6 cm, a 62% improvement over the 4.2 cm cross-range resolution achieved with the same aperture without the metasurface-enabled beam steering. The dynamic MSA offers the superior image resolution of a beam-steering device without the hardware burden of conventional phased array antennas.

Kirigami/Origami‐Based Soft Deployable Reflector for Optical Beam Steering

The beam steering mechanism has been a key element for various applications ranging from sensing and imaging to solar tracking systems. However, conventional beam steering systems are bulky and complex and present significant challenges for scaling up. This work introduces the use of soft deployable reflectors combining a soft deployable structure with simple kirigami/origami reflective films. This structure can be used as a macroscale beam steering mechanism that is both simple and compact. This work first develops a soft deployable structure that is easily scalable by patterning of soft linear actuators. This soft deployable structure is capable of increasing its height several folds by expanding in a continuous and controllable manner, which can be used as a frame to deform the linearly stretchable kirigami/origami structures integrated into the structure. Experiments on the reflective capability of the reflectors are conducted and show a good fit to the modeling results. The proposed principles for deployment and for beam steering can be used to realize novel active beam steering devices, highlighting the use of soft robotic principles to produce scalable morphing structures.

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.

Electronically-Controlled Beam-Steering through Vanadium Dioxide Metasurfaces.

Engineered metamaterials offer unique functionalities for manipulating the spectral and spatial properties of electromagnetic waves in unconventional ways. Here, we report a novel approach for making reconfigurable metasurfaces capable of deflecting electromagnetic waves in an electronically controllable fashion. This is accomplished by tilting the phase front of waves through a two-dimensional array of resonant metasurface unit-cells with electronically-controlled phase-change materials embedded inside. Such metasurfaces can be placed at the output facet of any electromagnetic radiation source to deflect electromagnetic waves at a desired frequency, ranging from millimeter-wave to far-infrared frequencies. Our design does not use any mechanical elements, external light sources, or reflectarrays, creating, for the first time, a highly robust and fully-integrated beam-steering device solution. We demonstrate a proof-of-concept beam-steering metasurface optimized for operation at 100 GHz, offering up to 44° beam deflection in both horizontal and vertical directions. Dynamic control of electromagnetic wave propagation direction through this unique platform could be transformative for various imaging, sensing, and communication applications, among others.

Gate-Tunable Conducting Oxide Metasurfaces.

Metasurfaces composed of planar arrays of subwavelength artificial structures show promise for extraordinary light manipulation. They have yielded novel ultrathin optical components such as flat lenses, wave plates, holographic surfaces, and orbital angular momentum manipulation and detection over a broad range of the electromagnetic spectrum. However, the optical properties of metasurfaces developed to date do not allow for versatile tunability of reflected or transmitted wave amplitude and phase after their fabrication, thus limiting their use in a wide range of applications. Here, we experimentally demonstrate a gate-tunable metasurface that enables dynamic electrical control of the phase and amplitude of the plane wave reflected from the metasurface. Tunability arises from field-effect modulation of the complex refractive index of conducting oxide layers incorporated into metasurface antenna elements which are configured in reflectarray geometry. We measure a phase shift of 180° and ∼30% change in the reflectance by applying 2.5 V gate bias. Additionally, we demonstrate modulation at frequencies exceeding 10 MHz and electrical switching of ±1 order diffracted beams by electrical control over subgroups of metasurface elements, a basic requirement for electrically tunable beam-steering phased array metasurfaces. In principle, electrically gated phase and amplitude control allows for electrical addressability of individual metasurface elements and opens the path to applications in ultrathin optical components for imaging and sensing technologies, such as reconfigurable beam steering devices, dynamic holograms, tunable ultrathin lenses, nanoprojectors, and nanoscale spatial light modulators.

Simulation of electrically controlled nematic liquid crystal Rochon prism

AbstractOperation of an electrically controlled beam steering device based on Rochon prism made by use of nematic liquid crystal is modelled numerically. Deflection angles and angular distribution of light intensity in the deflected beam are calculated. Dynamics of the device is studied. Advantage of application of dual frequency nematic liquid crystal is demonstrated. Role of flexoelectric properties of the nematic is analyzed.

Application of twisted nematic cell in beam steering devices

Several simple beam steering devices composed of twisted nematic cells and typical optical elements are proposed. Principles of operation, based on elementary optical phenomena as total internal reflection or polarisation by reflection, are described. The deflection angles are calculated for exemplary parameters. The possibility of modifications of the proposed devices is discussed. Full Text: PDF References P. F. McManamon, P.J. Bos, M.J. Escuti, J. Heikenfeld, S. Serati, H. Xie, E.A. Watson, "A Review of Phased Array Steering for Narrow-Band Electrooptical Systems", Proc. IEEE 97, 1078 (2009). CrossRef S.-T. Wu, D.-K. Yang, Fundamentals of Liquid Crystal Devices (John Wiley & Sons, Chichester, 2006). X. Wang, D. Wilson, R. Muller, P. Maker, D. Psaltis, "Liquid-crystal blazed-grating beam deflector", Appl. Opt. 39, 6545 (2000). CrossRef T. Chan, E. Myslivets, J.E. Ford, "2-Dimensional beamsteering using dispersive deflectors and wavelength tuning", Opt. Expr. 16, 14617 (2008). CrossRef J. Kim, C. Oh, M.J. Escuti, L. Hosting, S. Serati, "Wide-angle nonmechanical beam steering using thin liquid crystal polarization gratings", Proc. SPIE 7093, 709302 (2008). CrossRef S. Valyukh, V. Chigrinow, H.S. Kwok, H. Arwin, "On liquid crystal diffractive optical elements utilizing inhomogeneous alignment", Opt. Expr. 20, 15209 (2012). CrossRef S. Valyukh, I. Valyukh, V. Chigrinov, "Liquid-Crystal Based Light Steering Optical Elements", Phot. Lett. Poland 3, 88 (2011). CrossRef A.B. Golovin, S.V. Shiyanovskii, O.D. Lavrentovich, "Gradient beam steering device based on a nematic cell with continuous ramp of the phase retardation", Proc. SPIE 5741, 146 (2005). CrossRef M. Bass et al., Handbook of Optics, vol. II 2nd Ed., Ch. 8, (McGraw Hill, New York, 1995). Schott (Optical Glass Data Sheets, 2012). DirectLink R. Herke, M.H. Anderson, T. Baur, Liquid crystal in precision optical devices (Meadowlark Optics, Inc., 2005).

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.