High-resolution aliasing-free optical beam steering
20 Aug 2016-Vol. 3, Iss: 8, pp 887-890
TL;DR: In this paper, a two-axis steerable optical phased array with over 500 resolvable spots and 80° steering in the phased array axis (measurement limited) and a record small divergence in both axes (0.14°).
Abstract: Many applications, including laser (LIDAR) mapping, free-space optical communications, and spatially resolved optical sensors, demand compact, robust solutions to steering an optical beam. Fine target addressability (high steering resolution) in these systems requires simultaneously achieving a wide steering angle and a small beam divergence, but this is difficult due to the fundamental trade-offs between resolution and steering range. So far, to our knowledge, chip-based two-axis optical phased arrays have achieved a resolution of no more than 23 resolvable spots in the phased-array axis. Here we report, using non-uniform emitter spacing on a large-scale emitter array, a dramatically higher-performance two-axis steerable optical phased array fabricated in a 300 mm CMOS facility with over 500 resolvable spots and 80° steering in the phased-array axis (measurement limited) and a record small divergence in both axes (0.14°). Including the demonstrated steering range in the other (wavelength-controlled) axis, this amounts to two-dimensional beam steering to more than 60,000 resolvable points.
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08 Aug 2019
TL;DR: An introductory overview of the technology linked to imaging lidars for autonomous vehicles is provided, and the main single-point measurement principles are started, and then the different imaging strategies implemented in the different solutions are presented.
Abstract: Imaging lidars are one of the hottest topics in the optronics industry. The need to sense the surroundings of every autonomous vehicle has pushed forward a career to decide the final solution to be implemented. The diversity of state-of-the art approaches to the solution brings, however, a large uncertainty towards such decision. This results often in contradictory claims from different manufacturers and developers. Within this paper we intend to provide an introductory overview of the technology linked to imaging lidars for autonomous vehicles. We start with the main single-point measurement principles, and then present the different imaging strategies implemented in the different solutions. An overview of the main components most frequently used in practice is also presented. Finally, a brief section on pending issues for lidar development has been included, in order to discuss some of the problems which still need to be solved before an efficient final implementation.Beyond this introduction, the reader is provided with a detailed bibliography containing both relevant books and state of the art papers.
4 citations
Cites background from "High-resolution aliasing-free optic..."
...Recently, sophisticated OPAs have been demonstrated with performance parameters that make them seem suitable for high power lidar applications [70,74,75]....
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TL;DR: The doping compensation technique overlaps P-type and N-type implantation windows at the waveguide core and enhances the responsivity, which is comparable to BDA based SiWG PDs relying on dedicated ion bombardments.
Abstract: Silicon waveguide photodiodes (SiWG PD) based on the bulk defect-mediated absorption (BDA) of sub-bandgap photons are suitable to realize in-line optical power monitors for silicon photonic integrated circuits. Deep-level states to enable the BDA can be induced by exploiting the ion implantation steps that are used to embed PN junctions for carrier-depletion-based modulators. This manner usually exhibits limited responsivities since relevant processing conditions are optimized for the modulation rather than the BDA. In this letter, we solve this issue with the doping compensation technique. This technique overlaps P-type and N-type implantation windows at the waveguide core. The responsivity is enhanced due to the increased density of lattice defects and the reduced density of free carriers in the compensated silicon. Influences of the dimension of the dopant compensation region on responsivity and operation speed are investigated. As the width of this region increases from 0 μm to 0.4 μm, the responsivity at −5 V is improved from 2 mA/W to 17.5 mA/W. This level is comparable to BDA based SiWG PDs relying on dedicated ion bombardments. On the other hand, a bit-error-rate test at 10 Gb/s suggests that the device with 0.2-μm-wide compensation region exhibits the highest sensitivity.
4 citations
01 Oct 2017
TL;DR: In this article, a 1 × 8 optical phased array (OPA) for one dimensional beam steering based on a 16 × 16 Benes-type silicon optical switch is presented, which shows a far-field pattern with 0.32° beam width.
Abstract: We experimentally demonstrate a 1 × 8 optical phased array (OPA) for one dimensional beam steering based on a 16 × 16 Benes-type silicon optical switch. The device shows a far-field pattern with 0.32° beam width, revealing the new application potential for the optical switch as a multi-functional platform.
4 citations
Cites background from "High-resolution aliasing-free optic..."
...With the development of integrated photonics, the last decade has witnessed the growing investigations and demonstrations of optical beamforming and beam steering based on optical phased array (OPA) for various applications including free-space optical communications [1-5], light detection and ranging (LiDAR) [1-5], image projection [6], holographic displays [7], as well as compressed sensing [8-9]....
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...While many efforts have been made to improve the far-field addressability of optical phased arrays, namely with an array of a larger scale [3], non-uniform spacing [2-4], as well as implementation on the silicon nitride nanophotonic platforms [5], most of them are based on a similar structure proposed by K....
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TL;DR: In this article , different beam-steering techniques are introduced using an http://www.w3.org/1998/Math/MathML" display="inline"> ...read more
Abstract: In this paper, different beam-steering techniques are introduced using an 8 × 8 hybrid plasmonic nano-antenna array operating at 1550 nm. Two conventional techniques of the switched-beam and phased array are considered for implementing beam steering. For a switched-beam antenna, the beam steering is achieved by switching between the feed antenna elements, whereas the feed antenna array is attached to the back surface of a fishnet achromatic-metalens to collimate the rays. In the phased array antenna, the beam is steered by estimating the appropriate feeding phases of the 64 elements using a deep neural network (DNN) either with or without a lens and comparing the results with those obtained using a traditional method. Finally, a hybrid technique based on activating only a subset of antenna elements in the existence of the lens is proposed to steer the pattern in a certain direction. By predicting the proper feeding phases of the antenna array elements, the neural network with the backpropagation technique and weighted hybrid gravitational search algorithm-particle swarm optimization approach is used to beam-steer the pattern. Furthermore, the DNN is applied to assign the required active subset elements for directing the main beam toward the desired direction. Several sample examples are provided to beam-steer the pattern in numerous directions to assess the correctness of the strategies.
4 citations
05 May 2019
TL;DR: In this paper, the authors demonstrate a platform for low power solid-state beam steering in 2D using a single wavelength, based on a metalens and a switchable emitter array, enabling steering of 12.4°×26.8° using less than 83 mW.
Abstract: We demonstrate a platform for low-power solid-state beam steering in 2D using a single wavelength. This platform, based on a metalens and a switchable emitter array, enables steering of 12.4°× 26.8° using less than 83 mW. © 2019 The Author(s)
4 citations
Cites background from "High-resolution aliasing-free optic..."
...An optical phased array with a thousand waveguides consumes tens of watts [2-3] unless one can reduce the power consumption of individual phase shifters [1]....
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...Solid-state beam steering is the key technology to enable on-chip LIDAR, free-space communications, and miniature sensors [1-5]....
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References
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TL;DR: This work demonstrates that a robust design, together with state-of-the-art complementary metal-oxide–semiconductor technology, allows large-scale NPAs to be implemented on compact and inexpensive nanophotonic chips and therefore extends the functionalities of phased arrays beyond conventional beam focusing and steering, opening up possibilities for large- scale deployment.
Abstract: A large-scale silicon nanophotonic phased array with more than 4,000 antennas is demonstrated using a state-of-the-art complementary metal-oxide–semiconductor (CMOS) process, enabling arbitrary holograms with tunability, which brings phased arrays to many new technological territories. Nanophotonic approaches allow the construction of chip-scale arrays of optical nanoantennas capable of producing radiation patterns in the far field. This could be useful for a range of applications in communications, LADAR (laser detection and ranging) and three-dimensional holography. Until now this technology has been restricted to one-dimensional or small two-dimensional arrays. This paper reports the construction of a large-scale silicon nanophotonic phased array containing 4,096 optical nanoantennas balanced in power and aligned in phase. The array was used to generate a complex radiation pattern—the MIT logo—in the far field. The authors show that this type of nanophotonic phased array can be actively tuned, and in some cases the beam is steerable. Electromagnetic phased arrays at radio frequencies are well known and have enabled applications ranging from communications to radar, broadcasting and astronomy1. The ability to generate arbitrary radiation patterns with large-scale phased arrays has long been pursued. Although it is extremely expensive and cumbersome to deploy large-scale radiofrequency phased arrays2, optical phased arrays have a unique advantage in that the much shorter optical wavelength holds promise for large-scale integration3. However, the short optical wavelength also imposes stringent requirements on fabrication. As a consequence, although optical phased arrays have been studied with various platforms4,5,6,7,8 and recently with chip-scale nanophotonics9,10,11,12, all of the demonstrations so far are restricted to one-dimensional or small-scale two-dimensional arrays. Here we report the demonstration of a large-scale two-dimensional nanophotonic phased array (NPA), in which 64 × 64 (4,096) optical nanoantennas are densely integrated on a silicon chip within a footprint of 576 μm × 576 μm with all of the nanoantennas precisely balanced in power and aligned in phase to generate a designed, sophisticated radiation pattern in the far field. We also show that active phase tunability can be realized in the proposed NPA by demonstrating dynamic beam steering and shaping with an 8 × 8 array. This work demonstrates that a robust design, together with state-of-the-art complementary metal-oxide–semiconductor technology, allows large-scale NPAs to be implemented on compact and inexpensive nanophotonic chips. In turn, this enables arbitrary radiation pattern generation using NPAs and therefore extends the functionalities of phased arrays beyond conventional beam focusing and steering, opening up possibilities for large-scale deployment in applications such as communication, laser detection and ranging, three-dimensional holography and biomedical sciences, to name just a few.
1,065 citations
01 Aug 1998
TL;DR: The digital display engine (DDE) as discussed by the authors is based on a single DMD device having array dimensions of 800/spl times/600 elements, illuminated by a metal halide arc lamp through a compact optics train.
Abstract: A period of rapid growth and change in the display industry has recently given rise to many new display technologies. One such technology, the Digital Micromirror Device/sup TM/ (DMD), developed at Texas Instruments, represents a unique application of microelectromechanical systems to the area of projection displays. In this paper, we describe a representative example of a DMD-based projection display engine, the digital display engine (DDE). The DDE is based on a single-DMD device having array dimensions of 800/spl times/600 elements, illuminated by a metal halide arc lamp through a compact optics train. The engine is designed for portable and fixed conference-room graphics and video display applications, and many design decisions were made to tailor the engine for its intended venue. The design of the projection engine optics and electronics is discussed, along with the basic operation, manufacture, and reliability of the DMD itself.
642 citations
TL;DR: A 16-channel, independently tuned waveguide surface grating optical phased array in silicon for two dimensional beam steering with a total field of view of 20° x 14° and full-window background peak suppression of 10 dB is demonstrated.
Abstract: We demonstrate a 16-channel, independently tuned waveguide surface grating optical phased array in silicon for two dimensional beam steering with a total field of view of 20° x 14°, beam width of 0.6° x 1.6°, and full-window background peak suppression of 10 dB.
373 citations
TL;DR: An integrated approach is followed in which a 1D optical phased array is fabricated on silicon-on-insulator in which continuous thermo-optical steering of 2.3 degrees and wavelength steering of 14.1 degrees is reported.
Abstract: Optical phased arrays are versatile components enabling rapid and precise beam steering. An integrated approach is followed in which a 1D optical phased array is fabricated on silicon-on-insulator. The optical phased array consists of 16 parallel grating couplers spaced 2 mum apart. Steering in one direction is done thermo-optically by means of a titanium electrode on top of the structure using the phased array principle, while steering in the other direction is accomplished by wavelength tuning. At a wavelength of 1550 nm, continuous thermo-optical steering of 2.3 degrees and wavelength steering of 14.1 degrees is reported.
299 citations
TL;DR: The photonic integrated circuit (PIC) consists of 164 optical components including lasers, amplifiers, photodiodes, phase tuners, grating couplers, splitters, and a photonic crystal lens and exhibited steering over 23° x 3.6°.
Abstract: In this work we present the first fully-integrated free-space beam-steering chip using the hybrid silicon platform. The photonic integrated circuit (PIC) consists of 164 optical components including lasers, amplifiers, photodiodes, phase tuners, grating couplers, splitters, and a photonic crystal lens. The PIC exhibited steering over 23° x 3.6° with beam widths of 1° x 0.6°.
283 citations