Optical phased array technology
01 Feb 1996-Vol. 84, Iss: 2, pp 268-298
TL;DR: In this paper, a phase profile is imposed on an optical beam as it is either transmitted through or reflected from the phase shifter array, and the imposed phase profile steers, focuses, fans out, or corrects phase aberrations on the beam.
Abstract: Optical phased arrays represent an enabling new technology that makes possible simple affordable, lightweight, optical sensors offering very precise stabilization, random-access pointing programmable multiple simultaneous beams, a dynamic focus/defocus capability, and moderate to excellent optical power handling capability. These new arrays steer or otherwise operate on an already formed beam. A phase profile is imposed on an optical beam as it is either transmitted through or reflected from the phase shifter array. The imposed phase profile steers, focuses, fans out, or corrects phase aberrations on the beam. The array of optical phase shifters is realized through lithographic patterning of an electrical addressing network on the superstrate of a liquid crystal waveplate. Refractive index changes sufficiently large to realize full-wave differential phase shifts can be effected using low (<10 V) voltages applied to the liquid crystal phase plate electrodes. High efficiency large-angle steering with phased arrays requires phase shifter spacing on the order of a wavelength or less; consequently addressing issues make 1-D optical arrays much more practical than 2-D arrays. Orthogonal oriented 1-D phased arrays are used to deflect a beam in both dimensions. Optical phased arrays with apertures on the order of 4 cm by 4 cm have been fabricated for steering green, red, 1.06 /spl mu/m, and 10.6 /spl mu/m radiation. System concepts that include a passive acquisition sensor as well as a laser radar are presented.
Citations
More filters
TL;DR: In this article, the field of femtosecond pulse shaping is reviewed, and applications of pulse shaping to optical communications, biomedical optical imaging, high power laser amplifiers, quantum control, and laser-electron beam interactions are reviewed.
Abstract: We review the field of femtosecond pulse shaping, in which Fourier synthesis methods are used to generate nearly arbitrarily shaped ultrafast optical wave forms according to user specification. An emphasis is placed on programmable pulse shaping methods based on the use of spatial light modulators. After outlining the fundamental principles of pulse shaping, we then present a detailed discussion of pulse shaping using several different types of spatial light modulators. Finally, new research directions in pulse shaping, and applications of pulse shaping to optical communications, biomedical optical imaging, high power laser amplifiers, quantum control, and laser-electron beam interactions are reviewed.
2,051 citations
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
Book•
01 Jan 2006
TL;DR: In this article, the authors present a model of liquid crystal display matrices, drive schemes and bistable displays, as well as a detailed analysis of the effects of electric fields on liquid crystal properties.
Abstract: Foreword. Series Editor's Foreword. Preface. 1. Liquid crystal physics.* Introduction.* Thermodynamics and statistic physics.* Orientational order.* Elastic properties of liquid crystals.* Response of liquid crystals to electro-magnetic fields.* Anchoring effects of nematic liquid crystal at surfaces. 2. Propagation of light in anisotropic optical medium.* Electromagnetic wave.* Polarization.* Propagation of light in uniform anisotropic optical media.* Propagation of light in cholesteric liquid crystals. 3. Optical modeling methods.* Jones matrix method.* Mueller matrix method.* Berreman 4x4 method. 4. Effects of Electric field on Liquid Crystals.* Dielectric interaction.* Flexoelectric Effect.* Ferroelectricity in liquid crystals. 5. Freedericksz transition.* Calculus of variation.* The Fredeericksz transition: statics.* The Freedericksz transition: dynamics. 6. Liquid Crystal Materials.* Introduction.* Refractive indices.* Dielectric constants.* Rotational Viscosity.* Elastic constant.* Figure-of-merits.* Refractive index matching between liquid crystals and polymers. 7. Modeling of liquid crystal director configuration.* Electric energy of liquid crystals.* Modeling electric field.* Simulation of liquid crystal director configuration. 8. Transmissive liquid crystal display.* Introduction.* Twisted nematic cells.* In plane switching (IPS) mode.* Vertical alignment (VA) mode.* Multi-domain Vertical Alignment (MVA) Cells.* Optically compensated bend (OCB) cell. 9. Reflective and Trasreflective display.* Introduction.* Reflective liquid crystal displays.* Transflector.* Classification of Transflective LCDs.* Dual-cell-gap Transflective LCDs.* Single-cell-gap Transflective LCDs.* Performance of transflective LCDs. 10. Liquid crystal display matrices, drive schemes and bistable displays.* Segmented displays.* Passive matrix displays and drive scheme.* Active Matrix Displays.* Bistable ferroelectric liquid crystal displays and drive scheme.* Bistable nematic displays.* Bistable cholesteric reflective display. 11. Liquid crystal/polymer composites. * Introduction.* Phase separation.* Scattering properties of liquid crystal/polymer composites.* Polymer dispersed liquid crystals.* Polymer stabilization liquid crystals.* Displays from liquid crystal/polymer composites. 12. Tunable liquid crystal photonic devices. * Introduction.* Laser beam steering.* Variable Optical Attenuators.* Tunable-Focus Lens.* Polarization-Independent LC Devices. Index.
878 citations
Patent•
13 Jul 2007
TL;DR: A LiDAR-based 3D point cloud measuring system includes a base, a housing, photon transmitters and photon detectors contained within the housing, a rotary motor that rotates the housing about the base, and a communication component that allows transmission of signals generated by the photon detectors to external components as mentioned in this paper.
Abstract: A LiDAR-based 3-D point cloud measuring system includes a base, a housing, a plurality of photon transmitters and photon detectors contained within the housing, a rotary motor that rotates the housing about the base, and a communication component that allows transmission of signals generated by the photon detectors to external components. In several versions of the invention, the system includes a vertically oriented motherboard, thin circuit boards such as ceramic hybrids for selectively mounting emitters and detectors, a conjoined D-shaped lens array, and preferred firing sequences.
403 citations
19 May 2009
TL;DR: Multiple nonmechanical steering approaches are developing that will allow high-efficiency steering, excellent steering accuracy, and wide fields of view, similar to microwave radar phased arrays.
Abstract: Nonmechanical steering of optical beams will enable revolutionary systems with random access pointing, similar to microwave radar phased arrays. An early approach was birefringent liquid crystals writing a sawtooth phase profile in one polarization, using 2pi resets. Liquid crystals were used because of high birefringence. Fringing fields associated with voltage control required to implement the 2pi resets have limited the efficiency and steering angle of this beam steering approach. Because of steering angle limitations, this conventional liquid crystal steering approach is usually combined with a large angle step-steering approach. Volume holograms, birefringent prisms or sawtooth-profile birefringent phase gratings, and circular-type polarization gratings are the large angle step steering approaches that will be reviewed in this paper. Alternate steering approaches to the combined liquid crystal and step-steering approach exist. Microelectromechanical system mirrors, lenslet arrays, electrowetting, and a variable birefringent grating approach will be reviewed and compared against the conventional liquid crystal and step-steering approaches. Step-steering approaches can also be combined with these approaches. Multiple nonmechanical steering approaches are developing that will allow high-efficiency steering, excellent steering accuracy, and wide fields of view.
383 citations
Cites background or methods from "Optical phased array technology"
...Here � is efficiency, � F is the width of the flyback region, and � is the width between resets [ 14 ]....
[...]
...Liquid crystal devices have been fabricated to implement both variable blaze [13] and variable period [ 14 ]–[16] steering....
[...]
...The best method of doing fine-angle beam steering is by adding up to a one-wavelength phase delay behind each lenslet in one of the lenslet arrays [ 14 ], [74]....
[...]
References
More filters
Book•
01 Jan 1962
TL;DR: This chapter discusses Radar Equation, MTI and Pulse Doppler Radar, and Information from Radar Signals, as well as Radar Antenna, Radar Transmitters and Radar Receiver.
Abstract: 1 An Introduction to Radar 2 The Radar Equation 3 MTI and Pulse Doppler Radar 4 Tracking Radar 5 Detection of Signals in Noise 6 Information from Radar Signals 7 Radar Clutter 8 Propogation of Radar Waves 9 The Radar Antenna 10 Radar Transmitters 11 Radar Receiver
6,010 citations
Book•
01 Jan 1988
TL;DR: In this article, the Electromagnetic Field and its interaction with Matter are discussed, and a matrix formulation for Isotropic Layered Media is proposed. But it is not shown how to apply it to a single homogeneous and isotropic layer.
Abstract: Chapter 1. The Electromagnetic Field. Chapter 2. Interaction of Electromagnetic Radiation with Matter. Chapter 3. Reflection and Refraction of Plane Waves. Chapter 4. Optics of A Single Homogeneous and Isotropic Layer. Chapter 5. Matrix Formulation for Isotropic Layered Media. Chapter 6. Optics of Periodic Layered Media. Chapter 7. Some Applications of Isotropic Layered Media. Chapter 8. Inhomogeneous Layers. Chapter 9. Optics of Anisotropic Layered Media. Chapter 10. Some Applications of Anisotropic Layered Media. Chapter 11. Guided Waves in Layered Media. Chapter 12. Optics of Semiconductor Quantum Wells and Superlattice Structures. Appendix: Zeros of Mode Dispersion RElation. Author Index. Subject Index.
2,324 citations
Book•
01 Jan 1988
TL;DR: Optics of Semiconductor Quantum Wells and Superlattice Structures: Optics of A Single Homogeneous and Isotropic Layer and some Applications of Isotropic Layered Media.
Abstract: Chapter 1. The Electromagnetic Field. Chapter 2. Interaction of Electromagnetic Radiation with Matter. Chapter 3. Reflection and Refraction of Plane Waves. Chapter 4. Optics of A Single Homogeneous and Isotropic Layer. Chapter 5. Matrix Formulation for Isotropic Layered Media. Chapter 6. Optics of Periodic Layered Media. Chapter 7. Some Applications of Isotropic Layered Media. Chapter 8. Inhomogeneous Layers. Chapter 9. Optics of Anisotropic Layered Media. Chapter 10. Some Applications of Anisotropic Layered Media. Chapter 11. Guided Waves in Layered Media. Chapter 12. Optics of Semiconductor Quantum Wells and Superlattice Structures. Appendix: Zeros of Mode Dispersion RElation. Author Index. Subject Index.
2,294 citations
TL;DR: In this article, a fully transparent optical component called a multiple phase hologram is inserted into a conventional optical imaging system by means of this artificial hologram, which in fact is a two-dimensional phase grating with a special groove shape.
553 citations