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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TL;DR: In this paper , a genetic algorithm using double fitness functions was proposed to optimize the array element arrangement of a one-dimensional non-uniform OPA and simulate a onedimensional OPA with different array element numbers.
Abstract: To effectively improve the far-field scanning range of an optical phased array (OPA), we propose a genetic algorithm using double fitness functions to optimize the array element arrangement of a one-dimensional non-uniform OPA and simulate a one-dimensional OPA with different array element numbers. The results show that the non-uniform OPA with more array elements exhibits an improved grating lobe suppression effect, and the optimized antenna array pattern exhibits improved comprehensive performance upon employing the double fitness function of grating lobe suppression and beam steering. Considering 128 array elements as an example, the sidemode suppression ratio (SMSR) exhibits a 2.8-dB improvement in the steering process, which verifies the importance of incorporating the novel fitness function of steering optimization. In addition, we further analyze the influence of manufacturing errors such as emission intensity and array position on the SMSR; it is found that the OPA obtained by simulation is sufficiently robust. Our research lays a theoretical foundation for the development of a one-dimensional non-uniform OPA sparse array.
4 citations
15 May 2019
TL;DR: In this article, the authors used widely tunable lasers combined with properly cascaded transmission gratings to achieve ultrafast speed, large angle, and high resolution optical beam steering with an angular resolution of about 0.15° and a small beam divergence of below 0.06°.
Abstract: Ultrafast speed, large angle, and high resolution optical beam steering using widely tunable lasers combined with properly cascaded transmission gratings has been demonstrated. An efficacy of 0.26°/nm has been achieved in free space with three cascaded transmission gratings. Combined with angular magnification through a 4-f system, 28° sweeping angle has been demonstrated with a 34 nm wavelength tuning. Through fast wavelength tuning, ultra-fast beam steering (>108°/s) has been achieved with an angular resolution of about 0.15° and a small beam divergence of below 0.06°.
4 citations
TL;DR: In this paper, the basic principle of OPA for beam steering is introduced and detailed advances of different solutions such as micro-electromechanical system OPA, liquid crystal OPA and metasurface OPA are discussed.
Abstract: Light detection and ranging (LiDAR), combining traditional radar technology with modern laser technology, has much potential for applications in navigation, mapping, and so on. Benefiting from the superior performance, an all-solid-state beam steering realized by integrated optical phased array (OPA) is one of the key components in the LiDAR system. In this review, we first introduce the basic principle of OPA for beam steering. Then, we briefly review the detailed advances of different solutions such as micro-electromechanical system OPA, liquid crystal OPA, and metasurface OPA, where our main focus was on the recent progress of OPA in photonic integrated chips. Finally, we summarize the different solutions and discuss the challenges and perspectives of all-solid-state beam steering for LiDAR.
4 citations
TL;DR: A unified model for thermo-optic feedback tuning that can be specialized to different applications is presented, its recent advances are reviewed, and its future trends are discussed.
Abstract: As Moore’s law approaching its end, electronics is hitting its power, bandwidth, and capacity limits. Photonics is able to overcome the performance limits of electronics but lacks practical photonic register and flexible control. Combining electronics and photonics provides the best of both worlds and is widely regarded as an important post-Moore’s direction. For stability and dynamic operations considerations, feedback tuning of photonic devices is required. For silicon photonics, the thermo-optic effect is the most frequently used tuning mechanism due to the advantages of high efficiency and low loss. However, it brings new design requirements, creating new design challenges. Emerging applications, such as optical phased array, optical switches, and optical neural networks, employ a large number of photonic devices, making PCB tuning solutions no longer suitable. Electronic-photonic-converged solutions with compact footprints will play an important role in system scalability. In this paper, we present a unified model for thermo-optic feedback tuning that can be specialized to different applications, review its recent advances, and discuss its future trends.
4 citations
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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