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2. Establishing exhaustive metasurface robustness against fabrication uncertainties through deep learning

Author

Jenkins Ronald P., Campbell Sawyer D., and Werner Douglas H.

Subjects
deep learning, fabrication, robustness, supercell, tolerance, Physics, QC1-999
Abstract

Photonic engineered materials have benefitted in recent years from exciting developments in computational electromagnetics and inverse-design tools. However, a commonly encountered issue is that highly performant and structurally complex functional materials found through inverse-design can lose significant performance upon being fabricated. This work introduces a method using deep learning (DL) to exhaustively analyze how structural issues affect the robustness of metasurface supercells, and we show how systems can be designed to guarantee significantly better performance. Moreover, we show that an exhaustive study of structural error is required to make strong guarantees about the performance of engineered materials. The introduction of DL into the inverse-design process makes this problem tractable, enabling optimization runtimes to be measurable in days rather than months and allowing designers to establish exhaustive metasurface robustness guarantees.

Published
2021
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3. Roadmap on electromagnetic metamaterials and metasurfaces

Author

Cui, Tie Jun, primary, Zhang, Shuang, additional, Alu, Andrea, additional, Wegener, Martin, additional, Pendry, John, additional, Luo, Jie, additional, Lai, Yun, additional, Wang, Zuojia, additional, Lin, Xiao, additional, Chen, Hongsheng, additional, Chen, Ping, additional, Wu, Rui-Xin, additional, Yin, Yuhang, additional, Zhao, Pengfei, additional, Chen, Huanyang, additional, Li, Yue, additional, Zhou, Ziheng, additional, Engheta, Nader, additional, Asadchy, V. S., additional, Simovski, Konstantin, additional, Tretyakov, Sergei A, additional, Yang, Biao, additional, Campbell, Sawyer D., additional, Hao, Yang, additional, Werner, Douglas H, additional, Sun, Shulin, additional, Zhou, Lei, additional, Xu, Su, additional, Sun, Hong-Bo, additional, Zhou, Zhou, additional, Li, Zile, additional, Zheng, Guoxing, additional, Chen, Xianzhong, additional, Li, Tao, additional, Zhu, Shi-Ning, additional, Zhou, Junxiao, additional, Zhao, Junxiang, additional, Liu, Zhaowei, additional, Zhang, Yuchao, additional, Zhang, Qiming, additional, Gu, Min, additional, Xiao, Shumin, additional, Liu, Yongmin, additional, Zhang, Xiaoyu, additional, Tang, Yutao, additional, Li, Guixin, additional, Zentgraf, Thomas, additional, Koshelev, Kirill, additional, Kivshar, Yuri S., additional, Li, Xin, additional, Badloe, Trevon, additional, Huang, Lingling, additional, Rho, Junsuk, additional, Wang, Shuming, additional, Tsai, Din Ping, additional, Bykov, A. Yu., additional, Krasavin, Alexey V, additional, Zayats, Anatoly V, additional, McDonnell, Cormac, additional, Ellenbogen, Tal, additional, Luo, Xiangang, additional, Pu, Mingbo, additional, Garcia-Vidal, Francisco J, additional, Liu, Liangliang, additional, Li, Zhuo, additional, Tang, Wenxuan, additional, Ma, Hui Feng, additional, Zhang, Jingjing, additional, Luo, Yu, additional, Zhang, Xuanru, additional, Zhang, Hao Chi, additional, He, Pei Hang, additional, Zhang, Le Peng, additional, Wan, Xiang, additional, Wu, Haotian, additional, Liu, Shuo, additional, Jiang, Wei Xiang, additional, Zhang, Xin Ge, additional, Qiu, Chengwei, additional, Ma, Qian, additional, Liu, Che, additional, Li, Long, additional, Han, Jiaqi, additional, Li, Lianlin, additional, Cotrufo, Michele, additional, Caloz, Christophe, additional, Deck-Léger, Z.-L., additional, Bahrami, A., additional, Céspedes, O., additional, Galiffi, Emanuele, additional, Huidobro, P. A., additional, Cheng, Qiang, additional, Dai, Jun Yan, additional, Ke, Jun Cheng, additional, Zhang, Lei, additional, Galdi, Vincenzo, additional, and Di Renzo, Marco, additional

Published
2024
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5. Design for quality: reconfigurable flat optics based on active metasurfaces

Author

Shalaginov Mikhail Y., Campbell Sawyer D., An Sensong, Zhang Yifei, Ríos Carlos, Whiting Eric B., Wu Yuhao, Kang Lei, Zheng Bowen, Fowler Clayton, Zhang Hualiang, Werner Douglas H., Hu Juejun, and Gu Tian

Subjects
deep neural network, inverse design, metasurface, meta-optics, phase-change material, reconfigurable, Physics, QC1-999
Abstract

Optical metasurfaces, planar subwavelength nanoantenna arrays with the singular ability to sculpt wavefront in almost arbitrary manners, are poised to become a powerful tool enabling compact and high-performance optics with novel functionalities. A particularly intriguing research direction within this field is active metasurfaces, whose optical response can be dynamically tuned postfabrication, thus allowing a plurality of applications unattainable with traditional bulk optics. Designing reconfigurable optics based on active metasurfaces is, however, presented with a unique challenge, since the optical quality of the devices must be optimized at multiple optical states. In this article, we provide a critical review on the active meta-optics design principles and algorithms that are applied across structural hierarchies ranging from single meta-atoms to full meta-optical devices. The discussed approaches are illustrated by specific examples of reconfigurable metasurfaces based on optical phase-change materials.

Published
2020
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6. A Shaped Reflector Antenna Design Approach for Contoured Beam Synthesis With Surface Curvature Constraints

Author

Balasubramanian, Manushanker, Campbell, Sawyer D., Werner, Douglas H., and Hand, Thomas H.

Abstract

An efficient B-spline curvature-based reflector shape synthesis technique for generating a continental US (CONUS) beam pattern is presented. The approach is based on representing a reflector as a set of curves that can be modified to alter the reflector’s shape. Instead of directly optimizing the curves as done in other commercial software packages, the curvature is evaluated and represented using B-spline polynomials. The control points of each spline curve are defined as optimization variables, which generate new curvature profiles at each iteration. The set of curves with the corresponding curvature is synthesized using the natural equation method and is then used to construct the reflector surface. This two-step process of first optimizing the curvature and then reconstructing a reflector surface greatly facilitates the ability to impose constraints on surface curvature arising from the choice of the manufacturing process. Furthermore, no significant degradation in the convergence behavior was observed when including curvature bounds in the cost function. This makes the approach very attractive when compared to existing methods. In addition, this method can be applied to arbitrary reflector configurations of interest and be paired with any optimization method. The accuracy and validity of the proposed method are verified by multiple application examples.

Published
2024
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11. Simultaneous Optimization of 1-bit 3-D Coding Meta-Volumes for Both Broadband and Wide Field-of-View Radar Cross-Section Reduction

Author

Chaky, Ryan J., Beneck, Ryan J., Campbell, Sawyer D., and Werner, Douglas H.

Abstract

Coding metasurfaces (CMSs) rely on the proper tiling of two or more kinds of complementary unit cells within an array to enable phase cancellation and corresponding destructive interference thereby reducing the radar cross-section (RCS) of a given scatterer. Typically, these unit cells are planar and inherently limited in their field of view (FoV). This work demonstrates that breaking this traditional unit cell design paradigm in favor of novel 3-D meta-volumes enables both broadband and wide-FoV RCS reduction. Further, this work introduces a modified genetic algorithm (GA) framework for simultaneously tailoring the reflection phase of multiple unit cells to achieve the best composite response. By applying these identical pair-optimization strategies, it is shown that 3-D unit cells outperform their 2-D counterparts of the same lateral size in terms of both the fractional bandwidth (FBW) and FoV. One exemplary 3-D solution purely improves the $H_{\mathrm {x}}$ response with FBW exceeding 75% across a full 70° FoV. A second 3-D solution provides an improved $E_{\mathrm {x}}$ polarization response with a near 70% FBW at 45° and up to 75% FBW at 70° for the $H_{\mathrm {x}}$ polarization at the expense of reduced FBW close to 50% for incidence angles less than 45°.

Published
2023
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31. Superscattering of electromagnetic waves from subwavelength dielectric structures.

Author

Beneck RJ, Kang L, Jenkins RP, Campbell SD, and Werner DH

Abstract

Superscattering, corresponding to the scattering cross section of a scatterer being significantly larger than its single-channel limit, has attracted increasing attention due to its huge potential for practical applications. The realization of superscattering relies on the overlapping of multiple resonance modes in a scatterer. Accordingly, superscattering phenomena have been observed primarily in alternating plasmonic/dielectric layered structures which support surface plasmons. However, such systems suffer from high Ohmic loss due to the excitation of surface plasmons, hindering broader application of the plasmonic/dielectric hybrid systems. On the other hand, subwavelength structures based on high permittivity dielectric materials (such as ferroelectric ceramics) offer expansive opportunities to realize electric and magnetic resonances at microwave and THz frequencies. Here, based on optimization methods involving mode analysis, we numerically demonstrate superscattering from individual multilayered dielectric cylinders. The maximum scattering cross section achieved is determined by the collective contributions from several resonance modes excited in a complex cylinder. Our results reveal that a combination of mode analysis and a custom optimization method can enable efficient designs of complex dielectric structures exhibiting exotic scattering responses.

Published
2024
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32. Broadband plasmonic chiral meta-mirrors.

Author

Whiting EB, Kang L, Jenkins RP, Campbell SD, and Werner DH

Abstract

Chiral meta-mirrors provide a unique opportunity for achieving handedness-selective strong light-matter interaction at the nanometer scale. Importantly, the chiral resonances observed in chiral meta-mirrors arise from the spin-dependent resonant cavity which, however, is generally narrowband. In this paper, by exploiting a genetic algorithm (GA) based optimization method, we numerically validate a chiral meta-mirror with octave bandwidth. In particular, in the wavelength range from 1000 to 2000 nm, the proposed chiral meta-mirror strongly absorbs circularly polarized light of one handedness while highly reflecting the other. A field analysis indicates that the observed broadband chiroptical response can be attributed to the multiple chiral resonances supported by the optimized meta-mirror across the band of interest. The observed broadband chiral response confirms the potential of advanced inverse-design approaches for the creation of chiral metadevices with sophisticated functionalities. Based on the Lorentz reciprocity theorem, we show that the proposed meta-mirror can enable chiral-selective broadband second harmonic generation (SHG). Our study indicates that the application of advanced inverse-design approaches can greatly facilitate the development of metadevices with strong chiral response in both the linear and nonlinear regimes.

Published
2023
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33. Size, weight, and power reduction regimes in achromatic gradient-index singlets.

Author

Campbell SD, Brocker DE, Nagar J, and Werner DH

Abstract

By analyzing the limitations that achromatic gradient-index (GRIN) lens solutions in the radial and axial extremes place on lens thickness and surface curvature, a radial-axial hybrid GRIN theory is developed in order to overcome these restrictions and expose a larger solution space. With the achromatic hybrid GRIN theory, the trade-offs between thickness, curvature, and GRIN type can be directly studied in the context of size, weight, and power (SWaP) reduction. Finally, the achromatic solution space of a silicon-germanium-based material system is explored, and several designs are verified with ray tracing.

Published
2016
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