Empowering Metasurfaces with Inverse Design: Principles and Applications

Li, Zhaoyi; Pestourie, Raphaël; Lin, Zin; Johnson, Steven G.; Capasso, Federico

doi:10.1021/acsphotonics.1c01850

Cited by 108 publications

(72 citation statements)

References 137 publications

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“…In the case of our local periodic approximation (LPA, see below), ∇ p v ends up being diagonal (each unit cell only affects the near field directly below it), so we can compute it explicitly. More generally, one could apply an adjoint method 9,10 in which the Maxwell solve A − † in ∇ p v = −A − † ∇ p A † v is applied to the left on a "source" term v † W. The Maxwell operator A is a composition 9,11 of a Green's function, which does not depend on the geometry p, and the local metasurface transmission for each unit cell as a function of the nanopillar diameter, which is computed from a surrogate polynomial fit. 9,11 Hence, the derivative ∇ p A † merely involves the derivatives of these polynomials.…”

Section: Tr( ) Tr( )mentioning

confidence: 99%

Efficient Inverse Design of Large-Area Metasurfaces for Incoherent Light

et al. 2022

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Incoherent light is ubiquitous, yet designing optical devices that can handle its random nature is very challenging, since directly averaging over many incoherent incident beams can require a huge number of scattering calculations. We show how to instead solve this problem with a reciprocity technique that leads to 3 orders of magnitude speedup: one Maxwell solve (using any numerical technique) instead of thousands. This improvement enables us to perform efficient inverse design, large-scale optimization of metasurfaces for applications such as light collimators and concentrators. We show the impact of the angular distribution of incident light on the resulting performance and show especially promising designs for the case of “annular” beams distributed only over nonzero angles.

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Section: Tr( ) Tr( )mentioning

confidence: 99%

Efficient Inverse Design of Large-Area Metasurfaces for Incoherent Light

et al. 2022

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“…For a large portion of metasurfaces, the geometrical parameters of the building blocks are determined by forward design method [ 16 , 17 , 18 ]. A typical workflow of the forward design method includes three steps.…”

Section: Introductionmentioning

confidence: 99%

Quasi-Freeform Metasurfaces for Wide-Angle Beam Deflecting and Splitting

et al. 2023

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Metasurfaces attracted extensive interests due to their outstanding ability to manipulate the wavefront at a subwavelength scale. In this study, we demonstrated quasi-freeform metasurfaces in which the radius, location, and height of the nanocylinder building blocks were set as optimized structure parameters, providing more degrees of freedom compared with traditional gradient metasurfaces. Given a desired wavefront shaping objective, these structure parameters can be collectively optimized utilizing a hybrid optimized algorithm. To demonstrate the versatility and feasibility of our method, we firstly proposed metasurfaces with deflecting efficiencies ranging from 86.2% to 94.8%, where the deflecting angles can vary in the range of 29°–75.6°. With further study, we applied our concept to realize a variety of high-efficiency, wide-angle, equal-power beam splitters. The total splitting efficiencies of all the proposed beam splitters exceeded 89.4%, where a highest efficiency of 97.6%, a maximum splitting angle of 75.6°, and a splitting uniformity of 0.33% were obtained. Considering that various deflecting angles, and various splitting channels with different splitting angles, can be realized by setting the optical response of metasurfaces as the optimization target, we believe that our method will provide an alternative approach for metasurfaces to realize desired wavefront shaping.

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“…There is now interest in applying inverse design techniques for the geometric optimization of time-varying media [24]. This is an exciting prospect, though challenging due to the computa-tional/memory requirements involved.…”

Section: Introductionmentioning

confidence: 99%

Inverse design of optical pulse shapes for time-varying photonics

Baxter¹,

Ramunno²

2023

Preprint

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There has been an explosion of interest in time-varying photonics due to the recent discovery and design of materials and metamaterials with strong, time-varying, nonlinear optical responses. This opens the door to novel optical phenomena including reciprocity breaking, frequency translation, and amplification that can be enhanced by optimizing the light-matter interaction. Although there has been recent interest in applying topology-based inverse design to this problem, we have decided to take a more novel approach. In this article, we will introduce a method for the inverse design of optical pulse shapes to enhance their interaction with time-varying media. We test our objective-first approach by maximizing the transmittance of optical pulses of equal intensity through time-varying media. Indeed, without requiring a change in pulse energy, we demonstrate large, broadband enhancements in the pulse energy transmission through the thin-films, including gain. Our final test includes maximizing pulse transmission through indium tin oxide, a time-varying medium when strongly pumped in its ENZ band. Through this work, we hope to inspire exploration of this new degree of freedom.

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Empowering Metasurfaces with Inverse Design: Principles and Applications

Cited by 108 publications

References 137 publications

Efficient Inverse Design of Large-Area Metasurfaces for Incoherent Light

Efficient Inverse Design of Large-Area Metasurfaces for Incoherent Light

Quasi-Freeform Metasurfaces for Wide-Angle Beam Deflecting and Splitting

Inverse design of optical pulse shapes for time-varying photonics

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