Dynamic recognition and mirage using neuro-metamaterials

Abstract

Breakthroughs in the field of object recognition facilitate ubiquitous applications in the modern world, ranging from security and surveillance equipment to accessibility devices for the visually impaired. Recently-emerged optical computing provides a fundamentally new computing modality to accelerate its solution with photons; however, it still necessitates digital processing for in situ application, inextricably tied to Moore’s law. Here, from an entirely optical perspective, we introduce the concept of neuro-metamaterials that can be applied to realize a dynamic object- recognition system. The neuro-metamaterials are fabricated from inhomogeneous metamaterials or transmission metasurfaces, and optimized using, such as topology optimization and deep learning. We demonstrate the concept in experiments where living rabbits play freely in front of the neuro-metamaterials, which enable to perceive in light speed the rabbits’ representative postures. Furthermore, we show how this capability enables a new physical mechanism for creating dynamic optical mirages, through which a sequence of rabbit movements is converted into a holographic video of a different animal. Our work provides deep insight into how metamaterials could facilitate a myriad of in situ applications, such as illusive cloaking and speed-of-light information display, processing, and encryption, possibly ushering in an “Optical Internet of Things” era.

Breaking the fundamental scattering limit with gain metasurfaces

“…Other than scattering enhancement, the potential and versatility of NDR-enabled gain metasurfaces may proliferate across other fields of active metamaterials 32 , nano-lasers 33 , and non-Hermitian invisibility 34 . For example, we envisage a small-scale drone disguised as a large-scale aircraft to deceive enemy detection systems because the gain-assisted device can create a much larger scattering field than it's physical size [35][36][37][38] . The application of other gain materials could help extend the concept to higher frequencies, such as terahertz NDR diodes, optical pulse-pumped organic dye molecules, and quantum dots 39 .…”

Perspective on Meta-Boundaries

“…To further improve the capability of meta-boundaries, one may add the spatial modulation into the active meta-boundary. Such kinds of active (or spatiotemporal) meta-boundaries can be achieved by actively and separately tuning each unit cell of metasurface, through the electronic or optical programming. − These active meta-boundaries can perform many advanced functions, such as intelligent communication and holographic imaging. Figure b shows one typical active meta-boundary, which is created by arrays of complementary metal-oxide-semiconductor (CMOS)-based chip tiles and can digitally control the amplitude and phase of light .…”

Optical Neural Networks for Holographic Image Recognition (Invited Paper)

“…Based on these two models, several on-chip optical neural network schemes have been proposed to make ONNs more feasible, most of which adopt MZI (Mach-Zehnder interferometer) arrays rather than the original beam splitters to perform MVM, considering the integration capability and compatibility [16]. Besides, spatial light computing, which is another alternative method for ONN implementation and always operates by well-designed or programmable metasurfaces, sacrificing space occupation for ultra-large computing power, is also a trend of development [17][18][19]. In addition, the practicability of utilizing fast Fourier transform [20] or frequency multiplexing [21,22] to achieve a similar effect has been demonstrated as unconventional routes to achieve ONNs on chips.…”