Performing differential operation with a silver dendritic metasurface at visible wavelengths

Abstract

We design a reflective silver dendritic metasurface that can perform differential operation at visible wavelengths. The metasurface consists of an upper layer of silver dendritic structures, a silica spacer, and a lower layer of silver film. Simulation results show that the metasurface can realize differential operation in red, yellow, and green bands. Such a functionality is readily extended to infrared and communication wavelengths. The metasurface samples that respond to green and red bands are prepared by using the electrochemical deposition method, and their differential operation properties are proved through tests. Silver dendritic metasurfaces that can conduct the mathematical operation in visible light pave the way for realizing miniaturized, integratable all-optical information processing systems. Their differentiation functionality, which is used for real-time ultra-fast edge detection, image contrast enhancement, hidden object detection, and other practical applications, has a great development potential.

Analog Optical Spatial Differentiators Based on Dielectric Metasurfaces

“…There already exist a few potential application examples about metasurface‐based analog optical spatial devices such as differentiators, integrators, and even equation solvers . The artificial materials utilized in these studies could be classified into three categories: multilayer films, 1D gratings, and general 2D metasurfaces . Among these structures, the general 2D metasurfaces with strong modulation flexibility are widely employed to realize the desired spatial operation functions mathematically defined by different Green's functions.…”

“…For practice, simple structures are more preferable, for example by a single layer of resonant metasurface . As an important component for optical processing, the first‐order analog optical spatial differentiator has attracted special attentions . The practicability has been greatly improved in recent works.…”

“…By introducing metasurfaces, the combined system became thinner and much compact than conventional ones. This progress sheds light on the potential development of optical analog processors based on metasurfaces.There already exist a few potential application examples about metasurface-based analog optical spatial devices such as differentiators, [18][19][20][21][22][23][24][25][26][27][28] integrators, [18,19,25] and even equation solvers. [29][30][31] The artificial materials utilized in these studies could be classified into three categories: multilayer films, [18,21,22] 1D gratings, [23,24,26] and general 2D metasurfaces.…”

“…[29][30][31] The artificial materials utilized in these studies could be classified into three categories: multilayer films, [18,21,22] 1D gratings, [23,24,26] and general 2D metasurfaces. [19,20,25,[27][28][29][30][31] Among these structures, the general 2D metasurfaces with strong modulation flexibility are widely employed to realize the desired spatial operation functions mathematically defined by different Green's functions. For practice, simple structures are more preferable, for example by a single layer of resonant metasurface.…”

“…[25,28] As an important component for optical processing, the first-order analog optical spatial differentiator has attracted special attentions. [18][19][20][22][23][24][25][26][27] The practicability has been greatly improved in recent works. In 2017, Zhu et al has experimentally realized such an optical differentiation device utilizing the angle sensitive excitation of surface plasmonic polariton on metal films.…”