Optical edge detection based on high-efficiency dielectric metasurface

Abstract

Optical edge detection is a useful method for characterizing boundaries, which is also in the forefront of image processing for object detection. As the field of metamaterials and metasurface is growing fast in an effort to miniaturize optical devices at unprecedented scales, experimental realization of optical edge detection with metamaterials remains a challenge and lags behind theoretical proposals. Here, we propose a mechanism of edge detection based on a Pancharatnam–Berry-phase metasurface. We experimentally demonstrated broadband edge detection using designed dielectric metasurfaces with high optical efficiency. The metasurfaces were fabricated by scanning a focused laser beam inside glass substrate and can be easily integrated with traditional optical components. The proposed edge-detection mechanism may find important applications in image processing, high-contrast microscopy, and real-time object detection on compact optical platforms such as mobile phones and smart cameras.

Metasurfaces-based imaging and applications: from miniaturized optical components to functional imaging platforms

“…In addition, metasurfaces are expected to expand their inuence by combining with articial intelligence, 178 3D holographic display, 179 phase imaging 180 and detecting technology. 181 Metasurfaces have been demonstrated as a new paradigm that can displace optical components. Methods to fabricate metasurfaces are inexpensive; large-scale fabrication methods like nanoimprint lithography and deep UV lithography can be considered due to their advantages in mass production, low cost and high speed.…”

Optical phase mining by adjustable spatial differentiator

“…In recent years, optical analog computing of spatial differentiation has attracted great attention, which enables an entire image processes on a single shot [12][13][14][15][16][17][18][19][20][21][22]. Various optical analog computing devices were designed for edge detection [2,[23][24][25][26][27][28][29][31][32][33][34].…”

“…Later a subwavelength-scale plasmonic differentiator of a 50-nmthick silver layer was experimentally demonstrated and applied for real-time edge detection [23]. Most recently, spatial differentiation methods were developed based on the geometric phases, including the Rytov-Vladimirskii-Berry phase [2] and the Pancharatnam-Berry phase * zhichao@zju.edu.cn [31,35]. However, so far the current application of optical spatial differentiation is only limited to edge detection.…”

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.…”