Terahertz metasurface multifunctional space optical simulation differentiator

Abstract

The invention relates to a terahertz metasurface multifunctional space optical simulation differentiator which comprises a bottom metal film, a polyimide dielectric layer and a metal layer arranged on the polyimide dielectric layer, the metal layer is in an S shape formed by connecting two U-shaped split rings, and the metal layer and the bottom metal film form a Fabry-Perot resonant cavity. Polarization angular dispersion can be obviously regulated and controlled, a required transfer function can be directly realized in a Fourier space, first-order and second-order space simulation differential calculation with an ultra-large numerical aperture is simultaneously realized by utilizing a fixed structure, and the multifunctional space simulation differentiator can be miniaturized and integrated; signal and image processing is carried out by using the angle-dependent response of the superstructure, under the dual-polarization incident light, the numerical aperture is maximally close to 1, and the spatial resolution limit is 1.27 lambda.

Description

Technical Field

[0001] This invention belongs to the field of optical technology, specifically relating to a terahertz metasurface multifunctional spatial optical simulation differentiator. Background Technology

[0002] Terahertz (THz) bands (0.1–10 THz) are ideal candidates for sixth-generation (6G) communication technology, promising terabits per second wireless links and providing innovative solutions for information processing in the post-Moore's Law era. Spatial optical simulation computing, due to its inherent parallel processing capabilities and fast computation speed, has shown great potential in efficiently performing mathematical operations and image processing, and has therefore attracted considerable attention. Spatial optical simulation computing involves modulating the wavefront of incident light in space or momentum space, thereby enabling various mathematical operations with two-dimensional spatial parallelism. Spatial differentiation, as a core operator in optical simulation computing, can realize various functions, such as edge enhancement imaging and phase singularity detection.

[0003] In existing technologies, the structure of space optical simulation differentiators is difficult to precisely control angular dispersion in resonant and non-resonant electrodynamics, and also has complex structural parameter dependencies. By utilizing metasurfaces based on strategies such as guided mode resonance and Mie resonance, multifunctional space simulation differential calculations with low numerical aperture can be achieved by changing structural parameters.

[0004] Therefore, there is an urgent need to design a multifunctional differential calculator with a fixed structure that can simultaneously achieve large numerical apertures. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings and deficiencies of existing technologies by providing a terahertz metasurface multifunctional spatial optical simulation differentiator. This terahertz metasurface enables simultaneous realization of first- and second-order spatial simulation differentiators with ultra-large numerical apertures in the terahertz band, and in the future, it can realize high-resolution optical information processing chips with composite functions.

[0006] The technical problem solved by this invention is achieved through the following technical solution: A terahertz metasurface multifunctional spatial optical analog differentiator includes a bottom metal film, a polyimide dielectric layer, and a metal layer disposed on the polyimide dielectric layer. The metal layer is formed by two U-shaped open rings connected to form an "S" shape. The metal layer and the bottom metal film form a Fabry-Perot resonant cavity.

[0007] Furthermore, the thickness of the bottom metal film is 0.2 μm; the thickness of the polyimide substrate layer is 125 μm; and the thickness of the metal layer is 0.2 μm. The side length of the polyimide dielectric layer is 1400 μm.

[0008] Furthermore, the U-shaped opening ring of the metal layer has a lateral connection length of 980 μm, a longitudinal metal arm length of 620 μm, and upper and lower metal short arms lengths of 240 μm; the width of the U-shaped opening ring is 144 μm.

[0009] Moreover, p-polarized incident surface can realize second-order spatial differential calculations with an angular bandwidth of 0° to 89.9°; s-polarized incident surface can realize first-order and second-order spatial differential calculations simultaneously with angular bandwidths of 20° to 89.9° and 0° to 89.9°, respectively.

[0010] The advantages and beneficial effects of this invention are as follows: 1. The terahertz metasurface multifunctional spatial optical simulation differentiator of the present invention utilizes a fixed structure to simultaneously realize first-order and second-order spatial simulation differential calculations with ultra-large numerical aperture, enabling the multifunctional spatial simulation differentiator to be miniaturized and integrated. Under dual-polarized incident light, its spatial resolution limit is 1.27λ.

[0011] 2. The terahertz metasurface multifunctional spatial optical simulation differentiator of the present invention combines the energy of the near field and the evanescent field, and achieves precise control of the momentum space of the terahertz metasurface through synergistic critical coupling effect. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram illustrating the synergistic mechanism of critical coupling and near-field and far-field multi-wave superposition in this invention. Figure 3 The following are simulation diagrams of the first-order differential and dual-polarization second-order differential transfer functions of this invention; Figure 4 This is a schematic diagram of image processing for simulating the second-order spatial differential calculation of a metasurface under different incident polarizations according to the present invention. Figure 5 The image processing results are shown in the experimental test results of the second-order differential with different polarizations of this invention. Detailed Implementation

[0013] The present invention will be further described in detail below through specific embodiments. The following embodiments are merely descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0014] like Figure 1 As shown, a terahertz metasurface multifunctional spatial optical analog differentiator is innovative in that it includes a bottom metal film, a polyimide dielectric layer, and a metal layer disposed on the polyimide dielectric layer. The metal layer is formed by two U-shaped open rings connected to form an "S" shape. The metal layer and the bottom metal film form a Fabry-Perot resonant cavity.

[0015] Furthermore, the thickness of the bottom metal film is 0.2 μm; the thickness of the polyimide substrate layer is 125 μm; the thickness of the metal layer is 0.2 μm; and the side length of the polyimide dielectric layer is 1400 μm.

[0016] The U-shaped opening ring of the metal layer has a lateral connection length of 980 μm, a longitudinal metal arm length of 620 μm, and upper and lower metal short arms lengths of 240 μm; the width of the U-shaped opening ring is 144 μm.

[0017] p-polarized incident surface can realize second-order spatial differential calculations with an angular bandwidth of 0° to 89.9°; s-polarized incident surface can realize first-order and second-order spatial differential calculations simultaneously with angular bandwidths of 20° to 89.9° and 0° to 89.9°, respectively.

[0018] This invention can be viewed as a polarized Fabry-Perot resonator with polarization conversion, combining the energy of the near-field and evanescent field, such as... Figure 2 As shown in (a) and (b). Simultaneously, by combining the synergistic critical coupling effect, the operating angle of the second-order differentiator is further widened, as shown in... Figure 2 As shown in (c) and (d). On the other hand, by combining localized surface plasmon resonance, the operating angle of the first-order differentiator is further improved. The maximum value of the operating angle determines the numerical aperture of the metasurface, and thus the maximum spatial resolution of the information that the metasurface can process.

[0019] Figure 3 (a) When the incident radiation is p-polarized, the metasurface can realize a spatial second-order differential meter. Figure 3 (b) and (c) show that the metasurface can simultaneously perform second-order and first-order spatial differential calculations when the incident radiation is s-polarized. It is noteworthy that our designed multifunctional differentiator can simultaneously perform first-order and second-order spatial differential calculations with ultra-large numerical apertures without altering the metasurface's structural parameters.

[0020] Spatial second-order differential calculation is an important mathematical tool widely used in image processing. As an example, this invention simulates the ability of metasurfaces to perform edge detection on two-dimensional image information. Figure 4 (a) Input rectangles of different widths as detection objects. Figure 4 (b) and (c) show the image edge detection results of the metasurface under s and p polarization, respectively. Under different polarized wave incident conditions, the metasurface achieves an image edge detection resolution on the order of wavelength, 1.27λ.

[0021] Figure 5 (a) is a scanning electron microscope image of the prepared sample. Figure 5(b) Input rectangles of different widths as detection objects. The experimental test results of the samples are used for image processing, such as... Figure 5 As shown in (c) and (d), the edge information of rectangles of different widths can be clearly captured for incident light with different polarizations, while effectively suppressing low-frequency spatial components.

[0022] This invention provides a terahertz metasurface multifunctional spatial optical simulation differentiator that utilizes a fixed structure to simultaneously perform first-order and second-order spatial simulation differential calculations with ultra-large numerical apertures. This enables the multifunctional spatial simulation differentiator to be miniaturized and integrated, and its spatial resolution limit is 1.27λ under dual-polarized incident light.

[0023] Although embodiments and drawings of the present invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A terahertz metasurface multifunctional spatial optical simulation differentiator, characterized in that: It includes a bottom metal film, a polyimide dielectric layer, and a metal layer disposed on the polyimide dielectric layer. The metal layer is formed by two U-shaped open rings connected to form an "S" shape. The metal layer and the bottom metal film form a Fabry-Perot resonant cavity.

2. The terahertz metasurface multifunctional spatial optical simulation differentiator according to claim 1, characterized in that: The thickness of the bottom metal film is 0.2 μm, and the thickness of the polyimide substrate layer is 125 μm; the thickness of the metal layer is 0.2 μm, and the side length of the polyimide dielectric layer is 1400 μm.

3. The terahertz metasurface multifunctional spatial optical simulation differentiator according to claim 1, characterized in that: The U-shaped opening ring of the metal layer has a lateral connection length of 980 μm, a longitudinal metal arm length of 620 μm, and upper and lower metal short arms lengths of 240 μm; the width of the U-shaped opening ring is 144 μm.

4. The terahertz metasurface multifunctional space optical simulation differentiator according to claim 1, characterized in that: p-polarized incident surface can realize second-order spatial differential calculations with an angular bandwidth of 0° to 89.9°; s-polarized incident surface can realize first-order and second-order spatial differential calculations simultaneously with angular bandwidths of 20° to 89.9° and 0° to 89.9°, respectively.

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