Wide field of view superlens based on independent control of unit tilt angles

Abstract

The application provides a wide-field superlens based on unit tilt angle independent control, and relates to the technical field of superlens, and comprises a diaphragm, a silicon dioxide substrate located above the diaphragm, and a super unit located on the silicon dioxide substrate, wherein the super unit is a cylindrical silicon column, and each cylindrical silicon column is tilted by a certain angle alpha with respect to the normal direction of the silicon dioxide substrate. The technical scheme of the application overcomes the problems in the prior art that the superlens cannot realize high-precision imaging, the structure is complex, and complete field imaging cannot be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of superlenses, in particular to a wide-field superlens based on independent control of unit tilt angles. BACKGROUND

[0002] A superlens is a new type of planar optical device that can precisely control the wavefront of light and is composed of a plurality of supercell units carrying focusing phases. By changing the geometric parameters of the supercell units, the amplitude, phase and polarization of light can be flexibly adjusted. Compared with traditional optical devices, superlenses have the advantages of being ultra-thin, ultra-light and flexible control. However, under wide-angle illumination, superlenses inevitably have aberrations such as coma, field curvature and astigmatism, which affect the imaging quality of superlenses in wide-field conditions and hinder their application in practical scenarios.

[0003] The prior art has proposed various solutions to overcome the above problems, mainly covering multi-layer super surface lens design, super surface lens converging phase correction and super lens structure design.

[0004] Multi-layer super surface lens design effectively reduces the control pressure on a single super surface layer by increasing the control dimension. However, this method not only greatly increases the complexity of the design, but also destroys the planar nature of the super surface lens while improving the imaging effect.

[0005] For the method of super surface lens converging phase correction, the quadratic phase distribution is a typical means. It can convert the linear phase generated by oblique incidence into a spatial phase shift, so that the focal point of the oblique incidence beam produces a spatial displacement related to the incidence angle. However, this method has limitations, as the light rays only meet the quadratic phase focusing criterion under the paraxial approximation condition, and other light rays will form background noise, affecting the imaging quality. To solve this problem, a light filtering aperture is usually used to limit the incident light to achieve wide-angle field imaging without background noise. However, this method improves the wide-angle field imaging performance, but inevitably introduces spherical aberration. Therefore, only when the focal length of the super surface lens is much larger than its own size, can a relatively accurate image be obtained.

[0006] For the super lens structure design method, a research team led by Li Tao of a university has manufactured a super surface lens by tilting all the units of the super lens, achieving efficient focusing of large-angle light beams. However, to achieve complete field imaging, multiple lenses must be used, which undoubtedly increases the complexity of the structure.

[0007] Therefore, there is a need for a wide-field superlens based on independent control of unit tilt angles that can achieve high-precision imaging. SUMMARY

[0008] The main purpose of the present application is to provide a wide-field superlens based on unit tilt angle independent control, so as to solve the problems of the prior art that the superlens cannot realize high-precision imaging, the structure is complex, and the complete field of view cannot be imaged.

[0009] To achieve the above-mentioned purpose, the present application provides a wide-field superlens based on unit tilt angle independent control, comprising: a diaphragm, a silicon dioxide substrate located above the diaphragm, and a super unit located on the silicon dioxide substrate, the super unit is a cylindrical silicon column, and each cylindrical silicon column is tilted by an angle alpha with respect to the normal direction of the silicon dioxide substrate.

[0010] Further, the plurality of cylindrical silicon columns are uniformly distributed on the silicon dioxide substrate, the plurality of cylindrical silicon columns form a plurality of angles alpha with the normal direction of the silicon dioxide substrate, and the range formed by the plurality of angles alpha is the same as the range of the field of view of the superlens, that is, the angle alpha covers the entire field of view.

[0011] Further, the height H of the cylindrical silicon column ranges from 0.1 to 2 microns.

[0012] Further, the height H of the cylindrical silicon column is 740 nm.

[0013] Further, the distance between the diaphragm and the silicon dioxide substrate is L, and a coordinate system is established with the center of the silicon dioxide substrate as the origin, then:

[0014]

[0015] Wherein, x and y are the coordinates of the super unit on the silicon dioxide substrate.

[0016] Further, the theoretical phase carried by the superlens is:

[0017]

[0018] Wherein, represents the phase value, lambda represents the working wavelength of the superlens, and f is the preset focal length.

[0019] Further, the preset focal length f ranges from 10 to 200 microns.

[0020] Further, the preset focal length f is 20 microns.

[0021] Further, the axis direction of the super unit points to the center of the diaphragm.

[0022] Further, the diaphragm is made of PVC material, and the super unit is made of silicon.

[0023] The present application has the following beneficial effects:

[0024] This invention achieves wide-field imaging in the near-infrared band using only a single metalens, offering high resolution, high integration, and an ultra-wide field of view. Compared to traditional quadratic phase metalens, this metalens offers higher precision and a wider field of view than hyperbolic phase metalens. Its simple and compact structure suggests broad application prospects in projection, imaging, infrared detection, medical diagnosis, and other fields, providing new insights into the design of wide-field-of-view metalens. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0026] Figure 1 A schematic diagram of the principle of a wide-field metalens based on independent control of the unit tilt angle of the present invention is shown.

[0027] Figure 2 A stereoscopic diagram of a wide-field metalens based on independent control of the unit tilt angle of the present invention is shown.

[0028] Figure 3 A schematic diagram of the tilt angle of the super unit is shown.

[0029] Figure 4 The wide-field focusing light field of the wide-field superlens provided by the present invention is shown.

[0030] Figure 5 Shown Figure 2 The full width at half maximum of the focal point of the metalens wide-field focusing.

[0031] Figure 6 Shown Figure 2 Modulation transfer function of the wide-field focusing metalens.

[0032] The reference numerals in the above drawings are:

[0033] 10. Aperture; 21. Silicon dioxide substrate; 22. Metacell; 30. Focal plane. DETAILED DESCRIPTION

[0034] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0035] As shown in Figure 1 and Figure 2 A wide-field superlens based on independent control of the tilt angle of the unit, comprising: a diaphragm, a silicon dioxide substrate above the diaphragm, and a super unit on the silicon dioxide substrate, the super unit is a cylindrical silicon column, and each cylindrical silicon column is tilted at an angle α relative to the normal direction of the silicon dioxide substrate. The light wave is incident at a certain angle at the diaphragm, propagates to the silicon dioxide substrate through the diaphragm, and the tilt of the super unit compensates for the phase difference caused by the tilt of the incident light, so that the light beam is redirected and focused at a preset focal length of the super unit.

[0036] As shown in Figure 1 and Figure 2 The light beam incident at a certain angle is irradiated onto the super unit 22 after passing through the diaphragm 10. The super unit here is tilted relative to the normal direction of the superlens, and the tilt angle is set in relation to the distance L from the diaphragm to the silicon dioxide substrate 21 and the position r of the super unit. The tilt of the super unit can compensate for the phase difference caused by the tilt of the light beam. The superlens is set to carry a hyperbolic phase profile that can accurately focus the light beam. The light beam whose wavefront phase has been compensated will be focused on the focal plane 30 at a preset distance f from the superlens, thereby achieving high-precision wide-field imaging.

[0037] Specifically, as shown in Figure 3 A plurality of cylindrical silicon columns are uniformly distributed on the silicon dioxide substrate, and the plurality of cylindrical silicon columns form a plurality of angles α with the normal direction of the silicon dioxide substrate. The range formed by the plurality of angles α is the same as the range of the field of view of the superlens, that is, the angle α covers the entire field of view.

[0038] Specifically, the height H of the cylindrical silicon column ranges from 0.1 to 2 microns, and H is specifically taken as 740 nm.

[0039] Specifically, the distance between the diaphragm and the silicon dioxide substrate is L. A coordinate system is established with the center of the silicon dioxide substrate as the origin, then:

[0040]

[0041] Where x and y are the coordinates of the super unit on the silicon dioxide substrate.

[0042] The independent setting of the tilt angle of the super unit at different positions not only enables wide-field imaging, but also improves the imaging accuracy.

[0043] Specifically, the theoretical phase carried by the superlens is:

[0044]

[0045] Where, represents a phase value, represents a working wavelength of the superlens, and f is a preset focal length.

[0046] Specifically, the preset focal length f is 10-200 microns.

[0047] Specifically, the preset focal length f is 20 microns.

[0048] Specifically, the axis direction of the super unit points to the center of the diaphragm.

[0049] Specifically, the diaphragm is made of PVC material, and the super unit is made of silicon.

[0050] As shown in the following table, the first row of images is the axial x-z plane focusing light field intensity distribution, and the second row of images is the radial x-y plane focusing light field intensity distribution. Figure 4 The preset focal length f is 20 microns, and the working wavelength is 0.94 microns. When the incident light angle changes from 0° to 60°, the focusing spot shape keeps good shape and there is no sidelobe interference.

[0051] As shown in the following table, the first row of images is the axial x-z plane focusing light field intensity distribution, and the second row of images is the radial x-y plane focusing light field intensity distribution. Figure 5 And Figure 6 The imaging performance of the embodiment is quantitatively evaluated by introducing modulation transfer function (MTF) and full width at half maximum (FWHM). At low spatial frequency, the super surface lens shows similar MTF values for different angle incident light. At higher spatial frequency, the MTF value of the super surface lens decreases slightly as the incident angle increases. The smaller the FWHM value, the higher the focusing resolution. Within the entire field of view, the minimum FWHM value is 1.1 wavelengths, and the maximum FWHM value is 2.6 wavelengths, which means that the wide field of view superlens provided by the present application can still maintain good imaging quality under a larger field of view angle.

[0052] Of course, the above description is not a limitation of the present application, and the present application is not limited to the above examples. Changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present application should also be within the scope of the present application.

Claims

1. A wide-field metalens based on independent control of unit tilt angles, characterized in that: include: The aperture, the silicon dioxide substrate located above the aperture, and the meta-unit located on the silicon dioxide substrate. The meta-unit is a cylindrical silicon column, each of which is tilted at a certain angle relative to the normal direction of the silicon dioxide substrate. ; Multiple cylindrical silicon pillars are evenly distributed on the silicon dioxide substrate, and multiple cylindrical silicon pillars form multiple angles with the normal direction of the silicon dioxide substrate , multiple angles The range of the composition is the same as the range of the field of view of the super lens, that is, the angle Cover the entire field of view; The distance between the aperture and the silicon dioxide substrate is , establish a coordinate system with the center of the silicon dioxide substrate as the origin, then: ； in, and are the coordinates of the metacell on the silicon dioxide substrate.

2. A wide-field metalens based on independent control of unit tilt angles according to claim 1, characterized in that: The height H of the cylindrical silicon pillars ranges from 0.1 to 2 microns.

3. A wide-field metalens based on independent control of unit tilt angles according to claim 2, characterized in that: The height of the cylindrical silicon pillar is H = 740 nm.

4. The wide-field metalens based on independent control of unit tilt angle according to claim 1, characterized in that The theoretical phase carried by the metalens is: ； in, represents the phase value, represents the operating wavelength of the metalens, is the preset focal length.

5. A wide-field metalens based on independent control of unit tilt angles according to claim 4, characterized in that: Preset focal length The range is 10~200 microns.

6. The wide-field metalens based on independent control of unit tilt angle according to claim 5, characterized in that: Preset focal length .

7. The wide-field metalens based on independent control of unit tilt angle according to claim 1, characterized in that The axis of the meta-unit points to the center of the aperture.

8. The wide-field metalens based on independent control of unit tilt angle according to claim 1, characterized in that The aperture is made of PVC material and the meta-unit is made of silicon.

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