CN212460095U - Super lens group and super imaging device - Google Patents

Abstract

The application provides a super lens group and a super imaging device. The super lens set sequentially comprises the following components along the direction of incident light: a first superlens, a second superlens and a third superlens, wherein the incident light includes a first handedness polarized light and a second handedness polarized light orthogonal to the first handedness polarized light, each of the first superlens, the second superlens and the third superlens has a plurality of phase compensation structures on a surface thereof, wherein the phase compensation structures of the first superlens and the third superlens compensate the same phase for the first handedness polarized light and the second handedness polarized light, respectively; and the phase compensation structure of the second superlens compensates different phases for the first and second handedness polarized light.

Description

Super lens group and super imaging device

Technical Field

The present application relates to the field of optical elements, and more particularly, to a superlens group and a superimaging device.

Background

Lenses for imaging, transmission and the like in the existing camera shooting field are all made of transparent materials such as resin, plastic, glass and the like. Such lenses generally need to have larger dimensions because they introduce optical path differences through the gradual change in thickness, which results in focusing or diverging of the light. Capasso et al, 6.2016, published a super-surface paper in the Science journal, Vol.352, 6290, and have thus triggered worldwide research on superlenses.

A super-surface optical element is a new type of planar optical element that has been proposed and attracted much attention in recent years, and generally includes a planar substrate and a micro-nano structure array disposed on the substrate. The superlens adopts a Pancharatnam-Berry phase difference which is introduced by a micro-nano scale structure and is related to the shape, so that the phase of scattered incident light can be randomly modulated, and effects such as focusing, defocusing, refracting and the like which are common in various geometric optics are generated. The super-surface optical element can be smaller than a macroscopic optical element in geometric optics by several orders of magnitude, so that the super-surface optical element has wide application prospect in the aspect of constructing an optical element suitable for integration, ultra-thin and microminiature.

Although the current performance of superlenses is different from that of conventional glass or plastic lenses due to limitations in processing power and size, since the physical principles on which they are based are different from those of conventional lenses, superlenses have sufficient potential to avoid the intractable problems of aberration or flare that cannot be avoided in conventional lenses.

SUMMERY OF THE UTILITY MODEL

One aspect of the present application provides such a superlens group. The super lens group sequentially comprises the following components along the direction of incident light: the system comprises a first superlens, a second superlens and a third superlens, wherein the incident light comprises a first handedness polarized light and a second handedness polarized light orthogonal to the first handedness polarized light. A plurality of phase compensation structures are arranged on the surface of each of the first superlens, the second superlens and the third superlens, wherein the phase compensation structures of the first superlens and the third superlens compensate the same phase for the first handedness polarized light and the second handedness polarized light respectively; and the phase compensation structure of the second superlens compensates different phases for the first and second handedness polarized light. In one embodiment, the phase compensation structure is a nano-substructure.

In one embodiment, the plurality of phase compensation structures of the first superlens are rotated by a first angle and then overlapped with the plurality of phase compensation structures of the third superlens in the direction of the incident light.

In one embodiment, the first chiral polarized light is left circularly polarized light; the second chiral polarized light is right-handed circularly polarized light.

In one embodiment, the phase compensation structures at different positions of the first superlens compensate for different phases of the first and second linearly polarized light.

In one embodiment, the phase compensation structures at different positions of the third superlens compensate for different phases of the first and second linearly polarized light.

In one embodiment, the phase compensation structures at different positions of the second superlens compensate the same phase for the first and second linearly polarized light.

In one embodiment, the first angle is π/8.

In one embodiment, the first superlens, the second superlens, and the third superlens further include a transparent substrate, wherein the phase compensation structure is formed on the transparent substrate by a dielectric material.

In one embodiment, the dielectric material forming the phase compensation structure is an inorganic dielectric material having a refractive index different from a refractive index of a material forming the transparent substrate.

In one embodiment, the inorganic dielectric material has a refractive index greater than a refractive index of a material forming the transparent substrate.

In one embodiment, the inorganic dielectric material comprises at least one of zinc sulfide, magnesium fluoride, titanium dioxide, zirconium oxide, silicon hydride, crystalline silicon, silicon nitride, amorphous silicon, gallium nitride, gallium phosphide, gallium arsenide.

In one embodiment, the dielectric material forming the phase compensation structure is organic glass.

In one embodiment, the phase compensation structure is formed as a rectangular parallelepiped fin.

In one embodiment, the phase compensation structure is a rectangular parallelepiped fin having a height of 200nm to 800nm, and a length and width of 30nm to 500 nm.

In one embodiment, the length or width of the nanostructure is from 50nm to 2000 nm.

In one embodiment, the phase compensation structure is formed as a solid micro-nano structure of a cuboid, cylinder or hemisphere.

In one embodiment, a cuboid, cylinder or hemisphere hollow structure is further formed on the solid micro-nano structure.

Another aspect of the present application provides a super imaging apparatus, including: the super lens group; and an imaging sensor converting the light passing through the superlens group into an electrical signal proportional to a signal of the light.

Drawings

Other features, objects, and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments when taken in conjunction with the accompanying drawings. In the drawings:

FIG. 1 is a schematic view of a superlens according to an embodiment of the present application;

FIG. 2 is a schematic diagram of a phase compensation architecture according to an embodiment of the present application;

FIG. 3 is a schematic diagram of a phase compensation architecture according to another embodiment of the present application;

FIG. 4 is a schematic diagram of a superlens group according to an embodiment of the present application;

FIG. 5 is a schematic diagram of a phase compensation structure of a normally incident light beam in a superlens group according to an embodiment of the present application; and

FIG. 6 is a schematic diagram of a phase compensation structure of a back-reflected light beam in a superlens group according to an embodiment of the present application.

Detailed Description

For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that the detailed description is merely illustrative of exemplary embodiments of the present application and does not limit the scope of the present application in any way. Like reference numerals refer to like elements throughout the specification. The expression "and/or" includes any and all combinations of one or more of the associated listed items.

It should be noted that in this specification, the expressions first, second, third, etc. are used only to distinguish one feature from another, and do not represent any limitation on the features. Thus, the first superlens discussed below may also be referred to as the second superlens without departing from the teachings of the present application. And vice versa.

In the drawings, the thickness, size and shape of the components have been slightly adjusted for convenience of explanation. The figures are purely diagrammatic and not drawn to scale. As used herein, the terms "approximately", "about" and the like are used as table-approximating terms and not as table-degree terms, and are intended to account for inherent deviations in measured or calculated values that would be recognized by one of ordinary skill in the art.

It will be further understood that terms such as "comprising," "including," "having," "including," and/or "containing," when used in this specification, are open-ended and not closed-ended, and specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, elements, components, and/or groups thereof. Furthermore, when a statement such as "at least one of" appears after a list of listed features, it modifies that entire list of features rather than just individual elements in the list. Furthermore, when describing embodiments of the present application, the use of "may" mean "one or more embodiments of the present application. Also, the term "exemplary" is intended to refer to an example or illustration.

Unless otherwise defined, all terms (including engineering and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.

The features, principles and other aspects of the present application are described in detail below.

FIG. 1 is a schematic view of a superlens according to an embodiment of the present application, FIG. 2 is a schematic view of a phase compensation structure according to an embodiment of the present application, and FIG. 3 is a schematic view of a phase compensation structure according to another embodiment of the present application

Superlens 100 may include a substrate 110 and a plurality of phase compensation structures, such as 101, 102, 103, and 104, on substrate 110. The substrate 110 may be a transparent substrate. The plurality of phase compensation structures may be nano-substructures. The plurality of nano-substructures may deflect a light beam incident to the superlens 100, thereby performing phase compensation on the light beam. The incident light will be introduced into a Pancharatnam-berry (pb) phase difference associated with the shape of the phase compensation structure, etc., by the phase compensation structure on the superlens 100, thereby compensating the phase of the incident light to change the shape of its propagating wavefront. After the incident lights 111, 112, 113 and 114 at different positions in fig. 1 pass through the corresponding phase compensation structures 101, 102, 103 and 104, respectively, the propagation directions thereof are changed, i.e. the incident light 111 becomes the light beam 121, the incident light 112 becomes the light beam 122, the incident light 113 becomes the light beam 123 and the incident light 114 becomes the light beam 124.

The phase compensation structures 101, 102, 103, and 104 are formed by a dielectric material on the transparent substrate 110. The dielectric material forming the phase compensation structures 101, 102, 103, and 104 may be an inorganic dielectric material mainly including at least one of inorganic dielectric materials such as zinc sulfide, magnesium fluoride, titanium dioxide, zirconium oxide, silicon hydride, crystalline silicon, silicon nitride, amorphous silicon, gallium nitride, gallium phosphide, gallium arsenide, and the like, but may also include an organic material such as polymethyl methacrylate (PMMA), and the like. The refractive index of the material forming the phase compensation structures 101, 102, 103, and 104 is different from the refractive index of the material forming the substrate 110, and it is generally required that the refractive index of the material forming the phase compensation structures 101, 102, 103, and 104 is high. The dimensions of the individual phase compensation structures 101, 102, 103 or 104 are similar to or smaller than the wavelength of light, and their maximum length or height may, for example, be in the range of 50nm to 2000nm, depending on the operating band. In the superlens 100, although a plurality of the above-described phase compensation structures 101, 102, 103, and 104 are arranged on the transparent substrate 110, since the dimensions of the phase compensation structures 101, 102, 103, and 104 are many orders of magnitude smaller than the substrate 110, the superlens 100 can be considered to be a planar optical device, i.e., the superlens 100 is approximately flat.

The phase compensation structures 101, 102, 103, and 104 may be rectangular parallelepiped fins. The height of each rectangular parallelepiped fin may be set in the range of 200nm to 800nm according to the kind of material, and the length and width of each rectangular parallelepiped fin may be set in the range of 30nm to 500nm according to the kind of material, so that the phase compensation structure is arranged on the superlens 100 as much as possible. It will be appreciated by those skilled in the art that such a rectangular parallelepiped fin may act to phase-adjust incident light of circular polarization approximately to a half-wave plate, such that incident left-handed or right-handed circularly polarized light rotated by a fin rotation angle α emerges as right-handed or left-handed polarized light rotated by 2 α or-2 α, respectively. Thus, the rotation angles of the rectangular parallelepiped fins are different from each other, and different PB phase differences are introduced at different positions.

Those skilled in the art will also know that each single phase compensation structure 101, 102, 103, or 104 is not limited to a rectangular parallelepiped fin, but may adopt a solid micro-nano structure such as a rectangular parallelepiped, a cylinder, a hemisphere, or a hollow or partially hollow micro-nano structure having a recess or hole of a rectangular parallelepiped, a cylinder, a hemisphere thereon to achieve further fine tuning of the phase, so as to achieve further effects of eliminating chromatic aberration, polarization sensitivity, and the like. It should be particularly noted that the phase compensation structure may be formed by combining a plurality of solid or hollow micro-nano structures with different sizes to form a single phase compensation unit, and the further effects of eliminating chromatic aberration, polarization sensitivity and the like are achieved by using the combination of a plurality of phase compensation units. The phase compensation provided by the more complex phase compensation structure of the non-finned shape also varies in response to wavelength variations and therefore can be configured to produce phase compensation that varies as needed with respect to wavelength variations, thereby achieving approximately the same phase compensation over a wider spectral range. That is, the size, pitch, and rotation angle of the phase compensation structures 101, 102, 103, and 104 on the superlens 100 may be different from each other, and are not limited to the case of being identical to each other. If such a complex phase compensation structure is used, it is difficult to calculate the size, pitch, rotation angle, and the like of the required phase compensation structure in an analytic form, and analysis using a numerical simulation method such as FDTD (finite difference time domain), finite element FEM, and the like is required.

In order to realize arbitrary angular deflection of incident light in the form of plane waves, the superlens 100 shown in fig. 1 can satisfy phase compensation shown in the following equation (1):

wherein, + -represents the wavelength of lambda, the position coordinate of the phase compensation structure of r and the required refraction angle of theta for the left-handed and right-handed circularly polarized lights.

In an exemplary embodiment, as shown in fig. 2, considering the case where the plurality of phase compensation structures 201 may be the simplest rectangular parallelepiped fins, rotating the angle of the fins at each position by Δ Φ/2 may separate two circularly polarized lights.

In an exemplary embodiment, the superlens 100 as shown in fig. 1 may also implement phase compensation as shown in the following equation (2):

where ± denotes circularly polarized light for left and right handed. As shown in fig. 3, when the plurality of phase compensation structures 301 are rectangular parallelepiped fins, they are rotated by the same angle regardless of r so as to generate the same phase shift. c can be freely selected depending on the case, for example, c ═ pi/8 or c ═ 3 pi/4. Respective regions may also be provided for the separated left-handed and right-handed polarized light to reduce the overlap of the phase compensation structures corresponding to the two polarized lights.

FIG. 4 is a schematic diagram of a superlens group according to an embodiment of the present application, and FIG. 5 is a schematic diagram of a phase compensation structure of a normally incident light beam in the superlens group according to the embodiment of the present application; and FIG. 6 is a schematic diagram of a phase compensation structure of a back-reflected light beam in a superlens group according to an embodiment of the present application.

The superlens group 1000 may include a first superlens 400, a second superlens 500, and a third superlens 600.

The first, second, and third superlenses 400, 500, and 600 are sequentially disposed along a direction of incident light, i.e., a z-axis. The incident light may include a first handedness polarized light and a second handedness polarized light orthogonal to the first handedness polarized light. Each of the first, second, and third superlenses 400, 500, and 600 has a plurality of phase compensation structures on a surface thereof, as shown in fig. 2 or 3. The plurality of phase compensation structures perform a deflection process on the light beams passing through the first, second, and third superlenses 400, 500, and 600 to perform phase compensation thereof. The present application provides a superlens group 1000 having the effect of preventing back reflection. The first, second and third do not indicate a restriction on the order of precedence, but merely to distinguish the direction of incident light and reflected light. While in the direction of propagation along the optical axis the first, second and third are used to distinguish between different superlenses. The superlens group 1000 may include, but is not limited to, three lenses, such as more than three superlenses. In this case, three of the superlenses can be used for the purpose of preventing back reflection, without having to use more superlenses for this purpose.

As shown in fig. 4, the first and third superlenses 400 and 600 may each be used to provide phase compensation as a function of r, for example, as shown in equation (1) above, thereby creating the effect of separately refracting left-and right-handed polarized light components. That is, the phase compensated by the phase compensation structure at different positions on the first and third superlenses 400 and 600 may be different. The second superlens 500 may then be used to provide phase compensation that does not vary with r (or at least does not vary continuously with r), such as shown in equation (2) above. I.e., the phase compensated by the phase compensation structure at different positions on the second superlens 500 may be the same. This configuration of the present application facilitates removal of polarization dependence, since any incident light can be decomposed into a combination of left-handed and right-handed polarized light, thereby not being limited to only the single chiral polarization relied upon by typical superlenses. The phase compensation structures of the first and third superlenses 400 and 600 may be the same or different, and preferably, the phase compensation structures of the first and third superlenses 400 and 600 are the same as each other. The phase compensation structure of the third superlens 600 may be rotated with respect to the phase compensation structure at each position of the first superlens 400. Preferably, the phase compensation structures on the first and third superlenses 400 and 600 may be made identical, only rotated with respect to each other. For example, the phase compensation structure on the first superlens 400 is rotated by a first angle, preferably, the first angle is pi/8, and then overlapped with the phase compensation structure on the third superlens 600 in the direction of the incident light. And the phase compensation structure of the second superlens 500 is not identical to that of the first and third superlenses 400 and 600. In the case where the phase compensation structure is a rectangular parallelepiped fin, the phase compensation structure of the second superlens 500 may be rotated ± c/2 in the corresponding region with respect to the polarized light of different chiralities. As shown in fig. 4, when the light beam 410 on the first superlens 400 along the Y-axis direction passes through the second superlens 500, the light beam 410 can be deflected by a certain angle α to form a light beam 510 forming an angle α with the Y-axis because the phase compensation structure of the second superlens 500 is different from the phase compensation structure of the first superlens 400. Since the phase compensation structure of the third superlens 600 can be rotated with respect to the phase compensation structure at each position of the first superlens 400, the light beam 510 is not deflected again when passing through the third superlens 600, and still forms an angle α with the Y-axis, i.e. the light beam 510 becomes the light beam 610.

As shown in fig. 5, the light beam incident in the positive direction travels through the superlens group 1000, i.e. the incident light passes through the first superlens 400, the second superlens 500 and the third superlens 600 along the optical axis from the object side in sequence, and finally exits. Of the incident light, a first handly polarized light 420, such as a left-handed light beam, and a second handly polarized light 430, such as a right-handed light beam. Preferably, the first chiral polarized light 420 is left circularly polarized light; the second chiral polarized light 430 is right-handed circularly polarized light. The first superlens 400 has different phase compensation for the first and second linearly polarized light 420 and 430. The first and second handedness polarized light 420 and 430, respectively, will be deflected by respective rotation angles Δ φ when passing through the first superlens 400, wherein the first handedness is orthogonal to the second handedness. The direction of propagation of one of the beams may be set to the z-axis, e.g., the direction of propagation of beam 430 may be set to the z-axis. When the light beam 420 and the light beam 430 pass through the first superlens 400, the light beam 430 becomes a light beam 431, and the light beam 420 becomes a light beam 421 and is shifted in the Y direction. When the light beam 421 and the light beam 431 pass through the second superlens 500, the second superlens 500 may have the same phase compensation for the light beam 421 and the light beam 431, and the phases of the light beam 431 and the light beam 421 may be rotated in opposite directions by the same rotation angle to form the light beam 432 and the light beam 422, respectively, that is, the light beam 431 becomes the light beam 432 and the light beam 421 becomes the light beam 422. When the light beams 432 and 422 pass through the third super lens 600, the third super lens 600 can have different phase compensation for the light beams 432 and 422, that is, the light beams 432 and 422 are deflected again, at this time, the light beams 432 become light beams 433, the light beams 433 exit the super lens group to form light beams 434, and the light beams 434 can continue to reach a sensor and the like along the z-axis. However, beam 422 is further deflected to beam 423, and beam 423 exits the superlens group to form beam 424, where beam 424 is further off the z-axis and thus prevented from reaching the following sensor.

In practical applications, since the stray light is caused by the back reflection of the light beam, the light beam incident in the forward direction is reflected and then travels in the superlens group 1000 as shown in fig. 6. At this time, the first and second linearly polarized lights 530 and 520 of the reflected light are incident on the third superlens 600, and then the light beam 520 is deflected in the Y direction to become the light beam 521, the light beam 530 remains undeflected and becomes the light beam 531 in the z-axis direction, and when the light beam 521 and the light beam 531 pass through the second superlens 500, the light beam 531 becomes the light beam 532, and the light beam 521 becomes the light beam 522. The light beam 522 and the light beam 532 are deflected again when passing through the first superlens 400, and at this time, the light beam 532 is deflected in the Y direction to become a light beam 533 and the light beam 522 becomes a light beam 523. After beams 523 and 533 have passed through first superlens 400, beams 524 and 534 are formed off the z-axis. This makes it possible to absorb the reflected light beam by arranging light absorbing structures, such as coated films, rough surfaces, etc., in directions other than the z-axis, to avoid further reflection of the reflected light. Thus, an integrated unidirectional propagation mechanism can be realized by the superlens group, and the integrated unidirectional propagation mechanism is used for reducing back reflection under various light transmission conditions.

The application also provides a super imaging device. The super imaging apparatus may include: a superlens group; and an image sensor. The image sensor may convert the light passing through the superlens group into an electrical signal proportional to a signal of the light to achieve an imaging effect.

The above description is only an embodiment of the present application and an illustration of the technical principles applied. It will be appreciated by a person skilled in the art that the scope of protection covered by the present application is not limited to the embodiments with a specific combination of the features described above, but also covers other embodiments with any combination of the features described above or their equivalents without departing from the technical idea described above. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.

Claims (19)

1. A super lens set, comprising in order along the direction of incident light: a first superlens, a second superlens, and a third superlens, wherein the incident light includes a first handedness polarized light and a second handedness polarized light orthogonal to the first handedness polarized light,

it is characterized in that the preparation method is characterized in that,

each of the first, second, and third superlenses has a plurality of phase compensation structures on a surface thereof,

the phase compensation structures of the first superlens and the third superlens compensate the same phase for the first handedness polarized light and the second handedness polarized light respectively; and

the phase compensation structure of the second superlens compensates for different phases of the first and second linearly polarized light.

2. A superlens group according to claim 1, wherein the phase compensation structure is a nano-substructure.

3. The superlens group of claim 1, wherein the plurality of phase compensation structures of the first superlens are rotated by a first angle to overlap with the plurality of phase compensation structures of the third superlens in the direction of the incident light.

4. A superlens group according to claim 1, wherein the first handedness polarized light is left-handed circularly polarized light; the second chiral polarized light is right-handed circularly polarized light.

5. The superlens group of claim 1, wherein the differently positioned phase compensation structures of the first superlens compensate for different phases of the first and second manually polarized light.

6. The superlens group of claim 1, wherein the differently positioned phase compensation structures of the third superlens compensate for different phases of the first and second manually polarized light.

7. The superlens group of claim 1, wherein the phase compensation structures of the second superlens at different positions compensate the same phase for the first and second manually polarized light.

8. A superlens group according to claim 3, wherein the first angle is pi/8.

9. The superlens group of claim 1, wherein the first, second, and third superlenses further comprise a transparent substrate, wherein the phase compensation structure is formed on the transparent substrate by a dielectric material.

10. The superlens group of claim 9, wherein the dielectric material forming the phase compensation structure is an inorganic dielectric material having a refractive index different from a refractive index of a material forming the transparent substrate.

11. The superlens group of claim 10, wherein the inorganic dielectric material has a refractive index greater than a refractive index of a material forming the transparent substrate.

12. The superlens group of claim 10, wherein the inorganic dielectric material comprises at least one of zinc sulfide, magnesium fluoride, titanium dioxide, zirconium oxide, silicon hydride, crystalline silicon, silicon nitride, amorphous silicon, gallium nitride, gallium phosphide, gallium arsenide.

13. A superlens group according to claim 9, wherein the dielectric material forming the phase compensation structure is organic glass.

14. The superlens group of claim 1, wherein the phase compensation structure is formed as a rectangular parallelepiped fin.

15. A superlens group according to claim 14, wherein the phase compensation structure is a cuboid fin having a height of 200nm-800nm and a length and width of 30nm-500 nm.

16. A superlens group according to claim 2, wherein the nano-substructures have a length or width of 50nm-2000 nm.

17. The superlens group of claim 1, wherein the phase compensation structure is formed as a solid micro-nano structure of a cuboid, cylinder or hemisphere.

18. The superlens group of claim 17, wherein the solid micro-nano structure is further formed with a hollow structure of a cuboid, a cylinder or a hemisphere.

19. A super imaging apparatus, characterized in that the super imaging apparatus comprises:

the superlens group of any one of claims 1-18; and

and an imaging sensor converting the light passing through the superlens group into an electrical signal proportional to a signal of the light.

Images