A device, method and device design method for off-axis arbitrary decomposition of singular light beams

Abstract

The present invention discloses an off-axis arbitrary decomposition device and method of a singular light beam, and a device design method, and relates to the field of optical information processing. The device comprises a first metasurface, and the first metasurface is used to perform geometric transformation of the light beam; a second metasurface, and the second metasurface is arranged opposite to the first metasurface, and the second metasurface is used to perform phase correction of the light beam; the present invention arbitrarily decomposes an incident singular light beam into a plurality of complementary fan-shaped light beams according to proportional requirements on the first metasurface, and each fan-shaped light beam forms a ring-shaped light beam respectively during spatial transmission, and phase correction is simultaneously performed on the plurality of ring-shaped light beams on the second metasurface and the mode characteristics are restored, so as to realize the off-axis arbitrary decomposition of the incident light beam, and the arbitrary proportional decomposition of the device does not depend on the size of the incident singular light beam, and is compatible with the response singular phase / polarization mode, and has the advantages of small size, high integration, low process complexity, flexible regulation and good mode decomposition performance.

Description

Technical Field

[0001] The present invention relates to the field of optical information processing, and in particular to an off-axis arbitrary decomposition device and method for a singular light beam, and a device design method. Background Art

[0002] Singular beams usually refer to vortex beams, cylindrical vector beams and cylindrical vector vortex beams. Singular beams usually have lateral distribution characteristics of light fields with singular phase / polarization. The cross-sectional light field intensity distribution of the beam is all in the shape of a ring. The above three beam modes can be regarded as a combination superposition of (left-handed / right-handed) circularly polarized vortex beam modes as basis vectors, that is, the basic unit of the singular beam mode can be regarded as a (left-handed / right-handed) circularly polarized vortex beam mode. In addition, different vortex beam modes are orthogonal to each other, and the modes are theoretically infinite. These characteristics have promoted the rapid development of mode division multiplexing technology related to singular phase / polarization modes in large-capacity and high-speed optical communications, and have shown great application prospects in free space and optical fiber communications.

[0003] In addition, the control related to the singular beam mode can be realized by passive optical devices, so the mode is considered to be an important dimension for building a new passive optical network to achieve high-speed communication and all-optical interconnection. In the interconnected nodes of the all-optical network, when the high-order mode channel needs to be connected to multiple off-axis low-order mode channels to achieve data interconnection and distribution requirements similar to "terminal-multi-user connection", the off-axis decomposition of the mode is a key issue. Among them, the optical geometric transformation method shows obvious advantages in the control of mode decomposition. For example, one decomposition scheme is to map the vortex beam carrying the orbital angular momentum mode into a rectangular plane wave with a transverse phase distribution based on the logarithmic polar coordinate transformation of the two-step modulation, intercept part of the rectangular area and then perform the inverse coordinate transformation to achieve effective decomposition of the vortex beam mode. However, this scheme has serious system redundancy and power loss; while the azimuthally scaled spiral coordinate transformation uses the mapping and restoration scheme of the spiral line shape, which shows higher performance in mode decomposition, but still has obvious power loss; in addition, both of the above two schemes can only decompose the high-order mode into a single low-order mode, which limits the flexibility of mode decomposition. In addition, both of the above decomposition schemes can only decompose vortex beams, but cannot decompose cylindrical vector beams and cylindrical vector vortex beams at the same time. Therefore, the existing technology still needs further development and breakthroughs. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present application is to provide a device, method and device design method for off-axis arbitrary decomposition of singular light beams, aiming to solve the problem of how to achieve off-axis arbitrary decomposition of compatible light beams with singular phase / polarization modes to meet the application requirements of channel data connection and distribution in optical network nodes.

[0005] In order to solve the above technical problems, the first aspect of the embodiments of the present application provides an off-axis arbitrary decomposition device of a singular light beam, the device comprising:

[0006] a first metasurface for performing a geometric transformation of a light beam;

[0007] A second metasurface, wherein the second metasurface is arranged opposite to the first metasurface, and the second metasurface is used to perform phase correction of the light beam.

[0008] As a further improved technical solution, both the first metasurface and the second metasurface are polarization-insensitive metasurfaces.

[0009] As a further improved technical solution, the polarization-insensitive metasurface includes a substrate and a plurality of nano-cylindrical structures with different radii, wherein the plurality of nano-cylindrical structures are evenly distributed on the substrate and are perpendicular to the substrate.

[0010] As a further improved technical solution, the material used for the substrate is silicon dioxide, and the material used for the nano-column structure is silicon.

[0011] As a further improved technical solution, the height of the nano-cylindrical structure is 800 nm.

[0012] As a further improved technical solution, the distance between the first metasurface and the second metasurface is 2 mm, and the plane size of the polarization-insensitive metasurface is 0.64 mm. 2 .

[0013] A second aspect of an embodiment of the present application provides a method for arbitrary off-axis decomposition of a singular light beam, comprising:

[0014] Directing the singular light beam vertically toward the first metasurface;

[0015] The first metasurface decomposes the incident singular light beam into a plurality of fan-shaped light beams according to a preset ratio, and the plurality of fan-shaped light beams are respectively emitted to the second metasurface, wherein the fan-shaped light beams are shrunk and transformed into ring-shaped light beams in the process of emitting to the second metasurface;

[0016] The second metasurface performs phase correction on the multiple annular beams respectively to obtain corrected beams, thereby completing off-axis decomposition of the singular beams, wherein the corrected beams have the same singular characteristics as the incident singular beams.

[0017] A third aspect of the embodiments of the present application provides a method for designing an off-axis arbitrary decomposition device for a singular light beam, comprising:

[0018] Determine the first layer phase plane through the first polar coordinate distribution expression;

[0019] Determine the second layer phase plane through the second polar coordinate distribution expression;

[0020] Based on the first phase plane, the second phase plane and the corresponding information of the preset phase radius, the radius sizes of several nano-cylindrical structures are determined in sequence and the positions of several nano-cylindrical structures are arranged on the substrate to obtain the periodic distribution of several nano-cylindrical structures on the substrate.

[0021] As a further improved technical solution, the first polar coordinate distribution expression is:

[0022]

[0023] In the formula,

[0024] As a further improved technical solution, the second polar coordinate distribution expression is:

[0025]

[0026] In the formula,

[0027] Among them, in the first polar coordinate distribution expression and the second polar coordinate distribution expression, n is the number of decompositions, aj and bj are proportional constants, mj is the decomposition proportional factor, which satisfies 0<|mj|<1, and the decomposition sector angle satisfies θj=(|mj|+2|mj-1|-1)π, m0=0, θj∈[-π,π], and f is the two-layer cascade spacing. is the phase shear function, and its function expression is:

[0028]

[0029] Where H is a step function.

[0030] Beneficial effect: Compared with the prior art, the device of the present invention includes a first metasurface, which is used to perform geometric transformation of the light beam; a second metasurface, which is arranged opposite to the first metasurface, and is used to perform phase correction of the light beam; after the present invention adopts the above device, the incident singular light beam is arbitrarily decomposed into multiple complementary fan-shaped light beams according to proportional requirements on the first metasurface, each fan-shaped light beam forms a ring-shaped light beam respectively during the spatial transmission process, and the multiple ring-shaped light beams are simultaneously phase corrected and the mode characteristics are restored on the second metasurface to achieve arbitrary off-axis decomposition of the singular phase / polarization mode of the incident light beam, the device performs arbitrary proportional decomposition and does not depend on the size of the incident singular light beam, and has the characteristics of compatible response to singular phase / polarization modes, the device has the advantages of small size, high integration, low process complexity, flexible regulation, good mode decomposition performance, etc., and has potential application prospects in the fields of singular light beam mode modulation and mode optical network interconnection. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural diagram of the off-axis arbitrary decomposition device of the singular light beam of the present invention.

[0032] Figure 2 It is a flow chart of the off-axis arbitrary decomposition method of the singular light beam of the present invention.

[0033] Figure 3 It is a flow chart of the design method of the off-axis arbitrary decomposition device of the singular light beam of the present invention.

[0034] Figure 4 The invention discloses an off-axis arbitrary decomposition device for a singular light beam, and shows a light intensity and phase distribution diagram before and after two different decomposition ratios are respectively performed on an incident vortex light beam mode.

[0035] Figure 5 The off-axis arbitrary decomposition device of the singular light beam of the present invention respectively performs two intensity and vector detection characteristic diagrams before and after different decomposition ratios on the incident column vector beam mode.

[0036] Figure 6 The off-axis arbitrary decomposition device of the singular light beam of the present invention respectively performs two intensity and vector detection characteristic diagrams before and after different decomposition ratios on the incident column vector vortex beam mode.

[0037] Figure 7 This is a diagram showing the corresponding relationship between the radius and phase of the nano-cylindrical structure of the present invention.

[0038] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0039] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thoroughly and comprehensively understood.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0041] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the examples of various specific processes and materials provided by the present invention, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0042] It should be pointed out that in the description of the present invention, it should be explained that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] The inventor has found through research that the prior art has the following problems:

[0044] (1) The control of singular beam modes can be realized by passive optical devices. Therefore, modes are considered to be an important dimension for building new passive optical networks to achieve high-speed communication and all-optical interconnection. In the interconnected nodes of all-optical networks, when high-order mode channels need to be connected to multiple off-axis low-order mode channels to achieve data interconnection and distribution requirements similar to "terminal-multi-user connection", the off-axis decomposition of modes is a key issue. Among them, the optical geometric transformation method has shown obvious advantages in the control of mode decomposition. For example, one decomposition scheme is to map the vortex beam carrying the orbital angular momentum mode into a rectangular plane wave with a transverse phase distribution based on the logarithmic polar coordinate transformation of the two-step modulation, intercept part of the rectangular area and then perform the inverse coordinate transformation to achieve effective decomposition of the vortex beam mode. However, this scheme has serious system redundancy and power loss; while the azimuthally scaled spiral coordinate transformation uses the mapping and restoration scheme of the spiral line shape, which shows higher performance in mode decomposition, but still has obvious power loss; in addition, both of the above two schemes can only decompose high-order modes into a single low-order mode, which limits the flexibility of mode decomposition. In addition, both of the above decomposition schemes can only decompose vortex beams, but cannot decompose cylindrical vector beams and cylindrical vector vortex beams at the same time. Therefore, the existing technology still needs further development and breakthroughs.

[0045] In order to solve the above problems, various non-limiting implementation methods of the present application are described in detail below with reference to the accompanying drawings.

[0046] like Figure 1 As shown, an embodiment of the present application provides an off-axis arbitrary decomposition device for a singular light beam, the device comprising:

[0047] A first metasurface 1, wherein the first metasurface 1 is used to perform a geometric transformation of a light beam;

[0048] A second metasurface 2, wherein the second metasurface 2 is arranged opposite to the first metasurface 1, and the second metasurface 2 is used to perform phase correction of the light beam.

[0049] Specifically, the metasurface is a subwavelength micro-nanoscale two-dimensional planar optical device, which has the characteristics of multi-dimensional response to light field amplitude, phase and polarization, and shows significant advantages in complex mode field control and device integration. This embodiment adopts two relatively arranged metasurfaces, namely the first metasurface 1 and the second metasurface 2. The first metasurface 1 is located directly in front of the second metasurface 2. The first metasurface 1 and the second metasurface 2 are arranged opposite to each other, and the front side of the first metasurface 1 faces the front side of the second metasurface 2. The singular light beam L0 is emitted from the back side of the first metasurface 1, then emitted from the front side of the first metasurface 1 and emitted into the front side of the second metasurface 2, and finally emitted from the back side of the second metasurface 2.

[0050] Wherein, the first metasurface 1 and the second metasurface 2 are both polarization-insensitive metasurfaces.

[0051] Specifically, the polarization-insensitive metasurface is used as an actuator to achieve the off-axis arbitrary decomposition function requirement for singular phase / polarization mode input.

[0052] The polarization-insensitive metasurface includes a substrate and a plurality of nano-cylindrical structures 3 with different radii. The plurality of nano-cylindrical structures 3 are evenly distributed on the substrate and perpendicular to the substrate. The substrate is made of silicon dioxide, the nano-cylindrical structures 3 are made of silicon, and the height of the nano-cylindrical structures 3 is 800 nm.

[0053] Specifically, since the phase delay of the nano-cylindrical structure 3 on the substrate to the polarization component in any direction of the plane is the same, it has a polarization-insensitive pure phase modulation characteristic.

[0054] The distance between the first metasurface 1 and the second metasurface 2 is 2 mm, and the plane size of the polarization-insensitive metasurface is 0.64 mm. 2 .

[0055] The incident singular light beam will be subjected to phase conformal mapping from a circle to a multi-sector region of arbitrary proportion by the first metasurface 1. With the polarization-insensitive metasurface as the actuator, the off-axis arbitrary decomposition function requirement of the singular phase / polarization mode input is realized, that is, the incident singular light beam on the first metasurface 1 will be arbitrarily decomposed into multiple complementary fan-shaped light beams according to the proportional requirements. Each fan-shaped light beam shrinks and transforms into a ring-shaped light beam in the process of irradiating to the second metasurface 2. When the singular light beam pattern is vertically incident on the first metasurface, the metasurface will perform a geometric transformation on the singular phase / polarization mode of the incident light beam, and the distribution expression of its plane phase in polar coordinates is:

[0056]

[0057] in,

[0058] Subsequently, the transformed annular beam interacts with the second metasurface 2, which performs phase correction on the decomposed multiple annular beams to restore the mode characteristics. The distribution expression of its plane phase in polar coordinates is:

[0059]

[0060] in,

[0061] In the first polar coordinate distribution expression and the second polar coordinate distribution expression, n is the number of decompositions, aj and bj are proportional constants, mj is the decomposition proportional factor, which satisfies 0<|mj|<1, and the decomposition sector angle satisfies θj=(|mj|+2|mj-1|-1)π, m0=0, θj∈[-π,π], and f is the two-layer cascade spacing. is the phase shear function, and its function expression is:

[0062]

[0063] Where H is a step function;

[0064] After the above two phase plane modulations, the off-axis arbitrary decomposition of the incident singular light beam can be realized. The number and proportion of the decomposition modes are customized to n and mj, and the decomposition condition must satisfy ∑mj=1. According to the above geometric transformation phase and mode correction phase distribution requirements, the polarization-insensitive metasurface as a passive control device will perform arbitrary proportion decomposition and does not depend on the size of the incident singular light beam mode. It has the all-optical control characteristics that are compatible with responding to singular phase / polarization modes.

[0065] Embodiment 1:

[0066] Figure 4 The off-axis arbitrary decomposition device of the singular light beam described in the present invention performs two intensity and phase distribution diagrams on the incident vortex light beam mode before and after performing two different decomposition ratios. The intensity distribution is normalized to 0 to 1, and the phase distribution is 0 to 2π. The vortex beam mode distribution can be expressed as exp(ilθ), where l is the topological charge number, which can also represent the mode size.

[0067] Specifically, when the mode decomposition ratio is set to 1:(-3) and the incident vortex beam mode is +4, then the outgoing vortex beam modes after the off-axis decomposition of the mode are performed are +1 and -3 respectively; when the mode decomposition ratio is set to 1:2:3 and the incident vortex beam mode is +6, then the outgoing vortex beam modes after the off-axis decomposition of the mode are performed are +1, +2 and +3 respectively; in addition, the setting of the above two mode decomposition ratios will also execute the decomposition output of the corresponding ratio for the remaining vortex beam modes.

[0068] Embodiment 2:

[0069] Figure 5 Based on the off-axis arbitrary decomposition device of the singular light beam of the present invention, the light intensity and vector detection characteristic diagrams before and after two different decomposition ratios are respectively performed on the incident column vector beam mode, and the light intensity distribution is normalized to 0 to 1. The column vector beam mode can be expressed as:

[0070]

[0071] It can be seen from the above formula that the cylindrical vector beam mode can be formed by superposition of left-handed and right-handed circularly polarized conjugate vortex beam modes, where m can be expressed as the size of the cylindrical vector beam mode.

[0072] Specifically, when the mode decomposition ratio is set to 1:(-3), the incident column vector beam mode is +4, that is, the vortex beam mode of the left-handed circular polarization component is +4, and the vortex beam mode of the right-handed circular polarization component is -4. Since the polarization-insensitive metasurface does not affect the polarization change of left and right circular polarizations, the output column vector beam modes after the mode off-axis decomposition is performed are +1 and -3 respectively; similarly, when the mode decomposition ratio is set to 1:2:3, the incident column vector beam mode is +6, then the output column vector beam modes after the mode off-axis decomposition is performed are +1, +2 and +3 respectively; wherein, the vector detection characteristic diagram is a light intensity distribution diagram of the column vector beam after passing through the polarizer in the direction of the arrow in the figure, which can be used to characterize the mode size. In addition, the setting of the above two mode decomposition ratios will also execute the corresponding ratio of decomposition output for the remaining column vector beam modes.

[0073] Embodiment 3:

[0074] Figure 6 The off-axis arbitrary decomposition device of the singular beam according to the present invention performs two different decomposition ratios on the incident column vector vortex beam mode and the vector detection characteristic diagram, and the intensity distribution is normalized to 0 to 1. The column vector vortex beam mode can be expressed as:

[0075]

[0076] It can be seen from the above formula that the cylindrical vector vortex beam mode can be formed by the superposition of the left-handed and right-handed circularly polarized l+m and lm vortex beam modes, where m and l jointly determine the size of the cylindrical vector vortex beam mode.

[0077] Specifically, when the mode decomposition ratio is set to 1:(-3), the incident column vector vortex beam mode is (8,-4), that is, the mode factors are l=+2 and m=+6. At this time, the vortex beam mode of the left-handed circular polarization component is l+m=+8, and the vortex beam mode of the right-handed circular polarization component is lm=-4. Since the polarization-insensitive metasurface does not affect the polarization change of left and right circular polarizations, the two column vector vortex beam modes emitted after the mode off-axis decomposition is performed are (2,-1) and (-6,3), respectively. Similarly, when the mode decomposition ratio is set to 1:2:3, the incident column vector vortex beam mode is (6,-12), then the three column vector vortex beam modes emitted after the mode off-axis decomposition is performed are (1,-2), (2,-4) and (3,-6), respectively. Among them, the vector detection characteristic diagram is the light intensity distribution diagram of the column vector vortex beam after passing through the polarizer in the direction of the arrow in the figure, which can be used to characterize the mode size. In addition, the setting of the above two mode decomposition ratios will also execute corresponding ratio decomposition output for the other column vector vortex beam mode incidences.

[0078] In summary, for a set mode decomposition ratio, the polarization-insensitive metasurface as a passive control device has the all-optical control characteristics that are compatible with responding to singular phase / polarization modes. Therefore, the device can be fully applied to the off-axis arbitrary decomposition of singular beam modes.

[0079] Compared with the prior art, the device of the present invention includes a first metasurface 1, wherein the first metasurface 1 is used to perform geometric transformation of the light beam; a second metasurface 2, wherein the second metasurface 2 is arranged opposite to the first metasurface 1, and the second metasurface 2 is used to perform phase correction of the light beam; after adopting the above device, the present invention decomposes the incident singular light beam into multiple complementary fan-shaped light beams according to proportional requirements on the first metasurface 1, and each fan-shaped light beam forms a ring-shaped light beam respectively during the spatial transmission process, and phase correction is simultaneously performed on the multiple ring-shaped light beams on the second metasurface 2 and the mode characteristics are restored to achieve arbitrary off-axis decomposition of the singular phase / polarization mode of the incident light beam, the device performs arbitrary proportional decomposition independently of the size of the incident singular light beam, and has the characteristics of being compatible with and responding to singular phase / polarization modes, the device has the advantages of small size, high integration, low process complexity, flexible regulation, good mode decomposition performance, etc., and has potential application prospects in the fields of singular light beam mode modulation and mode optical network interconnection.

[0080] Based on the above-mentioned off-axis arbitrary decomposition device of a singular light beam, this embodiment provides an off-axis arbitrary decomposition method of a singular light beam, comprising the following steps:

[0081] S1, directing the singular light beam vertically toward the first metasurface;

[0082] Specifically, the singular light beam includes one or more of a vortex light beam, a cylindrical vector light beam and a cylindrical vector vortex light beam. The singular light beam usually has a lateral distribution characteristic of a light field with a singular phase / polarization. The cross-sectional light field intensity distribution of the light beam is in a ring shape. The singular light beam is directed perpendicularly to the first metasurface. Specifically, when the singular light beam is directed to the reverse side of the first metasurface, it is perpendicular to the reverse side of the first metasurface.

[0083] S2, the first metasurface decomposes the incident singular light beam into a plurality of fan-shaped light beams according to a preset ratio, and the plurality of fan-shaped light beams are respectively directed toward the second metasurface, wherein the fan-shaped light beams are shrunk and transformed into ring-shaped light beams in the process of being directed toward the second metasurface;

[0084] Specifically, the preset ratio is set in advance. By changing the radius distribution law of the nano-cylindrical structure, a number of nano-cylindrical structures with different radius sizes are arranged in a certain order on the substrate, thereby setting the corresponding mode decomposition ratio. The first metasurface decomposes the incident singular light beam with a ring-shaped cross-section into multiple fan-shaped light beams according to the preset ratio. The multiple fan-shaped light beams form complementary fan-shaped areas. After being emitted from the first metasurface, the multiple fan-shaped light beams are respectively emitted to the second metasurface. In the process of emitting to the second metasurface, the multiple fan-shaped light beams are contracted and transformed into ring-shaped light beams with a ring-shaped cross-section.

[0085] S3, the second metasurface performs phase correction on the multiple annular beams respectively to obtain corrected beams, and completes the off-axis decomposition of the singular beams, wherein the corrected beams have the same singular characteristics as the incident singular beams.

[0086] Specifically, after the annular light beam is shrunk and transformed into a ring-shaped light beam with a ring-shaped cross-section and injected into the second metasurface, the second metasurface performs phase correction on the multiple annular light beams respectively to obtain corrected light beams. The corrected light beams have the same singular characteristics as the incident singular light beam, thereby completing the off-axis arbitrary decomposition of the singular phase / polarization mode of the incident light beam.

[0087] Based on the above-mentioned off-axis arbitrary decomposition device of a singular light beam, this embodiment provides a design method of an off-axis arbitrary decomposition device of a singular light beam, including:

[0088] S1, determine the first layer phase plane through the first polar coordinate distribution expression;

[0089] The first polar coordinate distribution expression is:

[0090]

[0091] In the formula,

[0092] S2, the second layer phase plane is determined by the second polar coordinate distribution expression;

[0093] The second polar coordinate distribution expression is:

[0094]

[0095] In the formula,

[0096] Among them, in the first polar coordinate distribution expression and the second polar coordinate distribution expression, n is the number of decompositions, aj and bj are proportional constants, mj is the decomposition proportional factor, which satisfies 0<|mj|<1, and the decomposition sector angle satisfies θj=(|mj|+2|mj-1|-1)π, m0=0, θj∈[-π,π], and f is the two-layer cascade spacing. is the phase shear function, and its function expression is:

[0097]

[0098] Where H is a step function.

[0099] S3, based on the first layer phase plane, the second layer phase plane and the corresponding information of the preset phase radius, the radius sizes of several nano-cylindrical structures are determined in sequence and the positions of several nano-cylindrical structures are arranged on the substrate to obtain the periodic distribution of several nano-cylindrical structures on the substrate.

[0100] Specifically, the preset phase radius corresponding information may be a corresponding relationship diagram between the radius and phase of the nano-cylindrical structure, such as Figure 7 As shown, the radius sizes of several nano-cylindrical structures are determined by the first phase plane, the second phase plane and the radius and phase correspondence diagram of the nano-cylindrical structure, and the positions of several nano-cylindrical structures are arranged on the substrate, so as to obtain the periodic distribution of several nano-cylindrical structures on the substrate, and finally a decomposition device is designed and manufactured according to the periodic distribution of several nano-cylindrical structures on the substrate.

[0101] It should be pointed out that in the description of the present invention, it should be understood that the terms "thickness", "up", "down", "inside" and "outside" indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0102] In the description of this specification, the description with reference to the terms "certain embodiments", "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0103] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. An off-axis arbitrary decomposition device for a singular light beam, characterized in that: The device includes: a first metasurface for performing a geometric transformation of a light beam; a second metasurface, the second metasurface being arranged opposite to the first metasurface, and the second metasurface being used to perform phase correction of the light beam; The first metasurface and the second metasurface are both polarization-insensitive metasurfaces; The polarization-insensitive metasurface includes a substrate and a plurality of nano-cylindrical structures of different radii, wherein the plurality of nano-cylindrical structures are evenly distributed on the substrate and are perpendicular to the substrate; the nano-cylindrical structures on the substrate have the same phase delay for polarization components in any direction of the plane, and have a polarization-insensitive pure phase modulation characteristic; The material used for the substrate is silicon dioxide, and the material used for the nano-column structure is silicon.

2. The off-axis arbitrary decomposition device of a singular light beam according to claim 1, characterized in that: The height of the nano-column structure is 800 nm.

3. The off-axis arbitrary decomposition device of a singular light beam according to claim 2, characterized in that: The distance between the first metasurface and the second metasurface is 2 mm, and the plane size of the polarization-insensitive metasurface is 0.64 mm².

4. A method for arbitrary off-axis decomposition of a singular light beam, the method being applied to the device for arbitrary off-axis decomposition of a singular light beam as claimed in claim 2, characterized in that: include: Directing the singular light beam vertically toward the first metasurface; The first metasurface decomposes the incident singular light beam into a plurality of fan-shaped light beams according to a preset ratio, and the plurality of fan-shaped light beams are respectively directed to the second metasurface, wherein the fan-shaped light beams are shrunk and transformed into ring-shaped light beams in the process of being directed to the second metasurface; by changing the radius distribution law of the nano-cylindrical structure, a plurality of nano-cylindrical structures with different radius sizes are arranged in a certain order on the substrate, so as to set the preset ratio; The second metasurface performs phase correction on the multiple annular beams respectively to obtain corrected beams, thereby completing off-axis decomposition of the singular beams, wherein the corrected beams have the same singular characteristics as the incident singular beams.

5. A method for designing an off-axis arbitrary decomposition device for a singular light beam, the method being applied to the off-axis arbitrary decomposition device for a singular light beam as claimed in claim 2, characterized in that: include: Determine the first layer phase plane through the first polar coordinate distribution expression; Determine the second layer phase plane through the second polar coordinate distribution expression; Based on the first phase plane, the second phase plane and the preset phase radius corresponding information, the radius sizes of a plurality of nano-cylindrical structures are determined in sequence and the positions of the plurality of nano-cylindrical structures are arranged on the substrate to obtain a periodic distribution of the plurality of nano-cylindrical structures on the substrate; The first polar coordinate distribution expression is: ； In the formula, ; Where n is the number of decompositions, and is the proportionality constant, is the decomposition scale factor, which satisfies , the decomposition sector angle size satisfies , , , is the distance between two layers of cascade, is the phase shear function, and its function expression is: ； Where H is a step function.

6. The method for designing an off-axis arbitrary decomposition device for a singular light beam according to claim 5, characterized in that: The second polar coordinate distribution expression is: ； In the formula, .

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