Metasurface element, laser and preparation method

Abstract

The invention relates to the technical field of semiconductor lasers, in particular to a metasurface element, a laser and a preparation method. The metasurface element comprises a first column body and a second column body, and the first column body and the second column body are sequentially arranged from bottom to top; the first column body is an elliptic column, and the second column body is a circular column; in addition, the first column body and the second column body have biaxial anisotropy, namely, the polarization state of light is regulated and controlled through the anisotropy. According to the embodiment of the invention, different structural designs of the upper layer and the lower layer of the metasurface element are utilized, that is, the metasurface element can be used for biaxial anisotropy and regulation and control of the polarization state of light, so that radial and angular high-order modes of output light of the laser are effectively inhibited, high-order transverse modes are reduced, the signal-to-noise ratio is improved, and finally the quality of the output light is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor lasers, and in particular to a metasurface element, a laser and a preparation method thereof. Background Art

[0002] At present, high-speed modulated VCSEL is the research focus of the laser industry. At present, VCSEL with 25GHz bandwidth has been relatively mature, but there are still many challenges in how to further improve the performance of VCSEL. For example, the output light of VCSEL has high-order multi-transverse modes, and the existence of high-order transverse modes will reduce the signal-to-noise ratio and affect the quality of the output light.

[0003] In the process of realizing the present invention, the inventors of the present invention found that: currently, to control the output polarization effect of VCSEL lasers, an external polarization controller is often required, which greatly increases the laser space and increases the cost. It is difficult to control the output polarization of semiconductor lasers without reducing the space and cost. Summary of the invention

[0004] In view of the above problems, the present invention is proposed to provide a metasurface element, a laser and a preparation method that overcome the above problems or at least partially solve the above problems.

[0005] In a first aspect, an embodiment of the present invention provides a metasurface element for use at a light output port of a semiconductor laser, the metasurface element comprising: a first column and a second column, the first column and the second column being arranged sequentially from bottom to top; The first cylinder is an elliptical cylinder, and the second cylinder is a circular cylinder; and the first cylinder and the second cylinder have biaxial anisotropy, that is, the polarization state of light is regulated by anisotropy.

[0006] In a further embodiment, the cross section of the first cylinder is elliptical; the cross section of the second cylinder is circular; and the area of ​​the cross section of the first cylinder is greater than the area of ​​the cross section of the second cylinder.

[0007] In a further embodiment, the major axis of the ellipse is controlled to be 200-250 nm, and the minor axis is controlled to be 160-200 nm; the diameter of the circle is controlled to be 130-160 nm.

[0008] In a further embodiment, the first column and the second column are TiO2 columns or SiN columns.

[0009] A second aspect also discloses a semiconductor laser, comprising: a semiconductor laser light emitting structure having a vertical cavity surface emitting laser structure; And, the metasurface element, the metasurface element array forms a metasurface, and the metasurface is arranged at the light output port of the semiconductor laser light-emitting structure.

[0010] In a further embodiment, an isolation film is provided between the metasurface and the semiconductor laser light-emitting structure, and the isolation film reduces optical coupling between the two.

[0011] In a further embodiment, the isolation film is a SiO2 piece.

[0012] The third aspect also discloses a method for preparing a semiconductor laser, the steps comprising: An isolation film is plated on the semiconductor laser light emitting structure by a magnetron sputtering process; Manufacturing a first column layer by printing a first mask layer on the upper side of the isolation film, wherein the first mask layer is provided with a first column pattern corresponding to the light output port, and then plating a first filling column inside the first column pattern to obtain the first column layer; Making a second column layer, printing a second mask layer on the upper side of the first column layer, the second mask layer being provided with a second column pattern corresponding to the first filling column, and then plating a second filling column inside the second column pattern to obtain the second column layer; The first mask layer and the second mask layer on the conductor laser light-emitting structure are cleaned with a solvent, thereby leaving the first filling column and the second filling column, and obtaining a semiconductor laser with a super surface.

[0013] According to a further embodiment, after the semiconductor laser light-emitting structure is coated with an isolation film, photoresist is printed on the isolation film through a two-photon polymerization process, thereby obtaining the first photoresist layer on the isolation film, and the first column layer is provided with a first column pattern at a position corresponding to the light output port, and the first column pattern is an elliptical pattern.

[0014] In a further embodiment, the first filling column and the second filling column are made of TiO2 or SiN respectively.

[0015] The beneficial effects of the above technical solution provided by the embodiment of the present invention include at least: A metasurface element is provided in an embodiment of the present invention, and the metasurface element includes a first cylinder and a second cylinder, wherein the first cylinder is an elliptical cylinder and the second cylinder is a circular cylinder. The metasurface element is designed with different upper and lower structures, that is, the metasurface element can be used for biaxial anisotropy to regulate the polarization state of light, thereby effectively suppressing the radial and angular high-order modes of the output light of the laser, thereby reducing high-order transverse modes, improving the signal-to-noise ratio, and ultimately improving the quality of the output light.

[0016] In the embodiment, the basic mode of the output light is angularly adjusted through an elliptical metasurface structure, thereby achieving the effect of reducing the angular high-order transverse modes; then, the basic mode of the output light is focused and adjusted through a circular metasurface structure, that is, when the output light passes through the circular column, the output light can be more focused on the axis, thereby achieving the effect of reducing the radial high-order transverse modes.

[0017] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings.

[0018] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the description of the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0020] Figure 1 is a semiconductor laser of an embodiment; Figure 2 is a schematic diagram of a metasurface according to an embodiment of the present invention; Figure 3 is a schematic diagram of a metasurface element according to an embodiment of the present invention; Figure 4 A semiconductor laser according to an embodiment of the present invention; Figure 5 is a spot diagram of the output light of the semiconductor laser of the present invention; Figure 6 is a schematic diagram of a two-photon polymerization device for printing a mask layer of the present invention; Figure 7 is a schematic diagram of a first column layer and a second column layer according to an embodiment of the present invention; Figure 8 is a schematic diagram of a first column layer according to an embodiment of the present invention; Fig. 9 It is a flow chart of a method for preparing a semiconductor laser according to an embodiment of the present invention.

[0021] Indicated in the figure: 100. Semiconductor laser; 110. Semiconductor laser light-emitting structure; 120. Polarization regulator; 121. Metasurface; 101, substrate; 102, N-type DBR portion; 103, N-electrode; 104, active region layer; 105, P-type DBR portion; 106, P-electrode; 107, metasurface element; 108, isolation film; 1070, first column; 1071, second column; 300, first mask layer; 301, first filling column; 302, second mask layer; 303, second filling column; 304, first column pattern. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application.

[0023] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply 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 application. In addition, the terms "first" and "second" are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0024] In this application, the word "exemplary" is used to mean "used as an example, illustration, or description." Any implementation described in this application as "exemplary" is not necessarily to be construed as being more preferred or advantageous than other implementations. The following description is given to enable any technician in the field to implement and use the present application. In the following description, details are listed for the purpose of explanation. It should be understood that a person of ordinary skill in the art can recognize that the present application can be implemented without using these specific details. In other examples, well-known structures and processes will not be elaborated in detail to avoid obscuring the description of the present application with unnecessary details. Therefore, the present application is not intended to be limited to the embodiments shown, but is consistent with the widest scope consistent with the principles and features disclosed in the present application.

[0025] See attached Figure 1 , schematically showing a semiconductor laser 100 according to an example embodiment. Figure 1 , an embodiment of a semiconductor laser 100 may include a substrate 101, a semiconductor laser light emitting structure, and a polarization regulator 120 disposed at a light output end. The polarization regulator 120 is disposed on one side of the semiconductor laser light emitting structure. The semiconductor laser light emitting structure may be a VCSEL. The polarization regulator 120 may include a metasurface 121. For example, the metasurface 121 may include an array of nano-metasurface elements 107 (e.g., a plurality of nano-metasurface elements 107) as an example of a light polarization regulating structure. The metasurface 121 includes the same type of material as the material forming the semiconductor laser light emitting structure.

[0026] The metasurface is a sub-wavelength artificial nanostructure film, which can modulate the incident light according to the metasurface element 107 thereon. The metasurface element 107 includes a fully dielectric or plasma nanoantenna, which can directly regulate the phase, amplitude, polarization and other characteristics of the light. The metasurface elements 107 are arranged in an array, and the metasurface elements 107 can be regular hexagons and / or squares. The center position of each metasurface element 107 is a regular hexagonal and square metasurface structure unit arrangement diagram. It should be understood that the metasurface element 107 can also be other shapes, and the position of the nanostructure can also be other positions other than the center / vertex position.

[0027] As an embodiment, the semiconductor laser light emitting structure may include an N-type DBR portion 102, an active region layer 104, and a P-type DBR portion 105 on a substrate 101. The semiconductor laser light emitting structure may include a III-V compound semiconductor material. For example, the semiconductor laser light emitting structure may include a GaAs-based compound semiconductor material. For example, the semiconductor laser light emitting structure may include at least one of GaInP, AlGaInP, GaAs, GaInAs, AlGaAs, and AlGaInAs.

[0028] As an example embodiment, the substrate 101 may be a semiconductor substrate 101. For example, a Si substrate, a GaAs substrate, etc. may be used as the substrate. If necessary, a buffer layer and a seed layer whose material for forming the semiconductor laser light emitting structure is lattice-matched with the substrate 101 may be provided between the substrate 101 and the semiconductor laser light emitting structure.

[0029] The active region layer 104 may include one or more quantum wells or quantum dots.

[0030] The N-electrode 103 may be disposed on a portion of the N-type DBR portion 102. The active region layer 104 may be provided in a region of the N-type DBR portion 102 that is not occupied by the N-electrode 103. The P-electrode 106 may be disposed on a portion of the P-type DBR portion 105.

[0031] Figure 1 The semiconductor laser light emitting structure shown is only an example and the scope of the present invention is not limited to Figure 1 The semiconductor laser light emitting structure shown in FIG. may include Figure 1 Various additional components / layers not shown.

[0032] In example embodiments, the emitting semiconductor laser 100 has a metasurface 121 , for example, the semiconductor laser light emitting structure may have a VCSEL structure that generates laser light.

[0033] In an exemplary embodiment, the polarization regulator 120 including the metasurface 121 is arranged on the light output side relative to the active region layer 104, for example, on the side opposite to the N-type DBR portion 102 relative to the active region layer 104, and by pairing with the P-type DBR portion 105, the metasurface 121 can be used as an upper reflector layer for forming a cavity of a VCSEL.

[0034] The metasurface may include an array of multiple metasurface elements 107. For example, the array of multiple metasurface elements 107 may be arranged in an area on the P-type DBR portion 105 that is not occupied by the P electrode 106. The metasurface may also perform a feedback function of the cavity of the semiconductor laser light emitting structure, i.e., VCSEL.

[0035] Figure 1 An example embodiment of a metasurface is shown. Figure 1 , the metasurface 121 may include a plurality of metasurface elements 107 spaced apart from each other. The plurality of metasurface elements 107 may form an array of the metasurface elements 107.

[0036] Before describing the embodiments of the present invention in detail, the design concept of the present invention is briefly described below. Figure 4 As shown, the present invention designs a metasurface 121, and the metasurface element 107 includes a first cylinder 1070 and a second cylinder 1071, wherein the first cylinder 1070 is an elliptical cylinder, and the second cylinder 1071 is a circular cylinder. The metasurface element 107 has two different structural designs, that is, the metasurface element 107 can be used for biaxial anisotropy to regulate the polarization state of light, thereby effectively suppressing the radial and angular high-order modes of the output light of the laser, thereby reducing high-order transverse modes, improving the signal-to-noise ratio, and ultimately improving the quality of the output light.

[0037] The inventor of the present application is continuing to study how to effectively solve the problem of unsatisfactory regulation of the current metasurface vector polarization. The inventor's research at least includes: how the semiconductor laser 100 regulates the output polarization, and how to regulate the radial polarization and angular polarization by changing the metasurface structure. After a lot of repeated research, the inventor proposed the metasurface 121 and semiconductor laser 100 of the present application.

[0038] See attached Figure 2 As shown, in an embodiment of the present invention, a metasurface element 107 is provided, which is used for the light output port of a semiconductor laser 100. The metasurface element 107 includes: a first column 1070 and a second column 1071, wherein the first column 1070 and the second column 1071 are sequentially arranged from bottom to top; The first column 1070 is an elliptical column, and the second column 1071 is a circular column; and the first column 1070 and the second column 1071 have biaxial anisotropy, that is, the polarization state of light is regulated by anisotropy.

[0039] It can be understood that in the embodiment, the metasurface element 107 includes two parts, a first cylinder 1070 and a second cylinder 1071, wherein the first cylinder 1070 is an elliptical cylinder, and the second cylinder 1071 is a circular cylinder. The metasurface element 107 has two different structural designs, that is, the metasurface element 107 can be used for biaxial anisotropy to regulate the polarization state of light, thereby effectively suppressing the radial and angular high-order modes of the output light of the laser, thereby reducing high-order transverse modes, improving the signal-to-noise ratio, and ultimately improving the quality of the output light.

[0040] The first cylinder 1070 is an elliptical cylinder, and the basic mode of the output light is angularly adjusted through the elliptical metasurface structure, so as to reduce the angular high-order transverse modes; the second cylinder 1071 is a circular cylinder, and the embodiment focuses the basic mode of the output light through the circular metasurface structure, that is, when the output light passes through the circular cylinder, the output light can be more focused on the axis, so as to reduce the radial high-order transverse modes.

[0041] ‌It should be pointed out that anisotropy in optics refers to the different refractive indices and absorptivity in different directions in the medium, or the dielectric constant is a scalar. In anisotropic media, light will undergo birefringence, that is, a beam of light is divided into two or more beams. This is caused by the chaotic refractive index fluctuations inside the medium. For anisotropic materials such as uniaxial liquid crystals, due to their special physical structure, when light propagates in them, two refractive indices, ordinary light and extraordinary light, will be produced, corresponding to the situations where the electric vector vibrates perpendicular to the optical axis of the liquid crystal and the electric vector vibrates parallel to the optical axis of the liquid crystal, respectively. This birefringence phenomenon is a basic optical property of anisotropic materials, which makes the propagation behavior of light in these materials different from that in isotropic media, thereby affecting the propagation direction, speed, and polarization state of light. ‌ See attached Figure 3 As shown, in the embodiment further, the cross section of the first column 1070 is elliptical; the cross section of the second column 1071 is circular; the area of ​​the cross section of the first column 1070 is greater than the area of ​​the cross section of the second column 1071.

[0042] It can be understood that in order to achieve the regulation of light by biaxial anisotropy, the first cylinder 1070 is set as an elliptical cylinder, that is, the cross section of the first cylinder 1070 is elliptical. The second cylinder 1071 is set as a circular cylinder, that is, the cross section of the second cylinder 1071 is circular. In addition, one end of the first cylinder 1070 is set close to the light output port of the semiconductor laser 100, and the other end is connected to the second cylinder 1071. The area of ​​the cross section of the first cylinder 1070 is set to be larger than the area of ​​the cross section of the second cylinder 1071, and light modulation is achieved through structural differences.

[0043] The cross section described here is the cross section of the parallel light output port.

[0044] See attached Figure 5 As shown, in one example, in the metasurface element 107 of the metasurface 121, the heights of the first column 1070 and the second column 1071 are set to 250nm, and at the same time, the first column 1070 is a TiO2 elliptical column with a long axis of 0.22um and a short axis of 0.18um, and the second column 1071 is a TiO2 circular column with a diameter of 0.15um. By observing the light spot output by the laser with the metasurface 121, the result is: the light spot is focused at the center and is limited to the center position by the circular nanocolumn of the second column 1071; at the same time, the light spot has a rotation angle, which is polarized and regulated by the elliptical nanocolumn of the first column 1070.

[0045] In a further embodiment, the major axis of the ellipse is controlled to be 200-250 nm, and the minor axis is controlled to be 160-200 nm; the diameter of the circle is controlled to be 130-160 nm.

[0046] In a further embodiment, the first column 1070 and the second column 1071 are TiO2 columns or SiN columns.

[0047] Based on the same inventive concept, refer to the attached Figure 4 As shown, a semiconductor laser 100 includes: a semiconductor laser light emitting structure 110 having a vertical cavity surface emitting laser structure; The metasurface elements 107 are arrayed into a metasurface 121 , and the metasurface 121 is disposed at the light output port of the semiconductor laser light-emitting structure 110 .

[0048] In a further embodiment, an isolation film 108 is provided between the metasurface 121 and the semiconductor laser light emitting structure 110 , and the isolation film 108 reduces the optical coupling between the two.

[0049] In a further embodiment, the isolation film 108 is a SiO2 member.

[0050] Based on the same inventive concept, a method for preparing the super surface 121 is also disclosed. Fig. 9 As shown, the steps include: Step S001: coating an isolation film 108 on the semiconductor laser light emitting structure 110 by a magnetron sputtering process.

[0051] By setting an isolation film 108 between the metasurface 121 and the semiconductor laser light-emitting structure 110, specifically at the output hole position of the output light of the semiconductor laser light-emitting structure 110, the isolation film 108 can effectively reduce the optical coupling between the semiconductor laser light-emitting structure 110 and the metasurface 121, and at the same time act as a stress relief layer.

[0052] In the embodiment to be explained, the isolation film 108 is a SiO2 layer, and the thickness of the SiO2 layer is controlled to be 15-25 nm.

[0053] In some embodiments, a SiO2 thin film layer is directly deposited on a patterned VCSEL wafer by a magnetron sputtering process, wherein the thickness of the SiO2 thin film layer is controlled to be 20 nm; in other embodiments, a SiO2 thin film layer is directly deposited on a patterned VCSEL wafer by a magnetron sputtering process, wherein the thickness of the SiO2 thin film layer is controlled to be 16 nm; in some embodiments, a SiO2 thin film layer is directly deposited on a patterned VCSEL wafer by a magnetron sputtering process, wherein the thickness of the SiO2 thin film layer is controlled to be 24 nm.

[0054] It is understandable that the isolation membrane 108 may be replaced by another material.

[0055] Step S002: making a first column layer by printing a first mask layer 300 on the upper side of the isolation film 108, wherein the first mask layer 300 is provided with a first column pattern 304 corresponding to the light output port, and then plating a first filling column 301 inside the first column pattern 304 to obtain the first column layer.

[0056] In a further embodiment, after the semiconductor laser light-emitting structure is plated with an isolation film 108, a photoresist is printed on the isolation film 108 by a two-photon polymerization process, thereby obtaining the first mask layer 300 on the isolation film 108, and the first mask layer 300 sets a first columnar pattern 304 at a position corresponding to the light output port, and the first columnar pattern 304 is an elliptical pattern.

[0057] In actual implementation, please refer to the attached Figure 6 The figure shows a schematic diagram of a two-photon polymerization device printing a mask layer. After the isolation film 108 is plated, the semiconductor laser light-emitting structure is placed on a fixed frame of the two-photon polymerization device. The positive photoresist is 3D printed on the upper side of the isolation film 108 using a two-photon polymerization process, so that a layer of positive photoresist is formed on the upper side of the isolation film 108. Here, the upper side of the isolation film 108 can be considered as the side away from the semiconductor laser light-emitting structure. And when printing, at the position corresponding to the light output port of the semiconductor laser light-emitting structure 110, a first column pattern 304 is reserved for design. The first column pattern 304 is a cross-sectional pattern of the first column 1070. Here, the first column pattern 304 is an elliptical pattern. Other structures are not excluded. It is only necessary to achieve biaxial superposition and cooperate with the second column 1071 to form biaxial anisotropy, so as to polarize and control the output light.

[0058] See attached Figure 8 As shown, the elliptical pattern here can be considered as a hollow column structure, that is, the elliptical pattern is surrounded by photoresist, and the elliptical hollow column is formed by the solidified photoresist.

[0059] Next, the filler is plated into the first pillar pattern 304 by using a magnetron sputtering process. When plating the first pillar pattern 304, one of Si3N4 or TiO2 materials is selected for plating, thereby obtaining a first filling column 301 at a reserved position in the photoresist layer, thereby obtaining a first pillar layer.

[0060] Step S003: Make a second column layer, print a second mask layer 302 on the upper side of the first column layer, the second mask layer 302 is provided with a second column pattern corresponding to the first filling column 301, and then plate the second filling column 303 inside the second column pattern to obtain the second column layer.

[0061] In a further embodiment, after the first column layer is set in the semiconductor laser light-emitting structure, photoresist is printed on the upper side of the first column layer through a two-photon polymerization process, thereby obtaining the second mask layer 302 on the first column layer, and the second mask layer 302 sets a second column pattern corresponding to the position of the light output port, and the second column pattern is a circular pattern.

[0062] In actual implementation, after obtaining the first column layer, the semiconductor laser light-emitting structure is placed on a fixed frame of the two-photon polymerization device, and again, the positive photoresist is 3D printed on the upper side of the first column layer using the two-photon polymerization process, so that a layer of positive photoresist is formed on the upper side of the isolation film 108. Here, the upper side of the first column layer can be considered as the side away from the semiconductor laser light-emitting structure. And when printing, at the position corresponding to the light output port of the first column layer, a second column pattern is reserved for design. The second column pattern is a cross-sectional pattern of the second column 1071. Here, the second column pattern is a circular pattern. Other structures are not excluded. It only needs to be able to achieve biaxial superposition and cooperate with the second column 1071 to form bi-circular anisotropy, so as to polarize and control the output light.

[0063] The circular pattern here can be considered as a hollow column structure, that is, the circular pattern is surrounded by photoresist, and a circular hollow column is formed by solidifying the photoresist.

[0064] See attached Figure 7 As shown, then, the filler is plated into the second pillar pattern by using a magnetron sputtering process. When the second pillar pattern is plated, one of Si3N4 or TiO2 materials is selected for plated, so as to obtain a second filling column 303 at the reserved position of the photoresist layer, thereby obtaining a second pillar layer. The thickness of the plated film of the second filling column 303 is controlled to be the same as the thickness of the second pillar layer, and the thickness is controlled to be 250nm in the embodiment.

[0065] In order to meet the tuning requirements of the laser on the output light, the embodiment controls the heights of the first column 1070 and the second column 1071 so as to achieve the adjustment function as much as possible while also ensuring the space requirements of the metasurface 121 in the laser.

[0066] In a further embodiment, the thickness of the first pillar pattern 304 layer and the second pillar pattern layer is controlled to be 200-300 nm; the thickness of the first filling region and the second filling region is 200-300 nm.

[0067] In a further embodiment, the major axis of the ellipse is 220 nm, the minor axis is 180 nm, and the circular diameter is controlled within a range of 150 nm to 180 nm.

[0068] In a further embodiment, the first filler and the second filler are made of Si3N4 or TiO2.

[0069] For example: In some embodiments, the thickness of the first column layer is controlled to be 200 nm, the height of the first column is 200 nm, and the filler is TiO2, and the finally obtained elliptical column is a TiO2 column. The thickness of the second column layer is controlled to be 200 nm, the height of the second column is 200 nm, and the filler is TiO2, and the finally obtained circular column is a TiO2 column.

[0070] In some other embodiments, the thickness of the first column layer is controlled to be 300nm, the height of the first column is 300nm, and the filler is Si3N4, and the finally obtained elliptical column is a Si3N4 column. The thickness of the second column layer is controlled to be 250nm, the height of the second column is 250nm, and the filler is TiO2, and the finally obtained circular column is a TiO2 column.

[0071] In some other embodiments, the thickness of the first column layer is controlled to be 240nm, the height of the first column is 240nm, and the filler is Si3N4, and the circular column finally obtained is a Si3N4 column. The thickness of the second column layer is controlled to be 220nm, the height of the second column is 220nm, and the filler is Si3N4, and the elliptical column finally obtained is a Si3N4 column.

[0072] It should also be pointed out that in the embodiment here, the super surface 121 is set as a stacked structure of the circular column, the elliptical column and the SiO2 layer from top to bottom. In another embodiment, the super surface 121 can also be designed as a stacked structure of the elliptical column, the circular column and the SiO2 layer from top to bottom. The preparation method refers to the above steps and will not be repeated here.

[0073] Meanwhile, the heights of the first column 1070 and the second column 1071 can be set to the same height or different heights. Furthermore, the first column 1070 and the second column 1071 can be made of the same material, or the first column 1070 and the second column 1071 can be made of different materials. It is also possible to achieve biaxial superposition, and form biaxial anisotropy with the second column 1071, so as to perform polarization control on the output light.

[0074] Step S004 : using a solvent to clean the first mask layer 300 and the second mask layer 302 on the semiconductor laser light emitting structure 110 , thereby leaving the first filling column 301 and the second filling column 303 , and obtaining a semiconductor laser 100 having a metasurface 121 .

[0075] It can be understood that in the embodiment, a double-layer structured metasurface 121 is manufactured with the assistance of a mask layer, and then the first mask layer 300 and the second mask layer 302 are removed to obtain the desired metasurface 121 on the isolation layer, thereby achieving the desired light through the metasurface 121.

[0076] In actual work, an acetone solution is used to dissolve the positive photoresist. Specifically, the semiconductor laser light-emitting structure 110 is placed in an ultrasonic device and an appropriate acetone solution is added. During cleaning, the cleaning power of the ultrasonic device is set to 20-25W, and the cleaning time is controlled to 5-10 minutes, thereby effectively cleaning the photoresist 3D printed on the semiconductor laser light-emitting structure 110. The remaining first filling column 301 and the second filling column 303 are the first column 1070 and the second column 1071 for forming the metasurface element 107, thereby obtaining a semiconductor laser 100 with a metasurface.

[0077] See attached Figure 5As shown, in the metasurface element 107 of the metasurface 121, the heights of the first column 1070 and the second column 1071 are set to 250nm, and at the same time, the first column 1070 is a TiO2 elliptical column with a long axis of 0.22um and a short axis of 0.18um, and the second column 1071 is a TiO2 circular column with a diameter of 0.15um. By observing the light spot output by the laser with the metasurface 121, the result is that the light spot is focused at the center and is restricted to the center position by the circular nanocolumn of the second column 1071; at the same time, the light spot has a rotation angle, which is polarized and regulated by the elliptical nanocolumn of the first column 1070.

[0078] The light spot results show that in the laser prepared by the above-mentioned preparation method in the embodiment, the first column 1070 is an elliptical column, and the basic mode of the output light is angularly adjusted by the elliptical metasurface structure, so as to reduce the angular high-order transverse mode; the second column 1071 is a circular column, and the embodiment focuses the basic mode of the output light by the circular metasurface structure, that is, when the output light passes through the circular column, the output light can be more focused on the axis, so as to reduce the radial high-order transverse mode.

[0079] That is, the embodiment utilizes the different structural designs of the upper and lower layers of the metasurface element 107, that is, the metasurface element 107 can be used for biaxial anisotropy to regulate the polarization state of light, thereby effectively suppressing the radial and angular high-order modes of the output light of the laser, thereby reducing the high-order transverse modes, achieving an improvement in the signal-to-noise ratio, and ultimately improving the quality of the output light.

[0080] Based on the same inventive concept, a method for using a semiconductor laser 100 is also disclosed, wherein the semiconductor laser 100 includes the above-mentioned metasurface 121 .

[0081] For specific examples and descriptions of beneficial effects of the method described in this embodiment, reference may be made to the description of the semiconductor laser 100 described above, which will not be repeated here.

[0082] Obviously, various changes and modifications may be made to the present invention by those skilled in the art without departing from the spirit and scope of the present invention. The present disclosure is not limited to the precise structure described above and shown in the accompanying drawings, and various changes and modifications may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims. Thus, if these changes and modifications of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these changes and modifications.

Claims

1. A metasurface element for use at a light output port of a semiconductor laser, characterized in that: The metasurface element comprises: a first column and a second column, wherein the first column and the second column are arranged sequentially from bottom to top; The first cylinder is an elliptical cylinder, and the second cylinder is a circular cylinder; and the first cylinder and the second cylinder have biaxial anisotropy, that is, the polarization state of light is regulated by anisotropy.

2. The metasurface element according to claim 1, characterized in that: The cross section of the first cylinder is elliptical; the cross section of the second cylinder is circular; the area of ​​the cross section of the first cylinder is greater than the area of ​​the cross section of the second cylinder.

3. The metasurface element according to claim 2, characterized in that: The major axis of the ellipse is controlled to be 200-250 nm, and the minor axis is controlled to be 160-200 nm; the diameter of the circle is controlled to be 130-160 nm.

4. The metasurface element according to claim 2, characterized in that: The first column and the second column are TiO2 columns or SiN columns.

5. A semiconductor laser, characterized in that: include: Semiconductor laser light emitting structure with vertical cavity surface emitting laser structure ； The metasurface elements described in claims 1-4 are arrayed into a metasurface, and the metasurface is arranged at the light output port of the semiconductor laser light-emitting structure.

6. The semiconductor laser according to claim 5, characterized in that An isolation film is provided between the metasurface and the semiconductor laser light-emitting structure, and the optical coupling between the two is reduced by the isolation film.

7. The semiconductor laser according to claim 6, characterized in that The isolation film is a SiO2 member.

8. A method for preparing a semiconductor laser, characterized in that the steps include: An isolation film is plated on the semiconductor laser light emitting structure by a magnetron sputtering process; Manufacturing a first column layer by printing a first mask layer on the upper side of the isolation film, wherein the first mask layer is provided with a first column pattern corresponding to the light output port, and then plating a first filling column inside the first column pattern to obtain the first column layer; Making a second column layer, printing a second mask layer on the upper side of the first column layer, the second mask layer being provided with a second column pattern corresponding to the first filling column, and then plating a second filling column inside the second column pattern to obtain the second column layer; The first mask layer and the second mask layer on the conductor laser light-emitting structure are cleaned with a solvent, thereby leaving the first filling column and the second filling column, and obtaining a semiconductor laser with a super surface.

9. The method for preparing a semiconductor laser according to claim 7, characterized in that: After the semiconductor laser light-emitting structure is plated with an isolation film, photoresist is printed on the isolation film through a two-photon polymerization process, thereby obtaining the first photoresist layer on the isolation film, and the first column layer is provided with a first column pattern at a position corresponding to the light output port, and the first column pattern is an elliptical pattern.

10. The method for preparing a semiconductor laser according to claim 7, characterized in that: The first filling column and the second filling column are made of TiO2 or SiN, respectively.

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