A two-dimensional plasmonic photonic crystal with low-symmetry bloch modes
By introducing in-plane anisotropic materials and periodic defect structures into polariton photonic crystals, low-symmetry Bloch modes are excited, solving the problem of electromagnetic wave transmission symmetry limitations in traditional photonic crystals. This enables in-plane unidirectional transmission and efficient control of electromagnetic waves, and is suitable for highly integrated photonic circuits.
Patent Information
- Application Number
- CN202310716581.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-15
- Publication Date
- 2025-12-30
- Estimated Expiration
- 2043-06-15
AI Technical Summary
Traditional polariton photonic crystals are based on in-plane isotropic materials, and the excited Bloch modes exhibit high symmetry, making it difficult to achieve robust in-plane unidirectional transmission and efficient control of electromagnetic waves.
By employing in-plane anisotropic polariton materials, low-symmetry Bloch modes are formed through periodic modulation. Combined with specific periodic defect structures, electromagnetic waves are constrained and transmitted in specific directions. Furthermore, the optical response of the photonic crystal is modulated by rotating the orientation of the periodic structure.
It achieves robust unidirectional transmission and efficient control of electromagnetic waves in the subwavelength scale, enhances the control freedom of photonic crystals, breaks through the diffraction limit, and is suitable for highly integrated on-chip photonic circuits.
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Figure CN116859490B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of micro-nano photonics, and particularly relates to a two-dimensional plasmonic photonic crystal with low-symmetry Bloch modes. BACKGROUND
[0002] A photonic crystal is an artificial electromagnetic material with a periodic structure. Compared with a single continuous electromagnetic medium, a photonic crystal can periodically modulate a light field and form a photonic band gap similar to an electronic energy band structure. By changing the cell structure, period, dimension, etc. of the photonic crystal, electromagnetic waves can be flexibly manipulated, and various photonic components such as waveguides, filters, beam splitters, and resonant cavities can be obtained.
[0003] A plasmon is a quasi-particle generated by strong coupling between a photon and a material excitation, has strong light field confinement, and can break the diffraction limit to achieve precise manipulation of electromagnetic waves at a subwavelength scale. A plasmonic photonic crystal is a special photonic crystal based on a plasmonic material (i.e. a medium carrying plasmons), which can inherit and combine the advantages of both photonic crystals and plasmons. For example, a plasmonic photonic crystal can periodically modulate plasmons, excite Bloch modes and form a photonic band gap, and at the same time, the plasmonic photonic crystal can adjust the band structure of the photonic crystal by changing the dispersion relation and other properties of the plasmons, and achieve subwavelength or even deep subwavelength scale light field manipulation, greatly enriching the transmission modes and manipulation methods of electromagnetic waves.
[0004] Traditional plasmonic photonic crystals are usually based on in-plane isotropic plasmonic materials such as metals, graphene [L. Xiong, et al, Science Advances, 7, eabe8087 (2021)], hexagonal boron nitride [F. J. Alfaro-Mozaz, et al, Nature Communications, 10, 42, (2019)], etc. The plasmons in these materials are in-plane isotropic transmission, and the excited Bloch modes often exhibit high symmetry. In low-lattice-symmetry plasmonic materials, plasmons exhibit in-plane anisotropic transmission, and the resulting photonic crystal is expected to achieve oriented transmission of electromagnetic waves by changing the cell structure or arrangement. SUMMARY
[0005] The application provides a two-dimensional plasmonic photonic crystal with low-symmetry Bloch modes, which can excite low-symmetry Bloch modes by periodically modulating in-plane anisotropic plasmons, constrain electromagnetic waves in specific directions in the plane, and be immune to defects in other directions, and can realize robust in-plane unidirectional transmission of electromagnetic waves without changing the cell structure, and can regulate the optical response of the photonic crystal by changing the arrangement direction of the periodic structure, and greatly improve the regulation freedom of the photonic crystal.
[0006] The application provides a two-dimensional plasmonic photonic crystal with low-symmetry Bloch modes, which comprises a substrate layer and a plasmonic layer on the substrate layer, wherein the plasmonic layer is an in-plane anisotropic plasmonic material, and the plasmonic layer has a periodic defect structure.
[0007] Preferably, the substrate layer is at least one of a metal material, an inorganic dielectric material or an organic polymer material.
[0008] More preferably, when the substrate layer is a metal material, the metal material is at least one of gold, silver and aluminum; when the substrate layer is an inorganic dielectric material, the inorganic dielectric material is at least one of silicon dioxide, magnesium fluoride and calcium fluoride; and when the substrate layer is an organic polymer material, the organic polymer material is at least one of polymethyl methacrylate, polydimethylsiloxane and polyethylene terephthalate. The material of the substrate layer in the application can be a commonly used substrate material.
[0009] Preferably, the material of the plasmonic layer is at least one of alpha-phase molybdenum trioxide, alpha-phase vanadium pentoxide, black phosphorus, silver telluride, tungsten telluride, cadmium tungstate and calcite.
[0010] Preferably, the thickness of the plasmonic layer is 2 nm to 2 μm.
[0011] Preferably, the periodic defect structure is a through-hole structure which is periodically distributed and penetrates through the plasmonic layer. More preferably, the cross section of each through-hole structure is at least one of a circle, a circular ring, an ellipse, a rectangle, a triangle or a hexagon, the characteristic dimension (aperture for a circle, a circular ring or an ellipse, and side length for a triangle, a rectangle or other polygons) of each through-hole structure is 20 nm to 5 μm, and the distance (i.e. period) between the center of a hole and the center of an adjacent hole is 50 nm to 10 μm.
[0012] More preferably, the cell shape of the two-dimensional plasmonic photonic crystal is at least one of a square, a rectangle, a triangle or a hexagon, and the arrangement mode of the cell is one-dimensional linear arrangement or two-dimensional array arrangement.
[0013] The application further provides a preparation method of the two-dimensional plasmonic photonic crystal with low-symmetry Bloch modes, which comprises the following steps:
[0014] (1) providing a substrate layer;
[0015] (2) preparing a plasmonic layer on the substrate layer;
[0016] (3) preparing a periodic defect structure in the plasmonic layer;
[0017] (4) annealing to solidify the structure, obtaining the two-dimensional plasmonic photonic crystal with low-symmetry Bloch modes.
[0018] Preferably, the plasmonic layer in step (2) is prepared by any one of the following methods: mechanical exfoliation, chemical deposition or magnetron sputtering;
[0019] The periodic defect structure in step (3) is prepared by any one of the following methods: focused ion beam etching, laser direct writing or reactive ion etching.
[0020] The present application has the following advantages:
[0021] (1) The photonic crystal is based on plasmonic material, and the excited plasmons can break through the diffraction limit, realizing subwavelength scale light field confinement and regulation, and being expected to be applied to high-integration on-chip photonic circuits;
[0022] (2) Due to the in-plane anisotropy of the plasmons in the photonic crystal, the Bloch modes in the photonic crystal have low symmetry, and the energy band structure of the photonic crystal has different structures along different paths of the first Brillouin zone boundary;
[0023] (3) The low-symmetry Bloch modes make the energy localization in the photonic crystal exhibit high orientation in a specific direction in the plane, making the light field distribution immune to the arrangement of defects in the specific direction, and enabling the in-plane unidirectional robust transmission of subwavelength plasmons.
[0024] (4) The in-plane anisotropic plasmons can be used to regulate the optical response of the plasmonic photonic crystal by rotating the orientation of the periodic structure of the photonic crystal, providing a new means of regulating the photonic crystal. BRIEF DESCRIPTION OF DRAWINGS
[0025] Figure 1 is a bird's eye view of the two-dimensional plasmonic photonic crystal with low-symmetry Bloch modes of the present application.
[0026] Figure 2 is a preparation process flow chart of the two-dimensional plasmonic photonic crystal of the present application.
[0027] Figure 3 is a scanning electron microscope photo of the two-dimensional plasmonic photonic crystal in Example 1 of the present application.
[0028] Figure 4 is a near-field scanning microscope photo of the two-dimensional plasmonic photonic crystal in Embodiment 1 of the present application.
[0029] Figure 5 is a band structure diagram of the two-dimensional plasmonic photonic crystal in Embodiment 1 of the present application.
[0030] Figure 6 is a bird's eye view of the two-dimensional plasmonic photonic crystal in Embodiment 2 of the present application.
[0031] Figure 7 is a simulation result of the absorption spectrum of the two-dimensional plasmonic photonic crystal in Embodiment 2 of the present application.
[0032] Figure 8 is a bird's eye view of the two-dimensional plasmonic photonic crystal in Embodiment 3 of the present application.
[0033] Figure 9 is a simulation result of the absorption spectrum of the two-dimensional plasmonic photonic crystal in Embodiment 3 of the present application. DETAILED DESCRIPTION
[0034] The present application develops a two-dimensional plasmonic photonic crystal with low-symmetry Bloch mode, which is composed of a substrate layer and a plasmonic layer located on the substrate layer. The plasmonic layer is an in-plane anisotropic plasmonic material and has a specific periodic defect structure. The substrate layer in the present application is one of metal material, inorganic dielectric material or organic polymer material. The present application does not have special requirements for the material of the substrate layer, and the commonly used materials for the substrate in the prior art can be used. For example, when the substrate layer is a metal material, it is at least one of gold, silver and aluminum; when the substrate layer is an inorganic dielectric material, it is at least one of silicon dioxide, magnesium fluoride and calcium fluoride; when the substrate layer is an organic polymer material, it is at least one of polymethyl methacrylate, polydimethylsiloxane and polyethylene terephthalate.
[0035] The plasmonic layer is one of alpha-phase molybdenum trioxide, alpha-phase vanadium pentoxide, black phosphorus, silver telluride, tungsten telluride, cadmium tungstate or calcite; the thickness of the plasmonic layer is 2nm-2μm; the periodic defect structure of the plasmonic layer is a via structure, and the via cross-section is one of circular, circular ring, elliptical, rectangular, triangular or hexagonal; the characteristic size of the defect of the plasmonic layer is 20nm-5μm, the period is 50nm-10μm, and the cell structure is one or a combination of square, rectangular, triangular or hexagonal arrangement, and the arrangement mode of the cell is one-dimensional linear arrangement or two-dimensional array arrangement.
[0036] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings:
[0037] Example 1
[0038] like Figure 1 The image shown is an aerial view of a two-dimensional polaritonic photonic crystal with a low-symmetry Bloch mode. The substrate layer 1 is silicon dioxide, and the polariton layer 2 is α-phase molybdenum trioxide with a thickness of 230 nm. The defect geometry consists of circular vias with a diameter of 0.6 μm, arranged in a square pattern with a period of 2.3 μm, and oriented parallel to the crystal axis of the α-phase molybdenum trioxide, i.e., at an angle of 0°.
[0039] Reference Figure 2 The flowchart shown illustrates the fabrication method of a two-dimensional polaritonic photonic crystal with a low-symmetry Bloch mode. In this embodiment, Figure 1 The specific steps for fabricating the two-dimensional polaritonic photonic crystal shown are as follows:
[0040] Step 1: Fabrication of the polariton layer. Using molybdenum trioxide powder as the raw material, α-phase molybdenum trioxide nanosheets were grown on a silicon dioxide substrate by chemical vapor deposition in an oxygen atmosphere. The heating temperature of the molybdenum trioxide powder was 750℃, the deposition temperature of the α-phase molybdenum trioxide crystals was 400℃, and the reaction time was 30 min. α-phase molybdenum trioxide nanosheets with a thickness of 230 nm and a length and width greater than 20 μm were selected as the polariton layer.
[0041] Step 2: Fabrication of a two-dimensional polaritonic photonic crystal. Using focused ion beam etching, periodic vias are etched into the polariton layer according to the pre-designed structure. After annealing at 350℃, the two-dimensional polaritonic photonic crystal is obtained. The defect diameter is 0.6 μm, the cell shape is square, the period is 2.3 μm, and the alignment is parallel to the crystal axis of the α-phase molybdenum trioxide.
[0042] Figure 3 The image shows a scanning electron microscope image of a two-dimensional polaritonic photonic crystal, revealing approximately circular defects and square cell structures, with the cell arrangement direction parallel to the crystal axis of the polaritonic material.
[0043] Figure 4 The image shows a near-field scanning microscope image of a two-dimensional polaritonic photonic crystal. It can be seen that the excited polaritons are concentrated between two adjacent cells in the horizontal direction (i.e., the x-direction), while there is almost no polariton propagation in the vertical direction (i.e., the y-direction), indicating a low-symmetry Bloch mode.
[0044] Figure 5 The calculated band structure of the two-dimensional polariton photonic crystal shows that the band structures of the two different paths Γ-XM-Γ and Γ-X′-M-Γ along the boundary of the first Brillouin zone are different, indicating the low-symmetry Bloch mode in the photonic crystal.
[0045] Example 2
[0046] like Figure 6 The image shown is an aerial view of a two-dimensional polaritonic photonic crystal with a low-symmetry Bloch mode. The substrate layer 1 is gold, and the polariton layer 2 is α-phase vanadium pentoxide with a thickness of 2 μm. The defect geometry consists of square vias with sides of 5 μm, arranged in a square pattern with a period of 10 μm, and oriented at an angle of 45° to the crystal axis of the α-phase vanadium pentoxide.
[0047] Reference Figure 2 The flowchart shown illustrates the fabrication method of a two-dimensional polaritonic photonic crystal with a low-symmetry Bloch mode. Figure 6 The specific steps for fabricating the two-dimensional polaritonic photonic crystal shown are as follows:
[0048] Step 1: Fabrication of the polariton layer. Using α-phase vanadium pentoxide crystals as raw material, the crystals are peeled off with adhesive tape. This process is repeated 2–5 times to transfer the α-phase vanadium pentoxide nanosheets from the tape to the surface of a gold substrate. α-phase vanadium pentoxide nanosheets with a thickness of 2 μm and a length and width greater than 100 μm are selected as the polariton layer.
[0049] Step 2: Fabrication of a two-dimensional polaritonic photonic crystal. First, a layer of photoresist is spin-coated onto the surface of the polariton layer, and periodic defect structures are fabricated using photolithography as a mask. Reactive ion etching is then used to etch corresponding periodic vias in the polariton layer. After removing the photoresist and annealing at 350°C, the two-dimensional polaritonic photonic crystal is obtained. The defect side length is 5 μm, the cell shape is square, the period is 10 μm, and the orientation is at a 45° angle to the crystal axis of the α-phase vanadium pentoxide.
[0050] Figure 7 The absorption spectrum of the calculated two-dimensional polariton photonic crystal is shown and compared with that of an unrotated polariton photonic crystal (with an included angle of 0°). It can be seen that, under the condition that other parameters remain unchanged, changing the defect arrangement orientation of the photonic crystal can shift the resonant absorption peak and change the absorption intensity, proving that the optical response of the polariton photonic crystal can be modulated by rotating the orientation of the periodic structure of the photonic crystal.
[0051] Example 3
[0052] like Figure 8 The image shown is a bird's-eye view of a two-dimensional polaritonic photonic crystal with a low-symmetry Bloch mode. The substrate layer 1 is polymethyl methacrylate, and the polariton layer 2 is α-phase molybdenum trioxide with a thickness of 2 nm. The defect geometry consists of circular vias with a diameter of 20 nm, arranged in a rhombic pattern with a period of 50 nm, and oriented parallel to the crystal axis of the α-phase molybdenum trioxide, i.e., at an angle of 0°.
[0053] Referring to Figure 2 The preparation method flow chart of the two-dimensional plasmonic photonic crystal with low-symmetry Bloch mode is shown in the figure, Figure 8 The specific steps of the preparation method of the two-dimensional plasmonic photonic crystal are as follows:
[0054] Step 1, making a plasmonic layer. Take α-phase molybdenum trioxide crystal as raw material, use adhesive tape to peel off the crystal, and after repeating 10-15 times, transfer the α-phase molybdenum trioxide nanosheet on the adhesive tape to the surface of polymethyl methacrylate substrate. Select α-phase molybdenum trioxide nanosheet with a thickness of 2nm and a length-width ratio of more than 10μm as the plasmonic layer.
[0055] Step 2, making a two-dimensional plasmonic photonic crystal. Adopt the method of laser direct writing, according to the pre-designed structure, etch the corresponding periodic through hole in the plasmonic layer. After annealing at 350℃, a two-dimensional plasmonic photonic crystal is obtained. The defect diameter is 20nm, the cell shape is rhombus, the period is 50nm, and the angle between the arrangement direction and the crystal axis of α-phase molybdenum trioxide is 0°.
[0056] Figure 9 The absorption spectrum of the calculated plasmonic photonic crystal with rhombus cell is obtained, and compared with the absorption spectrum of the plasmonic photonic crystal with square cell (period of 50nm) and rectangular cell (x, y direction period is 50, 40nm respectively). It can be seen that under the condition that other parameters remain unchanged, changing the arrangement mode and period of the photonic crystal in the y direction, the absorption peak of the photonic crystal does not change obviously, indicating that the photonic crystal is immune to the defect arrangement in the y direction, and can realize the in-plane unidirectional robust transmission of subwavelength plasmon.
Claims
1. A two-dimensional plasmonic photonic crystal with low-symmetry Bloch modes, characterized in that, The polariton layer is an in-plane anisotropic polariton material, and the polariton layer has a periodic defect structure. The polariton layer is made of at least one of alpha-phase molybdenum trioxide, alpha-phase vanadium pentoxide, black scale, silver telluride, tungsten telluride, cadmium tungstate, and calcite. The periodic defect structure is a through-hole structure periodically distributed through the polariton layer. The method for preparing the two-dimensional polariton photonic crystal with low-symmetry Bloch modes comprises the following steps: (1) providing a substrate layer; (2) preparing a polariton layer on the substrate layer; (3) preparing a periodic defect structure in the polariton layer; (4) annealing to solidify the structure to obtain the two-dimensional polariton photonic crystal with low-symmetry Bloch modes.
2. The two-dimensional plasmonic photonic crystal with low-symmetry Bloch modes of claim 1, wherein, The substrate layer is at least one of a metal material, an inorganic dielectric material, or an organic polymer material.
3. The two-dimensional plasmonic photonic crystal having a low-symmetry Bloch mode according to claim 2, wherein When the substrate layer is a metal material, it is at least one of gold, silver, and aluminum. When the substrate layer is an inorganic dielectric material, it is at least one of silicon dioxide, magnesium fluoride, and calcium fluoride. When the substrate layer is an organic polymer material, it is at least one of polymethyl methacrylate, polydimethylsiloxane, and polyethylene terephthalate.
4. The two-dimensional plasmonic photonic crystal with low-symmetry Bloch modes of claim 1, wherein, The thickness of the polariton layer is 2 nm to 2 μm.
5. The two-dimensional plasmonic photonic crystal with low-symmetry Bloch modes of claim 1, wherein, The cross section of each through-hole structure is at least one of a circle, a circular ring, an ellipse, a rectangle, a triangle, or a hexagon, and the characteristic size of each through-hole structure is 20 nm to 5 μm, and the distance from the center of a hole to the center of an adjacent hole is 50 nm to 10 μm.
6. The two-dimensional plasmonic photonic crystal with low-symmetry Bloch modes of claim 1, wherein, The cell shape of the two-dimensional polariton photonic crystal is at least one of a square, a rectangle, a triangle, or a hexagon, and the arrangement mode of the cell is one-dimensional linear arrangement or two-dimensional array arrangement.
7. The method of claim 1-6 for fabricating a two-dimensional plasmonic photonic crystal with low-symmetry Bloch modes, wherein, The method comprises the following steps: (1) providing a substrate layer; (2) preparing a polariton layer on the substrate layer; (3) preparing a periodic defect structure in the polariton layer; (4) annealing to solidify the structure to obtain the two-dimensional polariton photonic crystal with low-symmetry Bloch modes.
8. The preparation method according to claim 7, characterized in that, In step (2), the polariton layer is prepared by any one of the following methods: mechanical exfoliation, chemical deposition, or magnetron sputtering; In step (3), the periodic defect structure is prepared by any one of the following methods: focused ion beam etching, laser direct writing, or reactive ion etching.