Intermediate infrared hyperbolic phonon polariton out-of-plane resonator and preparation method and application thereof

Abstract

The invention relates to the technical field of micro-nano resonators, and particularly discloses a mid-infrared hyperbolic phonon polariton out-of-plane resonator and a preparation method and application thereof. A hyperbolic reflection boundary is formed on a gold substrate through a micro-nano processing technology, directional transfer of alpha-MoO3 is carried out through a two-dimensional material transfer method, and a gold / alpha-MoO3 composite structure is obtained. Alpha-MoO3 can be coupled with mid-infrared electromagnetic waves to form hyperbolic phonon polaritons with high anisotropy and low optical loss, and the hyperbolic reflection boundary on the gold substrate can realize accurate regulation and control and resonance of hyperbolic phonon polariton propagation outside the molybdenum trioxide surface. Through combination of numerical simulation analysis and real space near-field imaging characterization, the physical essence that the gold boundary enhances polariton reflection and realizes resonance is disclosed. By optimizing incident light frequency and cavity structure parameters, a mid-infrared light local light field can be compressed to a mode volume of only 8 * 10 <-6 > mu m < 3 >, and a quality factor up to 71.41 is obtained.

Description

Technical Field

[0001] The present invention belongs to the field of micro-nano resonators, and in particular relates to a mid-infrared hyperbolic phonon polariton out-of-plane resonator and a preparation method and application thereof. Background Art

[0002] As core components of modern photonic devices, micro-nano optical resonators hold significant application value in fields such as optical field manipulation, quantum information processing, and ultrasensitive sensing. Currently, mainstream micro-nano optical resonators fall into two main categories: metal-based surface plasmon resonators and acoustic wave resonators. However, traditional metal-based surface plasmon resonators are significantly limited by their inherent high losses and short photon lifetimes, significantly hindering their performance and effectiveness in practical applications. Therefore, exploring new low-loss resonance mechanisms based on polaritons has become a key research direction to overcome existing technological bottlenecks. By introducing new polaritons (such as hyperbolic phonon polaritons), optical losses can be significantly reduced and photon lifetimes can be extended, thus opening up new possibilities for achieving higher-precision optical field manipulation and more efficient quantum information processing. This research direction not only provides an important avenue for improving the performance of photonic devices but also lays the foundation for a wide range of future applications in ultrasensitive sensing, integrated optics, and optoelectronics, presenting a promising future.

[0003] In recent years, molybdenum trioxide has attracted much attention due to its unique optical properties—natural hyperbolic properties and strong anisotropy. The synergistic effect of its low loss characteristics and high-momentum hyperbolic phonon polaritons provides an important physical basis for breaking through the traditional wavelength compression limit of light. Therefore, molybdenum trioxide can serve as a new research platform, opening up new directions for the study of micro-nano optical resonators. However, this material faces the following challenges in resonator applications: the coupling mechanism of in-plane and out-of-plane polariton propagation modes is unclear, which restricts the ability to control three-dimensional light fields. Therefore, the study of molybdenum trioxide phonon polariton resonant cavities is currently a research focus. Summary of the Invention

[0004] The purpose of the present invention is to address the shortcomings of the existing technology and provide a mid-infrared hyperbolic phonon polariton out-of-plane resonator and its preparation method and application. The nanostructure has a resonant regulating effect on the hyperbolic phonon polariton and improves the performance of the resonator, with a high quality factor and a low mode volume.

[0005] To achieve the above object, the present invention adopts the following technical solutions: The first object of the present invention is to provide a mid-infrared hyperbolic phonon polariton out-of-plane resonator, characterized in that the mid-infrared hyperbolic phonon polariton out-of-plane resonator is composed of a composite formed by a gold substrate after micro-nano processing and α-MoO3, wherein the α-MoO3 is arranged on the upper surface of the gold substrate, the thickness of the α-MoO3 is 50~250nm, and the pattern obtained by micro-nano processing is hyperbolic, and the formula is as follows: , Where x and y are the horizontal and vertical coordinates of the boundary points of the hyperbolic cavity, respectively; is the hyperbolic cavity angle; It is a hyperbolic cavity interval.

[0006] Furthermore, the micro-nano processing process is to use a focused ion beam (FIB) etching method to process a hyperbolic reflection boundary on a gold substrate.

[0007] Furthermore, the hyperbolic cavity angle φ ranges from 45° to 70°, the hyperbolic cavity gap ranges from 100 to 450 nm, 0.1 μm<|x|<0.5 μm, and 0.5 μm<|y|<0.7 μm.

[0008] A second object of the present invention is to provide a method for preparing the above-mentioned mid-infrared hyperbolic phonon polariton out-of-plane resonator, comprising the following steps: S1. Using a dual-temperature zone tubular furnace to perform physical vapor deposition to prepare α-MoO3 single crystals; S2. Mechanically exfoliating the α-MoO3 single crystal, placing the resulting single crystal on a tape, and then folding the tape in half multiple times and laminating it with an adhesive organic flexible substrate to obtain a nanoscale α-MoO3 flake; S3, using focused ion beam etching to process a hyperbolic reflection boundary on a gold substrate to obtain a gold substrate with a hyperbolic cavity, and then transferring the α-MoO3 thin sheet to the gold substrate, so that the adhesive flexible substrate of the α-MoO3 thin sheet is bonded to the gold substrate, and then fixed by heating; S4. Cleaning the α-MoO3 nanosheets transferred to the gold substrate obtained in S3 to remove the residual adhesive on the surface, thereby obtaining the mid-infrared hyperbolic phonon polariton out-of-plane resonator.

[0009] Furthermore, in step S1, the purity of the molybdenum trioxide powder used is not less than 99.9%.

[0010] Furthermore, the parameters of the dual-zone tubular furnace were set as follows: the temperature of the first zone was set to 750–780 °C, the heating rate was 5–10 °C / min, the holding time was 8–10 h, and an argon–oxygen mixture with a ratio of 2:1–4:1 was used as the carrier gas; the temperature of the second zone was set to 650–680 °C, the heating rate was 5–10 °C / min, the holding time was 8–10 h, and finally natural cooling was performed.

[0011] Furthermore, in step S2, the tape is an Ultron system blue film tape, the organic flexible substrate is polydimethylsiloxane, and the tape is folded 2 to 4 times.

[0012] Furthermore, in step S3, the processing current is 24-80 pA, and the processing depth is 60-100 nm.

[0013] Furthermore, in step S3, the heating temperature is 80-100°C, the heating rate is 5-10°C / min, and the holding time is 10-15 min.

[0014] The third object of the present invention is to provide the use of the above-mentioned mid-infrared phonon polariton out-of-plane resonator in the preparation of ultra-sensitive sensing and / or on-chip integrated optical circuit devices.

[0015] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects: (1) The present invention proposes an out-of-plane optical resonator based on a gold / α-MoO3 composite structure. Specifically, α-MoO3, as a natural hyperbolic material, can efficiently couple with light in the mid-infrared band to form hyperbolic phonon polaritons. These polaritons have high anisotropy and low optical loss characteristics. The gold hyperbolic reflection boundary obtained by focused ion beam etching can successfully achieve precise control of the propagation direction and energy density of the hyperbolic phonon polaritons in α-MoO3 in the composite structure. Compared with traditional optical resonators, the resonator has a larger quality factor Q and a smaller mode volume V. m It is smaller and is expected to be used in ultra-sensitive sensing, molecular detection and other fields. It also provides new ideas for the design of phonon polariton resonant cavities.

[0016] (2) The inventive concept provided by the present invention is to achieve an enhanced out-of-plane reflection effect of hyperbolic phonon polaritons by designing the boundary of the gold substrate, further resonating and enhancing the light field energy. At the same time, the resonator performance is tunable. The resonator performance can be controlled by changing the structural parameters (hyperbolic cavity angle, hyperbolic cavity spacing) and the incident frequency of light, which also provides convenience for subsequent practical applications.

[0017] (3) The raw materials required by the present invention are low in cost, the process operation is simple, and it meets environmental protection requirements. In addition, the material has promising application prospects in optical communications and sensors. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the gold substrate hyperbolic cavity structure prepared by the present invention; Figure 2 Schematic diagram of the structure of the mid-infrared hyperbolic phonon polariton out-of-plane resonator prepared by the present invention; Figure 3 This is a scanning electron microscope image of the gold substrate hyperbolic nanostructure prepared by the present invention; Figure 4 This is a common optical photograph of the gold / α-MoO3 hyperbolic phonon polariton out-of-plane reflection enhanced resonator constructed by the present invention; Figure 5 Simulated diagrams of the light field distribution on the surface and cross section of the gold / α-MoO3 hyperbolic phonon polariton in-plane negative reflection resonator constructed by the present invention at different incident light frequencies; Figure 6 This is an experimental diagram of the surface light field distribution of the gold / α-MoO3 hyperbolic phonon polariton in-plane negative reflection resonator constructed by the present invention at different incident light frequencies; Figure 7 The near-field optical amplitude images of the gold / α-MoO3 hyperbolic phonon polariton in-plane negative reflection resonator constructed by the present invention are extracted along the central axis of the molybdenum trioxide hyperbolic cavity at different incident light frequencies; Figure 8 This is an experimental diagram of the surface light field distribution of the gold / α-MoO3 hyperbolic phonon polariton in-plane negative reflection resonator constructed by the present invention at different hyperbolic cavity angles; Figure 9 The near-field optical amplitude images of the gold / α-MoO3 hyperbolic phonon polariton in-plane negative reflection resonator constructed by the present invention are extracted along the central axis of the molybdenum trioxide hyperbolic cavity under different hyperbolic cavity angle conditions; Figure 10 This is an experimental diagram of the surface light field distribution of the gold / α-MoO3 hyperbolic phonon polariton in-plane negative reflection resonator constructed by the present invention at different hyperbolic cavity angles; Figure 11 The light field intensity in the center area of the gold / α-MoO3 hyperbolic phonon polariton in-plane negative reflection resonator constructed by the present invention at different incident light frequencies when the hyperbolic cavity spacing is 250nm and the hyperbolic cavity angle is 60°; Figure 12The trend line of the resonant frequency and half-maximum width of the gold / α-MoO3 hyperbolic phonon polariton in-plane negative reflection resonator constructed by the present invention when the hyperbolic cavity angle is 60° changes with the hyperbolic cavity spacing; Figure 13 The trend line of the quality factor of the gold / α-MoO3 hyperbolic phonon polariton in-plane negative reflection resonator constructed by the present invention when the hyperbolic cavity angle is 60° changes with the hyperbolic cavity spacing; Figure 14 This is the trend line of the mode volume changing with the hyperbolic cavity spacing of the gold / α-MoO3 hyperbolic phonon polariton in-plane negative reflection resonator constructed by the present invention when the hyperbolic cavity angle is 60°. DETAILED DESCRIPTION

[0019] To make the purpose, technical solutions and advantages of the present invention clearer, the specific embodiments of the present invention are described in further detail below in conjunction with specific examples and accompanying drawings. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this field or the product specifications are used. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be obtained commercially.

[0020] The present invention provides a mid-infrared hyperbolic phonon polariton out-of-plane resonator. By micro-nanofabrication of a gold substrate and transferring α-MoO3 using a two-dimensional material transfer method, a gold / α-MoO3 composite structure is obtained. The pattern obtained by micro-nanofabrication is hyperbolic, and the formula is as follows:

[0021] Where x and y are the horizontal and vertical coordinates of the boundary points of the hyperbolic cavity, respectively; is the hyperbolic cavity angle; It is a hyperbolic cavity interval.

[0022] In the specific implementation, the plane effect of the gold substrate after micro-nano processing is as follows Figure 1 As shown in the figure, the cavity angle φ ranges from 45° to 70°, and the cavity gap gap ranges from 100 nm to 450 nm. The cavity center is the origin, and x and y are the horizontal and vertical coordinates of the cavity boundary points (where 0.1 μm < |x |< 0.5 μm, and 0.5 μm < |y |< 0.7 μm).

[0023] The gold / α-MoO3 composite structure is specifically that α-MoO3 is arranged on the upper surface of the gold substrate, and the bottom of the gold substrate is a silicon dioxide / silicon substrate (the gold substrate can be obtained commercially), such as Figure 2 As shown. The thickness of α-MoO3 ranges from 50 to 250 nm. The specific preparation method is as follows: (1) α-MoO3 single crystals were prepared by physical vapor deposition using a dual-zone tubular furnace. High-purity molybdenum trioxide powder was selected as the source and placed in the first temperature zone. A certain ratio of argon and oxygen was introduced as carrier gases. The temperature difference between the first and second temperature zones caused crystallization to occur, forming α-MoO3 bulk single crystals.

[0024] In a specific implementation, the molybdenum oxide powder has a purity of 99.98-99.998% and a mass of 0.1-1 g. The parameters of the dual-zone tubular furnace are set as follows: the first zone is set at 750-780°C, with a heating rate of 5-10°C / min and a holding time of 8-10 hours. An argon-oxygen mixture with a ratio of 2:1-4:1 is used as the carrier gas. The second zone is set at 650-680°C, with a heating rate of 5-10°C / min and a holding time of 8-10 hours, followed by natural cooling.

[0025] (2) Mechanical exfoliation of α-MoO3 single crystals. Select a well-shaped molybdenum trioxide single crystal and place it on a tape. Then, fold the tape in half several times and laminate it to an organic flexible substrate to obtain nanoscale α-MoO3 flakes.

[0026] In a specific implementation, the tape can be selected from Ultron system blue film tape, the organic flexible substrate can be selected from PDMS, and the tape is preferably folded 2 to 4 times.

[0027] (3) Focused Ion Beam Etching of Gold Substrates. Design the desired processing pattern using Klayout drawing software. Import the designed pattern into the focused ion beam etching system through file conversion and interface. In the system, select the appropriate processing current and processing depth to etch the gold substrate.

[0028] In a specific implementation, during the focused ion beam etching process, the processing current is preferably 24-80 pA, and the processing depth is 60-100 nm.

[0029] (4) Transfer to the target substrate. Place the gold substrate after micro-nano processing on the heating platform of the two-dimensional material transfer platform. Use the lifting platform to bond the PDMS with nano-scale α-MoO3 flakes to the gold substrate. Heat for a period of time and keep it warm. Then, measure the thickness of the α-MoO3 nanosheets.

[0030] In a specific implementation, the heating temperature is preferably 80-100°C, the heating rate is 5-10°C / min, and the holding time is 10-15 min.

[0031] (5) Remove the residual glue on the sample surface. The α-MoO3 nanosheets transferred to the gold substrate are transferred to an oxygen plasma cleaner for a certain period of cleaning. After cleaning, they are stored in a vacuum environment for future use.

[0032] In a specific embodiment, the cleaning method is preferably an oxygen plasma cleaning method, the mode is a high-pressure mode, and the cleaning time is 5 to 15 minutes.

[0033] The mid-infrared hyperbolic phonon polariton out-of-plane resonators prepared by the above method have excellent regulatory effects on the propagation of hyperbolic phonon polaritons, and also have the characteristics of enhancing the out-of-plane localized light field.

[0034] The embodiments of the present invention have achieved some positive results during the development or use process, and indeed have great advantages over the existing technology. The following content describes them in conjunction with data, charts, etc. from the experimental process.

[0035] Example 1 This embodiment provides a method for preparing a mid-infrared hyperbolic phonon polariton out-of-plane resonator (gold / α-MoO3 hyperbolic phonon polariton out-of-plane negative reflection resonator); (1) α-MoO3 single crystals were prepared by physical vapor deposition in a dual-zone tube furnace. Molybdenum trioxide powder with a purity of 99.998% and a mass of 0.1 g was selected as the source and placed in the first zone. The temperature of the first zone was set to 750°C, the heating rate was 5°C / min, the holding time was 8 h, and an argon-oxygen mixture with a ratio of 2:1 was used as the carrier gas. The temperature of the second zone was set to 650°C, the heating rate was 5°C / min, the holding time was 8 h, and the sample was cooled naturally. (2) The α-MoO3 single crystal obtained above was folded twice with Ultron system blue film tape and bonded to an organic flexible substrate to obtain a nanoscale α-MoO3 flake; (3) Use focused ion beam etching to process the hyperbolic boundary of the gold substrate, select the processing current of 24pA and the processing depth of 100nm; (4) Using a two-dimensional material transfer system, the PDMS with nanoscale α-MoO3 flakes was bonded to a gold substrate and heated to 80°C for 15 minutes. The thickness of the α-MoO3 nanosheets was then measured. The surface adhesive residue was removed using an oxygen plasma cleaner for 5 minutes. The sample was stored in a vacuum until subsequent near-field testing.

[0036] The gold / α-MoO3 hyperbolic phonon polariton out-of-plane negative reflection resonator prepared by the above method has an α-MoO3 thickness of 155 nm and a hyperbolic cavity length of 1 μm.

[0037] like Figure 3Figure 2 shows scanning electron microscope images of gold / α-MoO3 hyperbolic phonon polariton out-of-plane enhanced reflection resonators with different hyperbolic cavity spacings, obtained using focused ion beam etching (ThermoFisher Helios G4 CX) in Example 1. Due to the excellent conductivity of the gold substrate, the etched patterns have clear boundaries and a complete image.

[0038] like Figure 4 , which is a common optical image of the gold / α-MoO3 hyperbolic phonon polariton out-of-plane enhanced reflection resonator constructed in Example 1. The thickness of α-MoO3 is 155 nm.

[0039] like Figure 5 The following are the simulated distributions of the surface and cross-sectional light fields of the gold / α-MoO3 hyperbolic phonon polariton out-of-plane enhanced reflection resonator constructed in Example 1 at different incident light frequencies. The incident light source set in this simulation is ω = 890, 900, 910, 920 cm -1 , where the structural parameters of the resonant cavity are: gap = 250 nm; φ = 60°; h = 1 μm; and the thickness of α-MoO3 is 155 nm. Figure 5 (ad) and Figure 5 (eh) are the square distributions of

[010] and

[001] planes respectively. Figure 5 As shown in (ad), polaritons propagate in α-MoO3 in a zigzag waveguide mode. When light strikes the corner boundary of gold, reflection occurs. As the frequency of the incident light increases from 890 cm -1 Increased to 920 cm -1 , the light beam will be reflected from the lower surface to the upper surface of the molybdenum oxide more and more frequently. This phenomenon is normal because the wavelength of the polaritons themselves decreases as the frequency of the incident light increases. In addition, when the frequency of the incident light is 910 cm⁻¹, the reflection paths on both sides of the gold boundary coincide with each other and complete a complete reflection jump above the two gold boundaries. Compared with the incident light frequency of 900 cm⁻¹, the light path is significantly enhanced by reflection. Therefore, a relationship can be obtained: when λ p = gap, the polaritons will experience a reflection resonance enhancement effect.

[0040] like Figure 6 The figure shows the light field distribution of the gold / α-MoO3 hyperbolic phonon polariton out-of-plane enhanced reflection resonator constructed in Example 1 at different incident light frequencies. The incident light source of this experiment is ω = 875, 880, 885, 890, 895, 890 cm -1, where the resonator structural parameters are: gap = 250 nm; φ = 60°; and α-MoO3 thickness is 155 nm. The experimental results differ slightly from the simulations, showing varying degrees of resonance enhancement at the six test frequencies. This is because in actual experiments, polaritons experience inevitable propagation losses, resulting in relatively small differences in the wavelengths of polaritons excited by incident light at different frequencies. Therefore, samples with identical structural parameters can resonate at multiple frequencies.

[0041] like Figure 7 As shown, in order to analyze the effect of frequency on the resonator performance under this structural condition, Figure 4 The near-field optical amplitude image extracted along the central axis of the resonator. After comparative analysis, it is found that when ω = 880 cm -1 When the light field intensity reaches its highest level, the resonance effect is the best. This indicates that the excitation condition at this time is the incident frequency that achieves the strongest resonance. It also reflects that after the structural parameters of the optical cavity are fixed, the optical cavity will have the best resonance performance at a certain frequency.

[0042] like Figure 8 The figure shows the near-field optical distribution of the gold / α-MoO3 hyperbolic phonon polaritons out-of-plane enhanced reflection resonator constructed in Example 2 at different hyperbolic cavity angles. The incident light source ω = 870 cm -1 The resonator structure parameters are: gap = 250 nm; φ = 45°, 50°, 55°, 60°, 65°, 70°; and the thickness of α-MoO3 is 155 nm. The results show that all six cavities with different φ exhibit resonance enhancement.

[0043] like Figure 9 As shown, in order to analyze the effect of the hyperbolic cavity angle on the resonator performance, along Figure 6 The near-field optical amplitude image extracted along the central axis of the resonator. Comparative analysis revealed that the optical field intensity reaches its peak when φ = 60°. Therefore, the subsequent hyperbolic cavity angle is fixed at 60°.

[0044] like Figure 10 The figure shows the near-field optical distribution of the gold / α-MoO3 hyperbolic phonon polaritons out-of-plane enhanced reflection resonator constructed in Example 3 at different hyperbolic cavity spacings. The incident light source of this experiment is ω = 870 cm -1 , where the resonator structure parameters are: gap = 200, 250, 300, 350, 400, 450 nm; φ = 60°; the thickness of α-MoO3 is 155 nm. From the experimental results, when ω = 870 cm -1When gap = 200, 250, 300, and 350 nm, the near-field response is better. When gap = 400 and 450 nm, the optical field intensity becomes significantly weaker, indicating that the gap has a regulatory effect on the resonance performance of the hyperbolic optical cavity.

[0045] like Figure 11 Shown, showing Figure 8 Scatter plot of the optical intensity extracted at different frequencies in the center of the cavity when gap = 250 nm. After fitting, a quadratic curve is formed. The vertex of the quadratic curve corresponds to the optimal resonance frequency ω res , and its half-width is δω, which represents the frequency range in which the optical cavity can resonate.

[0046] like Figure 12 As shown, in order to explore the effect of the hyperbolic cavity spacing on the resonant cavity performance, the ω of the resonant cavity with different hyperbolic cavity spacing is res and δω were statistically analyzed and found that ω res As the gap increases, the polariton wavelength shifts toward lower frequencies. Specifically, as the gap widens, the polariton wavelength needs to be longer to properly match the gap, thereby achieving resonance. Simultaneously, δω also shows a decreasing trend as the gap increases. This means that as the gap widens, the frequency range within which the cavity can resonate decreases, resulting in a more selective resonance. This property facilitates the transmission and processing of optical signals at specific frequencies, allowing for more precise and rigorous selection of the cavity's resonant frequency.

[0047] like Figure 13 As shown in the figure, the effect of the hyperbolic cavity spacing on the quality factor of the resonant cavity is further explored. Quality factor Q = ω res / δω, it is found through calculation that when gap = 450 nm, the quality factor is even greater, 71.41, and the cavity performance is better.

[0048] like Figure 14 As shown in Figure 2, the effect of the hyperbolic cavity spacing on the resonant cavity mode volume is further explored. m =V / λ0 3 , it is found through calculation that when gap = 450 nm, the mode volume is even smaller, 8×10 -6 μm 3 , the resonant cavity performance is better.

[0049] Combined with the above results, when the thickness of α-MoO3 is 155 nm, the corresponding gap is 450 nm; and when φ = 60°, the gold / α-MoO3 hyperbolic phonon polariton out-of-plane enhanced reflection resonator exhibits good optical performance.

[0050] Example 2 This embodiment provides a method for preparing a mid-infrared hyperbolic phonon polariton out-of-plane resonator (gold / α-MoO3 hyperbolic phonon polariton out-of-plane negative reflection resonator); (1) α-MoO3 single crystals were prepared by physical vapor deposition in a dual-zone tube furnace. Molybdenum trioxide powder with a purity of 99.998% and a mass of 0.5 g was selected as the source and placed in the first zone. The temperature of the first zone was set to 765°C, the heating rate was 8°C / min, the holding time was 9 h, and an argon-oxygen mixture with a ratio of 3:1 was used as the carrier gas. The temperature of the second zone was set to 675°C, the heating rate was 8°C / min, the holding time was 9 h, and the sample was cooled naturally. (2) The α-MoO3 single crystal obtained above was folded in half three times using Ultron system blue film tape and then bonded to an organic flexible substrate to obtain a nanoscale α-MoO3 flake; (3) Use focused ion beam etching to process the hyperbolic boundary of the gold substrate, select the processing current of 40pA and the processing depth of 80nm; (4) Using a two-dimensional material transfer system, the PDMS with nanoscale α-MoO3 flakes was bonded to a gold substrate and heated to 90°C for 12 minutes. The thickness of the α-MoO3 nanosheets was then measured. The surface adhesive residue was removed using an oxygen plasma cleaner for 10 minutes. The sample was stored in a vacuum chamber pending subsequent near-field testing.

[0051] Example 3 This embodiment provides a method for preparing a mid-infrared hyperbolic phonon polariton out-of-plane resonator (gold / α-MoO3 hyperbolic phonon polariton out-of-plane negative reflection resonator); (1) α-MoO3 single crystals were prepared by physical vapor deposition in a dual-zone tube furnace. Molybdenum trioxide powder with a purity of 99.998% and a mass of 1 g was selected as the source and placed in the first zone. The temperature of the first zone was set to 780°C, the heating rate was 10°C / min, the holding time was 10 h, and an argon-oxygen mixture with a ratio of 4:1 was used as the carrier gas. The temperature of the second zone was set to 680°C, the heating rate was 10°C / min, the holding time was 10 h, and the sample was cooled naturally. (2) The α-MoO3 single crystal obtained above was folded in half four times using Ultron system blue film tape and bonded to an organic flexible substrate to obtain a nanoscale α-MoO3 flake; (3) Use focused ion beam etching to process the hyperbolic boundary of the gold substrate, select the processing current of 80 Pa and the processing depth of 60 nm; (4) Using a two-dimensional material transfer system, the PDMS with nanoscale α-MoO3 flakes was bonded to a gold substrate and heated to 100°C for 10 minutes. The thickness of the α-MoO3 nanosheets was then measured. The surface adhesive residue was removed using an oxygen plasma cleaner for 15 minutes. The sample was stored in a vacuum chamber pending subsequent near-field testing.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A mid-infrared hyperbolic phonon polariton out-of-plane resonator, characterized in that: The mid-infrared hyperbolic phonon polariton out-of-plane resonator is composed of a composite of a gold substrate processed by micro-nano processing and α-MoO3. The α-MoO3 is arranged on the upper surface of the gold substrate. The thickness of the α-MoO3 is 50-250 nm. The pattern obtained by micro-nano processing is hyperbolic, and the formula is as follows: , Where x and y are the horizontal and vertical coordinates of the boundary points of the hyperbolic cavity, respectively; is the hyperbolic cavity angle; It is a hyperbolic cavity interval.

2. The mid-infrared hyperbolic phonon polariton out-of-plane resonator according to claim 1, wherein: The micro-nano processing process is to use a focused ion beam (FIB) etching method to process a hyperbolic reflection boundary on a gold substrate.

3. The mid-infrared hyperbolic phonon polariton out-of-plane resonator according to claim 2, wherein: The hyperbolic cavity angle φ ranges from 45° to 70°, the hyperbolic cavity gap ranges from 100 to 450 nm, 0.1μm < ∣x∣ < 0.5 μm, 0.5 μm < ∣y∣ <0.7 μm.

4. A method for preparing a mid-infrared hyperbolic phonon polariton out-of-plane resonator according to claim 1, characterized in that: The following steps are involved: S1. Using a dual-temperature zone tubular furnace to perform physical vapor deposition to prepare α-MoO3 single crystals; S2. Mechanically exfoliating the α-MoO3 single crystal, placing the resulting single crystal on a tape, and then folding the tape in half multiple times and laminating it with an adhesive organic flexible substrate to obtain a nanoscale α-MoO3 flake; S3, using focused ion beam etching to process a hyperbolic reflection boundary on a gold substrate to obtain a gold substrate with a hyperbolic cavity, and then transferring the α-MoO3 thin sheet to the gold substrate, so that the adhesive flexible substrate of the α-MoO3 thin sheet is bonded to the gold substrate, and then fixed by heating; S4. Cleaning the α-MoO3 nanosheets transferred to the gold substrate obtained in S3 to remove the residual adhesive on the surface, thereby obtaining the mid-infrared hyperbolic phonon polariton out-of-plane resonator.

5. The preparation method according to claim 4, wherein In step S1, the purity of the molybdenum trioxide powder used is not less than 99.9%.

6. The preparation method according to claim 5, wherein The parameters of the dual-zone tubular furnace are set as follows: the temperature of the first zone is set to 750~780℃, the heating rate is 5~10℃ / min, the holding time is 8~10 h, and an argon-oxygen mixture with a ratio of 2:1~4:1 is used as the carrier gas. The temperature of the second zone is set to 650~680℃, the heating rate is 5~10℃ / min, the holding time is 8~10 h, and finally natural cooling is carried out.

7. The preparation method according to claim 4, wherein In step S2, the tape is Ultronsystem blue film tape, the organic flexible substrate is polydimethylsiloxane, and the tape is folded 2 to 4 times.

8. The preparation method according to claim 4, wherein In step S3, the processing current is 24-80 pA, and the processing depth is 60-100 nm.

9. The preparation method according to claim 4, wherein In step S3, the heating temperature is 80-100°C, the heating rate is 5-10°C / min, and the holding time is 10-15 min.

10. Use of the mid-infrared phonon polariton out-of-plane resonator according to any one of claims 1 to 3 in the preparation of ultrasensitive sensing and / or on-chip integrated optical devices.

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