Preparation method of gold nano array coupling photonic crystal microcavity based on tamm plasmon mode

Abstract

The application discloses a preparation method of a gold nano array coupled photonic crystal microcavity based on a Tamm plasmon mode, and aluminum is subjected to oxidation treatment through a periodic variable voltage method and an aluminum base at a back surface is removed to prepare an aluminum oxide photonic crystal. Gold nano arrays are used to replace a traditional gold film structure of a light incident surface, gold is evaporated on an oxidation surface and an aluminum-removed surface of the aluminum oxide photonic crystal through ion sputtering, and then a gold nano array-aluminum oxide photonic crystal-gold film microcavity structure is obtained. The preparation method of the gold nano array coupled photonic crystal microcavity based on the Tamm plasmon mode makes the preparation process simpler and more efficient, is convenient and easy to control, optimizes the absorption intensity of the Tamm plasmon, and further provides a wider freedom degree for the regulation of the Tamm plasmon mode.

Description

TECHNICAL FIELD

[0001] The present application relates to the fields of micro-nano structure preparation, design and optimization of micro-nano photonic devices and surface plasmon, and particularly relates to a preparation method of gold nano array coupling photonic crystal microcavity based on Tamm plasmon mode. BACKGROUND

[0002] Tamm plasmon is a novel surface localized plasmon mode in surface plasmon. Compared with the traditional surface plasmon, Tamm plasmon can be excited under normal incidence without a specific incident angle, and exhibits the same coupling effect under TE polarization and TM polarization. The excitation of Tamm plasmon mainly exists at the photonic crystal heterojunction and the metal-photonic crystal interface, and the mechanisms are different due to the different structures. The former is caused by the difference in refractive index of different photonic crystals to form Bragg reflection, which causes Tamm plasmon to be bound by the photonic band gap. The latter is caused by the Bragg reflection of electromagnetic waves on the surface of the photonic crystal and the negative dielectric constant of gold. Compared with the former, the Tamm plasmon generated at the metal-photonic crystal interface is not limited by the refractive index of the photonic crystal, and has stronger coupling performance and higher quality characteristics.

[0003] In recent years, due to the characteristics of easy excitation, narrow bandwidth and strong coupling of Tamm plasmon, people have achieved the design and optimization of micro-nano photonic devices based on Tamm plasmon in many fields, which has greatly improved the optical performance of the devices and widely applied in photoelectric detection, sensors, solar cells and other aspects. However, due to the limitations of the uniformity of the dielectric material and the complexity of the preparation process, the preparation of devices based on Tamm plasmon still faces challenges.

[0004] In the traditional metal-photonic crystal-metal structure, the metal generally exists in the form of a thin film. Tamm plasmon is excited at the interface between the gold film and the photonic crystal. Due to the limitation of the structure size, the coupling strength has certain limitations. By replacing the original gold film on the light incidence surface with a gold nano array, the excitation surface area of the interface can be effectively increased without expanding the overall structure size, which further enhances the capture ability of the structure to incident photons and greatly improves the coupling strength of Tamm plasmon. SUMMARY

[0005] The present application provides a preparation method of gold nano array coupling photonic crystal microcavity based on Tamm plasmon mode, to solve the problem of poor coupling performance of existing Tamm plasmon and make up for the deficiency of the preparation process of existing Tamm plasmon microcavity.

[0006] In order to achieve the above object, the technical scheme adopted by the present application is:

[0007] The preparation method of the gold nano array coupled photonic crystal microcavity based on Tamm plasmon mode comprises the following steps:

[0008] Step 1: A constant direct current voltage is used to perform primary oxidation treatment on a high-purity and clean aluminum sheet, and then a deoxidized layer treatment is performed thereon;

[0009] Step 2: The aluminum sheet obtained in step 1 is subjected to secondary oxidation by using a periodic variable voltage method, and after being washed and dried, the aluminum substrate on the back surface is removed by using a 9% copper chloride solution to prepare an aluminum oxide photonic crystal;

[0010] Step 3: The oxidation surface and the aluminum-removed surface of the aluminum oxide photonic crystal obtained in step 2 are subjected to gold evaporation treatment respectively to form a gold nano array-aluminum oxide photonic crystal-gold film microcavity structure;

[0011] Step 4: The reflection spectrum of the gold nano array-aluminum oxide photonic crystal-gold film microcavity structure formed after the gold evaporation in step 3 is tested by using an ultraviolet-visible-near infrared spectrophotometer.

[0012] Further, the primary oxidation in step 1 is performed in a 0.35 M oxalic acid solution under a constant voltage of 50 V and a constant temperature of 10 DEG C.

[0013] Further, in step 2, the oxidation conditions are the same as those of the primary oxidation, and the oxidation voltage process is: T a =120s, the voltage is kept constant at 25 V, T b =30s, the voltage is increased to 50 V at a slow-to-fast rate in a half-cosine manner, and T c =200s, the voltage is linearly decreased from 50 V to 25 V.

[0014] Further, in step 2, before removing the aluminum substrate on the back surface, the aluminum sheet is lightly polished with fine sandpaper to damage the oxide film formed on the surface of the aluminum.

[0015] Further, in step 3, the ion sputtering instrument is used to perform gold evaporation on the oxidation surface and the aluminum-removed surface respectively under the conditions of a gas pressure of 0.06 mPa and a current of 15 mA for 90 s and 60 s, wherein the gold nano array is arranged in an array along the holes of the aluminum oxide.

[0016] Further, the gold nano array, the aluminum oxide photonic crystal and the gold film are coupled together to form a Tamm plasmon microcavity.

[0017] Further, the Tamm plasmon resonance peak absorption intensity excited by the gold nano array-aluminum oxide photonic crystal-gold film microcavity structure reaches 71.5%.

[0018] Compared with the prior art, the present application has the advantages that: the present application provides a preparation method of gold nano array coupled photonic crystal microcavity based on Tamm plasmon mode. The aluminum oxide nanopores generated under periodic variable voltage oxidation are in the form of straight holes and bifurcated holes, and are stacked in layers to form an aluminum oxide photonic crystal with different refractive index layers. Compared with traditional photonic crystals, the preparation process is simple and efficient without the need for complex multilayer film structure processing such as photolithography and imprinting. The number of layers of the photonic crystal can be determined by setting the oxidation period. The gold nano array replaces the previous gold film to form a gold nano array-aluminum oxide photonic crystal-gold film microcavity structure, which can provide a wider excitation surface to enhance the ability to capture photons. The two resonances generated at the interface of the aluminum oxide photonic crystal and the gold nano array and the gold film are coupled at the same wavelength, the energy field is further enhanced, and good performance with narrow half peak width and high intensity is presented. Further, it provides a wider space for the regulation of Tamm plasmon mode. This has rich research significance in the fields of optoelectronic detection, sensors, solar cells and the like. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is the preparation flowchart of the gold nano array coupled photonic crystal microcavity based on Tamm plasmon mode in the present application.

[0020] Figure 2 is the periodic voltage and corresponding current diagram for preparing the aluminum oxide photonic crystal in the present application.

[0021] Figure 3 is the structure schematic diagram of the gold nano array coupled photonic crystal microcavity based on Tamm plasmon mode in the present application.

[0022] Figure 4 is the reflection spectrum diagram of the gold nano array coupled photonic crystal microcavity based on Tamm plasmon mode in the present application. DETAILED DESCRIPTION

[0023] The present application will be further described below in combination with the drawings and examples.

[0024] As shown in Figure 1 , the present embodiment discloses a preparation method of gold nano array coupled photonic crystal microcavity based on Tamm plasmon mode, comprising the following steps:

[0025] Step 1, cut high-purity aluminum sheet into a circular sheet with a diameter of 20 mm, and perform primary oxidation on the high-purity and clean aluminum sheet in a constant temperature water bath at 0.35 M oxalic acid solution, 50 V constant voltage and 10℃ constant temperature for 10 hours. After primary oxidation, the aluminum sheet is cleaned and dried, and then a deoxidized layer treatment is performed on it by using bichromic acid at 65℃ constant temperature for 20 hours.

[0026] Step 2, Preparation process of alumina photonic crystal:

[0027] (2.1) Adopting the following Figure 2 The periodic voltage variation shown, under the same conditions as the initial oxidation, further oxidizes the aluminum sheet obtained in step 1. The oxidation voltage process for a single cycle is: T a =120s, oxidation with voltage maintained at a constant 25V, T b =30s, the voltage rises to 50V at a rate that is first slow and then rapid, following a half-cosine pattern. T c =200s, the voltage drops linearly from 50V to 25V, when the voltage drops to 50V When the oxidation time reaches a certain value, the nanopores begin to grow in a branching pattern. After multiple cycles of oxidation, the alumina nanopores are stacked alternately in two states: straight pores and branched pores, forming alumina photonic crystals.

[0028] (2.2) Lightly sand the aluminum sheet obtained in step (2.1) with fine sandpaper to destroy the aluminum oxide film on the back aluminum surface. Then remove the aluminum substrate on the back using a 9% copper chloride solution to obtain a complete aluminum oxide photonic crystal.

[0029] Step 3: Using an ion sputtering instrument, the oxide surface and the dealuminized surface of the alumina photonic crystal obtained in step (2.2) are subjected to gold evaporation treatment for 90s and 60s respectively under the conditions of gas pressure 0.06 mPa and current 15mA to obtain the gold nanoarray-alumina photonic crystal-gold film microcavity structure.

[0030] Step 4: Using a UV-Vis-NIR spectrophotometer, select a wavelength range of 400nm-1000nm and test the reflection spectrum of the gold nanoarray-alumina photonic crystal-gold film microcavity structure formed after gold evaporation in Step 3 with the gold nanoarray as the perpendicular incident surface of the light. The absorption intensity of the excited Tamm plasmon resonance peak reaches 71.5%.

[0031] Figure 3 This diagram shows the structure and equivalent schematic of the gold nanoarray-alumina photonic crystal-gold film microcavity formed in this embodiment. It can be seen that because the alumina nanopores grow from top to bottom, the gold nanoarray is arranged in an array along with the alumina pores, increasing the excitation surface area of ​​the metal and photonic crystal, enhancing the localized energy field, and exhibiting a narrower resonance full width at half maximum (FWHM) and a higher resonance intensity. Furthermore, the alternating layers of straight pores and bifurcated layers in the alumina photonic crystal, due to their different porosities, can be equivalent to a photonic crystal composed of two layers of media with different effective refractive indices.

[0032] Figure 4The reflection spectrum of the gold nano array-alumina photonic crystal-gold film microcavity structure prepared in the embodiment is measured by using a UV-visible near infrared spectrophotometer under the condition of perpendicular incidence, and it can be seen from the figure that the visible near infrared wavelength range of 400nm-1000nm excites Tamm plasmon coupling at 715nm, so that the light field energy is enhanced, the reflection of light is highly suppressed, a downward reflection resonance peak is formed, the peak value is 28.5%, the half peak width is 12.5nm, the corresponding absorption intensity reaches 71.5%, and such narrow peak width and high intensity reflection absorption peak has rich research significance and practical value in subsequent related field research.

[0033] The preferred embodiments of the present application are described in detail above with reference to the drawings, and the embodiments described in the present application are only used to describe the preferred embodiments of the present application, and do not limit the concept and scope of the present application. In the above specific embodiments, various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction, and such combination should also be considered as disclosed by the present disclosure as long as it does not deviate from the technical concept of the present application. In order to avoid unnecessary repetition, various possible combinations are not described again in the present application.

[0034] The present application is not limited to the specific details in the above embodiments, and various modifications and improvements of the technical solutions of the present application made by those skilled in the art within the technical concept of the present application and without departing from the design idea of the present application should fall within the protection scope of the present application. The technical content of the present application claimed for protection has been fully recorded in the claims.

Claims

1. A method for preparing a gold nanoarray coupled photonic crystal microcavity based on Tamm plasmon mode, characterized in that, The method comprises the following steps: Step 1: primary oxidation treatment of high-purity and clean aluminum sheet by constant direct current voltage, and then removal of the oxide layer; Step 2: secondary oxidation treatment of the aluminum sheet obtained in step 1 by periodic variable voltage method, removal of the aluminum substrate on the back surface by 9% copper chloride solution after cleaning and drying, and preparation of an aluminum oxide photonic crystal; The oxidation condition in step 2 is the same as the primary oxidation, and the voltage process is: T a =120s, the voltage is kept constant at 25V for oxidation, T b =30s, the voltage is raised to 50V at a slow-to-fast rate in a half-cosine, T c =200s, the voltage is linearly decreased from 50V to 25V; Step 3: gold nano array-aluminum oxide photonic crystal-gold film microcavity structure formed by gold evaporation treatment on the oxidation surface and the aluminum-removed surface of the aluminum oxide photonic crystal obtained in step 2; Step 4: testing of the reflection spectrum of the gold nano array-aluminum oxide photonic crystal-gold film microcavity structure formed after gold evaporation in step 3 by ultraviolet-visible-near infrared spectrophotometer. 2.The method for preparing a Tamm plasmon mode based gold nanoarray coupled photonic crystal microcavity according to claim 1, wherein, The primary oxidation in step 1 is performed in a 0.35 M oxalic acid solution under a constant voltage of 50 V and a constant temperature of 10℃. 3.The method of claim 1, wherein, Before removing the aluminum substrate on the back surface in step 2, the aluminum sheet is slightly polished with fine sandpaper to destroy the oxide film formed on the surface of the aluminum sheet. 4.The method of claim 1, wherein, In step 3, the gold evaporation treatment is performed on the oxidation surface and the aluminum-removed surface by ion sputtering instrument under the conditions of a gas pressure of 0.06 mPa and a current of 15 mA for 90 s and 60 s, respectively, and the gold nano array is arranged in an array along the holes of the aluminum oxide.

5. The method for fabricating a gold nanoarray-coupled photonic crystal microcavity based on Tamm plasmon modes according to any one of claims 1-4, characterized in that, The Tamm plasmon microcavity is formed by the coupling of the gold nano array, the aluminum oxide photonic crystal and the gold film.

6. The method of claim 5, wherein the Tamm plasmon mode based gold nanoarray coupled photonic crystal microcavity is prepared by the steps of: The Tamm plasmon resonance peak absorption intensity excited by the gold nano array-aluminum oxide photonic crystal-gold film microcavity structure reaches 71.5%.

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