Preparation method of gold nano array coupled photonic crystal microcavity based on Tamm plasmon mode

Abstract

The invention discloses a preparation method of a gold nano array coupled photonic crystal microcavity based on a Tamm plasmon mode, and the method comprises the steps: carrying out the oxidation treatment of an aluminum sheet through a periodic variable voltage method, and removing a back aluminum substrate, thereby obtaining an aluminum oxide photonic crystal. A gold film structure of a traditional light incident surface is replaced by a gold nano array, gold evaporation is carried out on an oxidation surface and an aluminum removal surface of an aluminum oxide photonic crystal through ion sputtering, and then the gold nano array-aluminum oxide photonic crystal-gold film microcavity structure is obtained. According to the preparation method of the gold nano array coupled photonic crystal microcavity based on the Tamm plasmon mode, the preparation process is simpler, more efficient, convenient and easy to control, and the absorption intensity of Tamm plasmon is optimized, so that a wider degree of freedom is provided for regulation and control of the Tamm plasmon mode.

Description

Technical Field

[0001] The invention relates to the field of micro-nano structure preparation, design and optimization of micro-nano photonic devices and surface plasmon, and specifically to a method for preparing a gold nanoarray-coupled photonic crystal microcavity based on a Tamm plasmon mode. Background Art

[0002] Tamm plasmon is a novel surface localized plasmon mode among surface plasmons. Compared with traditional surface plasmons, Tamm plasmon can be excited under normal incidence conditions without the need for a specific incident angle, and exhibits the same coupling effect under TE polarization and TM polarization conditions. The excitation of Tamm plasmon mainly exists at the photonic crystal heterojunction and the metal-photonic crystal interface. Due to the different structures of the two, the generation mechanisms are also different. The former is due to the difference in the refractive index of different photonic crystals, which forms Bragg reflection, causing Tamm plasmon to be bound by the photonic bandgap; the latter is caused by the Bragg reflection of electromagnetic waves on the surface of photonic crystals 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 Tamm plasmons such as easy excitation, narrow bandwidth, and strong coupling, people have realized the design and optimization of micro-nano photonic devices based on Tamm plasmons in many fields, which has greatly improved the optical performance of the devices and is widely used in photoelectric detection, sensors, solar cells, etc. However, due to the limitations of insufficient uniformity of dielectric materials and the complexity of the preparation process, the preparation of devices based on Tamm plasmons still faces challenges.

[0004] In traditional metal-photonic crystal-metal structures, metal generally exists in the form of thin films. When Tamm plasmons are excited at the interface between the gold film and the photonic crystal, the coupling strength is limited due to the size of the structure. However, replacing the original gold film on the light incident surface with a gold nanoarray can effectively increase the excitation surface area of ​​the interface without expanding the overall structure size, further enhancing the structure's ability to capture incident photons and greatly improving the coupling strength of Tamm plasmons. Summary of the invention

[0005] The present invention provides a method for preparing a gold nanoarray-coupled photonic crystal microcavity based on a Tamm plasmon mode, so as to solve the problem of poor coupling performance of existing Tamm plasmons and to make up for the shortcomings of the existing preparation process of Tamm plasmon microcavity.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is: The method for preparing a gold nanoarray coupled photonic crystal microcavity based on Tamm plasmon mode comprises the following steps: Step 1: using a constant DC voltage to perform a primary oxidation treatment on a high-purity and clean aluminum sheet, and then performing a deoxidation treatment on the aluminum sheet; Step 2: The aluminum sheet obtained in step 1 is oxidized again by a periodic voltage variation method, and after cleaning and drying, the aluminum substrate on the back is removed by a 9% copper chloride solution to prepare an aluminum oxide photonic crystal; Step 3, the oxidized surface and the de-aluminized surface of the alumina photonic crystal obtained in step 2 are subjected to gold evaporation treatment respectively to form a gold nanoarray-alumina photonic crystal-gold film microcavity structure; Step 4: Testing the reflection spectrum of the gold nanoarray-aluminum oxide photonic crystal-gold film microcavity structure formed after gold evaporation in step 3 by using an ultraviolet-visible-near infrared spectrophotometer.

[0007] Furthermore, the initial oxidation in step 1 is carried out under the conditions of 0.35 M oxalic acid solution, 50 V constant voltage, and 10° C. constant temperature.

[0008] Furthermore, in step 2, the oxidation conditions are the same as the initial oxidation, and the oxidation voltage process is: T a = 120s, voltage maintained at 25V constant oxidation, T b =30s, the voltage rises to 50V at a rate of half cosine at first slow and then fast, T c =200s, the voltage drops linearly from 50V to 25V.

[0009] Furthermore, in step 2, the aluminum sheet is lightly polished with fine sandpaper before removing the back aluminum substrate to destroy the oxide film formed on the aluminum surface.

[0010] Furthermore, in step 3, an ion sputtering apparatus was used to evaporate gold on the oxidized surface and the de-aluminized surface for 90 s and 60 s respectively at a gas pressure of 0.06 mPa and a current of 15 mA, wherein the gold nanoarrays were arranged in an array along the alumina pores.

[0011] Furthermore, the gold nanoarray, alumina photonic crystal and gold film are coupled together to form a Tamm plasmon microcavity.

[0012] Furthermore, the absorption intensity of the Tamm plasmon resonance peak excited by the gold nanoarray-alumina photonic crystal-gold film microcavity structure reached 71.5%.

[0013] Compared with the prior art, the present invention has the advantages that: the present invention provides a method for preparing a gold nanoarray-coupled photonic crystal microcavity based on the Tamm plasmon mode. The aluminum oxide nanopores generated under periodic voltage-varying oxidation are cross-stacked in the form of straight holes and bifurcated holes to form aluminum oxide photonic crystals with different refractive index layers. Compared with traditional photonic crystals, there is no need to perform complex multilayer film structure processing such as photolithography and imprinting. The number of layers of the photonic crystal can be determined by setting the number of oxidation cycles, and the preparation process is simple and efficient. The gold nanoarray is used to replace the previous gold film to form a gold nanoarray-aluminum oxide photonic crystal-gold film microcavity structure, which can provide a wider excitation surface area to enhance the ability to capture photons. The two resonances generated by the incident photon at the interface between the aluminum oxide photonic crystal and the gold nanoarray and the gold film are coupled to the Tamm plasmon at the same wavelength, and the energy field is further enhanced, showing good performance of narrow half-peak width and high intensity. This provides a wider space for the regulation of the Tamm plasmon mode. This has rich research significance in the fields of photoelectric detection, sensors, solar cells, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a flow chart of the preparation of the gold nanoarray coupled photonic crystal microcavity based on the Tamm plasmon mode in the present invention.

[0015] Figure 2 It is a periodic voltage and corresponding current diagram of the aluminum oxide photonic crystal prepared in the present invention.

[0016] Figure 3 It is a schematic diagram of the structure of the gold nanoarray coupled photonic crystal microcavity based on the Tamm plasmon mode in the present invention.

[0017] Figure 4 It is a reflection spectrum diagram of the gold nanoarray coupled photonic crystal microcavity based on the Tamm plasmon mode in the present invention. DETAILED DESCRIPTION

[0018] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0019] like Figure 1 As shown, this embodiment discloses a method for preparing a gold nanoarray coupled photonic crystal microcavity based on Tamm plasmon mode, comprising the following steps: Step 1: Cut the high-purity aluminum sheet into a circular sheet with a diameter of 20 mm, and perform the primary oxidation of the high-purity and clean aluminum sheet in a constant temperature water bath under the conditions of 0.35 M oxalic acid solution, 50V constant voltage, and 10°C constant temperature for 10 hours. After the primary oxidation, the aluminum sheet is cleaned and dried, and then treated with dichromic acid for 20 hours at a constant temperature of 65°C to remove the oxide layer.

[0020] Step 2: Preparation process of alumina photonic crystals: (2.1) Figure 2 The periodic voltage variation shown in FIG. 1 is further oxidized under the same conditions as the initial oxidation. The oxidation voltage process of a single cycle is: T a = 120s, voltage maintained at 25V constant oxidation, T b =30s, the voltage rises to 50V at a rate of half cosine at first slow and then fast, T c = 200s, the voltage drops linearly from 50V to 25V. When the voltage drops to 50V times, the nanopores begin to grow in a forked shape. After multiple cycles of oxidation, the aluminum oxide nanopores alternately stack in two states: straight holes and forked holes, forming an aluminum oxide photonic crystal.

[0021] (2.2) Use fine sandpaper to lightly polish the aluminum sheet obtained in step (2.1) to destroy the aluminum oxide film on the back aluminum surface, and then use 9% copper chloride solution to remove the aluminum substrate on the back to obtain a complete aluminum oxide photonic crystal.

[0022] Step 3: Use an ion sputtering apparatus to perform gold evaporation treatment on the oxidized surface and de-aluminized surface of the alumina photonic crystal obtained in step (2.2) for 90 s and 60 s respectively at a gas pressure of 0.06 mPa and a current of 15 mA to obtain a gold nanoarray-alumina photonic crystal-gold film microcavity structure.

[0023] Step 4: Select a wavelength range of 400nm-1000nm by using an ultraviolet-visible-near-infrared spectrophotometer, and use the gold nanoarray as the vertical incident surface of light to test the reflection spectrum of the gold nanoarray-alumina photonic crystal-gold film microcavity structure formed after gold evaporation in step 3. The absorption intensity of the Tamm plasmon resonance peak excited by the structure reaches 71.5%.

[0024] Figure 3 This is the structural diagram and equivalent schematic diagram of the gold nanoarray-alumina photonic crystal-gold film microcavity formed in this embodiment. It can be seen that since the alumina nanopores grow from top to bottom, the gold nanoarray is arranged in an array with the alumina holes, which increases the excitation surface area of ​​the metal and the photonic crystal, enhances the local energy field, and presents a narrower resonance half-peak width and a higher resonance intensity. In addition, the straight hole layer and the bifurcated layer of the alumina photonic crystal are alternately stacked, and because of the different porosities, it can be equivalent to a photonic crystal with two different effective refractive index media stacked.

[0025] Figure 4This is a reflection spectrum of the gold nanoarray-alumina photonic crystal-gold film microcavity structure prepared in this embodiment, measured under vertical incidence by using an ultraviolet-visible-near-infrared spectrophotometer. It can be seen from the figure that in the visible-near-infrared wavelength range of 400nm-1000nm, the microcavity structure excites Tamm plasmon coupling at 715nm, which enhances the light field energy and highly suppresses the reflection of light, forming a downward reflection resonance peak with a peak value of 28.5% and a half-peak width of 12.5nm. The corresponding absorption intensity reaches 71.5%. This narrow peak width and high-intensity reflection absorption peak has rich research significance and practical value in subsequent research in related fields.

[0026] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. The embodiments described in the present invention are merely descriptions of the preferred embodiments of the present invention, and do not limit the concept and scope of the present invention. The various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction, and such combinations should also be regarded as the contents disclosed in the present disclosure as long as they do not violate the concept of the present invention. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0027] The present invention is not limited to the specific details of the above-mentioned embodiments. Within the technical concept of the present invention and without departing from the design concept of the present invention, various modifications and improvements made to the technical solution of the present invention by technical personnel in this field should fall within the protection scope of the present invention. The technical contents for which protection is sought in the present invention have 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 following steps are involved: Step 1: using a constant DC voltage to perform a primary oxidation treatment on a high-purity and clean aluminum sheet, and then performing a deoxidation treatment on the aluminum sheet; Step 2: The aluminum sheet obtained in step 1 is oxidized again by a periodic voltage variation method, and after cleaning and drying, the aluminum substrate on the back is removed by a 9% copper chloride solution to prepare an aluminum oxide photonic crystal; Step 3, the oxidized surface and the de-aluminized surface of the alumina photonic crystal obtained in step 2 are subjected to gold evaporation treatment respectively to form a gold nanoarray-alumina photonic crystal-gold film microcavity structure; Step 4: Testing the reflection spectrum of the gold nanoarray-aluminum oxide photonic crystal-gold film microcavity structure formed after gold evaporation in step 3 by using an ultraviolet-visible-near infrared spectrophotometer.

2. The method for preparing a gold nanoarray coupled photonic crystal microcavity based on Tamm plasmon mode according to claim 1, characterized in that: The primary oxidation in step 1 was carried out in 0.35 M oxalic acid solution, at a constant voltage of 50 V and a constant temperature of 10°C.

3. The method for preparing a gold nanoarray coupled photonic crystal microcavity based on Tamm plasmon mode according to claim 1, characterized in that: The oxidation conditions in step 2 are the same as those in the initial oxidation, and the oxidation voltage process is: T a = 120s, voltage maintained at 25V constant oxidation, T b =30s, the voltage rises to 50V at a rate of half cosine at first slow and then fast, T c =200s, the voltage drops linearly from 50V to 25V.

4. The method for preparing a gold nanoarray coupled photonic crystal microcavity based on Tamm plasmon mode according to claim 1, characterized in that: Before removing the back aluminum substrate in step 2, lightly grind the aluminum sheet with fine sandpaper to destroy the oxide film formed on the aluminum surface.

5. The method for preparing a gold nanoarray coupled photonic crystal microcavity based on Tamm plasmon mode according to claim 1, characterized in that: In step 3, an ion sputtering apparatus is used to evaporate gold on the oxidized surface and the de-aluminized surface for 90 s and 60 s respectively at a gas pressure of 0.06 mPa and a current of 15 mA, wherein the gold nanoarray is arranged in an array along the alumina pores.

6. The method for preparing a gold nanoarray coupled photonic crystal microcavity based on Tamm plasmon mode according to any one of claims 1 to 5, characterized in that: The Tamm plasmon microcavity is formed by coupling gold nanoarrays, alumina photonic crystals and gold films.

7. The method for preparing a gold nanoarray coupled photonic crystal microcavity based on Tamm plasmon mode according to claim 6, characterized in that: The absorption intensity of the Tamm plasmon resonance peak excited by the gold nanoarray-alumina photonic crystal-gold film microcavity structure reaches 71.5%.

Images