Yttrium barium copper oxide photonic crystal and preparation method thereof

Abstract

The application provides a yttrium barium copper oxide photonic crystal and a preparation method thereof. 7‑x The photonic crystal structure is composed of periodic yttrium barium copper oxide (YBa2Cu3O 7‑x ) superconducting material circular crystal columns, the lattice constant is 2630nm, and the radius of the circular crystal column is 500nm. The photonic crystal can change the position and width of the band gap by changing the light incidence angle, so that the middle infrared band gap is realized. The photonic crystal is prepared by adopting a magnetron sputtering method to prepare a yttrium barium copper oxide film on a strontium titanate single crystal substrate, and then adopting a focused ion beam method to process the yttrium barium copper oxide film into a periodic nanostructure composed of yttrium barium copper oxide circular crystal columns, so that the yttrium barium copper oxide photonic crystal is obtained. The preparation method of the yttrium barium copper oxide photonic crystal is simple and easy to control.

Description

Technical Field

[0001] This invention belongs to the field of photonic crystal preparation technology, specifically relating to a yttrium barium copper oxide photonic crystal and its preparation method. Background Technology

[0002] Photonic crystals are optical nanostructures composed of periodic dielectric structures that can block the propagation of light at specific frequencies; this is known as the photonic bandgap, the width of which is influenced by the refractive index contrast of the material. Currently, photonic crystal materials require relatively high dielectric constants to achieve larger photonic bandgapes, and the position of the bandgap is difficult to change. Introducing materials with superconducting properties into photonic crystals can solve this problem.

[0003] Yttrium barium copper oxide (YBA) is a crystalline compound with a critical temperature around 91 K. Compared to conventional metallic materials, high-temperature superconductors have two advantages: first, they possess a low dielectric constant, negligible dispersion, and a large bandwidth; second, they are tunable by magnetic field, temperature, and wavelength. By changing the magnitude of these parameters, the position and width of the bandgap can be altered, enabling detection and filtering applications across different wavelength bands. Different photonic crystal structures (including crystal pillar size, shape, and lattice constant) exhibit corresponding changes in bandgap with varying temperatures. Below the critical temperature of YBA, different lattice constants and crystal pillar sizes can control the wavelength range in which the bandgap appears. Compared to electron beam fabrication and dry etching methods for preparing photonic crystals, focused ion beam methods offer more direct and efficient applications in material etching and micro / nanostructure fabrication. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] This invention proposes a yttrium barium copper oxide photonic crystal and its preparation method to solve the technical problem of changing the band gap position and width.

[0006] (II) Technical Solution

[0007] To address the aforementioned technical problems, this invention proposes a yttrium barium copper oxide photonic crystal, which is composed of periodic yttrium barium copper oxide circular crystal pillars.

[0008] Furthermore, the lattice constant of the photonic crystal is 2630 nm, and the radius of the circular crystal pillar is 500 nm.

[0009] Furthermore, this invention also proposes a method for preparing the aforementioned yttrium barium copper oxide photonic crystal. This method involves preparing a yttrium barium copper oxide thin film using magnetron sputtering technology and etching the yttrium barium copper oxide thin film using focused ion beam technology to obtain the yttrium barium copper oxide photonic crystal.

[0010] Furthermore, the focused ion beam etching process conditions are: Ga ion beam, beam current 100pA, voltage 30kV, etching time 30 minutes.

[0011] (III) Beneficial Effects

[0012] This invention proposes a yttrium barium copper oxide photonic crystal and its preparation method. The photonic crystal structure consists of periodic yttrium barium copper oxide (YBa2Cu3O) 7-x The photonic crystal of this invention is composed of circular crystal pillars of superconducting material, with a lattice constant of 2630 nm and a radius of 500 nm. The photonic crystal of this invention can achieve a mid-infrared bandgap by changing the position and width of the bandgap by altering the incident light angle. The photonic crystal of this invention is prepared by magnetron sputtering on a strontium titanate single-crystal substrate using a magnetron sputtering method, and then processed into a periodic nanostructure composed of circular yttrium barium copper oxide crystal pillars using a focused ion beam method. The preparation method of the yttrium barium copper oxide photonic crystal of this invention is simple and easy to control. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the yttrium barium copper oxide photonic crystal structure according to an embodiment of the present invention;

[0014] Figure 2 This is a bandgap diagram of the yttrium barium copper oxide photonic crystal according to an embodiment of the present invention;

[0015] Figure 3 The following are transmission spectra of yttrium barium copper oxide photonic crystals at different incident angles in embodiments of the present invention: (a) diagram of the network superconducting photonic crystal structure, (b) incident angle of π / 4, (c) incident angle of π / 5, (d) incident angle of π / 6, (e) incident angle of π / 8, and (f) incident angle of π / 10. Detailed Implementation

[0016] To make the objectives, contents, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0017] This embodiment proposes a yttrium barium copper oxide photonic crystal, the photonic crystal structure of which consists of periodic yttrium barium copper oxide (YBa2Cu3O) 7-x The superconducting material is composed of circular crystal pillars with a lattice constant of 2630 nm and a radius of 500 nm. A schematic diagram of the photonic crystal structure is shown below. Figure 1 As shown in the figure, region A is air and region B is yttrium barium copper oxide material.

[0018] The bandgap diagram of yttrium barium copper oxide photonic crystal in the 82-92 THz (3.26-3.67 μm) was calculated through theoretical simulation, as follows: Figure 2 As shown.

[0019] Further theoretical simulations were used to analyze the transmission spectrum under different incident angles. A schematic diagram simulating light incident on a yttrium barium copper oxide photonic crystal is shown below. Figure 3 As shown in (a), the band gap diagrams of the yttrium barium copper oxide photonic crystals corresponding to incident angles of π / 4, π / 5, π / 6, π / 8, and π / 10 are respectively... Figure 3 (b), (c), (d), (e), (f). Figure 3 In (b), the portion with 0 transmittance nearby corresponds to Figure 2 The region with a gap. Figure 3 In (c), the band gap ranges from 75 THz to 87 THz (3.45–4 μm), and a second band gap gradually appears. Adjusting the incident angle can affect the position of the band gap, and even result in multiple band gaps. Figure 3 In (d), band gaps appear at two locations: 70-87THz (3.45~4.29um) and 90-93THz (3.23~3.33um), where the transmittance is 0, and the corresponding locations of the band gaps. Figure 3 In (e), the two band gaps are located at 65THz-87THz (3.45~4.62um) and 93THz-98THz (3.06~3.23um), respectively, and it can be observed that both band gaps show a widening trend. As the incident angle decreases, the width of the band gap gradually increases, and the center frequency of the band gap shifts towards lower frequencies. The center frequency of the wider band gap gradually shifts from the original 82THz (3.66um) to 75THz (4um), and the width gradually widens from the original 5THz to about 24THz. Figure 3 In (f), the band gaps at two positions are broadened to 63-87 THz (3.45–4.76 μm) and 97-104 THz (2.88–3.09 μm), respectively, indicating that reducing the incident angle can result in a wider band gap. Therefore, the band gap of yttrium barium copper oxide photonic crystal in the mid-infrared band can be altered by changing the incident angle.

[0020] Regarding the aforementioned yttrium barium copper oxide photonic crystal, this embodiment also proposes a method for preparing the photonic crystal, the specific process steps of which are as follows:

[0021] S1. Place a 5mm×5mm×0.5mm strontium titanate single crystal substrate into the magnetron sputtering equipment chamber, evacuate to about 10Pa using a mechanical pump, heat the deposition chamber, sputtering chamber, and heating pipe to 850℃, then continue evacuating to below 1Pa, introduce argon and oxygen, and begin sputtering a yttrium barium copper oxide thin film on the strontium titanate single crystal substrate. Sputter for 30 minutes, then turn off the mechanical pump and argon gas, and cool to room temperature to obtain a 20nm thick yttrium barium copper oxide thin film sample on the strontium titanate substrate.

[0022] S2. Place the yttrium barium copper oxide thin film sample in a rapid annealing furnace, heat it to 650°C, introduce oxygen for in-situ annealing, so that the strontium titanate substrate can fully absorb oxygen to increase the oxygen content. After holding at the temperature for half an hour, stop heating and wait for it to cool to 50°C before taking out the yttrium barium copper oxide thin film sample.

[0023] S3. Place the yttrium barium copper oxide thin film sample into the focused ion beam equipment, and press... Figure 1 The photonic crystal structure shown (lattice constant of 2630 nm, circular column radius of 500 nm) was etched to obtain a yttrium barium copper oxide photonic crystal. The focused ion beam etching conditions were: Ga ion beam, beam current 100 pA, voltage 30 kV, and etching time 30 minutes.

[0024] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A yttrium barium copper oxide photonic crystal, characterized in that, The photonic crystal is composed of periodic yttrium barium copper oxide circular crystal pillars. The lattice constant of the photonic crystal is 2630 nm, and the radius of the circular crystal pillars is 500 nm. The photonic crystal can form a bandgap in the range of 82-92 THz. As the incident angle decreases, the bandgap width gradually widens, the center frequency shifts to the lower frequency direction, and the wide bandgap portion is widened from 5 THz to 24 THz.

2. A method for preparing a yttrium barium copper oxide photonic crystal as described in claim 1, characterized in that, The method involves preparing a yttrium barium copper oxide thin film using magnetron sputtering, and then etching the yttrium barium copper oxide thin film using focused ion beam (FIP) technology to obtain a yttrium barium copper oxide photonic crystal. The FIP etching conditions are: Ga ion beam, beam current 100 pA, voltage 30 kV, and etching time 30 minutes.

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