Multifunctional metamaterial perfect absorber and manufacturing method thereof

Abstract

The invention relates to the technical field of electromagnetic wave absorption devices, in particular to a multifunctional metamaterial perfect absorber and a manufacturing method thereof. The invention provides a multifunctional metamaterial perfect absorber and a manufacturing method thereof. The absorber comprises a silicon substrate layer, an adhesion chromium layer, a silicon dioxide thin film spacing layer, a gold thin film spacing layer, a broadband absorption metasurface and a narrowband absorption metasurface. The zirconium nitride concentric ring array is arranged on the broadband absorption metasurface, and the average absorption rate in the visible to near-infrared region wave band is as high as 97.48%; the narrow-band absorption metasurface is provided with a 4 * 4 grid array formed by zirconium nitride, and has 99.99% ultrahigh narrow-band absorption and high refractive index sensitivity. The material has excellent refractive index sensing performance and high thermal chemical stability of the zirconium nitride material, is suitable for the fields of solar energy collection, biosensing, environmental protection and the like, and remarkably improves the energy collection efficiency and the sensing sensitivity.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic wave absorbing device technology, specifically to a multifunctional metamaterial perfect absorber and its fabrication method. Background Technology

[0002] With the increasing demand for precise control of electromagnetic waves, metamaterials, due to their artificially designed periodic structures, exhibit electromagnetic, acoustic, and mechanical properties that are difficult for natural materials to match, attracting widespread attention from academia and engineering. Since the concept of metamaterial absorbers was proposed, broadband and narrowband metamaterial absorbers have been developed based on the precise design of subwavelength structures to achieve near-perfect electromagnetic radiation absorption. Broadband absorbers exhibit high efficiency in capturing energy in the continuous wavelength range of hundreds of nanometers to several micrometers and have been widely used in solar energy collection, thermo-photovoltaic conversion, and electromagnetic interference suppression. Narrowband absorbers achieve high absorption peaks and high sensing performance of several nanometers to tens of nanometers, demonstrating significant value in fields such as high-precision refractive index detection, biomedical sensing, and environmental monitoring. Most existing devices in this field only have a single function, making it difficult to simultaneously achieve broadband energy capture and high-sensitivity narrowband sensing in a single device, thus hindering the progress of miniaturization and system integration. To further enhance the multifunctional integration of devices, some researchers have attempted to stack wide and narrow band structures on the same substrate. For example, the asymmetric multilayer metal-dielectric structure proposed by Gao et al. [H. Gao, Y. Liang, L. Yu, S. Chu, L.Cai, F. Wang, Q. Wang, and W. Peng, Bifunctional plasmonic metamaterialabsorber for narrowband sensing detection and broadband optical absorption, Opt. Laser Technol. 137 (2021), 106807] includes a nanopatterned gold array on the upper side to achieve narrowband detection, and a four-layer metal-dielectric alternating structure on the bottom side to achieve broadband absorption. Although it integrates wide and narrow band absorption, its narrow band refractive index sensitivity is only 37 RIU⁻¹, and its broadband absorption rate is low, with an absorption rate of 84.09% in the 400 to 900 nm band. This is still insufficient to meet the dual requirements of high-precision sensing and ultra-high absorption efficiency. On the other hand, most metamaterial absorber designs rely on precious metals such as gold and silver, which are not only expensive, but also have reduced stability in extreme environments such as high temperature and strong corrosion. There is still a need to explore alternatives with better thermochemical inertness and mechanical durability.

[0003] In recent years, transition metal nitrides have become strong candidates to replace noble metals due to their excellent optical properties, thermal stability, and chemical inertness. Among them, zirconium nitride exhibits metal-like free electron behavior, low resistivity, and higher thermochemical stability. Based on this, this invention proposes a novel multifunctional metamaterial absorber. A periodic concentric ring array of zirconium nitride is integrated into a grid array on both sides of a substrate. The top concentric rings, in conjunction with a silicon dioxide spacer layer, achieve broadband near-perfect absorption, while the bottom grid array is precisely tuned via electromagnetic resonance to achieve tunable, highly sensitive, narrow-band refractive index sensing. This not only balances efficient energy harvesting and precise spectral detection but also fully utilizes the stability of zirconium nitride in extreme environments, providing a new path for miniaturized, multifunctional integrated metamaterial devices. Summary of the Invention

[0004] The purpose of this invention is to provide a multifunctional metamaterial perfect absorber and its manufacturing method to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a multifunctional metamaterial perfect absorber and its manufacturing method.

[0006] In a first aspect, embodiments of this application provide a method for fabricating a multifunctional metamaterial perfect absorber, the absorber comprising a silicon substrate layer, an adhered chromium layer, a silicon dioxide thin film spacer layer, a gold thin film spacer layer, a broadband absorbing metasurface, and a narrowband absorbing metasurface; comprising the following steps:

[0007] Step 1: After cleaning the surface of the silicon substrate, an adhesive chromium layer is deposited on the surface of the silicon substrate through a thermal evaporation process. Then, a gold target is deposited onto the surface of the adhesive chromium layer using magnetron sputtering to form a gold thin film spacer layer.

[0008] Step 2: On the other side of the silicon substrate, a silicon dioxide thin film spacer layer is formed by chemical vapor deposition using tetraethyl orthosilicate as the silicon source;

[0009] Step 3: Using a zirconium metal target as the sputtering source and a mixture of argon and nitrogen as the carrier gas, zirconium nitride thin films are prepared on the surfaces of the gold thin film spacer layer and the silicon dioxide thin film spacer layer using magnetron sputtering technology.

[0010] Step 4: Using extreme ultraviolet lithography and reactive ion etching, and with the help of a customized mask pattern, a concentric ring array is fabricated on the zirconium nitride film on the surface of the silicon dioxide thin film spacer layer to form a broadband absorbing metasurface; a square array is fabricated on the gold thin film spacer layer to form a narrowband absorbing metasurface.

[0011] Furthermore, in step 1, the thickness of the adhered chromium layer is 2~5 nm.

[0012] Furthermore, in step 1, the thickness of the gold thin film spacer layer is 200~500nm.

[0013] Furthermore, in step 2, the thickness of the silicon dioxide thin film spacer layer is 110~200nm.

[0014] Furthermore, in step 3, the flow rate of argon is 26 sccm, and the flow rate of nitrogen is 3~10 sccm.

[0015] Furthermore, in step 4, the broadband absorbing metasurface structure is a concentric ring array formed by periodically arranging several concentric ring units with identical shapes and sizes; each concentric ring unit includes a central cylinder and three annular cylinders arranged coaxially along the radially outer side of the central cylinder.

[0016] Furthermore, in the direction perpendicular to the silicon dioxide thin film spacer layer, the thickness of the central cylinder is h1, and the thicknesses of the annular cylinders from the inside out are h2, h3, and h4 respectively; the inner diameters of the annular cylinders from the inside out are R1, R2, and R3 respectively, and the ring width of each annular cylinder is r; wherein, h1, h2, h3, and h4 are 10~60 nm; R1, R2, and R3 are 30~130 nm; and r = 10~50 nm.

[0017] Furthermore, the concentric ring unit period is Px = 200~400nm, and Py = 200~400nm.

[0018] Further, in step 4, the narrowband absorbing metasurface structure is a 4×4 grid array; the side length L of the grid array is 200~500nm, the width W is 20~80nm, the thickness H of the grid array is 50~100nm in the direction perpendicular to the gold thin film spacer layer, and the period P of the grid array is 800~1200nm.

[0019] Furthermore, the broadband average absorptivity of the aforementioned multifunctional metamaterial perfect absorber satisfies the following formula:

[0020] ;

[0021] Where A is the average absorption rate. This is the starting wavelength for broadband absorption. This is the wavelength at the end of broadband absorption.

[0022] Furthermore, the broadband absorption has an average absorption rate of over 97% in the visible to near-infrared band of 800-2500 nm.

[0023] Furthermore, the narrowband absorption has an absorption rate of over 99.99% at the resonant wavelength of 948.1 nm.

[0024] The design concept of the multifunctional metamaterial perfect absorber includes the following steps:

[0025] S1: Use the finite-difference time-domain method to establish a simulation model and determine the thickness of the silica thin film spacer layer required for the Fabry-Perot resonance corresponding to the target broadband absorption peak and the array period P required for the metal-air interface surface plasmon resonance mode corresponding to the narrow band absorption peak to be excited.

[0026] S2: Determine the thicknesses h1, h2, h3, h4 of the cylinders and annular cylinders in the zirconium nitride concentric ring unit based on the thickness of the silicon dioxide thin film spacer layer;

[0027] S3: Determine the inner diameter R1, R2, R3 and the ring width r of the annular cylinder based on the thickness of the silica thin film spacer layer and the thicknesses h1, h2, h3, h4 of the cylinder and the annular cylinder.

[0028] S4: Compare the effects of the x-direction period Px and the y-direction period Py on the bandwidth and average absorption rate of broadband absorption, and determine Px and Py.

[0029] S5: Determine the thickness of the grid array based on the array period P of the narrowband absorption;

[0030] S6: Determine the side length L and width W of the grid array based on the array period P and the grid array thickness;

[0031] S7: Using the parameters given in S1~S6 as initial values, adjust the parameters in the simulation model to determine the optimal size of the structure.

[0032] Compared with existing technologies, the beneficial effects achieved by this invention are as follows: This invention provides a multifunctional metamaterial perfect absorber based on zirconium nitride material. By constructing zirconium nitride metasurface arrays of different shapes on the upper and lower surfaces, it achieves the integration of ultra-wideband high-efficiency absorption from the visible to near-infrared bands with highly selective narrowband refractive index sensing. The device achieves an average absorptivity of 97.48% in the 800~2500nm range, and a narrowband absorption peak of 99.99% at 948.1nm (FWHM=23.14nm) with a high sensitivity of 1015.62nm / RIU. In addition, the electric field is highly concentrated at the zirconium nitride-silicon dioxide and zirconium nitride-gold interfaces, which is beneficial for the coupling of local surface plasmons and Rayleigh anomalous structures; the geometric parameters of the concentric rings and the square array can be precisely adjusted to adjust the position of the absorption peak; its inherent symmetry is insensitive to polarization and incident angle; the zirconium nitride material used has a melting point as high as 2980℃ and has excellent thermochemical stability, ensuring long-term reliable operation of the device under extreme conditions. This invention combines ultra-wideband light energy capture and high-spectral-selective refractive index sensing, providing a solid technical foundation for high-performance electromagnetic wave manipulation devices in multiple fields such as solar thermal photovoltaics, biosensing, and environmental monitoring. Attached Figure Description

[0033] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0034] Figure 1 This is a schematic diagram I of the structure of the multifunctional metamaterial perfect absorber in Embodiment 1 of the present invention;

[0035] Figure 2 This is a schematic diagram of the concentric ring unit structure of the multifunctional metamaterial perfect absorber in Embodiment 1 of the present invention;

[0036] Figure 3 This is the broadband absorption spectrum of the multifunctional metamaterial perfect absorber in Embodiment 1 of the present invention;

[0037] Figure 4 This is a graph showing the relationship between TE-polarized oblique incidence and average absorptivity of the multifunctional metamaterial perfect absorber in Embodiment 1 of the present invention.

[0038] Figure 5 This is a graph showing the relationship between TM polarized oblique incidence and average absorptivity of the multifunctional metamaterial perfect absorber in Embodiment 1 of the present invention.

[0039] Figure 6 This is a top view of the electric field distribution in the xy plane at a wavelength of 914.2 nm for the broadband absorption of the multifunctional metamaterial perfect absorber in Embodiment 1 of the present invention.

[0040] Figure 7 This is a top view of the electric field distribution in the xy plane at a wavelength of 1243.6 nm for the broadband absorption of the multifunctional metamaterial perfect absorber in Embodiment 1 of the present invention.

[0041] Figure 8 This is a top view of the electric field distribution in the xy plane at a wavelength of 1971.3 nm for the broadband absorption of the multifunctional metamaterial perfect absorber in Embodiment 1 of the present invention.

[0042] Figure 9 This is a cross-sectional view of the electric field distribution in the xz plane at a wavelength of 914.2 nm for the broadband absorption of the multifunctional metamaterial perfect absorber in Embodiment 1 of the present invention.

[0043] Figure 10 This is a cross-sectional view of the electric field distribution in the xz plane at a wavelength of 1243.6 nm for the broadband absorption of the multifunctional metamaterial perfect absorber in Embodiment 1 of the present invention.

[0044] Figure 11 This is a cross-sectional view of the electric field distribution in the xz plane at a wavelength of 1971.3 nm for the broadband absorption of the multifunctional metamaterial perfect absorber in Embodiment 1 of the present invention.

[0045] Figure 12 This is an impedance matching result diagram of broadband absorption of the multifunctional metamaterial perfect absorber in Embodiment 1 of the present invention;

[0046] Figure 13 This is a schematic diagram (II) of the structure of the multifunctional metamaterial perfect absorber in Embodiment 7 of the present invention;

[0047] Figure 14 This is a schematic diagram of the 4×4 square array unit of the multifunctional metamaterial perfect absorber in Embodiment 7 of the present invention;

[0048] Figure 15 This is the narrowband absorption spectrum of the multifunctional metamaterial perfect absorber in Embodiment 7 of the present invention;

[0049] Figure 16 This is a top view of the electric field distribution in the xy plane at a wavelength of 948.1 nm for the narrowband absorption of the multifunctional metamaterial perfect absorber in Embodiment 7 of the present invention.

[0050] Figure 17 This is a cross-sectional view of the electric field distribution in the xz plane at a wavelength of 948.1 nm for the narrowband absorption of the multifunctional metamaterial perfect absorber in Embodiment 7 of the present invention.

[0051] Figure 18 This is a graph showing the results of calculating the sensitivity of the narrowband sensing performance of the multifunctional metamaterial perfect absorber in Embodiment 7 of the present invention under different refractive indices. Detailed Implementation

[0052] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0053] The following embodiments provide a method for preparing the multifunctional metamaterial perfect absorber of the present invention, including the following steps:

[0054] Step 1: Place the silicon substrate in hexane, acetone, anhydrous ethanol, and deionized water for ultrasonic cleaning for 3 minutes to remove surface organic matter and particulate contamination; deposit an adhesion chromium layer on the surface of the silicon substrate using a thermal evaporation process, and then deposit a gold target on the adhesion chromium layer surface using magnetron sputtering to form a gold thin film spacer layer.

[0055] Step 2: On the other side of the silicon substrate, a silicon dioxide thin film spacer layer is formed by chemical vapor deposition using tetraethyl orthosilicate as the silicon source;

[0056] Step 3: Using a zirconium metal target as the sputtering source and a mixture of argon and nitrogen as the carrier gas, zirconium nitride thin films are prepared on the surfaces of the gold thin film spacer layer and the silicon dioxide thin film spacer layer using magnetron sputtering technology; wherein, the flow rate of Ar is kept constant at 26 sccm and the flow rate of N2 is controlled between 3 and 10 sccm.

[0057] Step 4: Using extreme ultraviolet lithography and reactive ion etching, and with the help of a customized mask pattern, a concentric ring array is fabricated on the zirconium nitride film on the surface of the silicon dioxide thin film spacer layer to form a broadband absorbing metasurface; a square array is fabricated on the gold thin film spacer layer to form a narrowband absorbing metasurface.

[0058] The concentric ring unit includes a central cylinder and three annular cylinders arranged coaxially along the radial outer side of the central cylinder. In the direction perpendicular to the silicon dioxide thin film spacer layer, the thickness of the central cylinder is h1, and the thicknesses of the annular cylinders from the inside out are h2, h3, and h4, respectively. The inner diameters of the annular cylinders from the inside out are R1, R2, and R3, respectively, and the ring width of each annular cylinder is r.

[0059] The narrowband absorbing metasurface structure is a 4×4 grid array.

[0060] To further investigate the various properties of the multifunctional metamaterial perfect absorber, the following Examples 1-6 study the properties of the broadband absorbing metasurface.

[0061] Example 1:

[0062] Figure 1This is a schematic diagram I of the structure of the multifunctional metamaterial perfect absorber in Embodiment 1 of the present invention;

[0063] Figure 2 This is a schematic diagram of the concentric ring unit structure of the multifunctional metamaterial perfect absorber in Embodiment 1 of the present invention;

[0064] In this embodiment, the thickness of the silicon dioxide spacer layer is 170nm. In the concentric ring unit, the thicknesses are h1=40nm, h2=20nm, h3=10nm, and h4=40nm, respectively. The inner diameter of the ring is R1=40nm, R2=70nm, and R3=110nm. The ring width is r=20nm. The period of the concentric ring array is Px=330nm and Py=300nm.

[0065] Figure 3 In the broadband absorption spectrum, the horizontal axis represents wavelength in nm, and the vertical axis represents absorbance. The average absorbance in the broadband absorption range of 800~2500 nm is 97.48%.

[0066] The effects of TE-polarized oblique incidence and TM-polarized oblique incidence on broadband average absorbance were investigated. Figure 4 The graph shows the relationship between the TE polarization angle at oblique incidence and the average absorbance. Figure 5 The graph shows the relationship between the TM polarization angle and the average absorbance. The horizontal axis represents the wavelength in nm, and the vertical axis represents the absorbance. Six different colored curves are used to represent the absorption spectra at different oblique incidence angles: 0°, 10°, 20°, 30°, 40°, and 50°. Figure 4 and Figure 5 The small graph inserted in the middle shows the horizontal axis as the oblique incidence angle and the vertical axis as the average absorptivity, which more clearly shows the magnitude of the average absorptivity corresponding to different oblique incidence angles.

[0067] from Figure 4 The results show that as the TE polarization oblique incident angle increases, the absorption peak undergoes a slight blue shift, and the calculated average absorptivity decreases slightly from 97.48% at an incident angle of 0° to 86.32% at 50°.

[0068] from Figure 5 The results show that the broadband absorption bandwidth gradually narrows with the increase of the TM polarization oblique incident angle, but its absorption spectrum remains almost unchanged, and the average absorptivity at an incident angle of 50° remains at a high level of 94.86%. This insensitivity of broadband absorption to the incident angle is attributed to the inherent geometric symmetry of the multifunctional metamaterial perfect absorber.

[0069] The electric field distribution in the xy plane (top view) and the electric field distribution in the xz plane (cross-sectional view) of the concentric ring structure at wavelengths of λ1 = 914.2 nm, λ2 = 1243.6 nm, and λ3 = 1971.3 nm, corresponding to broadband absorption, are calculated. Figures 6-11 .

[0070] At λ1, Figure 6 The electric field intensity in the xy plane is highly focused at the edge of the central disk, exhibiting a typical electric dipole mode. Figure 9 The cross-sectional electric field distribution shows that the electric field is mainly confined within the annular gap between the central zirconium nitride disk and the first ring, indicating strong LSPR coupling between them. For the resonance at λ2, the electric field is mainly distributed between the second and third rings, indicating the existence of strong plasmon hybridization gap resonance within the annular gap, which is also due to the relatively small thickness of the middle ring. At λ3, Figure 8 and Figure 11 This reveals that strong surface plasmon resonances (SPRs) concentrated at the outer ring edge dominate the broadband perfect absorption. Therefore, the broadband perfect absorption at λ1, λ2, and λ3 can be attributed to: the coupling between the electric dipole mode and the LSPR within the first ring, the plasmon hybridization gap resonance between the first and second rings, and the concentration of SPRs at the outer ring edge, respectively.

[0071] The formula for calculating the average absorptivity of the multifunctional metamaterial perfect absorber of this invention is as follows:

[0072] ;

[0073] λmax and λmin are defined as the maximum and minimum values ​​of the operating wavelength, respectively.

[0074] [See X. Yan, Q. Lin, L. Wang, and G. Liu, Active absorption modulation by employing strong coupling between magnetic plasmons and borophene surfaceplasmons in the telecommunication band, J. Appl. Phys. 132 (2022), 063101]

[0075] Based on the impedance matching principle, perfect absorption can be further explained as the incident light having the same impedance as free space at the metasurface [see D. Smith, D. Vier, T. Koschny, and C. Soukoulis, Electromagnetic parameter retrieval from inhomogeneous metamaterials, Physical Review E—Statistical, Nonlinear, and Soft Matter Physics 71 (2005), 036617]:

[0076] ;

[0077] Where S11 and S21 are S-parameters.

[0078] Figure 12 The calculated impedance Z-curves of a multifunctional metamaterial perfect absorber structure based on zirconium nitride are presented in the wavelength range of 800~2500nm, showing that it achieves excellent impedance matching over a wide spectral range.

[0079] Example 2:

[0080] In this embodiment, the thickness of the silicon dioxide spacer layer is 110 nm. In the concentric ring unit, the thicknesses are h1=40 nm, h2=20 nm, h3=10 nm, and h4=40 nm, respectively. The inner diameter of the ring is R1=40 nm, R2=70 nm, and R3=110 nm. The ring width is r=20 nm. The period of the concentric ring array is Px=280 nm and Py=280 nm. The broadband absorption has an average absorption rate of 94.02% in the range of 500~2200 nm.

[0081] Example 3:

[0082] In this embodiment, the silicon dioxide spacer layer has a thickness of 140 nm. In the concentric ring unit, the thicknesses are h1=40 nm, h2=20 nm, h3=10 nm, and h4=40 nm, respectively. The inner diameters of the rings are R1=40 nm, R2=70 nm, and R3=110 nm. The ring width is r=20 nm. The period of the concentric ring array is Px=330 nm and Py=330 nm. The broadband absorption has an average absorption rate of 97.32% in the range of 700~2400 nm.

[0083] Example 4:

[0084] In this embodiment, the silicon dioxide spacer layer has a thickness of 170 nm. In the concentric ring unit, the thicknesses are h1=40 nm, h2=20 nm, h3=10 nm, and h4=40 nm, respectively. The inner diameters of the rings are R1=40 nm, R2=70 nm, and R3=110 nm. The ring width is r=20 nm. The period of the concentric ring array is Px=380 nm and Py=380 nm. The broadband absorption has an average absorption rate of 97.29% in the range of 800~2500 nm.

[0085] Example 5:

[0086] In this embodiment, the thickness of the silicon dioxide spacer layer is 200 nm. In the concentric ring unit, the thicknesses are h1=40 nm, h2=20 nm, h3=10 nm, and h4=40 nm, respectively. The inner diameter of the ring is R1=40 nm, R2=70 nm, and R3=110 nm. The ring width is r=20 nm. The period of the concentric ring array is Px=430 nm and Py=430 nm. The broadband absorption has an average absorption rate of 96.44% in the range of 900~2600 nm.

[0087] Example 6:

[0088] In this embodiment, the silicon dioxide spacer layer has a thickness of 230 nm. In the concentric ring unit, the thicknesses are h1=40 nm, h2=20 nm, h3=10 nm, and h4=40 nm, respectively. The inner diameters of the rings are R1=40 nm, R2=70 nm, and R3=110 nm. The ring width is r=20 nm. The period of the concentric ring array is Px=480 nm and Py=480 nm. The broadband absorption has an average absorption rate of 95.65% in the range of 1000~2700 nm.

[0089] Examples 7-12 investigate the narrowband absorbing metasurface of the multifunctional metamaterial perfect absorber prepared in this invention.

[0090] Example 7:

[0091] Figure 13 This is a schematic diagram I of the structure of the multifunctional metamaterial perfect absorber in Embodiment 1 of the present invention;

[0092] Figure 14 This is a schematic diagram of the 4×4 grid array structure of the multifunctional metamaterial perfect absorber in Embodiment 1 of the present invention;

[0093] In this invention, the thickness of the adhered chromium layer is 2 nm, the thickness of the gold thin film spacer layer is 500 nm, the width W of the grid array is 50 nm, the length L of the grid array is 400 nm, the thickness H of the grid array is 90 nm, and the period P of the grid array is 1000 nm.

[0094] Figure 15In the narrowband absorption spectrum, the horizontal axis represents wavelength in nm, and the vertical axis represents absorbance. The narrowband absorption reaches a high absorbance of 99.99% at 948.1 nm, with a quality factor of 73.89.

[0095] from Figure 16 It can be seen that at the resonant wavelength of 948.1 nm, the electric field intensity on the top surface is mainly concentrated at the four corners of the square grid array based on zirconium nitride. This phenomenon is attributed to the strong field confinement of localized surface plasmons (LSPRs) in the zirconium nitride metamaterial.

[0096] from Figure 17 As can be seen, the electric field intensity in the cross section is symmetrically distributed and extends above the top surface of the square grid array, indicating typical surface plasmon (SPP) excitation and Rayleigh anomaly (RA) characteristics.

[0097] The refractive index sensitivity of narrowband sensors was tested within the refractive index range of 1.0 to 2.3, and analysis was performed based on the refractive index sensitivity. Figure 18 To extract the offset ∆λ of the resonant wavelength to the change in environmental refractive index, and to perform linear fitting with ∆n as the independent variable:

[0098] ;

[0099] The fitted sensitivity was 1015.62 nm RIU⁻¹. The multifunctional metamaterial perfect absorber proposed in this invention exhibits better sensing performance than some reported multifunctional absorbers [B. Liu, P. Wu, H. Zhu, and L.Lv, Ultra narrow dual-band perfect absorber based on a dielectric−dielectric−metal three-layer film material, Micromachines 12 (2021), 1552; S. Khonina, MA Butt, and N. Kazanskiy, Numerical investigation of metasurface narrowband perfect absorber and a plasmonic sensor for a near-infrared wavelength range, J. Opt. 23 (2021), 065102]. This result demonstrates that a 4×4 square grid array based on zirconium nitride can achieve high sensitivity and narrow spectral linewidth, making it suitable for precision sensing applications in advanced biosensing platforms and environmental monitoring systems that require high spectral resolution.

[0100] Example 8:

[0101] In this invention, the thickness of the adhered chromium layer is 3 nm, the thickness of the gold thin film spacer layer is 200 nm, the width W of the grid array is 50 nm, the length L of the grid array is 400 nm, the thickness H of the grid array is 50 nm, and the period P of the grid array is 600 nm. Narrowband absorption achieves a high absorption rate of 99.99% at 766.9 nm, with a quality factor of 9.43 and a refractive index sensitivity of 1015.62 nm RIU⁻¹.

[0102] Example 9:

[0103] In this invention, the thickness of the adhered chromium layer is 4 nm, the thickness of the gold thin film spacer layer is 300 nm, the width W of the grid array is 60 nm, the length L of the grid array is 400 nm, the thickness H of the grid array is 50 nm, and the period P of the grid array is 700 nm. Narrowband absorption achieves a high absorption rate of 99.99% at 810.8 nm, with a quality factor of 10.85 and a refractive index sensitivity of 1015.62 nm RIU⁻¹.

[0104] Example 10:

[0105] In this invention, the thickness of the adhered chromium layer is 5 nm, the thickness of the gold thin film spacer layer is 350 nm, the width W of the grid array is 70 nm, the length L of the grid array is 400 nm, the thickness H of the grid array is 50 nm, and the period P of the grid array is 800 nm. Narrowband absorption achieves a high absorption rate of 99.99% at 869.3 nm, with a quality factor of 16.01 and a refractive index sensitivity of 1015.62 nm RIU⁻¹.

[0106] Example 11: In this invention, the thickness of the adhered chromium layer is 3 nm, the thickness of the gold thin film spacer layer is 400 nm, the width W of the grid array is 80 nm, the length L of the grid array is 400 nm, the thickness H of the grid array is 50 nm, and the period P of the grid array is 900 nm. Narrowband absorption achieves a high absorption rate of 99.99% at 934.8 nm, with a quality factor of 30.51 and a refractive index sensitivity of 1015.62 nm RIU⁻¹.

[0107] Example 12:

[0108] In this invention, the thickness of the adhered chromium layer is 2 nm, the thickness of the gold thin film spacer layer is 450 nm, the width W of the grid array is 100 nm, the length L of the grid array is 400 nm, the thickness H of the grid array is 50 nm, and the period P of the grid array is 1100 nm. Narrowband absorption achieves a high absorption rate of 99.99% at 1025.44 nm, with a quality factor of 55.13 and a refractive index sensitivity of 1015.62 nm RIU⁻¹.

[0109] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

[0110] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0111] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a multifunctional metamaterial perfect absorber, characterized in that: Includes the following steps: Step 1: After cleaning the surface of the silicon substrate, an adhesive chromium layer is deposited on the surface of the silicon substrate through a thermal evaporation process. Then, a gold target is deposited onto the surface of the adhesive chromium layer using magnetron sputtering to form a gold thin film spacer layer. Step 2: On the other side of the silicon substrate, a silicon dioxide thin film spacer layer is formed by chemical vapor deposition using tetraethyl orthosilicate as the silicon source; Step 3: Using a zirconium metal target as the sputtering source and a mixture of argon and nitrogen as the carrier gas, zirconium nitride thin films are prepared on the surfaces of the gold thin film spacer layer and the silicon dioxide thin film spacer layer using magnetron sputtering technology. Step 4: Using extreme ultraviolet lithography and reactive ion etching, and with the help of a customized mask pattern, a concentric ring array is fabricated on the zirconium nitride film on the surface of the silicon dioxide thin film spacer layer to form a broadband absorbing metasurface; a square array is fabricated on the gold thin film spacer layer to form a narrowband absorbing metasurface.

2. The method for preparing a multifunctional metamaterial perfect absorber according to claim 1, characterized in that: In step 1, the thickness of the adhered chromium layer is 2~5nm.

3. The method for preparing a multifunctional metamaterial perfect absorber according to claim 1, characterized in that: In step 1, the thickness of the gold thin film spacer layer is 200~500nm.

4. The method for preparing a multifunctional metamaterial perfect absorber according to claim 1, characterized in that: In step 2, the thickness of the silicon dioxide thin film spacer layer is 110~200nm.

5. The method for preparing a multifunctional metamaterial perfect absorber according to claim 1, characterized in that: In step 3, the flow rate of argon is 26 sccm, and the flow rate of nitrogen is 3~10 sccm.

6. The method for preparing a multifunctional metamaterial perfect absorber according to claim 1, characterized in that: In step 4, the broadband absorbing metasurface structure is a concentric ring array formed by periodically arranging several concentric ring units with identical shapes and sizes; each concentric ring unit includes a central cylinder and three annular cylinders arranged coaxially along the radial outer side of the central cylinder.

7. The method for preparing a multifunctional metamaterial perfect absorber according to claim 6, characterized in that: In the direction perpendicular to the silicon dioxide thin film spacer layer, the thickness of the central cylinder is h1, and the thicknesses of the annular cylinders from the inside out are h2, h3, and h4 respectively; the inner diameters of the annular cylinders from the inside out are R1, R2, and R3 respectively, and the ring width of each annular cylinder is r; wherein, h1, h2, h3, and h4 are 10~60 nm; R1, R2, and R3 are 30~130 nm; and r = 10~50 nm.

8. The method for preparing a multifunctional metamaterial perfect absorber according to claim 6, characterized in that: The concentric ring unit period is Px = 200~400nm, Py = 200~400nm.

9. The method for preparing a multifunctional metamaterial perfect absorber according to claim 1, characterized in that: In step 4, the narrowband absorbing metasurface structure is a 4×4 grid array; the side length L of the grid array is 200~500nm, the width W is 20~80nm; the thickness H of the grid array is 50~100nm in the direction perpendicular to the gold thin film spacer layer; and the period P of the grid array is 800~1200nm.

10. The multifunctional metamaterial perfect absorber prepared by the preparation method according to any one of claims 1 to 9.

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