CN116203664A - Infrared absorber capable of achieving spectrum resolution - Google Patents

Abstract

The invention discloses a spectrum-resolved infrared absorber, which comprises a top metal patch layer, a middle dielectric layer and a bottom metal reflecting layer which are sequentially arranged from top to bottom, wherein the top metal patch layer comprises a plurality of patch unit structures, each patch unit structure comprises at least four metal micro patches with different sizes, the metal micro patches of each patch unit structure are arranged in disorder according to the length and the size, and two adjacent metal micro patches are arranged at intervals. According to the infrared absorber capable of being resolved in frequency spectrum, at least four metal micro-patches with different sizes are arranged in the patch unit structure of the top metal patch layer at intervals, the metal micro-patches of the patch unit structure are arranged in disorder according to the length, so that the metal micro-patches with response wavelengths close to each other are far away from each other as much as possible, coupling crosstalk between the metal micro-patches is reduced, different wavelengths corresponding to the metal micro-patches are resolved better, frequency spectrum resolution is achieved, and the infrared absorber has a multi-wavelength infrared absorption function.

Description

A Spectrum-Resolvable Infrared Absorber

technical field

The invention relates to the technical field of electromagnetic wave absorption, in particular to an infrared absorber capable of spectral resolution.

Background technique

Metal-Insulator-Metal-basedPlasmonic Metamaterial Perfect Absorbers (hereinafter referred to as MPA) consists of periodic metal micro-patches on the top, a middle dielectric layer and a bottom reflective layer. The bottom reflective layer can be composed of different Made of light-transmitting metal to effectively prevent the transmission of light, so that the light transmittance is 0. The top metal micro-patch can make the reflectance (R) of light in a certain wavelength range Both the light transmittance (T) and the light transmittance (T) are close to 0, so that the absorbance close to 100% can be achieved (A=1-R-T), therefore, the perfect absorption of single wavelength narrowband, multiple wavelengths or broadband in each frequency band can be obtained , with a wide range of applications in the visible and infrared (IR) wavelength regions, such as solar cells, refractive index sensors, optical camouflage, invisibility, optical switches, color pixels, thermal infrared sensors, infrared microscopy, and gas sensing. Therefore, it has attracted the attention of scientific researchers.

The thermal radiation spectrum of objects at room temperature is mainly concentrated in the long-wave infrared band. At present, the common infrared cameras are mainly long-wave infrared cameras. Compared with visible light band cameras (400-760nm), infrared cameras have a wider band range, and many MPA Due to the limited principle, its working range is very narrow, and even some can only achieve near-complete absorption at specific frequencies, which is even more limited for long-wave infrared with a wider band. Therefore, many scientific researchers have designed MPAs with wider bandwidths, but at the same time they have lost a certain degree of spectral resolution.

Contents of the invention

The technical problem to be solved by the present invention is to provide an infrared absorber capable of spectral resolution, which can simultaneously distinguish light of different wavelengths, and has a multi-wavelength infrared absorption function.

In order to solve the above technical problems, the object of the present invention is achieved through the following technical solutions: provide a spectrum-resolvable infrared absorber, including a top metal patch layer, an intermediate dielectric layer and a bottom metal patch layer arranged in sequence from top to bottom Reflective layer, the top metal patch layer includes a plurality of patch unit structures, each patch unit structure includes at least four metal micro patches of different sizes, the metal patch of each patch unit structure The micro-patches are arranged randomly according to the length, and two adjacent metal micro-patches are arranged at intervals.

Its further technical solution is: the metal micro-patches are long strips, and all the metal micro-patches in the same patch unit structure are arranged in parallel and juxtaposed.

Its further technical solution is: the patch unit structure includes five metal micro-patches of different sizes, which are respectively the first metal micro-patch, the second metal micro-patch, and the third metal micro-patch from short to long. sheet, the fourth metal micro-patch and the fifth metal micro-patch, the first metal micro-patch, the third metal micro-patch, the fifth metal micro-patch, the fourth metal micro-patch The sheet and the second metal micro-patch are arranged sequentially from front to back to form the patch unit structure.

Its further technical scheme is: the length of the first metal micro patch is 1050nm, the width of the first metal micro patch is 250nm, the length of the second metal micro patch is 1350nm, the second metal micro patch The width of the micro patch is 150nm, the length of the third metal micro patch is 1650nm, the width of the third metal micro patch is 150nm, and the length of the fourth metal micro patch is 2000nm. The width of the four metal micro patches is 250nm, the length of the fifth metal micro patch is 2450nm, and the width of the fifth metal micro patch is 250nm.

Its further technical solution is: the materials of the top metal patch layer and the bottom metal reflective layer are Au, Al, Ag, Ti, Fe or Cu.

Its further technical solution is: the material of the intermediate dielectric layer is SiO ₂ , Al ₂ O ₃ , TiO ₂ , NaF, LiF or MgF ₂ .

Its further technical solution is: the thickness of the intermediate dielectric layer is 100-500 nm.

Its further technical solution is: the thickness of the metal micro patch and the bottom metal reflective layer are both greater than 50nm.

Its further technical solution is: the patch unit structure is square, and the value range of the side length of the patch unit structure is 3-4 μm.

The beneficial technical effect of the present invention is that: a kind of spectral resolution infrared absorber of the present invention sets at least four different sizes in the patch unit structure of the top metal patch layer and arranges metal micro-patches at intervals, so that the whole patch The structure of the chip unit is compact, and the metal micro-patches of the patch unit structure are arranged in random order according to the size of the length, so that the metal micro-patches with similar response wavelengths are as far away as possible to reduce the distance between the metal micro-patches. Coupling crosstalk, avoiding the problem of being unable to ensure extremely narrow absorption peak width due to errors in actual production and manufacturing, and better distinguishing different wavelengths corresponding to each metal micro-patch at the same time to achieve spectral resolution without additional filtering The chip has a simple structure and is easy to prepare, and metal micro-patches of different sizes are arranged in a single patch unit structure to perform infrared absorption of various wavelengths, thereby realizing a wide-band infrared absorption function.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the drawings that need to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present invention. Ordinary technicians can also obtain other drawings based on these drawings on the premise of not paying creative work.

FIG. 1 is a schematic structural diagram of a spectrally resolvable infrared absorber provided by an embodiment of the present invention;

2 is a front view of a single resonant cavity combination unit of a spectrum-resolvable infrared absorber provided by an embodiment of the present invention;

3 is a side view of a single resonant cavity combination unit of a spectrum-resolvable infrared absorber provided by an embodiment of the present invention;

Fig. 4 is the absorptivity curve diagram of the single resonant cavity combination unit of the spectrally resolved infrared absorber provided by the embodiment of the present invention;

Fig. 5 is a curve diagram of the absorption rate of metal micro-patches with different lengths of the spectrally resolved infrared absorber provided by the embodiment of the present invention.

Instructions in the figure: 10. Spectrum-resolvable infrared absorber; 11. Top metal patch layer; 111. SMD unit structure; 1111. First metal micro-patch; 1112. Second metal micro-patch; 1113. The third metal micro patch; 1114, the fourth metal micro patch; 1115, the fifth metal micro patch; 12, the intermediate dielectric layer; 13, the bottom metal reflection layer; 14, the resonant cavity combination unit.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

It should be understood that when used in this specification and the appended claims, the terms "comprising" and "comprises" indicate the presence of described features, integers, steps, operations, elements and/or components, but do not exclude one or Presence or addition of multiple other features, integers, steps, operations, elements, components and/or collections thereof.

It should also be understood that the terminology used in the description of the present invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the present invention. As used in this specification and the appended claims, the singular forms "a", "an" and "the" are intended to include plural referents unless the context clearly dictates otherwise.

It should also be further understood that the term "and/or" used in the description of the present invention and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations .

Please refer to FIG. 1 to FIG. 3. FIG. 1 is a schematic structural diagram of a spectrally resolvable infrared absorber provided by an embodiment of the present invention. The spectrally resolvable infrared absorber 10 includes top metal stickers arranged sequentially from top to bottom. sheet layer 11, intermediate dielectric layer 12 and bottom metal reflective layer 13, the top metal patch layer 11 includes a plurality of patch unit structures 111, and each patch unit structure 111 includes five metal micro-stickers of different sizes The metal micro-patches of each patch unit structure 111 are arranged randomly according to the length, and two adjacent metal micro-patches are spaced apart.

Wherein, the structure and pattern of each patch unit structure 111 in the same spectrum-resolvable infrared absorber 10 are the same, and the intervals are arranged in an array on the upper surface of the intermediate dielectric layer 12, and the bottom metal reflective layer 13 is arranged on the intermediate dielectric layer. 12 lower surfaces. The top metal patch layer 11 is disposed on the top surface so as to adjust the length and width of the metal micro patch, thereby adjusting the corresponding response wavelength. During the preparation process, the patterning of the structure of the top metal patch layer 11 can be realized by means of electron beam exposure, ultraviolet lithography or nanoimprinting. Methods include magnetron sputtering, vacuum electron beam evaporation deposition, ion beam sputtering deposition or atomic layer deposition. Preferably, in this embodiment, electron beam exposure is used to realize the patterning of the structure of the top metal patch layer 11, so as to improve production accuracy and facilitate fabrication; Beam evaporation deposition method to improve production accuracy and efficiency. Metal micro-patches of different sizes in each patch unit structure 111 are combined with the intermediate dielectric layer region and the bottom metal reflective layer region corresponding to the metal micro-patches to form different plasmonic resonant cavities to selectively conduct electromagnetic waves. absorb. The plasma resonant cavities corresponding to the metal micro-patches of each patch unit structure 111 form a resonant cavity combination unit 14 , and the resonant cavity combination unit 14 corresponds to the patch unit structure 111 one by one. Each plasmonic cavity only responds to the infrared of the absorption wavelength of its corresponding metal micro-patch, and each plasmonic cavity corresponds to an operating mode, so that each cavity combination unit 14 has multiple operating modes, Improve the utilization efficiency of the probe light. The spectrally resolved infrared absorber 10 includes a plurality of resonant cavity combining units 14 . The response wavelength of each plasmonic cavity can be adjusted individually by changing the length of the metal micro-patches, and the metal micro-patches in the same patch unit structure 111 are arranged in random order according to the length, that is, the metal micro-patches in the same patch unit structure 111 The metal micro-patches are not completely arranged in the order of length, and the response wavelength can be adjusted to improve the spectral resolution while reducing the coupling crosstalk of the metal micro-patches. Compared with the traditional broadband infrared absorber, the spectrally resolvable infrared absorber 10 can subdivide the infrared light intensity information of the wider band into multiple narrower band light intensity information, and the corresponding response wavelengths are different. The same, and the coupling interference is low enough to be clearly distinguished, which realizes both the absorption capacity of a wider band and the spectrum resolution. At the same time, metal micro-patches with different response wavelengths are in the same patch unit structure 111, which can increase the utilization rate of the absorber's pixel space, detection time and detection light intensity. Certainly, in some embodiments, each patch unit structure 111 may include four or more metal micro-patches of different sizes. The spectrally resolvable infrared absorber 10 makes the entire patch unit structure 111 compact by arranging at least four different sizes in the patch unit structure 111 of the top metal patch layer 11 and arranging metal micro-patches at intervals, And the metal micro-patches of the patch unit structure 111 are arranged in random order according to the length, so that the metal micro-patches with close response wavelengths are as far away as possible, so as to reduce the coupling crosstalk between the metal micro-patches, and avoid due to actual production. The problem of inability to ensure extremely narrow absorption peak width caused by manufacturing errors can better distinguish the different response wavelengths corresponding to each metal micro-patch to achieve spectral resolution without additional filters. The structure is simple and easy prepared, and a single patch unit structure 111 is provided with metal micro-patches of different sizes, so as to perform infrared absorption of multiple wavelengths, so as to realize the infrared absorption function of a wider band.

Specifically, the materials of the top metal patch layer 11 and the bottom metal reflective layer 13 are both Au, which has better stability. Of course, in other embodiments, the materials of the top metal patch layer 11 and the bottom metal reflective layer 13 can also be Al, Ag, Ti, Fe or Cu.

Specifically, the thicknesses of the metal micro patch and the bottom metal reflective layer 13 are both greater than 50 nm. In this embodiment, the thickness of the metal micro patch and the bottom metal reflective layer 13 are both 50 nm. The thicknesses of the metal micro patch and the bottom metal reflective layer 13 do not need to be consistent.

Specifically, in this embodiment, the material of the intermediate dielectric layer 12 is SiO ₂ . Certainly, in other embodiments, the material of the intermediate dielectric layer 12 may also be Al ₂ O ₃ , TiO ₂ , NaF, LiF or MgF ₂ .

Specifically, the thickness of the intermediate dielectric layer 12 is 100-500 nm. The Q factor can be flexibly manipulated by changing the thickness of the intermediate dielectric layer 12 . Among them, the Q factor is the quality and factor, which is the ratio of the resolution level signal and noise at the receiving end (that is, the signal-to-noise ratio of the resolution circuit at the best sampling point). In the spectrogram, the peak with a high Q factor is narrow and sharp, A peak with a low Q factor is broad and slow. In this embodiment, the thickness of the intermediate dielectric layer 12 is 260 nm, correspondingly, the Q factor is 17-22, which ensures the obvious frequency resolution selectivity of the absorber.

Specifically, in this embodiment, the metal micro-patches are strip-shaped, and all the metal micro-patches in the same patch unit structure 111 are arranged in parallel and juxtaposed.

Specifically, the patch unit structure 111 is square, and the side length of the patch unit structure 111 ranges from 3 to 4 μm. Wherein, in this embodiment, the side length of the patch unit structure 111 is 3 μm, and 3 μm is the minimum period size of a single patch unit structure 111 to avoid mode crosstalk generated by the patch unit structure 111 . The shortest response wavelength of the resonant cavity combination unit 14 corresponding to a single patch unit structure 111 is 4 μm. Of course, in some embodiments, the overall size of the patch unit structure 111 may be slightly larger than the shortest response wavelength of its corresponding resonator combination unit 14 , but not much larger than the response wavelength of its corresponding resonator combination unit 14 .

Specifically, in this embodiment, the metal micro-patches of five different sizes in the patch unit structure 111 are respectively the first metal micro-patches 1111, the second metal micro-patches 1112, the third metal micro-patches from short to long. Metal micro-patch 1113, fourth metal micro-patch 1114 and fifth metal micro-patch 1115, wherein, the first metal micro-patch 1111, the third metal micro-patch 1113, the fifth metal micro-patch The patch 1115 , the fourth metal micro patch 1114 and the second metal micro patch 1112 are arranged in sequence from front to back to form the patch unit structure 111 .

Specifically, the length of the first metal micro patch 1111 is 1050nm, the width of the first metal micro patch 1111 is 250nm, the length of the second metal micro patch 1112 is 1350nm, and the second metal micro patch 1112 has a length of 1350nm. The width of the micro patch 1112 is 150nm, the length of the third metal micro patch 1113 is 1650nm, the width of the third metal micro patch 1113 is 150nm, and the length of the fourth metal micro patch 1114 is 2000nm , the width of the fourth metal micro patch 1114 is 250nm, the length of the fifth metal micro patch 1115 is 2450nm, and the width of the fifth metal micro patch 1115 is 250nm, because the first metal micro patch The patch 1111, the third metal micro patch 1113, the fifth metal micro patch 1115, the fourth metal micro patch 1114 and the second metal micro patch 1112 are arranged in sequence from front to back When the patch unit structure 111 is formed, the metal micro-patches with relatively close lengths are far apart, and the length difference between adjacent metal micro-patches is relatively large, so as to avoid coupling crosstalk between metal micro-patches.

Specifically, in this embodiment, the detection response band of the single resonant cavity combination unit 14 of the spectrally resolvable infrared absorber 10 is 3.3-7.5 μm.

Please refer to Fig. 4. Fig. 4 shows the absorptivity curve diagram of a single resonant cavity combined unit of the spectrally resolved infrared absorber provided by the embodiment of the present invention. As shown in Fig. 4, the absorptivity curves are respectively at 3.7 μm and 4.4 μm , 5.1 μm, 6.0 μm and 6.9 μm obtained the absorption peaks higher than 90%, corresponding to the first metal micropatch, the second metal micropatch, the third metal micropatch, the fourth metal micropatch and the first metal micropatch Five metal micro-patches, and there are less than 30% absorption pits between adjacent absorption peaks, and the absorption is poor, which reflects that the coupling interference between metal micro-patches is less, and the absorption of the response band of each metal micro-pattern There is a large difference in frequency, and it has obvious characteristics of resolving spectrum, and each metal micro-patch forms a wide absorption band according to the wavelength splicing, so that a single resonant cavity combination unit can achieve both spectrum resolution and wide absorption band.

Please refer to Fig. 5, Fig. 5 has shown the absorptivity curve graph of the metal micropatch of different lengths of the spectrally resolved infrared absorber provided by the embodiment of the present invention, as shown in Fig. 5, only adjust the length of the metal micropatch Then the adjustment of the response wavelength can be realized, and 50nm can be set as the minimum adjustment fluctuation. Of course, in some embodiments, the adjustment can be made with any nanometer length according to the requirement to obtain the required response wavelength. As shown in Fig. 5, the absorptivity curve basically shifts according to the corresponding response wavelength, so the shape of the absorptivity curve does not change significantly during the adjustment process, and the stability of the entire plasma resonant cavity is strong.

In summary, a spectrum-resolvable infrared absorber of the present invention sets at least four different sizes in the patch unit structure of the top metal patch layer and arranges metal micro-patches at intervals, so that the entire patch unit structure Compact, and the metal micro-patches of the patch unit structure are arranged in random order according to the length, so that the metal micro-patches with similar response wavelengths are as far away as possible, so as to reduce the coupling crosstalk between the metal micro-patches and avoid Due to the error in actual production and manufacturing, it is impossible to ensure a very narrow absorption peak width. It is better to distinguish the different wavelengths corresponding to each metal micro-patch to achieve spectral resolution. No additional filters are needed, and the structure is simple. It is easy to prepare, and metal micro-patches of different sizes are arranged in a single patch unit structure to perform infrared absorption of multiple wavelengths, thereby realizing the infrared absorption function of a wider band.

The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person familiar with the technical field can easily think of various equivalents within the technical scope disclosed in the present invention. Modifications or replacements shall all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims (9)

1. The utility model provides a but infrared absorber of frequency spectrum resolution, its characterized in that includes top metal paster layer, intermediate medium layer and the bottom metal reflection stratum that from top to bottom set up in proper order, top metal paster layer includes a plurality of paster unit structure, each the paster unit structure includes the metal micro-paster of at least four equidimension, every the metal micro-paster of paster unit structure is according to length unordered arrangement, and adjacent two the interval sets up between the metal micro-paster.

2. The spectrally resolved infrared absorber of claim 1 wherein the metal micro-patches are elongated and all metal micro-patches in the same patch unit structure are arranged in parallel and side-by-side relationship.

3. The spectrally resolved infrared absorber of claim 2 wherein the patch unit structure comprises five different sizes of the metal micro-patches, from short to long as a first metal micro-patch, a second metal micro-patch, a third metal micro-patch, a fourth metal micro-patch, and a fifth metal micro-patch, respectively, the first metal micro-patch, the third metal micro-patch, the fifth metal micro-patch, the fourth metal micro-patch, and the second metal micro-patch being sequentially arranged front to back to form the patch unit structure.

4. The spectrally resolved infrared absorber of claim 3 wherein the first metal micro-patch has a length of 1050nm, the first metal micro-patch has a width of 250nm, the second metal micro-patch has a length of 1350nm, the second metal micro-patch has a width of 150nm, the third metal micro-patch has a length of 1650nm, the third metal micro-patch has a width of 150nm, the fourth metal micro-patch has a length of 2000nm, the fourth metal micro-patch has a width of 250nm, the fifth metal micro-patch has a length of 2450nm, and the fifth metal micro-patch has a width of 250nm.

5. The spectrally resolved infrared absorber of claim 1, wherein the top metal patch layer and the bottom metal reflective layer are both Au, al, ag, ti, fe or Cu in material.

6. The spectrally resolved infrared absorber of claim 1, wherein the material of the intermediate dielectric layer is SiO ₂ 、Al ₂ O ₃ 、TiO ₂ NaF, liF or MgF ₂ 。

7. The spectrally resolved infrared absorber of claim 1, wherein the intermediate medium layer has a thickness of 100-500 nm.

8. The spectrally resolved infrared absorber of claim 1, wherein the thickness of both the metal micro-patch and the bottom metal reflective layer is greater than 50nm.

9. The spectrally resolved infrared absorber of claim 1 wherein the patch unit structure is square, and the patch unit structure has a side length ranging from 3 to 4 μm.

Images