CN105987757B - Terahertz focal plane array and detection and imaging device - Google Patents

Abstract

The invention discloses a terahertz focal plane array, which includes a frame, a cantilever beam, and an absorption structure; wherein, the absorption structure includes a sequentially stacked first metal layer, a first dielectric layer, and a metal square array; the cantilever beam, two cantilever beams The beams are respectively located on the opposite sides of the metal square array. Each cantilever beam is a multi-material deformable beam formed by sequentially connecting the longitudinal part and the transverse part end to end. One end is fixedly connected to the frame, and the other end is fixedly connected to the absorption structure. The terahertz focal plane array forms a metamaterial resonant cavity, which has a strong absorption ability for low-energy terahertz radiation.

Description

Terahertz focal plane array and detection and imaging device

technical field

The invention belongs to the field of MEMS, in particular to a terahertz focal plane array and a detection and imaging device.

Background technique

Terahertz radiation is electromagnetic radiation from 0.1-10THz. Terahertz technology is far less mature than infrared and microwave radiation technologies on both sides of the band. However, in recent years, with new material technology providing higher power emission sources, terahertz technology It has been proven that it has broad application prospects in more in-depth physical research and practical applications, and is considered to be "T-Ray", one of the top ten technologies that will change the future world.

The attractiveness of terahertz imaging technology mainly comes from its phase-sensitive spectral imaging capability, which makes it possible to realize material identification and functional imaging. Terahertz systems are ideal for imaging dielectric materials, including paper, plastics, and ceramics. These materials are relatively non-absorbing to this wave band, but due to the different refractive index, different materials can be easily distinguished by using the phase information of terahertz, and terahertz imaging technology has become a hot spot in imaging research.

However, since the electron energy of terahertz radiation is relatively low, 1 THz is about 4.1meV, it is difficult to detect its signal. How to detect terahertz radiation with low signal energy has become a difficult point in terahertz imaging technology.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art and provide a strongly absorbing terahertz focal plane array and a detection and imaging device.

To achieve the above object, the technical solution of the present invention is:

includes frames, cantilever beams, and absorbing structures; where,

The absorption structure includes a first metal layer, a first dielectric layer, and an array of metal squares stacked in sequence; and a split resonator ring; the metal square array is an array composed of metal squares, the first metal layer and the first The dielectric layer is a block structure in the shape of the outer contour of the metal square array to form a metamaterial resonant cavity, the split resonant ring surrounds the metal square array, and the split resonant ring and the metal square Array interval setting;

Cantilever beams, two cantilever beams are located on opposite sides of the metal square array, each cantilever beam is a multi-material deformation beam formed by sequentially connecting the longitudinal part and the transverse part end to end, one end of which is fixedly connected to the frame, and the other end is fixed to the absorption structure connect.

Optionally, the split resonant ring is located on the first dielectric layer.

Optionally, openings of the split resonant ring are arranged symmetrically along the central axis of the metal square array.

Optionally, a second dielectric layer is further included, the second dielectric layer is located under the first metal layer, and the other end of the cantilever beam is fixedly connected to the second dielectric layer.

Optionally, the second dielectric layer is a block structure having the same size as the first metal layer.

Optionally, the cantilever beam is a laminated structure, and at least one section of the cantilever beam has at least one material that is different from other sections of the cantilever beam.

Optionally, adjacent vertical sections include different materials, and the transverse section adopts the material of one of the vertical sections.

Optionally, one vertical portion is formed of the first material, and the adjacent vertical portion is formed of a laminate of the first material and the second material thereon.

Optionally, the cantilever beam is a single-layer structure, and at least one section of the cantilever beam is made of a material different from other sections.

In addition, the present invention also provides a terahertz detection and imaging device, which uses the visible light reflected by any of the above-mentioned terahertz focal plane arrays as input.

The terahertz focal plane array provided by the embodiment of the present invention has an absorption structure including a sequentially stacked first metal layer, a first dielectric layer, and a metal square array, and multi-material deformable beams, and the absorption structure forms a resonant cavity of a metamaterial , has a strong absorption capacity for low-energy terahertz radiation. After absorbing terahertz radiation, the temperature of the absorbing structure rises and is transmitted to the multi-material deformable beam. Different materials of the multi-material deformable beam have different expansion coefficients. When there is heat transfer, thermal deformation will occur. Driven by the thermal deformation, the absorbing structure will deflect, so that the visible light reflected by the metal square array will change. By detecting the visible light, the detection and reuse of terahertz signals will be realized.

In addition, a split resonant ring surrounding the metal square array is formed to further broaden the absorption frequency of terahertz radiation.

Description of drawings

In order to more clearly illustrate the technical solutions implemented by the present invention, the following will briefly introduce the accompanying drawings that need to be used in the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those skilled in the art Ordinary technicians can also obtain other drawings based on these drawings on the premise of not paying creative work.

FIG. 1 is a schematic top view of a terahertz focal plane array according to an embodiment of the present invention;

Fig. 2 is a schematic cross-sectional structure diagram of a terahertz focal plane array according to an embodiment of the present invention.

Detailed ways

In order to make the above objects, features and advantages of the present invention more comprehensible, specific implementations of the present invention will be described in detail below in conjunction with the accompanying drawings.

In the following description, a lot of specific details are set forth in order to fully understand the present invention, but the present invention can also be implemented in other ways different from those described here, and those skilled in the art can do it without departing from the meaning of the present invention. By analogy, the present invention is therefore not limited to the specific examples disclosed below.

Secondly, the present invention is described in detail in combination with schematic diagrams. When describing the embodiments of the present invention in detail, for the convenience of explanation, the cross-sectional view showing the device structure will not be partially enlarged according to the general scale, and the schematic diagram is only an example, and it should not be limited here. The protection scope of the present invention. In addition, the three-dimensional space dimensions of length, width and depth should be included in actual production.

Referring to FIG. 1 and FIG. 2, wherein FIG. 2 is a schematic cross-sectional structural diagram along the dotted line in FIG. 1, in an embodiment of the present invention, the absorption structure includes a first metal layer 110, a first dielectric layer 108 and The metal square array, the metal square array is an array composed of metal squares 104, the metal squares can be square or rectangular, the first metal layer 110 and the first dielectric layer 108 are basically the shape of the outer contour of the metal square array, which is a block structure, That is, there is no hollow or non-hollow pattern in the first metal layer 110 and the first dielectric layer 108. Of course, in order to improve the absorption rate or absorption frequency, etc., the first metal layer 110 and/or the first dielectric layer 108 can also be With patterns. The absorbing structure forms a resonant cavity of the metamaterial, which has the unique characteristics of adjustable permittivity, magnetic permeability and refractive index, and realizes superabsorption of low-energy terahertz radiation. The split resonant ring 102 surrounds the metal square array, the split resonant ring 102 is spaced apart from the metal square array, the split resonant ring 102 is also a metal material, and its opening 1021 can be arranged symmetrically along the central axis of the metal square array, which can widen the The frequency of the absorbed radiation.

In a specific embodiment, the metal square array is an array composed of 2x3 metal squares 104 , and the opening 1021 of the split resonator ring 102 is located above the gap between two columns of metal squares and arranged symmetrically along the gap.

Wherein, the first metal layer, the metal square array and the split resonator ring can be made of metal materials such as Au and Al, and the metal square array and the split resonator ring can be formed together on the same layer and have the same thickness. In a specific embodiment The first metal layer, the metal square array and the split resonator ring are Au, and the first dielectric layer can be silicon nitride, silicon nitride and other dielectric materials. In a specific embodiment, the first dielectric layer is SiN _x .

Referring to Fig. 1 and Fig. 2, cantilever beams 106 are respectively arranged on opposite sides of the metal square array, and the cantilever beams 106 are multi-material deformable beams formed by sequentially connecting the vertical part 1061 and the transverse part 1062 end-to-end. Deformable beam means that at least one section of the cantilever beam is made of materials with different expansion coefficients from other sections, that is, it is formed of at least two different materials, so that it deforms when subjected to heat changes. The cantilever beam usually uses a dielectric material, and it can also be a dielectric material Lamination with other materials.

In some embodiments, the cantilever beam can be a single-layer structure, and at least one section of the cantilever beam is made of a material different from that of other sections, thereby forming a multi-material deformable beam. For example, a vertical part is formed of one material, such as Silicon nitride and its adjacent vertical portion are formed of another material, such as silicon oxide. In some other embodiments, the cantilever beam can be a stacked structure, and at least one section of the cantilever beam has at least one material different from the material of other sections, for example, a vertical section adopts a stack of silicon nitride and Au, adjacent to it The vertical part adopts the lamination of silicon nitride and silicon oxide. In an embodiment of the present invention, the cantilever beam is a mixed structure of single-layer and multi-layer, at least one layer of the multi-layer part is made of different materials from the single-layer part, and different materials can be used for the adjacent vertical parts. , the horizontal part adopts the material of one of the vertical parts, in a specific embodiment, one vertical part is formed by the first material, and the vertical part adjacent to it is formed by the lamination of the first material and the second material thereon, The first material can be, for example, silicon nitride, the second material can be, for example, Au, and the lateral portion is formed of the first material. In this specific embodiment, as shown in FIG. 1 and FIG. 2 , the cantilever beam 106 is two A cantilever beam composed of connected foldback structures, a foldback structure consists of two vertical parts and a transverse part connecting adjacent vertical parts. The cantilever beam composed of multiple bends can effectively amplify the amount of deformation and improve the ability to capture signals.

One end of the cantilever beam is fixedly connected to the frame 100, and the other end is fixedly connected to the absorbing structure. The cantilever beam fixes the absorbing structure on the frame 100. The frame 100 is usually a dielectric material, such as silicon nitride, silicon nitride, etc., absorbing After absorbing radiation, the structure transfers heat to the cantilever beam. In this embodiment, a second dielectric layer 112 is provided under the first metal layer 110, and the other end of the cantilever beam 106 is fixedly connected to the absorbing structure through the second dielectric layer 112. , the second dielectric layer 112 can be a block structure with the same size as the first metal layer, that is, there is no hollow or non-hollow pattern in the second dielectric layer, which can increase the contact surface with the first metal layer, preferably heat transfer to the cantilever beam. Of course, in other embodiments, for the purpose of reducing weight, patterns may also be provided in the second dielectric layer, and it may also be fixedly connected to the absorption structure in other ways.

In the terahertz focal plane array provided in this embodiment, the absorption structure forms a metamaterial resonant cavity, and a split resonant ring is arranged around the metal square array. This device has a strong absorption capacity for low-energy terahertz radiation and has With a wide absorption frequency, after absorbing terahertz radiation, the temperature of the absorbing structure rises and is transferred to the multi-material deformable beam. Different materials of the multi-material deformable beam have different expansion coefficients. When there is heat transfer, heat will occur. Deformation, driven by the thermal deformation, the angular deflection of the absorbing structure causes the visible light reflected by the metal square array to change. By detecting the visible light, the detection and reuse of the terahertz signal is realized.

For the visible light reflected by the above array, a 4f optical detection device can be built to realize the detection and imaging of terahertz signals.

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any form.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person familiar with the art, without departing from the scope of the technical solution of the present invention, can use the methods and technical content disclosed above to make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent implementation of equivalent changes example. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention, which do not deviate from the technical solution of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims (10)

1. A terahertz focal plane array, characterized in that, comprises a frame, a cantilever beam and an absorbing structure; wherein, The absorption structure includes a first metal layer, a first dielectric layer, a metal square array and a split resonator ring stacked in sequence; the metal square array is an array composed of metal squares, the first metal layer and the first dielectric The layer is a block structure in the shape of the outer contour of the metal square array to form a metamaterial resonant cavity, the split resonant ring surrounds the metal square array, and the split resonant ring and the metal square array Set at intervals; cantilever beams, two cantilever beams are respectively located on opposite sides of the metal square array, each cantilever beam is a multi-material deformation beam formed by sequentially connecting the longitudinal part and the transverse part end to end, one end of which is fixedly connected to the frame, and the other end is connected to the The absorbent structure is fixedly connected. 2. The terahertz focal plane array according to claim 1, wherein the split resonant ring is located on the first dielectric layer. 3 . The terahertz focal plane array according to claim 2 , wherein the openings of the split resonator ring are arranged symmetrically along the central axis of the metal square array. 4 . 4. The terahertz focal plane array according to claim 1, further comprising a second dielectric layer, the second dielectric layer is located under the first metal layer, and the other end of the cantilever beam is fixedly connected to the second dielectric layer. 5. The terahertz focal plane array according to claim 4, wherein the second dielectric layer is a block structure having the same size as the first metal layer. 6. The terahertz focal plane array according to any one of claims 1-5, characterized in that the cantilever beam is a laminated structure, and at least one section of the cantilever beam has at least one material that is different from other sections. 7 . The terahertz focal plane array according to claim 6 , wherein adjacent vertical portions comprise different materials, and the transverse portion adopts the material of one of the vertical portions. 8 . The terahertz focal plane array according to claim 7 , wherein one vertical portion is formed of a first material, and the adjacent vertical portion is formed of a laminate of the first material and a second material thereon. 9. The terahertz focal plane array according to any one of claims 1-5, wherein the cantilever beam is a single-layer structure, and at least one section of the cantilever beam is made of a material different from other sections. 10. A terahertz detection and imaging device, characterized in that the visible light reflected by the terahertz focal plane array according to any one of claims 1-9 is used as input.