CN112129730A - Terahertz wave refractive index sensor based on sunflower photonic crystal structure - Google Patents

Abstract

The invention discloses a terahertz wave refractive index sensor based on a sunflower photonic crystal structure, which comprises a substrate area, a signal input end, a signal output end, an air area and a central sample pool area; the substrate area is composed of a polymer; The air area is composed of air holes arranged at equal intervals in the first and second layers, and air holes arranged at equal intervals in the third, fourth, and fifth layers of center symmetrical semi-annular period. The central sample pool area is composed of symmetrical air hole sample units. The terahertz wave is input from the signal input end, passes through the signal input end, the air area, and the central sample cell area in turn, and is output at the signal output end. The sensing function of the refractive index of different samples in the sample cell is realized through the function of the photonic crystal structure. The invention has the characteristics of high sensitivity, easy processing and the like, and has the advantages of broad application prospects in the fields of biochemistry and the like.

Description

Terahertz wave refractive index sensor based on sunflower photonic crystal structure

technical field

The present invention relates to a terahertz wave refractive index sensor, in particular to a terahertz wave refractive index sensor based on a sunflower-type photonic crystal structure.

Background technique

Terahertz waves are an electromagnetic wave region located between millimeter waves and infrared rays with wavelengths in the range of 30μm-3mm, also known as T-rays. The development of terahertz technology depends on the science and technology of electronics and photonics. Terahertz waves are in the intersection of macro-electronics and micro-photonics research. The research on terahertz can be carried out from the two fields of electronics and photonics. Filling this blank area of the electromagnetic spectrum has very important scientific significance and research value. Terahertz systems are mainly composed of radiation sources, detection devices and various functional devices. In practical applications, the resonant effect of the refractive index of different materials and the terahertz wave is used to cause different responses of the terahertz wave, which lays the foundation for the further application of the terahertz wave. The terahertz wave refractive index sensor with good performance attracts the attention of a large number of researchers.

The important role of terahertz wave refractive index sensors in terahertz systems has led to the successive proposals of terahertz wave refractive index sensors with different structures. However, most of the existing terahertz wave refractive index sensors have many shortcomings such as complex structure, low performance, high cost, and difficult processing. Therefore, it is of great significance to study the simple structure, low cost and easy fabrication of terahertz wave refractive index sensors.

SUMMARY OF THE INVENTION

In order to overcome the deficiencies of the prior art, the present invention provides a terahertz wave refractive index sensor based on a sunflower photonic crystal structure with a simple structure, high sensing performance and easy processing.

In order to achieve the above object, technical scheme of the present invention is as follows:

A terahertz wave refractive index sensor based on a sunflower photonic crystal structure, which includes a signal input end, a signal output end, an air hole area, a substrate material area, and a central sample cell unit area; the air hole area is composed of 5 layers in total. It consists of 114 air hole units opened on the substrate material area, and 5 layers of air hole units are arranged layer by layer on 5 concentric circles. The third, fourth and fifth layers are composed of two semi-circular air hole arrays arranged in mirror symmetry, and the two ends of the two semi-circular air hole arrays are composed of 18 air holes arranged at equal intervals. There is a space between them. The number of air holes included in the third, fourth and fifth layers of air hole units is 22, 28 and 34 respectively; the space between the third, fourth and fifth layers of air hole units is along the diameter are connected to each other, so that a signal input end and a signal output end are respectively formed on both sides of the substrate material area; the central sample cell unit area is arranged in the ring of the air hole unit of the first layer, and consists of an upper sample cell unit in the center and a lower center sample cell unit. The sample cell unit is composed of a sample cell unit; the sample cavity of the sample cell unit on the center is divided into two layers of cavity areas that are not connected to each other with the first high-density polyethylene wall as the boundary, and the first high-density polyethylene wall is formed by a first semicircular arc. The sample cavity of the lower sample cell unit in the center is divided into two layers of inner and outer unconnected cavity areas with the second high-density polyethylene wall as the boundary, and the second high-density polyethylene The polyethylene wall is composed of a second inferior arc section and a second semi-circular arc section connected end to end; the lower center sample cell unit and the center upper sample cell unit are arranged in a mirror-symmetrical form; the terahertz wave is input from the signal input end, and sequentially It enters the central sample cell unit area through the substrate material area and the air hole area, and finally outputs from the signal output end. Through the action of the photonic crystal structure in the air hole area, the refractive index of the different samples in the central upper sample cell unit and the central lower sample cell unit is realized. sensing function. The above-mentioned technical scheme can adopt the following preferred ways:

Preferably, the radius of each air hole in the air hole area is 40-44 μm, and the distance between two adjacent air holes of the same layer and the air hole unit of the adjacent layer is 14-18 μm

Preferably, in the air hole area, the center of the concentric circles is taken as the origin, and the arrangement of the air holes is expressed as:

where a is the lattice constant, M is the number of layers of air hole units, m is the number of air holes in a layer of air hole units, 1≤m≤6M, x(M,m) is the number of air hole units in the Mth layer. The x-axis coordinates of the m air holes, y(M,m) is the y-axis coordinate of the mth air hole in the M-th layer of air hole units.

Preferably, the material of the substrate material region is high-density polyethylene.

Preferably, the refractive index n of the substrate material region is 1.535.

Preferably, the distance between the sample cell unit above the center and the sample cell unit below the center is 0.

Preferably, in the sample cell unit on the center, the inner radius of the first semi-circular arc segment is 78-82 μm, and the outer radius is 98-102 μm; the inner radius and outer radius of the first inferior arc segment are both 123-82 μm 127 μm; the first HDPE wall thickness is 10 μm.

Preferably, in the sample cell unit under the center, the inner radius and outer radius of the second inferior arc segment are both 123-127 μm; the inner radius of the second semi-circular arc segment is 78-82 μm, and the outer radius is 98- 102 μm; the second HDPE wall thickness is 10 μm.

Preferably, the entire sensor is formed by 3D printing.

Compared with the prior art, the present invention has the following beneficial effects:

In the present invention, silicon materials can be replaced by organic macromolecular polymers such as relatively common high-density polyethylene as substrate materials, and mature and inexpensive 3D printing technology is used to replace silicon etching technology to make sensors, and the 3D printing technology is used to print refraction using polymer materials. The rate sensor can reduce the manufacturing cost while obtaining high-precision and high-performance devices; using a larger sample cell design in the middle sample area increases the interaction area between the terahertz wave and the sample, and can achieve higher sensitivity. The refractive index sensor of the invention has the advantages of high performance, easy processing and the like, and can play an important role in terahertz application systems such as biological and chemical sensing.

Description of drawings

1 is a schematic structural diagram of a terahertz wave refractive index sensor based on a sunflower-type photonic crystal structure;

Fig. 2 is the sample cell structure unit of the terahertz wave refractive index sensor based on the sunflower type photonic crystal structure;

Fig. 3 is the transmission spectrum of the terahertz wave refractive index sensor based on the sunflower photonic crystal structure when analyzing the refractive index of different samples.

Detailed ways

As shown in Figures 1-2, an embodiment of the present invention provides a terahertz wave refractive index sensor based on a sunflower photonic crystal structure, which includes a signal input end 1, a signal output end 2, an air hole region 3, Substrate material area 4 , central sample cell unit area 7 . The substrate material area 4 is the substrate of the entire sensor, and the signal input end 1 , the signal output end 2 , the air hole area 3 and the central sample cell unit area 7 are all disposed on the substrate. The entire sensor can be formed by 3D printing using a substrate material.

The air hole area 3 is composed of 5 layers with a total of 114 air hole units opened on the substrate material area 4. The 5 layers of air hole units are arranged on 5 concentric circles layer by layer. All air holes in each layer of air hole units The centers of the circles lie on the same circle. The air hole unit of the first layer is composed of 12 air holes arranged in a circular ring periodically and at equal intervals, and the 12 air holes are surrounded to form a complete ring. The second layer consists of 18 air holes arranged in a circular ring periodically and at equal intervals, and the 18 air holes are surrounded to form a complete ring. The third, fourth, and fifth layers are all composed of two semi-annular air hole arrays arranged in mirror symmetry, and space is left between both ends of the two semi-annular air hole arrays. Therefore, the air holes on the third, fourth and fifth layers are not complete rings, but are separated by a certain distance. The number of air holes included in the third, fourth and fifth layer air hole units is 22, 28 and 34 respectively. The spaces between the third, fourth, and fifth layers of air hole units are connected in a radial direction, so that a signal input end 1 and a signal output end 2 are respectively formed on both sides of the substrate material region 4 . During actual processing, the substrates at the positions of the signal input end 1 and the signal output end 2 are not opened, and the continuity of the substrate material can be maintained.

The central sample cell unit area 7 is arranged in the ring of the air hole unit of the first layer, and is composed of an upper central sample cell unit 5 and a central lower sample cell unit 6 . The center of the entire central cell unit area 7 coincides with the center of the aforementioned concentric circles. The center upper sample cell unit 5 and the center lower sample cell unit 6 are both sample cells opened on the substrate, and their sample chambers are used to add samples to be tested with different refractive indices. Referring to Fig. 2, the sample cavity of the sample cell unit 5 in the center is divided into two layers of cavity areas that are not connected to each other with the first high-density polyethylene wall as the boundary, and the first high-density polyethylene wall is formed by the first semicircle. The arc section 8 and the first inferior arc section 9 are connected end to end. Similarly, the sample cavity of the lower center sample cell unit 6 is divided into inner and outer two layers of cavity areas that are not connected to each other with the second HDPE wall as the boundary. The second HDPE wall is formed by the second inferior arc section 10 It is formed by connecting end to end with the second semicircular arc segment 11 . The center lower sample cell unit 6 is arranged in a mirror-symmetrical manner with the center upper sample cell unit 5 .

In this sensor, the terahertz wave is input from the signal input end 1, passes through the substrate material area 4 and the air hole area 3 in sequence, and enters the central sample cell unit area 7, and is refracted by the sample in the sample cell and then passes through the air hole area 3, the lining The bottom material region 4 is output from the signal output end 2. In this process, the sensing function of the refractive index of different samples in the upper center sample cell unit 5 and the center lower sample cell unit 6 is realized through the action of the photonic crystal structure of the air hole region 3.

The specific materials and parameters of each component in the present invention can be set as follows:

The radius of each air hole in the air hole region 3 is 40-44 μm, and the distance between two adjacent air holes of the air hole unit in the same layer and the adjacent layer is 14-18 μm. In the air hole area 3, the center of the concentric circles is used as the origin, and the position arrangement of the air holes is expressed as:

Among them, a is the lattice constant, M is the number of layers of air holes, m is the number of air holes in a layer of air holes, 1≤m≤6M, x(M,m) is the number of air holes in the M-th layer of air holes The x-axis coordinate of the m-th air hole, y(M,m) is the y-axis coordinate of the m-th air hole in the M-th air hole unit.

The material of the substrate material region 4 is high density polyethylene. The refractive index n of the substrate material region 4 is 1.535. The distance between the upper central sample cell unit 5 and the central lower sample cell unit 6 is 0, that is, the first inferior arc section 9 and the second inferior arc section 10 are abutted. In the sample cell unit 5 on the center, the inner radius of the first semi-circular arc segment 8 is 78-82 μm, and the outer radius is 98-102 μm; the inner radius and outer radius of the first inferior arc-shaped segment 9 are both 123-127 μm; A high density polyethylene wall thickness of 10 μm. In the sample cell unit 6 under the center, the inner radius and outer radius of the second inferior arc section 10 are both 123-127 μm; the inner radius of the second semi-circular arc section 11 is 78-82 μm, and the outer radius is 98-102 μm; The second HDPE wall thickness is 10 μm. The entire sensor is mirror-symmetrical with the center line between the signal input end 1 and the signal output end 2 as the center.

In the following, on the basis of the terahertz wave refractive index sensor based on the sunflower photonic crystal structure, its specific technical effect will be described through an embodiment.

Example 1

In this embodiment, the structure and material application of the terahertz wave refractive index sensor based on the sunflower-type photonic crystal structure are described in detail in the above content, and therefore are not repeated in this embodiment. The structural parameters of the terahertz wave refractive index sensor based on the sunflower photonic crystal structure are as follows:

其中，a是晶格常数，M是空气孔单元的层数，m是一层空气孔单元中空气孔的序数，1≤m≤6M，x(M,m)是第M层空气孔单元中第m个空气孔的x轴坐标，y(M,m)是第M层空气孔单元中第m个空气孔的y轴坐标。衬底材料区域4的材质为高密度聚乙烯。衬底材料区域4折射率n为1.535。中心上样品池单元5和中心下样品池单元6之间的间距为0。中心上样品池单元5中，第一半圆弧形段8的内半径为80μm，外半径为100μm；第一劣弧形段9的内半径和外半径均为125μm；第一高密度聚乙烯壁厚度为10μm。中心下样品池单元6中，第二劣弧形段10的内半径和外半径均为125μm；第二半圆弧形段11的内半径为80μm，外半径为100μm；第二高密度聚乙烯壁厚度为10μm。中心下样品池单元6与中心上样品池单元5镜像对称。中心下样品池单元6与中心上样品池单元5中可填充不同折射率的样品。图3为填充不同折射率样品时的太赫兹波透射谱。由图3可知，当待测试样品折射率在1.0到1.7之间变化时，传感器的谐振频率从1.154THz降低到1.141THz，可以通过谐振峰的频率实现不同的折射率结果。The radius of each air hole in the air hole region 3 is 42 μm, and the distance between two adjacent air holes of the same layer and the air hole unit of the adjacent layer is 16 μm. In the air hole area 3, the center of the concentric circles is used as the origin, and the position arrangement of the air holes is expressed as:

Among them, a is the lattice constant, M is the number of layers of air holes, m is the number of air holes in a layer of air holes, 1≤m≤6M, x(M,m) is the number of air holes in the M-th layer of air holes The x-axis coordinate of the m-th air hole, y(M,m) is the y-axis coordinate of the m-th air hole in the M-th air hole unit. The material of the substrate material region 4 is high density polyethylene. The refractive index n of the substrate material region 4 is 1.535. The distance between the upper center sample cell unit 5 and the center lower sample cell unit 6 is zero. In the sample cell unit 5 on the center, the inner radius of the first semi-circular arc section 8 is 80 μm, and the outer radius is 100 μm; the inner radius and outer radius of the first inferior arc section 9 are both 125 μm; the first high-density polyethylene wall The thickness is 10 μm. In the central lower sample cell unit 6, the inner radius and outer radius of the second inferior arc section 10 are both 125 μm; the inner radius of the second semi-circular arc section 11 is 80 μm, and the outer radius is 100 μm; the second high-density polyethylene wall The thickness is 10 μm. The center lower sample cell unit 6 is mirror-symmetrical to the center upper sample cell unit 5 . The lower central sample cell unit 6 and the central upper sample cell unit 5 can be filled with samples of different refractive indices. Figure 3 shows the transmission spectra of terahertz waves when filling samples with different refractive indices. It can be seen from Figure 3 that when the refractive index of the sample to be tested varies between 1.0 and 1.7, the resonant frequency of the sensor decreases from 1.154THz to 1.141THz, and different refractive index results can be achieved by the frequency of the resonant peak.

Claims (9)

1. A terahertz wave refractive index sensor based on a sunflower type photonic crystal structure is characterized by comprising a signal input end (1), a signal output end (2), an air hole region (3), a substrate material region (4) and a central sample cell unit region (7); the air hole area (3) consists of 114 air hole units which are arranged on the substrate material area (4) in 5 layers, the 5 layers of air hole units are arranged on 5 concentric circles layer by layer, the first layer consists of 12 air holes which are arranged in a circular ring shape periodically at equal intervals, the second layer consists of 18 air holes which are arranged in a circular ring shape periodically at equal intervals, the third layer, the fourth layer and the fifth layer consist of two semi-ring-shaped air hole arrays which are arranged in a mirror symmetry manner, a spacing space is reserved between two ends of the two semi-ring-shaped air hole arrays, and the number of the air holes contained in the third layer, the fourth layer and the fifth layer of air hole units is 22, 28 and 34 respectively; the spacing spaces of the third, fourth and fifth layers of air hole units are connected along the radial direction, so that a signal input end (1) and a signal output end (2) are respectively formed at two sides of the substrate material area (4); the central sample cell unit area (7) is arranged in a circular ring of the first layer of air hole units and consists of a central upper sample cell unit (5) and a central lower sample cell unit (6); the sample cavity of the sample cell unit (5) on the center is divided into an inner cavity area and an outer cavity area which are not communicated with each other by taking a first high-density polyethylene wall as a boundary, and the first high-density polyethylene wall is formed by connecting a first semicircular arc section (8) and a first inferior arc section (9) end to end; the sample cavity of the central lower sample cell unit (6) is divided into an inner cavity area and an outer cavity area which are not communicated with each other by taking a second high-density polyethylene wall as a boundary, and the second high-density polyethylene wall is formed by connecting a second inferior arc section (10) and a second semi-arc section (11) end to end; the central lower sample cell unit (6) and the central upper sample cell unit (5) are arranged in a mirror symmetry mode; terahertz waves are input from a signal input end (1), enter a central sample cell unit area (7) through a substrate material area (4) and an air hole area (3) in sequence, are output from a signal output end (2) finally, and the sensing function of different sample refractive indexes in a central upper sample cell unit (5) and a central lower sample cell unit (6) is realized through the action of a photonic crystal structure of the air hole area (3).

2. The terahertz wave refractive index sensor based on a sunflower type photonic crystal structure according to claim 1, wherein the radius of each air hole in the air hole region (3) is 40-44 μm, and the distance between two adjacent air holes of the air hole units in the same layer and adjacent layers is 14-18 μm.

3. The terahertz wave refractive index sensor based on the sunflower type photonic crystal structure according to claim 2, wherein the air hole region (3) has the center of the concentric circle as the origin, and the air hole position arrangement is represented as follows:

wherein a is a lattice constant, M is the number of layers of the air hole units, M is the ordinal number of the air holes in one layer of the air hole units, M is more than or equal to 1 and less than or equal to 6M, x (M, M) is the x-axis coordinate of the mth air hole in the mth layer of the air hole units, and y (M, M) is the y-axis coordinate of the mth air hole in the mth layer of the air hole units.

4. The terahertz wave refractive index sensor based on a sunflower type photonic crystal structure according to claim 1, characterized in that the material of the substrate material region (4) is high density polyethylene.

5. The terahertz-wave refractive index sensor based on a sunflower-type photonic crystal structure according to claim 4, characterized in that the substrate material region (4) has a refractive index n of 1.535.

6. The terahertz wave refractive index sensor based on a sunflower type photonic crystal structure according to claim 1, characterized in that the distance between the central upper sample cell unit (5) and the central lower sample cell unit (6) is 0.

7. The terahertz wave refractive index sensor based on a sunflower type photonic crystal structure according to claim 1, wherein in the central upper sample cell unit (5), the inner radius of the first semicircular arc-shaped section (8) is 78-82 μm, and the outer radius is 98-102 μm; the inner radius and the outer radius of the first inferior arc-shaped section (9) are both 123-127 mu m; the first high density polyethylene wall thickness was 10 μm.

8. The terahertz wave refractive index sensor based on a sunflower type photonic crystal structure according to claim 1, wherein in the central lower sample cell unit (6), the inner radius and the outer radius of the second minor arc-shaped segment (10) are both 123-127 μm; the inner radius of the second semi-arc section (11) is 78-82 mu m, and the outer radius is 98-102 mu m; the second high density polyethylene wall thickness was 10 μm.

9. The terahertz wave refractive index sensor based on a sunflower type photonic crystal structure according to claim 1, wherein the entire sensor is molded by 3D printing.

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