A dielectric refractive index sensor based on angle Goos-Hansen shift and its preparation method

Abstract

The present invention relates to a dielectric refractive index sensor based on angular Goos-Hansen shift, the structure of which can be expressed as D(BA) N BB(AB) N , where N is the period number of the photonic crystal, A and B are dielectric sheets with different refractive indices, respectively, D is a hemispherical dielectric optical waveguide, and B is a dielectric sheet with a refractive index to be measured; at the interface between the two layers of BB in the center of the structure, there is a topological boundary state. The present invention also provides a method for preparing the above-mentioned dielectric refractive index sensor. The present invention utilizes the angular Goos-Hansen shift near the topological boundary state of the photonic crystal to achieve accurate measurement of the refractive index of the dielectric, that is, the angular Goos-Hansen shift is a function of the incident angle and the refractive index, the incident angle of the light wave is fixed, and the refractive index of the dielectric is compared by measuring the angular Goos-Hansen shift of the reflected light.

Description

Technical Field

[0001] The invention belongs to the field of optical technology, and in particular relates to a dielectric refractive index sensor based on angular Goos-Hansen shift and a preparation method thereof. Background Art

[0002] With the development of detection and sensing technology, there is an urgent need to develop high-sensitivity refractive index sensors. Only under the condition of fine measurement of the refractive index can the refractive index of the dielectric be accurately controlled, and then used to realize photonic chips, all-optical switches and new lasers. In addition, the physical, chemical and biological properties of materials are often related to the refractive index. Therefore, the development of high-sensitivity refractive index sensors is a necessary condition for detecting some important physical, chemical and biological properties.

[0003] When light enters from one medium into another, there are reflected light and transmitted light at the interface between two media with different refractive indices. According to traditional geometric optics theory, the incident light, transmitted light, and reflected light are in the same plane, and on the interface, the incident point, transmission point, and reflection point coincide.

[0004] However, when light waves are reflected at the interface between two media, part of the light field energy will enter another medium from one dielectric. This makes a virtual reflection surface exist below or above the interface. Then, the actual reflected light will undergo a lateral displacement relative to the position predicted by geometric optics. This position is called the spatial Goos-Hansen displacement ( shift: GH displacement).

[0005] Furthermore, the study found that the actual reflected light also deflects at an angle relative to the position predicted by geometric optics, which is called the angular Goos-Hansen shift. Light waves that undergo spatial and angular Goos-Hansen shifts are generally transverse magnetic excitation waves.

[0006] The spatial Goos-Hansen shift is proportional to the rate of change of the reflection coefficient phase. Near the defect mode of the photonic crystal, the reflection coefficient phase fluctuates violently, thus inducing a large spatial Goos-Hansen shift. However, the reflection coefficient at the defect mode is the smallest, and the angular Goos-Hansen shift is proportional to the rate of change of the reflection coefficient. Therefore, the angular Goos-Hansen shift at the defect mode is zero.

[0007] If two photonic crystals are combined to form a symmetrical structure, the structure supports topological edge states, also called boundary modes. Boundary modes have strong resonance and electric field localization, so near the topological edge state, the transmission coefficient is extremely large and the reflection coefficient is extremely small, and the reflection coefficient increases sharply with the change of the incident angle or incident wavelength. Therefore, a large angle Goos-Hansen shift can be achieved near the topological edge state.

[0008] The angular Goos-Hansen shift is very sensitive to the refractive index of the dielectric. A sensitivity range with good linearity can be selected to apply this property to high-sensitivity refractive index sensors. Summary of the invention

[0009] The present invention aims at the technical problems existing in the prior art and provides a dielectric refractive index sensor based on angular Goos-Hansen shift and a preparation method thereof.

[0010] The technical solution of the present invention to solve the above technical problems is as follows:

[0011] A dielectric refractive index sensor based on angular Goos-Hansen shift, the structure of which can be expressed as D(BA) N BB(AB) N , where N is the period number of the photonic crystal, A and B are dielectric sheets with different refractive indices, D is a hemispherical dielectric optical waveguide, and B is a dielectric sheet with a refractive index to be measured; that is, excluding the incident waveguide D, the main body of the entire structure consists of two photonic multilayer structures (BA) N B and B (AB) N Composition, two photonic multilayer structures are symmetrically distributed about the center point and composited into a structure (BA) N BB(AB) N , there is a topological boundary state at the interface between the two layers of BB in its center.

[0012] Based on the above technical solution, the present invention can also be improved as follows.

[0013] Furthermore, the material of the dielectric sheet A is lithium niobate, and its refractive index is n a =2.2494; the material of the hemispherical dielectric optical waveguide D is silicon dioxide, and its refractive index is n d =1.4525; the length and width of the dielectric sheets A and B are more than two orders of magnitude larger than the incident wavelength.

[0014] Furthermore, the thickness of the dielectric sheet A is d a = 0.2 μm, the thickness of dielectric sheet B is d b=0.3μm, the incident wavelength λ=0.85μm, the length and width of the dielectric sheets A and B are both 100μm, and the radius of the optical waveguide D is 50μm.

[0015] Furthermore, the dielectric sheet B is any dielectric, and its refractive index variation range is set to n b =[1.1, 1.4].

[0016] Furthermore, the dielectric sheet B is a liver pathological section, and its refractive index variation range is set to n b =[1.1, 1.5], the incident angle of the light wave is fixed at θ=35°.

[0017] Furthermore, the period number N of the photonic crystal is 2 or 4.

[0018] Another object of the present invention is to provide a method for preparing the above-mentioned dielectric refractive index sensor.

[0019] The specific technical solutions are as follows:

[0020] A method for preparing a dielectric refractive index sensor comprises the following steps:

[0021] 1) Prepare dielectric sheets A and B, and arrange the dielectric sheets A and B alternately to form a multilayer dielectric structure: (BA) N BB(AB) N ;

[0022] 2) Make a hemispherical dielectric optical waveguide D and place it in the above structure (BA) N BB(AB) N One end of the structure D(BA) N BB(AB) N .

[0023] Furthermore, in step 1), the dielectric sheet A is manufactured according to the following process: a =2.2494 lithium niobate crystal preform rod directional slicing → grinding → polishing; in the step 2), the hemispherical dielectric optical waveguide D is made according to the following process: refractive index n d =1.4525 silicon dioxide crystal preform rod is directional sliced ​​→ ground → polished to make a hemispherical shape.

[0024] Furthermore, the thickness of the dielectric sheet A is d a = 0.2 μm, the thickness of dielectric sheet B is d b =0.3μm, the incident wavelength λ=0.85μm, the length and width of the dielectric sheets A and B are both 100μm, and the radius of the optical waveguide D is 50μm.

[0025] Furthermore, in step 1), the dielectric slice B is a liver pathological slice, which is made according to the following process: sampling → fixation → dehydration → transparent treatment → wax dipping → wax melting → embedding → cooling → wax repair → slicing → sticking → spreading → baking → staining → air drying and sealing.

[0026] The beneficial effects of the present invention are as follows: the dielectric refractive index sensor designed by the present invention comprises two photonic multilayers (i.e., truncated photonic crystals) symmetrical about the center and a hemispherical optical waveguide. The structure of the symmetrical photonic multilayer supports topological boundary states, near which a larger angular Goos-Hansen shift can be achieved. The angular Goos-Hansen shift is a function of the incident angle and the refractive index of the dielectric. The incident angle of the light wave is fixed, and the angular Goos-Hansen shift of the reflected light is used to accurately measure the refractive index of the dielectric. The maximum sensitivity coefficient of the refractive index sensor based on the angular Goos-Hansen shift can be as high as 10 4 When it is applied to the detection of liver pathological sections, it is a non-destructive detection of pathological sections, the pathological sections can be used repeatedly, and the detection speed is fast, the operation is simple, and it is convenient for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of a dielectric refractive index sensor based on angular Goos-Hansen shift according to Example 1 of the present invention (N=2);

[0028] Figure 2 (a) is the relationship between the light wave reflectivity and the incident angle in Example 2 of the present invention, Figure 2 (b) is the relationship between the real part of the light wave reflection coefficient and the incident angle in Example 2 of the present invention, Figure 2 (c) is the relationship between the angular Goos-Hansen shift and the incident angle in Example 2 of the present invention, where the number of periods of the photonic crystal is N=4;

[0029] Figure 3 (ad) are the relationship between the Goos-Hansen shift and the refractive index of the dielectric sheet B corresponding to the incident angles of θ=20°, 25°, 30° and 35° in Example 3 of the present invention;

[0030] Figure 4 (a) is the relationship between the sensitivity coefficient of the dielectric refractive index sensor based on the angle Goos-Hansen shift and the refractive index in Example 3 of the present invention, and (b) is Figure 4 (a) A partial enlarged diagram of the relationship between the sensitivity coefficient of the dielectric refractive index sensor based on the angle Goos-Hansen shift and the refractive index;

[0031] Figure 5 This is a flow chart of manufacturing liver pathological slices, dielectric sheets and optical waveguides according to Example 4 of the present invention;

[0032] Figure 6 Schematic diagram of the steps for making a liver pathology slice detection structure based on angular Goos-Hansen shift according to Example 4 of the present invention. DETAILED DESCRIPTION

[0033] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0034] Unless otherwise specified, the raw materials and equipment used in the present invention are conventional raw materials and equipment (conventional commercial products) in the art and can be purchased on the market.

[0035] Example 1

[0036] like Figure 1 As shown, the dielectric refractive index sensor based on the angle Goos-Hansen shift designed in this embodiment has an overall structure that can be expressed as D(BA) 2 BB(AB) 2 , that is, the period number of the photonic crystal is N = 2. Symbols A and B represent two dielectric sheets with different refractive indices, and D is a hemispherical dielectric optical waveguide. θ is the incident angle, I i is the incident light, I r3 is the reflected light predicted by geometric optics, I r2 is the actual reflected light, I r1 is the reflected ray considering only the spatial Goos-Hansen shift. r1 Relative to the reflected light I r3 There is a certain lateral displacement, namely the spatial Goos-Hansen displacement; and the actual reflected light I r2 Relative to I r3 or I r1 There is a certain angle deflection, denoted as Θ GH , called the angular Guth-Hansen shift.

[0037] Here, the incident light is assumed to be a TM (transverse magnetic) excited wave and a Gaussian beam. The angular Goos-Hansen shift can be expressed as

[0038]

[0039] Where r is the reflection coefficient of the light wave, θ0=λ / (πw0) is the angular width of the incident light beam, w0 is the beam waist of the incident light beam, λ is the incident wavelength, and θ is the incident angle of the light wave. Re() represents the real part operation, and ln() represents the natural logarithm operation.

[0040] The incident wavelength is set to λ = 0.85 μm, which is in the visible light band. The waist of the Gaussian beam is set to w0 = 50λ.

[0041] Depend on Figure 1 It can be seen that the setting of the hemispherical optical waveguide D can ensure that no matter what value of the incident angle of the incident light, the incident light always remains perpendicular to the outer surface of the hemispherical medium; excluding the incident waveguide D, the main body of the entire structure consists of two truncated photonic crystals (BA) N B and B (AB) N The two photonic crystals are symmetrically distributed about the center point, where N is called the period number of the photonic crystal, and N is a positive integer. Here, N = 2 in the structure shown in the figure. The truncated photonic crystal is also called a photonic multilayer. The two photonic multilayers are combined into a structure (BA) N BB(AB) N At the interface between the two layers of BB in the center, there exists a topological boundary state, which is similar to the defect mode of a defect photonic crystal.

[0042] At the topological boundary state, a considerable reflectivity and a large angular Goos-Hansen shift of the reflected light beam can be observed. However, because the reflectivity corresponding to the topological boundary state is extremely small, it can be seen from equation (1) that the angular Goos-Hansen shift at the topological boundary state should be zero, but a large angular Goos-Hansen shift can be obtained on both sides of the topological boundary state.

[0043] Example 2

[0044] This embodiment takes the photon multilayer structure made of N=4 as an example for measurement, and the entire structure is represented by D(BA) 4 BB(AB) 4 The incident wavelength is λ=0.85 μm, and it is a TM excitation wave. It is incident from the optical waveguide D into the photon multilayer.

[0045] The material of the hemispherical optical waveguide D is silicon dioxide (SiO2) with a refractive index of n d =1.4525; dielectric sheet A is lithium niobate (LiNbO3), and its refractive index is n a =2.2494; dielectric sheet B is the dielectric to be tested, and its refractive index variation range is set to n b =[1.1, 1.4].

[0046] The thickness of the dielectric sheet A is d a = 0.2 μm (micrometer); the thickness of the dielectric sheet B is d b =0.3μm. The length and width of dielectric sheets A and B can be at least two orders of magnitude larger than the incident wavelength, and in this embodiment, it is 100μm. The shape of optical waveguide D is hemispherical, and its radius is 50μm.

[0047] The refractive index of the dielectric sheet B is written as n b =n br+i*n bi , where n br represents the real part of the refractive index of dielectric sheet B, n bi represents the imaginary part of the refractive index of the dielectric sheet B, and i represents an imaginary unit.

[0048] This structure can be used to detect the refractive index of any dielectric, such as magnesium fluoride (MgF2), sodium fluoride (NaF) and other slices. When the incident light wavelength is λ = 0.85μm, the real part of the refractive index of a normal magnesium fluoride slice can be found to be n br =1.3746, the imaginary part of the refractive index is negligible; the real part of the refractive index of a normal sodium fluoride slice is n br =1.3223, the imaginary part of the refractive index is negligible. When magnesium fluoride and sodium fluoride are doped with impurities, the refractive index of the slice changes. The imaginary part of the refractive index represents the optical loss, and its value is originally small, so the change in the imaginary part is small and can be ignored. The main consideration is the change in the real part of the refractive index of the dielectric. Therefore, in the following calculations, it is assumed that the imaginary part of the refractive index of the dielectric slice B is n bi = 0, and the real part n br The range of variation is [1.1, 1.4], which is exactly n b range of change.

[0049] Figure 2 (a) shows the relationship between the reflectivity of the light wave and the incident angle. The vertical axis R represents the reflectivity of the light wave. It can be seen that the different real parts of the refractive index of the dielectric sheet B correspond to different reflectivity curves; as the incident angle changes, within the incident angle change range [20°, 50°], there is a minimum value in each reflectivity curve, marked by a circle ○, and the minimum value point corresponds to the topological boundary state. The horizontal axis unit deg represents degree, that is, "°".

[0050] Figure 2(b) shows the relationship between the real part of the reflection coefficient of the light wave and the incident angle. The ordinate Re(r) represents the real part of the reflection coefficient r. It can be seen that: as the incident angle changes, the different refractive indices of the dielectric sheet B correspond to different real part curves of the reflection coefficient; within the incident angle variation range [20°, 50°], there is a minimum value in each real part curve of the reflection coefficient, marked by a circle ○; the minimum value in each real part curve of the reflection coefficient is also the minimum value of each reflectivity curve. According to the angle Goos-Hansen shift formula, it can be known that the angle Goos-Hansen shift is proportional to the rate of change of the real part of the reflection coefficient to the angle, so at the lowest point of the real part curve of the reflection coefficient, that is, at the topological boundary state, the angle Goos-Hansen shift is zero. On both sides of the circle ○ of each curve, the slope of the real part curve of the reflection coefficient is larger, and there is a larger angle Goos-Hansen shift; in addition, the slopes of the curves on both sides of the circle ○ of each curve are opposite in positive and negative polarity, and the corresponding angle Goos-Hansen shifts are also opposite in positive and negative polarity.

[0051] Figure 2 (c) shows the relationship between the angle Goos-Hansen shift and the incident angle. The vertical coordinate unit rad represents radians. It can be seen that: for each given refractive index of a dielectric sheet B, there is a corresponding angle Goos-Hansen shift curve; the angle Goos-Hansen shift changes with the change of the incident angle; at the lowest reflectivity, that is, the topological boundary state, the angle Goos-Hansen shift is zero, marked by a circle ○; on both sides of the circle ○ of each curve, the positive and negative polarities of the angle Goos-Hansen shift are opposite; relative to n br =1.1, 1.2 and 1.3, n br =1.4 corresponds to the maximum peak angle of the Guth-Hansen shift.

[0052] Example 3

[0053] This embodiment also takes the photon multilayer structure made with N=4 as an example to measure the refractive index of human tissue slices. The entire structure is represented by D(BA) 4 BB(AB) 4 , the incident wavelength is λ=0.85μm, and it is a TM excitation wave, which is incident into the photon multilayer from the optical waveguide D. That is, the entire structure is different from that of Example 2, except that the dielectric sheet B in this example is a liver pathological section, and its refractive index variation range is set to n b =[1.1, 1.5], the rest of the structure is the same.

[0054] When the incident light wavelength is λ = 0.85 μm, it can be found that the real part of the refractive index of a normal human liver pathological section is n br =1.3694, the imaginary part of the refractive index is n bi=0.0031719. When a tissue is diseased, the refractive index of its slice changes. The imaginary part of the refractive index represents optical loss, and its value is small. Therefore, when a disease occurs, the change in its imaginary part is small and can be ignored. The main consideration is the change in the real part of the refractive index of the tissue slice. Therefore, in the following calculations, it is assumed that the imaginary part of the refractive index of the dielectric slice B is n bi =0.0031719.

[0055] Figure 3 (a) shows the relationship between the angular Goos-Hansen shift and the refractive index of dielectric sheet B corresponding to an incident angle of θ = 20°. Figure 3 (b) shows the relationship between the angular Goos-Hansen shift and the refractive index of dielectric sheet B corresponding to an incident angle of θ = 25°. Figure 3 (c) shows the relationship between the angular Goos-Hansen shift and the refractive index of dielectric sheet B for an incident angle of θ = 30°. Figure 3 (d) shows the relationship between the angle Goos-Hansen shift and the refractive index of dielectric sheet B when the incident angle is θ = 35°. It can be seen that different angle Goos-Hansen shift curves correspond to different incident angles; for each given incident angle, the angle Goos-Hansen shift changes with the refractive index of dielectric sheet B; relative to θ = 20°, 25° and 30°, the peak angle Goos-Hansen shift corresponding to θ = 35° is the largest.

[0056] When the incident angle of the light wave is fixed, the refractive index of the slice will decrease or increase when the human tissue is diseased, and the corresponding angle Goos-Hansen shift will change. Therefore, the pathological detection of human tissue can be performed by measuring the angle Goos-Hansen shift of the reflected light beam.

[0057] Taking the liver as an example, the refractive index of a normal liver slice is n br =1.3694. Assume that the light wave is incident at θ=35°, and the normal liver slice n br = 1.3694 corresponding to the angle Goos-Hansen shift θ GH =-0.0013rad, Figure 3 (d) is the position of ☆. When the liver refractive index decreases, for example, n br = 1.2 corresponding to the angle Goos-Hansen shift θ GH =0.0384rad; when the liver refractive index increases, for example, n br = 1.4 corresponding to the angle Goos-Hansen shift Θ GH =-0.0215rad.

[0058] Figure 4(a) shows the relationship between the sensitivity coefficient of the dielectric refractive index sensor based on the angular Goos-Hansen shift and the refractive index. The incident angle is fixed at θ = 35°. It can be seen that the angular Goos-Hansen shift is extremely sensitive to the refractive index of the material, so it can be applied to the detection of pathological sections of human tissue for quantitative analysis; when the angular Goos-Hansen shift is applied to the refractive index sensor, the sensor sensitivity is a function of the refractive index; at the refractive index n br When =1.435, the sensor sensitivity coefficient reaches a maximum value.

[0059] In order to more clearly show the sensitivity of the sensor, Figure 4 (b) is given by Figure 4 (a) is a partial enlarged view of the relationship between the sensitivity coefficient of the dielectric refractive index sensor based on the angle Goos-Hansen shift and the refractive index. It can be seen that the sensor sensitivity has a peak and a valley; the sensor sensitivity coefficient can be as high as 10 4 rad. When n br =1.4351, the sensitivity coefficient has the maximum value S Θ =3.538×10 4 rad; when n br =1.4349, the sensitivity coefficient has the maximum amplitude S Θ =9.523×10 3 rad.

[0060] Example 4

[0061] In this embodiment, N=2 and the dielectric sheet B is a photonic multilayer structure D(BA) made of a liver pathological section. 2 BB(AB) 2 As an example, the manufacturing method and implementation process of each dielectric sheet and optical waveguide are given. The incident wavelength is λ=0.85μm, and it is a TM excitation wave, which is incident into the photon multilayer from the optical waveguide D. The entire structure of this embodiment is different from that of embodiment 2, except that N=2 and the dielectric sheet B is a liver pathological section, and the rest of the structure is the same.

[0062] like Figure 5 As shown in the figure, the production process of dielectric sheet A is as follows: lithium niobate (LiNbO3) crystal preform rod is oriented and sliced ​​→ ground → polished to a thickness of d a =0.2μm.

[0063] The production process of the hemispherical dielectric incident waveguide D is as follows: the silicon dioxide crystal preform rod is directional sliced ​​→ ground → polished to form a hemispherical shape with a radius of 50 μm.

[0064] Production process of liver pathological sections B: Take the diseased specimen within 30 minutes of ex vivo treatment → fix the pathological specimen (place it in a sealed container with 10% formaldehyde solution, the volume of the solution is 10 times the volume of the specimen, and the fixation time is 12h-48h) → sample the specimen (wash and cut into pieces of 100μm×100μm×100μm size, and place in an embedding box) → dehydrate (treat with 50% ethanol reagent for 30min, 60% ethanol reagent for 30min, 70% ethanol reagent for 30min, 80% ethanol reagent for 30min, and 100% ethanol reagent for 30min) → remove the specimen (wash and cut into pieces of 100μm×100μm×100μm size, and place in an embedding box) → remove the specimen (treat with 50% ethanol reagent for 30min, 60% ethanol reagent for 30min, 70% ethanol reagent for 30min, and 80% ethanol reagent for 30min). 30min treatment with xylene I reagent, 30min treatment with 90% ethanol reagent, 30min treatment with 95% ethanol I reagent, 30min treatment with 95% ethanol II reagent, 20min treatment with anhydrous ethanol I reagent, 20min treatment with anhydrous ethanol II reagent) → transparent (xylene I reagent and xylene I reagent are treated for 10min each, and the treatment time can be determined according to the transparent effect) → wax immersion (paraffin I immersion for 10min, paraffin II immersion for 10min, open the water bath at 80℃ (Celsius) in advance, and adjust to 6 after the paraffin is almost completely melted 0℃, constant temperature box treatment for 120min) → wax melting (need to open the embedding machine in advance, preheat for half an hour to melt the paraffin) → embedding (take the tissue to the middle of the iron embedding frame, drip the melted paraffin for embedding, pay attention to the relative position of the tissue and the wax block during the period) → cooling (place in a -10℃ refrigerator) → trimming and slicing (put the embedded tissue on the slicer after trimming, adjust the position and set the slice thickness to 0.3μm) → unfolding (take the slide that has been ultrasonically rinsed with 30% ethanol, unfold it in 30% ethanol, take the slide and put it in a 40℃ water bath after 5s Unfold, and take out the slices when they are completely neat) → bake (60℃ constant temperature oven baking for 20-30min) → dewaxing and staining (hematoxylin staining for 4min, water washing for 2min, 1% hydrochloric acid alcohol differentiation for 20s, water washing for 2min, 1% dilute ammonia water blueing for 30s, water washing for 2min, distilled water washing for 1min, eosin staining for 90s, rinse with running water) → dry and seal (after the residual liquid around the slide tissue is dried, immediately drop a drop of neutral gum on the tissue, cover it with a coverslip to cover it naturally, and lay it flat) to obtain the finished liver pathological slice B.

[0065] like Figure 6 As shown, the dielectric sheet A, liver pathological slice B and optical waveguide D prepared above are used to prepare the photonic multilayer structure D (BA) of this embodiment. 2 BB(AB) 2 The method comprises the following steps:

[0066] 1) Dielectric sheets A and liver pathological sections B are arranged alternately to form a multilayer dielectric structure: (BA) N BB(AB) N , where N = 2, that is, BABABBABAB, such as Figure 6 (a) shown.

[0067] 2) Place the dielectric incident waveguide D at one end of the above structure BABABBABAB to form a photonic multilayer structure DBABABBABAB, such as Figure 6 (b) The angle of the incident TM excitation light is used to control the angle of the reflected light, and the Goos-Hansen shift is used to determine the pathology of the liver.

[0068] In summary, the present invention utilizes the angular Goos-Hansen shift near the topological boundary state of the photonic crystal to achieve accurate measurement of the refractive index of the dielectric. The angular Goos-Hansen shift is a function of the incident angle and the refractive index. The maximum sensitivity coefficient of the dielectric refractive index sensor based on the angular Goos-Hansen shift can be as high as 10 4 When the photonic crystal is applied to the detection of liver pathological sections, the pathological sections are non-destructive, the pathological sections can be used repeatedly, and the detection speed is fast, with ultra-high sensitivity, and the operation is simple, which is convenient for large-scale production.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A dielectric refractive index sensor based on angular Goos-Hansen shift, characterized in that: The structure of the dielectric refractive index sensor is represented by D(BA) N BB(AB) N , placing the dielectric incident waveguide D in a multilayer dielectric structure (BA) N BB(AB) N At one end, the incident wave is a TM excitation wave, which is incident into the photonic multilayer from the optical waveguide D, where N is the number of periods of the photonic crystal, A and B are dielectric sheets with different refractive indices, D is a hemispherical dielectric optical waveguide, and B is a dielectric sheet with a refractive index to be measured; that is, excluding the incident waveguide D, the main body of the entire structure consists of two photonic multilayer structures (BA) N B and B (AB) N Composition, two photonic multilayer structures are symmetrically distributed about the center point and composited into a structure (BA) N BB(AB) N , there is a topological boundary state at the interface between the two layers of BB in its center.

2. The dielectric refractive index sensor based on angular Goos-Hansen shift according to claim 1, characterized in that: The material of the dielectric sheet A is lithium niobate, and its refractive index is n a =2.2494; the material of the hemispherical dielectric optical waveguide D is silicon dioxide, and its refractive index is n d =1.4525; the length and width of the dielectric sheets A and B are more than two orders of magnitude larger than the incident wavelength.

3. A dielectric refractive index sensor based on angular Goos-Hansen shift according to claim 1 or 2, characterized in that: The thickness of the dielectric sheet A is d a = 0.2 μm, the thickness of dielectric sheet B is d b =0.3μm, the incident wavelength λ=0.85μm, the length and width of the dielectric sheets A and B are both 100μm, and the radius of the optical waveguide D is 50μm.

4. The dielectric refractive index sensor based on angular Goos-Hansen shift according to claim 3, characterized in that: The dielectric sheet B is any dielectric, and its refractive index variation range is set to n b =[1.1, 1.4].

5. The dielectric refractive index sensor based on angular Goos-Hansen shift according to claim 3, characterized in that: The dielectric sheet B is a liver pathological slice, and its refractive index variation range is set to n b =[1.1, 1.5], the incident angle of the light wave is fixed at θ=35°.

6. The dielectric refractive index sensor based on angular Goos-Hansen shift according to claim 1, characterized in that: The period number N of the photonic crystal is 2 or 4.

7. A method for preparing a dielectric refractive index sensor according to any one of claims 1 to 6, characterized in that: The following steps are involved: 1) Prepare dielectric sheets A and B, and arrange the dielectric sheets A and B alternately to form a multilayer dielectric structure: (BA) N BB(AB) N ; 2) Make a hemispherical dielectric optical waveguide D and place it in the above structure (BA) N BB(AB) N One end of the structure D(BA) N BB(AB) N .

8. The method for preparing a dielectric refractive index sensor according to claim 7, characterized in that: In step 1), the dielectric sheet A is made according to the following process: a =2.2494 lithium niobate crystal preform rod directional slicing → grinding → polishing; in the step 2), the hemispherical dielectric optical waveguide D is made according to the following process: refractive index n d =1.4525 silicon dioxide crystal preform rod is directional sliced ​​→ ground → polished to make a hemispherical shape.

9. The method for preparing a dielectric refractive index sensor according to claim 7 or 8, characterized in that: The thickness of the dielectric sheet A is d a = 0.2 μm, the thickness of dielectric sheet B is d b =0.3μm, the incident wavelength λ=0.85μm, the length and width of the dielectric sheets A and B are both 100μm, and the radius of the optical waveguide D is 50μm.

10. The method for preparing a dielectric refractive index sensor according to claim 9, characterized in that: In the step 1), the dielectric slice B is a liver pathological slice, which is made according to the following process: sampling → fixation → dehydration → transparent treatment → wax dipping → wax melting → embedding → cooling → wax repair → slicing → sticking → spreading → baking → staining → air drying and sealing.

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