Fano resonance-based sensor and detection method of mixed solution

Abstract

The invention provides a Fano resonance-based sensor and a detection method of a mixed solution. The sensor comprises a waveguide structure, the waveguide structure comprises a strip-shaped waveguide and a plurality of annular waveguides coupled with the strip-shaped waveguide; the strip-shaped waveguide is provided with a plurality of reflection units; the strip-shaped waveguide is used for receiving incident light; the reflection unit is used for reflecting the incident light to form reflected light in a discrete state; the annular waveguide is used for circularly spreading incident light in the annular waveguide to form continuous transmission light; wherein the reflected light and the transmission light interfere with each other to generate Fano resonance. According to the invention, the plurality of reflection units are arranged in the strip-shaped waveguide to form reflected light in a discrete state, so that fano resonance can be generated, detection of a mixed solution is realized without using a functionalized cavity array, the detection efficiency and the detection accuracy are improved, the detection difficulty is reduced, and the application range is expanded; the device is small in size, greatly improves the integration level, and has a wide application prospect.

Description

Technical Field

[0001] The present disclosure relates to the technical field of optical devices, and in particular to a sensor based on Fano resonance and a detection method for a mixed solution. Background Art

[0002] A microring resonator is a miniature resonant structure based on an optical waveguide. It utilizes the cyclic interference of light to create resonance and is widely used in fields such as integrated photonics, optical communications, and biosensing. Light is input through a straight waveguide and enters the microring through evanescent field coupling, where it circulates within the ring. Resonance occurs when the phase change of light after one cycle of propagation within the ring is an integer multiple of 2π. During resonance, light is enhanced within the ring, resulting in a Lorentz line shape in the transmission spectrum of the straight waveguide. The Lorentz line shape is widely used due to its simplicity, but it has drawbacks in applications such as high-sensitivity sensing, complex media detection, and multi-parameter analysis.

[0003] Fano resonance arises from the interference between a narrow-linewidth discrete state and a broad-spectrum continuous state. Its asymmetric line shape is extremely sensitive to changes in the surrounding environment. This unique resonance significantly enhances the detection sensitivity of sensors, making it particularly suitable for detecting trace molecules or weak physical quantities. The sharp asymmetric peak of Fano resonance effectively suppresses background noise and improves signal contrast, thereby enhancing the sensor's signal-to-noise ratio and maintaining high-precision detection even in complex environments. Its high sensitivity enables the detection of extremely low concentrations of analytes (e.g., at the single-molecule level), and has important applications in biomedical testing, environmental monitoring, and other fields.

[0004] Traditional waveguide sensors (such as Mach-Zehnder interferometers and microring resonators) detect the object under test through phase / wavelength changes. They usually strive to minimize losses to improve the sensitivity of real refractive index detection. They can only provide indirect information on the concentration or composition of the object under test and cannot fully characterize the material properties. Summary of the Invention

[0005] The technical problem to be solved by the present disclosure is to overcome the defects of the existing waveguide sensor in detecting the object to be tested by phase / wavelength changes, such as the inability to fully characterize the properties of the material, and to provide a sensor based on Fano resonance and a detection method for a mixed solution.

[0006] The present disclosure solves the above technical problems through the following technical solutions:

[0007] The present disclosure provides a sensor based on Fano resonance, the sensor comprising a waveguide structure;

[0008] The waveguide structure includes a strip waveguide and a plurality of ring waveguides coupled to the strip waveguide;

[0009] The strip waveguide is provided with a plurality of reflection units;

[0010] The strip waveguide is used to receive incident light;

[0011] The reflecting unit is used to reflect the incident light to form discrete reflected light;

[0012] The ring waveguide is used to allow the incident light to circulate and propagate within the ring waveguide to form continuous transmission light;

[0013] The reflected light and the transmitted light interfere with each other to generate the Fano resonance.

[0014] Optionally, the sensor is used to detect the concentration of each component in the mixed solution;

[0015] The concentration is obtained based on the real refractive index and / or the imaginary refractive index of the mixed solution;

[0016] The real refractive index is obtained based on the wavelength of the resonance peak of the Fano resonance generated by the mixed solution;

[0017] The imaginary refractive index is obtained based on the intensity of the resonance peak of the Fano resonance generated by the mixed solution.

[0018] Optionally, the number of the reflection units is an odd number.

[0019] Optionally, the number of the reflection units is 3.

[0020] Optionally, the distance between two adjacent reflecting units is 500 nm;

[0021] and / or,

[0022] The first center of the reflection unit at the middle position and the second center of the ring waveguide are located on the same straight line, and the straight line is perpendicular to the length direction of the strip waveguide.

[0023] Optionally, the number of the ring waveguides is 2, and the two ring waveguides are arranged on both sides of the strip waveguide.

[0024] Optionally, the coupling gap between each of the ring waveguides and the strip waveguide is the same.

[0025] Optionally, the coupling gap is 200 nm.

[0026] Optionally, the material of the waveguide structure is a chalcogenide material;

[0027] and / or,

[0028] The height of the waveguide structure is 300 nm;

[0029] and / or,

[0030] The width of the waveguide structure is 600 nm;

[0031] and / or,

[0032] The radius of the reflection unit is 200 nm;

[0033] and / or,

[0034] The sensor further includes a substrate layer disposed below the waveguide structure;

[0035] and / or,

[0036] The sensor further includes a cladding surrounding the waveguide structure.

[0037] The present disclosure also provides a method for detecting a mixed solution, the method comprising:

[0038] Using the above-described Fano resonance-based sensor, peak information of the Fano resonance peak generated by the mixed solution is obtained, wherein the peak information includes wavelength and / or intensity;

[0039] Acquire a refractive index of the mixed solution corresponding to the peak information, where the refractive index includes a real refractive index and / or an imaginary refractive index;

[0040] Based on the refractive index, the concentration of each component in the mixed solution is obtained.

[0041] On the basis of conforming to the common sense in this field, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present disclosure.

[0042] The positive progress of this disclosure is:

[0043] The present invention provides a plurality of reflection units in a strip waveguide to form discrete reflected light, thereby generating Fano resonance. This overcomes the defect of existing waveguide sensors that detect the object to be tested through phase / wavelength changes, resulting in an inability to fully characterize the material properties. Without the need for a functionalized cavity array, the present invention realizes the detection of mixed solutions, improves detection efficiency and accuracy, reduces detection difficulty, and expands the scope of application. The device is small in size, greatly improves integration, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a plan view of a waveguide structure of a sensor according to an embodiment of the present disclosure;

[0045] Figure 2 Schematic diagram of the transmission spectrum of the sensor of the embodiment of the present disclosure in the 1520nm-1600nm band;

[0046] Figure 3 Schematic diagram of the transmission spectrum of the sensor according to the embodiment of the present disclosure at different real refractive indices;

[0047] Figure 4 is a fitting diagram of the sensitivity of the real refractive index of the sensor according to an embodiment of the present disclosure;

[0048] Figure 5 Schematic diagram of the transmission spectrum of the sensor according to the embodiment of the present disclosure at different imaginary refractive indices;

[0049] Figure 6 is a fitting diagram of the sensitivity of the imaginary refractive index of the sensor according to an embodiment of the present disclosure;

[0050] Figure 7 1 is a comparison diagram of transmission spectra when the number of reflective units in the sensor of the embodiment of the present disclosure is 1, 3, and 5 respectively;

[0051] Figure 8 Schematic diagram of the spacing between reflective units in the sensor according to an embodiment of the present disclosure;

[0052] Figure 9 1 is a comparison diagram of transmission spectra when the spacing L between the reflective units in the sensor of the embodiment of the present disclosure is 500 nm, 550 nm, and 600 nm respectively;

[0053] Figure 10 A comparison of transmission spectra of a sensor comprising a single ring and a sensor comprising two rings according to an embodiment of the present disclosure;

[0054] Figure 11 1 is a comparison diagram of transmission spectra when the radius r of the reflective unit in the sensor of the embodiment of the present disclosure is 100 nm, 150 nm, and 200 nm respectively;

[0055] Figure 12 A three-dimensional schematic diagram of a sensor according to an embodiment of the present disclosure;

[0056] Figure 13 Flowchart of a method for detecting a mixed solution according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0057] The present disclosure is further illustrated below by way of examples, but the present disclosure is not limited to the scope of the examples.

[0058] In the embodiments of the present disclosure, prefixes such as "first" and "second" are used only to distinguish different description objects and have no limiting effect on the position, order, priority, quantity or content of the described objects. In the embodiments of the present disclosure, the use of prefixes such as ordinal numbers to distinguish description objects does not constitute a restriction on the described objects. For the statement of the described objects, please refer to the description in the context of the embodiments, and the use of such prefixes should not constitute an unnecessary restriction. In addition, in the description of this embodiment, unless otherwise specified, the meaning of "plurality" is two or more.

[0059] Example 1

[0060] This embodiment provides a sensor based on Fano resonance, the sensor including a waveguide structure;

[0061] like Figure 1 As shown, the waveguide structure 1 includes a strip waveguide 11 and a plurality of ring waveguides 12 coupled with the strip waveguide 11;

[0062] The strip waveguide 11 is provided with a plurality of reflection units 111;

[0063] The strip waveguide 11 is used to receive incident light;

[0064] The reflection unit 111 is used to reflect the incident light to form discrete reflected light;

[0065] The ring waveguide 12 is used to allow the incident light to circulate and propagate within the ring waveguide 12 to form a continuous state of transmitted light;

[0066] The reflected light and the transmitted light interfere with each other, generating Fano resonance.

[0067] Specifically, the strip waveguide is linear and has several reflective units, which can be circular or elliptical. The ring waveguide, for example, includes a first microring waveguide and a second microring waveguide. The strip waveguide and the ring waveguide are located in the same plane. The strip waveguide with the reflective units forms discrete reflected light, while the ring waveguide forms continuous transmitted light. The two interfere with each other, generating an asymmetric Fano resonance peak.

[0068] The reflective unit in the strip waveguide can reflect the incident light, causing phase change and thus generating asymmetric Fano resonance. The reflective unit in the strip waveguide is the key to generating Fano resonance. The transmission spectrum of the sensor in the 1520nm-1600nm band is as follows: Figure 2 As shown, Figure 2 The horizontal axis is wavelength (nm), and the vertical axis is normalized transmittance (Normalized Transmission). Figure 2The multiple Fano resonances are shown. The resonance peak of the Fano resonance can be used to test the real part of the refractive index and the imaginary part of the refractive index of the solution to realize the complex refractive index sensing. The sensitivity of the real part of the resonance peak of the Fano resonance and the sensitivity of the imaginary part of the refractive index are high, which can greatly improve the detection accuracy of the sensor.

[0069] In the scheme, by arranging a plurality of reflection units in the strip waveguide, the discrete state of the reflected light is formed, and then the Fano resonance can be generated. The defect that the existing waveguide sensor cannot fully characterize the characteristics of the substance due to the change of phase / wavelength for detecting the measured object is overcome. The detection of the mixed solution is realized without using the functional processing of the cavity array. The detection efficiency and detection accuracy are improved. The detection difficulty is reduced. The application range is expanded. The device size is small. The integration is greatly improved. The scheme has a wide application prospect.

[0070] In an implementable scheme, the sensor is used for detecting the concentration of each component in the mixed solution.

[0071] The concentration is obtained based on the real part of the refractive index and / or the imaginary part of the refractive index of the mixed solution.

[0072] The real part of the refractive index is obtained based on the wavelength of the resonance peak of the Fano resonance generated by the mixed solution.

[0073] The imaginary part of the refractive index is obtained based on the intensity of the resonance peak of the Fano resonance generated by the mixed solution.

[0074] Specifically, the resonance peak of the Fano resonance can be used to realize the complex refractive index sensor of the scheme. The complex refractive index includes the real part of the refractive index and the imaginary part of the refractive index. The real part of the refractive index of the mixed solution is characterized by the wavelength or phase change of the resonance peak of the Fano resonance, that is, the wavelength shift. The imaginary part of the refractive index is characterized by the intensity change of the resonance peak. The imaginary part of the refractive index reflects the degree of absorption of light.

[0075] The sensitivity of the real part of the refractive index of the sensor can be tested. In order to better compare the spectrum change, the imaginary part of the environmental refractive index is kept unchanged, and is set to 0. Only the real part is changed. As shown in Figure 3 The abscissa is wavelength, unit: nm, and the ordinate is normalized transmittance. When the real part of the refractive index changes from 1.33, 1.331, 1.332, 1.333, 1.334 RIU in order, the resonance peak is red-shifted. The sensitivity of the real part of the refractive index is obtained by fitting As shown in Figure 4 Figure 4 ​The horizontal axis is the real part of the refractive index (RIU), and the vertical axis is the resonance wavelength (nm). Among them, λ represents the wavelength position corresponding to the resonance peak of Fano resonance, Δλ represents the change in the wavelength position corresponding to the resonance peak of Fano resonance, n represents the real part of the refractive index, Δn represents the change in the real part of the refractive index, S n Indicates the sensitivity of the real part of the refractive index. Figure 4 The five points near the midline and Figure 3 The wavelength position of the resonance peak of each spectral line corresponds to the real refractive index. Figure 4 It can be clearly reflected that the resonance wavelength of the resonance peak of Fano resonance increases with the increase of the real refractive index. The wavelength shift of the resonance peak and the real refractive index show a good linear relationship. The slope of the straight line is the sensitivity of the real refractive index.

[0076] The sensitivity of the imaginary refractive index of the sensor can be tested. In order to better compare the spectral changes, the real part of the ambient refractive index remains unchanged and is set to 1.331, and only the imaginary part is changed. Figure 5 As shown, the horizontal axis is the wavelength in nm, and the vertical axis is the normalized transmittance. -4 , 5×10 -4 , 7.5×10 -4 When the RIU sequence changes, the peak width of the Fano resonance peak gradually increases and the slope of the resonance peak gradually decreases. Figure 5 middle Represents the refractive index, including the real and imaginary refractive indexes. The real refractive index is 1.331RIU. The calculation formula corresponding to the sensitivity of the imaginary refractive index is as follows:

[0077] ;

[0078] ;

[0079] ;

[0080] ;

[0081] ;

[0082] Among them, V represents the intensity of the resonance peak, that is, the light intensity contrast; λ peak and λ dip The wavelengths corresponding to the peak and valley values ​​of the Fano resonance peak are represented by T, max and T min Respectively expressed in λ peak and λdip The transmittance at the wavelength, D(λ) represents the peak width, P represents the slope of the Fano resonance peak, F represents the logarithm of P, ΔF represents the change in the logarithm of P, k represents the imaginary refractive index, Δk represents the change in the imaginary refractive index, S k Represents the sensitivity of the real part of the refractive index. P is a curve with respect to k, so taking the logarithm of P gives F.

[0083] The fitting diagram of the sensitivity of the imaginary refractive index obtained by fitting is as follows Figure 6 As shown, Figure 6 The horizontal axis is the imaginary part of the refractive index (RIU), and the vertical axis is the logarithm of the slope of the Fano resonance peak. Figure 6 The four points near the midline and Figure 5 The slope of the resonance peak of each spectral line corresponds to the imaginary refractive index. Figure 6 It can be clearly reflected that the logarithmic value of the slope of the resonance peak of Fano resonance decreases with the increase of the imaginary refractive index. The logarithmic value of the slope of the resonance peak and the imaginary refractive index show a good linear relationship. The slope of the straight line is the sensitivity of the imaginary refractive index.

[0084] The sensitivity of the real refractive index and the sensitivity of the imaginary refractive index can reflect the sensing performance of the sensor. The higher the sensitivity, the more accurate the measurement of the real refractive index and the imaginary refractive index of a mixed solution of unknown concentration, and the more accurate the concentration of each component of the mixed solution obtained.

[0085] By testing the sensor, two mapping relationships can be obtained: a first mapping relationship between the wavelength of the resonance peak and the real refractive index, and a second mapping relationship between the intensity of the resonance peak and the imaginary refractive index. The first mapping relationship is a linear relationship. By converting the intensity of the resonance peak in the second mapping relationship, a second mapping relationship between the logarithm of the slope of the Fano resonance peak and the imaginary refractive index can be further obtained. The third mapping relationship is also a linear relationship.

[0086] For a ternary mixed solution of unknown concentration, such as a ternary mixed solution of water, methanol and acetonitrile, the higher the content of acetonitrile, the greater the harm to the human body. To detect the content of acetonitrile in the solution, first measure the wavelength position and corresponding intensity of the resonance peak of the Fano resonance of the solution. According to the intensity, the slope of the Fano resonance peak can be obtained, and then the logarithm of the slope of the Fano resonance peak can be obtained. Then, the wavelength position and the logarithm of the slope of the Fano resonance peak are substituted into the two linear relationships of the first mapping relationship and the third mapping relationship to obtain the real refractive index and imaginary refractive index of the ternary mixed solution. Finally, the real refractive index and the imaginary refractive index of the ternary mixed solution are substituted into the equivalent complex refractive index formula of the mixed solution to obtain the concentration of each component of the ternary mixed solution. The equivalent complex refractive index formula of the mixed solution is the linear superposition relationship between the equivalent complex refractive index and the complex refractive index of its components. The corresponding formula is as follows:

[0087] ;

[0088] ;

[0089] Among them, n med represents the real refractive index of the mixed solution, k med represents the imaginary refractive index of the mixed solution, j represents the index of the components of the mixed solution, j≤the total number of components in the mixed solution, c j represents the concentration of each component, n j and k j denote the real refractive index and imaginary refractive index of each component, n j and k j It can be found in existing literature and materials.

[0090] The concentration of each component in the ternary mixed solution can be used to determine the content of acetonitrile; the degree of harm the solution may cause to the human body can be determined based on the content of acetonitrile.

[0091] By combining real and imaginary refractive indices, this sensor can detect not only binary but also ternary mixed solutions without the need for a functionalized cavity array. This improves detection efficiency, reduces detection difficulty, and expands its application range. The sensor is applicable to all ternary mixed solutions. For any ternary mixed solution containing an unknown concentration of a toxic component, the sensor can detect the concentration of the toxic component, thereby determining its safety and contamination level.

[0092] In this solution, by fully utilizing the direct and interference-resistant detection capability of the imaginary refractive index, the detection efficiency and accuracy are improved, the detection difficulty is reduced, and the application scope is expanded.

[0093] In an implementable solution, the number of the reflection units is an odd number.

[0094] The number of reflective elements in a strip waveguide affects the realization of Fano resonance and should be designed to be an odd number and symmetrically distributed. An even number of reflective elements may lead to mode degeneracy, while an odd number of reflective elements can break the symmetry, enhance the interference effect, and promote the formation of Fano resonance.

[0095] In this solution, an odd number of reflection units are set in the strip waveguide to promote the formation of Fano resonance and ensure the reliability and effectiveness of the sensor.

[0096] In one feasible solution, the number of the reflection units is 3.

[0097] Specifically, if Figure 7 As shown in the figure, the horizontal axis is the wavelength in nm, and the vertical axis is the normalized transmittance. When the number of reflective units is 1, the spectrum is close to the Lorentz line type, indicating that the phase change is very small and the Fano resonance is not obvious. When the number of reflective units is 3, obvious Fano resonance appears. When the number of reflective units is 5, the loss of incident light in the reflective unit is very large, and a spectrum close to the anti-Lorentz line type appears. Therefore, the number of reflective units is designed to be 3.

[0098] In this solution, three reflection units are set in the strip waveguide to ensure the formation of Fano resonance and guarantee the reliability and effectiveness of the sensor.

[0099] In one feasible solution, the distance between two adjacent reflective units is 500 nm;

[0100] Specifically, if Figure 8 As shown, the distance L between the two reflective units, that is, the distance between the centers of the reflective units, will affect the phase change. In order to meet the preparation conditions, the distance between two adjacent reflective units cannot be less than 500nm. Figure 9 As shown in the figure, the abscissa is wavelength (nm), and the ordinate is normalized transmittance. As the spacing L decreases from 600nm to 550nm and finally to 500nm, the Fano resonance becomes more pronounced and the extinction ratio increases. However, a spacing L that is too small can affect device fabrication, so L is designed to be 500nm.

[0101] In this solution, the spacing between two adjacent reflection units is set to 500 nm, which meets the device preparation conditions, ensures the generation of Fano resonance, increases the extinction ratio of the transmission spectrum, and improves the reliability of the measurement results.

[0102] In an implementable solution, the first center of the reflection unit in the middle position and the second center of the ring waveguide are located on the same straight line, and the straight line is perpendicular to the length direction of the strip waveguide.

[0103] Specifically, a rectangular coordinate system is established with the first center of the reflective unit in the middle position as the origin, the length direction of the strip waveguide as the Y-axis, and the direction perpendicular to the length direction of the strip waveguide as the X-axis. In this coordinate system, the Y-axis coordinate y1 of the first center of the reflective unit in the middle position of the strip waveguide is consistent with the Y-axis coordinate y2 of the second center of the ring waveguide. At this time, the Fano resonance effect is the strongest. The larger the difference in the Y-axis coordinates, the less obvious the Fano resonance is, and it will gradually become a Lorentz line type, so it is necessary to ensure that the Y-axis coordinates are consistent.

[0104] In this solution, the first center of the reflection unit in the middle position and the second center of the ring waveguide are located in the same straight line, and the straight line is perpendicular to the length direction of the strip waveguide, ensuring the generation of Fano resonance and guaranteeing the reliability and effectiveness of the sensor.

[0105] In an implementable solution, the number of the ring waveguides is two, and the two ring waveguides are arranged on both sides of the strip waveguide.

[0106] Specifically, due to the presence of reflective units in the strip waveguide, the extinction ratio of the transmission spectrum is relatively small, and the resonance peak may be submerged by noise. The higher the extinction ratio, the higher the contrast between the resonance peak and the background noise, and the more reliable the measurement results. In order to increase the extinction ratio, two ring waveguides, i.e., double rings, are set. Figure 10 As shown in the figure, the horizontal axis is wavelength in nm, and the vertical axis is transmittance in dB. It can be seen that the dual-ring design significantly improves the extinction ratio compared to the single-ring design. A single-ring design, i.e., a single ring waveguide, exhibits a significant increase in the extinction ratio. Using three or more ring waveguides results in a high number of Fano resonance peaks with very low extinction ratios, which is detrimental to sensor sensitivity testing.

[0107] In this scheme, by designing two ring waveguides, the extinction ratio of the transmission spectrum is increased, and the reliability of the measurement results is improved.

[0108] In one embodiment, the coupling gaps between each ring waveguide and the strip waveguide are the same.

[0109] Specifically, to ensure that the Fano resonances do not overlap, the coupling gaps between the two ring waveguides and the straight waveguide need to remain the same.

[0110] In this solution, by setting the coupling gap between each ring waveguide and the strip waveguide to be the same, it is ensured that the Fano resonances do not overlap, thereby improving the reliability of the measurement results.

[0111] In one embodiment, the coupling gap is 200 nm.

[0112] In this scheme, the coupling gap between each ring waveguide and strip waveguide is set to 200nm, which ensures a high quality factor Q value and extinction ratio, and improves the reliability of the measurement results.

[0113] In one embodiment, the waveguide structure is made of a chalcogenide material.

[0114] Specifically, the chalcogenide material is chalcogenide glass (ChGs), such as Ge 28 Sb 12 Se 60 .

[0115] ChGs are amorphous materials primarily composed of chalcogenide elements (such as sulfur (S), selenium (Se), and tellurium (Te)) covalently bonded with certain metals or non-metallic elements. These materials exhibit excellent light transmittance in the near-infrared (NIR) band. Sulfides, selenides, and tellurides have light transmittances of up to 12, 14, and 20 microns, respectively, fully covering the critical NIR sensing wavelength range.

[0116] Compared to traditional semiconductor materials such as silicon and germanium, chalcogenide glass has a wider band gap and therefore exhibits lower two-photon absorption, making it an ideal optical material. Furthermore, compared to crystalline fluorides and crystalline semiconductors, chalcogenide glass can be deposited directly onto substrate wafers without having to consider lattice matching, making it easier to prepare ultra-thin films. The fabrication process for chalcogenide devices is fully compatible with complementary metal oxide semiconductor (CMOS) micro- and nanofabrication technologies, offering significant advantages for their application in integrated optics and optoelectronics.

[0117] In this solution, a waveguide structure made of chalcogenide materials is used to ensure the effectiveness and reliability of the sensor and improve the optical performance of the sensor.

[0118] In one embodiment, the height of the waveguide structure is 300 nm, and the width of the waveguide structure is 600 nm.

[0119] Specifically, for a strip waveguide, its height and width jointly determine the number of modes. When the waveguide height is greater than 300nm, higher-order modes will appear if the waveguide width exceeds 740nm. To ensure single-mode transmission of the TE0 fundamental mode, a waveguide width of 600nm and a height of 300nm are selected. A waveguide width less than 740nm is the theoretical critical value for TE0 fundamental mode transmission. However, in actual processes, fluctuations and errors exist. If the width is exactly 740nm, higher-order modes may be excited. Selecting 600nm provides a process tolerance of 140nm, significantly reducing the risk of multimode transmission caused by process fluctuations.

[0120] The height of the reflection unit is consistent with the height of the waveguide structure, both of which are 300 nm.

[0121] In this solution, the height of the waveguide structure is set to 300 nm and the width of the waveguide structure is set to 600 nm, which meets the requirements of TE0 fundamental mode single-mode transmission and the preparation process requirements of the device.

[0122] In one feasible solution, the radius of the reflection unit is 200 nm.

[0123] Specifically, the radius r of the reflective unit will affect the reflectivity, thereby affecting the phase change. Figure 11 As shown, the horizontal axis is the wavelength in nm, and the vertical axis is the normalized transmittance. As the radius r gradually increases from 100 nm to 150 nm and finally to 200 nm, the phase change increases and the Fano resonance becomes stronger. The spectrum gradually changes from a Lorentz line type to a Fano line type. The reflective unit is embedded in the strip waveguide. Therefore, the diameter of the reflective unit cannot be greater than or equal to the width of the strip waveguide, for example, 600 nm, that is, the radius r of the reflective unit cannot be greater than or equal to 300 nm. In order to ensure the transmittance of light, the radius r of the reflective unit is designed to be 200 nm.

[0124] In this solution, the radius of the reflection unit is set to 200 nm, which ensures the transmittance of light and meets the preparation requirements of the device.

[0125] In one feasible solution, Figure 12 As shown, the sensor further comprises a substrate layer 2 disposed below the waveguide structure. The substrate layer 2 comprises a first layer 21 and a second layer 22. The substrate layers are Si and SiO2 from bottom to top, i.e., the first layer is Si and the second layer is SiO2.

[0126] The sensor further includes a cladding layer surrounding the waveguide structure, wherein the cladding layer is air or an analyte.

[0127] In this solution, a complete sensor is formed by providing a cladding layer and a substrate layer, thereby ensuring the reliability of the sensor.

[0128] Example 2

[0129] This embodiment provides a method for detecting a mixed solution, such as Figure 13 As shown, the detection method includes:

[0130] S101, using the Fano resonance-based sensor as in Example 1, obtaining peak information of a resonance peak of the Fano resonance generated by the mixed solution, the peak information including wavelength and / or intensity;

[0131] S102, obtaining a refractive index of the mixed solution corresponding to the peak information, where the refractive index includes a real refractive index and / or an imaginary refractive index;

[0132] S103. Based on the refractive index, the concentration of each component in the mixed solution is obtained.

[0133] Specifically, by testing the sensor, two mapping relationships can be obtained: a first mapping relationship between the wavelength of the resonance peak and the real refractive index, and a second mapping relationship between the intensity of the resonance peak and the imaginary refractive index. The first mapping relationship is a linear relationship; by converting the intensity of the resonance peak in the second mapping relationship, a second mapping relationship between the logarithm of the slope of the Fano resonance peak and the imaginary refractive index can be further obtained. The third mapping relationship is also a linear relationship.

[0134] For the detection of a mixed solution, the wavelength position and corresponding intensity of the resonance peak of the Fano resonance of the solution are first measured. The slope of the Fano resonance peak can be obtained based on the intensity, and then the logarithm of the slope of the Fano resonance peak can be obtained. The wavelength position and the logarithm of the slope of the Fano resonance peak are then substituted into the two linear relationships of the first mapping relationship and the third mapping relationship to obtain the real refractive index and imaginary refractive index of the mixed solution. Finally, the real refractive index and imaginary refractive index of the mixed solution are substituted into the equivalent complex refractive index formula of the mixed solution to obtain the concentration of each component of the mixed solution.

[0135] In this solution, by combining the real and imaginary refractive indices, the detection of not only binary but also ternary mixed solutions is possible without the need for a functionalized cavity array. This improves detection efficiency, reduces detection difficulty, and expands the scope of application. This sensor is applicable to all ternary mixed solutions. For any ternary mixed solution containing an unknown concentration of a toxic component, the sensor can be used to detect the concentration of the toxic component, thereby determining its safety and contamination level.

[0136] While specific embodiments of the present disclosure have been described above, those skilled in the art will appreciate that these are merely illustrative and that the scope of protection of the present disclosure is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present disclosure, and such changes and modifications are intended to fall within the scope of protection of the present disclosure.

Claims

1. A sensor based on Fano resonance, characterized in that: The sensor includes a waveguide structure; The waveguide structure includes a strip waveguide and a plurality of ring waveguides coupled to the strip waveguide; The strip waveguide is provided with a plurality of reflection units; The strip waveguide is used to receive incident light; The reflecting unit is used to reflect the incident light to form discrete reflected light; The ring waveguide is used to allow the incident light to circulate and propagate within the ring waveguide to form continuous transmission light; The reflected light and the transmitted light interfere with each other to generate the Fano resonance.

2. The sensor based on Fano resonance according to claim 1, wherein: The sensor is used to detect the concentration of each component in the mixed solution; The concentration is obtained based on the real refractive index and / or the imaginary refractive index of the mixed solution; The real refractive index is obtained based on the wavelength of the resonance peak of the Fano resonance generated by the mixed solution; The imaginary refractive index is obtained based on the intensity of the resonance peak of the Fano resonance generated by the mixed solution.

3. The sensor based on Fano resonance according to claim 1, wherein: The number of the reflection units is an odd number.

4. The sensor based on Fano resonance according to claim 1, wherein: The number of the reflection units is 3.

5. The sensor based on Fano resonance according to claim 3 or 4, characterized in that: The distance between two adjacent reflection units is 500 nm; and / or, The first center of the reflection unit at the middle position and the second center of the ring waveguide are located on the same straight line, and the straight line is perpendicular to the length direction of the strip waveguide.

6. The sensor based on Fano resonance according to claim 1, wherein: The number of the annular waveguides is 2, and the two annular waveguides are arranged on both sides of the strip waveguide.

7. The sensor based on Fano resonance according to claim 1, wherein: The coupling gap between each of the ring waveguides and the strip waveguide is the same.

8. The sensor based on Fano resonance according to claim 7, wherein: The coupling gap is 200 nm.

9. The sensor based on Fano resonance according to claim 1, wherein: The material of the waveguide structure is a chalcogenide material; and / or, The height of the waveguide structure is 300 nm; and / or, The width of the waveguide structure is 600 nm; and / or, The radius of the reflection unit is 200 nm; and / or, The sensor further includes a substrate layer disposed below the waveguide structure; and / or, The sensor further includes a cladding surrounding the waveguide structure.

10. A method for detecting a mixed solution, characterized in that: The detection method comprises: Using the Fano resonance-based sensor according to any one of claims 1 to 9, obtaining peak information of the Fano resonance peak generated by the mixed solution, the peak information including wavelength and / or intensity; Acquire a refractive index of the mixed solution corresponding to the peak information, where the refractive index includes a real refractive index and / or an imaginary refractive index; Based on the refractive index, the concentration of each component in the mixed solution is obtained.

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