One-dimensional photonic crystal refractive index sensor and refractive index detection method

Abstract

The application discloses a one-dimensional photonic crystal refractive index sensor and a refractive index detection method. The one-dimensional photonic crystal refractive index sensor comprises a vertical coupling incident grating, a plurality of micro resonant cavities and a vertical coupling output grating. The micro resonant cavities are realized based on a strip waveguide, an air slit structure and a silicon-based triangular synapse. The vertical coupling incident grating, the plurality of micro resonant cavities and the vertical coupling output grating jointly constitute a one-dimensional photonic crystal. After an input optical signal passes through a beam splitter, the input optical signal passes through a specially designed one-dimensional photonic crystal, interacts with a liquid substance to be detected in the one-dimensional photonic crystal, and is then output. The application realizes an optical refractive index sensor with a one-dimensional photonic crystal, a slit waveguide and a synapse structure, and has the advantages of small size, low preparation cost and large-scale integration. The optical refractive index sensor is a basic element of an optical sensing chip, a bio-lab-on-chip and the like, and has a wide market prospect.

Description

Technical Field

[0001] This invention relates to the field of optical sensor technology, specifically to a one-dimensional photonic crystal refractive index sensor and a refractive index detection method. Background Technology

[0002] Optical sensors are fundamental components in optical sensing chips and environmental protection and food safety detection systems, widely used in biosensing, atmospheric monitoring, and water quality testing. In practical applications, optical sensors generally require high sensitivity for component differentiation and concentration determination. One-dimensional photonic crystal refractive index sensors are particularly important, as low-sensitivity sensors are often limited in practical applications due to their inability to distinguish analytes. They can measure the refractive index information of analytes to determine their composition and concentration.

[0003] A photonic crystal is an optical material composed of a homogeneous medium that exhibits a specific periodicity in a certain direction. Based on the different dimensions of the periodic structure, photonic crystals can be divided into one-dimensional photonic crystals, two-dimensional photonic crystals, and three-dimensional photonic crystals. Photonic crystals of different dimensions have photonic band gaps of different dimensions. The photonic band gap property has a good confinement effect on light, and a strong resonant optical field can be obtained in a microcavity.

[0004] One-dimensional photonic crystals exhibit periodicity in only one direction, making their structure the simplest. They can be achieved simply by arranging two or more materials at equal intervals. In contrast, two-dimensional and three-dimensional photonic crystal structures are an order of magnitude larger than one-dimensional photonic crystal structures and have extremely high requirements for fabrication process error rates.

[0005] However, most optical sensors currently available both domestically and internationally have a sensitivity of less than 800 nm / RIU, and it is difficult to improve their performance and mass-produce them, thus failing to meet the needs of optical sensing systems.

[0006] Therefore, improving traditional optical solution detectors based on the principle of refractive index sensing to achieve low-volume, fast-response, and high-sensitivity refractive index measurement is an important research topic in silicon-based optical sensors. Summary of the Invention

[0007] This invention provides a one-dimensional photonic crystal refractive index sensor to address the technical problems that most current optical sensors have a sensitivity of less than 800 nm / RIU, making it difficult to improve performance and achieve large-scale manufacturing, and failing to meet the requirements of optical sensing systems.

[0008] To address the above problems, this invention provides a one-dimensional photonic crystal refractive index sensor, comprising:

[0009] Strip waveguide;

[0010] A micro-resonant cavity structure is formed by etching multiple micro-resonant cavities at equal intervals on the strip waveguide.

[0011] Each of the microresonant cavities includes a portion of the strip waveguide, air slit structure, silicon-based triangular synapse, etched via, and inter-via silicon waveguide;

[0012] The etched holes and air slit structures of each micro resonator are symmetrically arranged about the center of the strip waveguide, and the air slit structures are symmetrically arranged on the left and right sides of each etched hole. Each silicon-based triangular synapse is symmetrically arranged on the upper and lower sides of the etched hole.

[0013] A vertically coupled incident grating is connected to one end of the strip waveguide to receive incident light;

[0014] A vertically coupled output grating is connected to the other end of the strip waveguide;

[0015] The vertically coupled incident grating, the strip waveguide, the micro-resonant cavity structure, and the vertically coupled output grating together constitute a one-dimensional photonic crystal;

[0016] During measurement, the one-dimensional photonic crystal is placed in the liquid to be tested, and the liquid to be tested is immersed in the etched hole of the micro resonant cavity. By changing the refractive index of the liquid to be tested in the etched hole, the resonant wavelength of the resonant light generated in the micro resonant cavity will change accordingly, thereby obtaining the corresponding transmission spectrum in the vertically coupled output grating.

[0017] Furthermore, the strip waveguide includes a first strip waveguide and a second strip waveguide respectively disposed on the upper and lower end faces of the micro resonant cavity, and the length and width of the first strip waveguide and the second strip waveguide are equal.

[0018] Furthermore, the air slit structure includes a first air slit and a second air slit arranged symmetrically at the top and bottom, and the length and width of the first air slit and the second air slit are equal.

[0019] Furthermore, the silicon-based triangular synapse includes a first silicon-based triangular synapse and a second silicon-based triangular synapse, and the angles and side lengths of the first silicon-based triangular synapse and the second silicon-based triangular synapse are equal.

[0020] Furthermore, the first strip waveguide is connected to the first air slit, the first silicon-based triangular synapse, and the etched hole;

[0021] The second strip waveguide is connected to the second air slit, the second silicon-based triangular synapse, and the etched hole.

[0022] Furthermore, the etched hole is a cylindrical hole with a radius of 194-196 nm.

[0023] Furthermore, the center-to-center distance between the first air slit and the second air slit is 200 nm.

[0024] Furthermore, the strip waveguide is made of non-metallic material, and the width of the strip waveguide is 640nm and the height is 220nm.

[0025] Furthermore, both the first silicon-based triangular synapse and the second silicon-based triangular synapse are equilateral triangles, and the distance between each of the first silicon-based triangular synapse and the second silicon-based triangular synapse is 90 nm.

[0026] Compared with the prior art, the present invention has significant advantages and beneficial effects, specifically reflected in the following aspects:

[0027] This invention combines a strip waveguide, an air slit structure, and a silicon-based triangular synapse structure to design a one-dimensional photonic crystal refractive index sensor. The strip waveguide, air slit structure, silicon-based triangular synapse, etched holes, and the silicon waveguide between the holes together constitute a one-dimensional photonic crystal. By utilizing the focusing ability of the micro-resonant cavity of the one-dimensional photonic crystal to concentrate the light field, the sensing sensitivity of the one-dimensional photonic crystal refractive index sensor is greatly improved, while maintaining a small device size. The addition of silicon-based triangular synapses further enhances the performance of the device, which is beneficial for building a high-precision on-chip optical biosensing laboratory.

[0028] The second objective of this invention is to provide a method for refractive index detection using a one-dimensional photonic crystal refractive index sensor as described above, comprising the following steps:

[0029] Place the photonic crystal refractive index sensor in the liquid to be measured;

[0030] The incident light is received by a vertically coupled incident grating and enters the micro-resonant cavity;

[0031] The input light is confined inside the micro-resonant cavity and resonates through the interaction of strip waveguide, air slit structure and silicon-based triangular synapse;

[0032] The corresponding transmission spectrum is obtained by vertically coupling the output grating and displayed on the spectrometer. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of a one-dimensional photonic crystal refractive index sensor in an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the micro-resonant cavity structure in an embodiment of the present invention;

[0035] Figure 3 This is a simulated light field distribution diagram of a one-dimensional photonic crystal refractive index sensor in an embodiment of the present invention;

[0036] Figure 4 These are transmission spectra of one-dimensional photonic crystal refractive index sensors with different refractive indices in embodiments of the present invention;

[0037] Figure 5 This is a graph showing the linear variation of the transmission spectrum of a one-dimensional photonic crystal refractive index sensor with refractive index in an embodiment of the present invention.

[0038] Explanation of reference numerals in the attached figures:

[0039] 1-Strip waveguide;

[0040] 11-First strip waveguide; 12-First strip waveguide;

[0041] 2-Micro resonant cavity structure;

[0042] 3-Air slit structure;

[0043] 31 - First air slit; 32 - Second air slit;

[0044] 4-Silicon-based triangular synapses;

[0045] 41 - First silicon-based triangular synapse; 42 - Second silicon-based triangular synapse;

[0046] 5-Etched aperture; 6-Inter-aperture silicon waveguide; 7-Vertical-coupled incident grating; 8-Vertical-coupled output grating. Detailed Implementation

[0047] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] In the description of this invention, it should be noted that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0049] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the directional terms such as front, back, top, and bottom are defined according to the location of the components in the drawings and their relative positions to each other, and are only for the purpose of clarity and convenience in expressing the technical solution. It should be understood that these are relative concepts and can vary accordingly depending on different ways of use and placement, and the use of these directional terms should not limit the scope of protection claimed in this application.

[0050] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0051] The main performance indicators of a refractive index sensor include the detection limit (DL) and sensitivity (S), among which:

[0052] Sensitivity refers to the ratio between the change in the sensor's output variable and the change in the measured signal. The greater the change in the sensor's output signal caused by a unit change in the measured signal, the higher the sensor's sensitivity, and the more accurately it can detect minute signal changes. The formula for calculating sensitivity is as follows:

[0053]

[0054] in: Δ λ is the offset of the resonant wavelength. Δ n represents the change in refractive index of the analyte.

[0055] The detection limit refers to the smallest change in refractive index that a sensor can detect, usually denoted by DL and measured in RIU (refractive index unit). The lower the detection limit, the lower the concentration of the analyte that can be detected, and the better the sensing performance.

[0056] The detection limit of a sensor is related to its own structure, the performance of the measuring device, and the intensity of the noise signal. If the noise signal is ignored, the detection limit of the sensor can be expressed by the following formula:

[0057]

[0058] Besides sensitivity and detection limit, sensor size, Q value and extinction ratio are also commonly used performance indicators. Under the same performance, the smaller the sensor size, the easier it is to integrate.

[0059] The Q factor is the ratio of the total energy in the resonant cavity to the energy consumed per unit time. It characterizes the ability of a resonant device to maintain an optical field. Devices with high Q factors can maintain a high-intensity optical field, which enhances the interaction between light and the object under test in the resonant cavity and has a positive effect on the performance of the sensor.

[0060] The extinction ratio refers to the ratio of the power of the main resonance peak to the power of the side lobes in the transmission spectrum of a sensor. Increasing the extinction ratio can prevent noise signals from being confused with resonance peak signals, thus improving sensor performance. Overall, improving refractive index sensitivity also leads to an improvement in the detection limit performance.

[0061] Depending on the dimensionality of the periodic structure, photonic crystals can be classified into one-dimensional photonic crystals, two-dimensional photonic crystals, and three-dimensional photonic crystals. Photonic crystals of different dimensions have photonic band gaps of different dimensions. The photonic band gap property has a good confinement effect on light and can obtain a strong resonant light field in a microcavity.

[0062] Since one-dimensional photonic crystals exhibit periodicity in only one direction, their structure is the simplest, requiring only the arrangement of two or more materials at equal intervals. In contrast, two-dimensional and three-dimensional photonic crystal structures are an order of magnitude larger than one-dimensional photonic crystal structures and have extremely high requirements for the error rate of the manufacturing process.

[0063] To resolve the above technical issues, please refer to... Figure 1-2 As shown, this embodiment of the invention provides a one-dimensional photonic crystal refractive index sensor, which includes a strip waveguide 1, a micro-resonant cavity structure 2, a vertically coupled incident grating 7, and a vertically coupled output grating 8, wherein:

[0064] Multiple micro-resonant cavities are etched at equal intervals on a strip waveguide 1 to form the micro-resonant cavity structure 2. Each micro-resonant cavity includes a portion of the strip waveguide 1, an air slit structure 3, a silicon-based triangular synapse 4, an etched hole 5, and an inter-hole silicon waveguide 6. The etched holes 5 and air slit structures 3 of each micro-resonant cavity are symmetrically arranged about the center of the strip waveguide 1, and the air slit structures 3 are symmetrically arranged on the left and right sides of each etched hole 5. Each silicon-based triangular synapse 4 is symmetrically arranged on the upper and lower sides of the etched hole 5, respectively.

[0065] Specifically, in this embodiment, the micro-resonator structure 2 first establishes a single micro-resonator as the center on the strip waveguide 1, and then etches fourteen micro-resonators at equal intervals on both sides, forming a total of twenty-nine micro-resonators. Having more or less than this number of micro-resonators will lead to a decrease in the extinction ratio of the resonance peak and an increase in the transmission spectrum noise signal, negatively impacting actual measurements.

[0066] A vertically coupled incident grating 7 is connected to one end of the strip waveguide 1 to receive incident light; a vertically coupled output grating 8 is connected to the other end of the strip waveguide 1 to output the transmission spectrum.

[0067] In this embodiment, the vertically coupled incident grating 7, the strip waveguide 1, the micro-resonant cavity structure 2, and the vertically coupled output grating 8 together constitute a one-dimensional photonic crystal.

[0068] During measurement, a one-dimensional photonic crystal is placed in the liquid to be measured, and the liquid to be measured is immersed in the etching hole 5 of the micro resonant cavity. By changing the refractive index of the liquid to be measured in the etching hole 5, the resonant wavelength of the resonant light generated in the micro resonant cavity will change accordingly, thereby obtaining the corresponding transmission spectrum at the vertically coupled output grating 8 to complete the refractive index of the photonic crystal.

[0069] Considering the simplicity of the design and the level of difficulty in fabrication, a one-dimensional photonic crystal structure was chosen as the main body of the refractive index sensor. The micro-resonant cavity structure of the one-dimensional photonic crystal is used to focus the light field. At the same time, the air slit structure 3 is combined to design the one-dimensional photonic crystal refractive index sensor, which greatly improves the sensing sensitivity of the one-dimensional photonic crystal refractive index sensor while maintaining a small device size. The addition of silicon-based triangular synapses 4 further enhances the performance of the device, which is conducive to building a high-precision on-chip optical biosensing laboratory.

[0070] Specifically, in the embodiments of the present invention, the micro-resonant cavity is tested to have a radius of 195 nm, at which point the optimal sensing sensitivity can be obtained. The spacing between the micro-resonant cavities is 640 nm, which can fix the resonance peak within the required wavelength range.

[0071] Specifically, please refer to Figure 1 , 2 As shown, in an embodiment of the present invention, the strip waveguide 1 includes a first strip waveguide 11 and a second strip waveguide 12 respectively disposed on the upper and lower end faces of the micro resonant cavity, and the length and width of the first strip waveguide 11 and the second strip waveguide 12 are equal.

[0072] Traditional planar waveguides utilize the fact that the refractive index of the core material is greater than that of the surrounding cladding material to confine light within the waveguide core. However, the large refractive index contrast between the core and cladding results in significant scattering at the core / cladding interface. By controlling its period, light can be directed to propagate along the waveguide axis. Controlling the period alters the equivalent refractive index of the optical waveguide, thereby affecting the mode size and dispersion.

[0073] Specifically, please refer to Figure 1 , 2 As shown, in an embodiment of the present invention, the air slit structure 3 includes a first air slit 31 and a second air slit 32, and the length and width of the first air slit 31 and the second air slit 32 are equal.

[0074] The air slit structure 3 is symmetrical with respect to the line connecting the centers of the multiple micro-resonant cavities. This is to maintain the periodicity of the structure, thereby ensuring that there is only a single resonance peak within the selected wavelength range, without interference from other resonance peaks.

[0075] Furthermore, as a preferred embodiment of the present invention, the widths of the first air slit 31 and the second air slit 32 are both 30 nm. A resonance peak with a width greater than this will cause a decrease in sensing sensitivity, while a slit with a width less than this will prevent the substance to be measured from entering the air slit.

[0076] Specifically, please refer to Figure 1 , 2As shown, in an embodiment of the present invention, the silicon-based triangular synapse 4 includes a first silicon-based triangular synapse 41 and a second silicon-based triangular synapse 42, and the angles and side lengths of the first silicon-based triangular synapse 41 and the second silicon-based triangular synapse 42 are equal.

[0077] In this embodiment, a first silicon-based triangular synapse 41 and a second silicon-based triangular synapse 42 are symmetrically placed in each micro-resonant cavity. The symmetrically arranged triangular synapse structure introduces a refractive index difference between the device and the outside world inside the resonant cavity, thereby enhancing the light field intensity inside the micro-resonant cavity and improving the refractive index sensitivity.

[0078] Specifically, please refer to Figure 1 , 2 As shown, in an embodiment of the present invention, the first strip waveguide 11 is connected to the first air slit 31, the first silicon-based triangular synapse 41, and the etched hole 5;

[0079] The second strip waveguide 12 is connected to the second air slit 32, the second silicon-based triangular synapse 42, and the etched hole 5.

[0080] Specifically, in the embodiments of the present invention, the etched hole 5 is a cylindrical hole with a radius of 194-196 nm.

[0081] By changing the spacing of the etched holes 5 in the main body of the sensor, the light field distribution in the micro-resonant cavity formed by the etched holes 5 better satisfies the Gaussian function model, which greatly improves the light confinement capability of the photonic crystal and thus greatly improves the sensitivity of the one-dimensional photonic crystal refractive index sensor.

[0082] Specifically, in the embodiments of the present invention, the center distance between the first air slit 31 and the second air slit 32 is 200 nm. Under this center distance, the resonance peak can achieve the best extinction ratio, thereby obtaining a suitable resonance peak for sensing.

[0083] Therefore, the two added slit structures introduce the object to be measured into a region with a higher light field intensity, thereby improving the performance of the sensor.

[0084] Specifically, in the embodiments of the present invention, the strip waveguide 1 is made of non-metallic material, and the width of the strip waveguide 1 is 640nm. This width is set to take into account that the conventional width of a single-mode waveguide is about 600nm. At the same time, in order to avoid mode interference, the height is set to 220nm, which is in line with the conventional height of silicon-based optical devices.

[0085] Therefore, a one-dimensional photonic crystal refractive index sensor with a height of 220nm and a waveguide width of 640nm was designed, which conforms to SOI fabrication technology. At the same time, it has extremely low light loss at the designed operating wavelength, thus improving the sensing performance.

[0086] In the preferred embodiment of this invention, the strip waveguide 1 is made of silicon. Since metal-based electrical interconnects suffer from defects such as overheating, delay, and electronic interference, they become a bottleneck in development. Using optical interconnects to replace electrical interconnects can effectively solve this problem. In specific implementations of optical interconnects, silicon-based optical interconnects are the preferred choice due to their unparalleled cost and technological advantages. Silicon-based optical interconnects can leverage the advantages of optical interconnects, such as high speed, large bandwidth, anti-interference, and low power consumption, while also fully utilizing the advantages of mature microelectronic processes, high-density integration, high yield, and low cost, thus having broad market application prospects.

[0087] Specifically, in the embodiments of the present invention, the first silicon-based triangular synapse 41 and the second silicon-based triangular synapse 42 are both equilateral triangles, and the distance between each first silicon-based triangular synapse 41 and the second silicon-based triangular synapse 42 is 90nm. The equilateral triangular synapse structure has the best reflection and refraction angles for light in the microcavity, and can generate a highly concentrated light field. After scanning and verification of the synapse spacing, the best refractive index sensing performance can be obtained at this spacing.

[0088] Specifically, in the embodiments of the present invention, the vertically coupled incident grating 7 and the vertically coupled output grating 8 are composed of multiple fan rings with a height of 220nm, a fan ring width of 100nm, and a spacing of 100nm between the fan rings.

[0089] Figure 2 The diagram shows the planar structure of a high-sensitivity one-dimensional photonic crystal refractive index sensor. The main body of the sensor consists of a strip waveguide 1 and twenty-nine equally spaced etched holes 5. Two additional air slit structures 3 and twenty-nine symmetrical silicon-based triangular synapses 4 are also added.

[0090] The first strip waveguide 11, the first air slit 31, the second air slit 32, the twenty-nine first silicon-based triangular synapses 41, the twenty-nine second silicon-based triangular synapses 42, the inter-aperture silicon waveguide 6, and the second strip waveguide 12 together construct twenty-nine one-dimensional photonic crystal microcavities, which are used to confine the input light inside the microcavities to generate resonance.

[0091] This invention also provides a method for refractive index detection using a one-dimensional photonic crystal refractive index sensor, the method comprising the following steps:

[0092] Place the photonic crystal refractive index sensor in the liquid environment to be measured;

[0093] The incident light is received by the vertically coupled incident grating 7 and enters the micro-resonant cavity structure;

[0094] The input light is confined inside the micro-resonant cavity by the interaction of the strip waveguide 1, the air slit structure 3 and the silicon-based triangular synapse 4, and resonance is generated.

[0095] The corresponding transmission spectrum is obtained by vertically coupling output grating 8 and displayed on the spectrometer.

[0096] Figure 3 The figure shows the simulated resonant light field distribution of a high-sensitivity one-dimensional photonic crystal refractive index sensor. As can be seen from the figure, the light field is confined inside the one-dimensional photonic crystal micro-resonant cavity and interacts strongly with the material to be measured here. Furthermore, a certain light field intensity is maintained at the air slit structure 3.

[0097] Figure 4 The image shows a simulated transmission spectrum of a high-sensitivity one-dimensional photonic crystal refractive index sensor, where n is the refractive index. Under different refractive index environments, the resonance peak of the high-sensitivity one-dimensional photonic crystal refractive index sensor undergoes significant changes. An initial refractive index is set and the resonant wavelength at this time is recorded. After changing the refractive index of the environment, the detection is performed again, and the resonant wavelength at this time is recorded. By comparing it with the initial resonant wavelength, the refractive index parameter of the analyte can be obtained.

[0098] Figure 5 The image shows the superimposed transmission spectrum measured under various refractive index changes, where n is the refractive index. Under linear refractive index changes, the changes in the resonant wavelength are also linear. This means that within the working band, it is not necessary to record the refractive index corresponding to all resonant wavelengths. Only the resonant wavelength at the initial refractive index needs to be recorded to calculate the refractive index corresponding to different resonant wavelengths.

[0099] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the scope of protection of this invention.

Claims

1. A one-dimensional photonic crystal refractive index sensor, characterized in that, include: Strip waveguide (1); Micro-resonant cavity structure (2), multiple micro-resonant cavities are etched at equal intervals on the strip waveguide (1) to form the micro-resonant cavity structure (2). Each of the micro-resonant cavities includes a portion of the strip waveguide (1), an air slit structure (3), a silicon-based triangular synapse (4), an etched hole (5), and an inter-hole silicon waveguide (6). The etched holes (5) and air slit structures (3) of each micro resonator are symmetrically arranged about the center of the strip waveguide (1). The air slit structure (3) includes a first air slit (31) and a second air slit (32) arranged symmetrically up and down, and the length and width of the first air slit (31) and the second air slit (32) are equal. Furthermore, the air slit structure (3) is symmetrically arranged on the left and right sides of each etching hole (5), and each silicon-based triangular synapse (4) is symmetrically arranged on the upper and lower sides of the etching hole (5), with the apex of the silicon-based triangular synapse (4) facing the center of the etching hole (5); The silicon-based triangular synapse (4) includes a first silicon-based triangular synapse (41) and a second silicon-based triangular synapse (42), and the angles and side lengths of the first silicon-based triangular synapse (41) and the second silicon-based triangular synapse (42) are equal; A vertically coupled incident grating (7) is connected to one end of the strip waveguide (1) for receiving incident light; A vertically coupled output grating (8) is connected to the other end of the strip waveguide (1); The vertically coupled incident grating (7), the strip waveguide (1), the micro-resonant cavity structure (2), and the vertically coupled output grating (8) together constitute a one-dimensional photonic crystal; During measurement, the one-dimensional photonic crystal is placed in the liquid to be tested, and the liquid to be tested is immersed in the etching hole (5) of the micro resonant cavity. By changing the refractive index of the liquid to be tested in the etching hole (5), the resonant wavelength of the resonant light generated in the micro resonant cavity will change accordingly, thereby obtaining the corresponding transmission spectrum in the vertically coupled output grating (8).

2. The one-dimensional photonic crystal refractive index sensor according to claim 1, characterized in that, The strip waveguide (1) includes a first strip waveguide (11) and a second strip waveguide (12) respectively disposed on the upper and lower end faces of the micro resonant cavity, and the length and width of the first strip waveguide (11) and the second strip waveguide (12) are equal.

3. The one-dimensional photonic crystal refractive index sensor according to claim 2, characterized in that, The air slit structure (3) includes a first air slit (31) and a second air slit (32) arranged symmetrically at the top and bottom, and the length and width of the first air slit (31) and the second air slit (32) are equal.

4. The one-dimensional photonic crystal refractive index sensor according to claim 2, characterized in that, The first strip waveguide (11) is connected to the first air slit (31), the first silicon-based triangular synapse (41), and the etched hole (5); The second strip waveguide (12) is connected to the second air slit (32), the second silicon-based triangular synapse (42), and the etched hole (5).

5. The one-dimensional photonic crystal refractive index sensor according to claim 1, characterized in that, The etched hole (5) is a cylindrical hole with a radius of 194-196 nm.

6. The one-dimensional photonic crystal refractive index sensor according to claim 3, characterized in that, The center-to-center distance between the first air slit (31) and the second air slit (32) is 200 nm.

7. The one-dimensional photonic crystal refractive index sensor according to claim 6, characterized in that, The strip waveguide (1) is made of non-metallic material, and the width of the strip waveguide (1) is 640nm and the height is 220nm.

8. The one-dimensional photonic crystal refractive index sensor according to claim 1, characterized in that, The first silicon-based triangular synapse (41) and the second silicon-based triangular synapse (42) are both equilateral triangles, and the distance between each first silicon-based triangular synapse (41) and the second silicon-based triangular synapse (42) is 90nm.

9. A method for detecting the refractive index based on the one-dimensional photonic crystal refractive index sensor according to any one of claims 1-8, characterized in that, Includes the following steps: Place the photonic crystal refractive index sensor in the liquid to be measured; The incident light is received by a vertically coupled incident grating and enters the micro-resonant cavity; The input light is confined inside the micro-resonant cavity and resonates due to the interaction of the strip waveguide (1), the air slit structure (3) and the silicon-based triangular synapse (4); The corresponding transmission spectrum is obtained by vertically coupling the output grating (8) and displayed on the spectrometer.

Images