Slit grating-assisted high-quality factor micro-ring resonant cavity sensor and test method thereof

Abstract

The invention relates to a slit grating-assisted high-quality factor micro-ring resonant cavity sensor, which is connected with an input light source and a detector, and comprises a sensor chip module provided with an input optical fiber, an input grating coupler, a slit grating micro-ring resonant cavity sensor, an output grating coupler and an output optical fiber, eight inclination angles are formed between the input optical fiber and the input grating coupler and between the output grating coupler and the output optical fiber; the slit grating micro-ring resonant cavity sensor comprises an upper channel straight waveguide and a sensing ring. The slit grating-assisted micro-ring resonant cavity sensor is introduced, a sensing test shows that the quality factor (Q value) is higher, the higher quality factor (Q value) means a sharper harmonic peak and lower energy loss, the sensor can accurately detect extremely weak chemical / biological signals in combination with high sensitivity, and the signal-to-noise ratio and the measurement precision are greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical waveguide sensors, and in particular to a high-quality factor micro-ring resonant cavity sensor assisted by a slit grating. Background Art

[0002] Conventional microring resonant cavity sensors, due to their large-scale silicon-based integration and microfluidic compatibility, provide a fast track to basic medical testing. By tracking the resonant wavelength shift caused by biomolecular binding, they enable point-of-care (POCT) diagnostics. Automated testing can be performed with minimal sample volumes, significantly shortening the traditional laboratory cycle of several days and providing a cost-effective diagnostic tool for primary care and resource-poor regions. This compact photonic sensing technology has gradually replaced some enzyme-linked immunosorbent assays (ELISAs) as an effective supplement to routine pathogen screening.

[0003] However, the practicality of conventional microring resonator sensors is limited by their low Q and sensitivity. The high optical loss of the rough resonator results in a broad and flat resonant peak, making it easy for tiny signals to be drowned out by system noise. This results in an insufficient detection limit and missed early warning windows for disease. The broad peak also causes wavelength shift measurement errors, significantly reducing reliability in scenarios requiring high-precision quantification of concentration gradients, limiting their reliability in critical scenarios such as intensive care. Summary of the Invention

[0004] To achieve the purpose of the present invention, the technical solution adopted by the present invention is as follows: a slit grating-assisted high-quality factor microring resonant cavity sensor is connected to an input light source and a detector, comprising: a sensor chip module, wherein the sensor chip module is provided with an input optical fiber, an input grating coupler, a slit grating microring resonant cavity sensor, an output grating coupler, and an output optical fiber; the input light source passes through the input optical fiber, the input grating coupler, the slit grating microring resonant cavity sensor, the output grating coupler, and the output optical fiber in sequence and finally enters the detector; the input optical fiber and the input grating coupler, as well as the output grating coupler and the output optical fiber, are coupled and connected at an inclination angle of 8 degrees;

[0005] The slit grating micro-ring resonant cavity sensor comprises an upper channel straight waveguide and a sensing ring.

[0006] Preferably, the coupling mode between the upper channel straight waveguide and the sensing ring is end-face coupling, the upper cladding of the sensing ring is the test agent, and the lower cladding is SiO2.

[0007] Preferably, the slit grating is an isosceles triangle.

[0008] Preferably, the input light source is a tunable laser or a broadband light source; and the detector is an optical power meter or a spectrometer.

[0009] Preferably, a method for testing a high-quality factor micro-ring resonator sensor assisted by a slit grating comprises: inputting light from a light source through an input optical fiber and an input grating coupler, thereby coupling light output to the slit grating micro-ring resonator sensor;

[0010] After the light source interacts with the test agent above the sensing ring, it is output from the right straight-through end of the upper channel straight waveguide;

[0011] The light source output from the through-end will be coupled to the detector through the output grating coupler and the output optical fiber. The detector will hand over the received spectral image to the computer to collect and process the data, and finally calculate the sensing sensitivity and quality factor of the microring resonator sensor.

[0012] Preferably, the quality factor Q value is the ratio of the light field energy in the microring resonator sensor to the energy consumed by the light field during one transmission cycle. The larger the Q value, the sharper the transmission spectrum resonance peak, which is more conducive to improving the sensing performance. The Q value is defined as the ratio of the central wavelength λ0 to the full width at half maximum FWHM, that is:

[0013]

[0014] Where λ0 is the center wavelength and FWHM is the full width at half maximum, which refers to the difference between two adjacent wavelengths corresponding to half the peak height of the transmission spectrum within a free spectral range under linear coordinates.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The present invention uses a slit grating-assisted microring resonant cavity sensor, which has a higher quality factor Q value after sensor testing. A higher quality factor Q value means a sharper resonance peak and lower energy loss. Combined with high sensitivity, the sensor can accurately detect extremely weak chemical / biological signals, greatly improving the signal-to-noise ratio and measurement accuracy, and enhancing stability and anti-interference. It can be applied to cutting-edge directions such as single-molecule detection, precision measuring instruments and miniaturized equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic structural diagram of the high-quality factor micro-ring resonator sensor assisted by a slit grating according to the present invention;

[0018] Figure 2 This is the energy field distribution diagram of the present invention at the resonant wavelength;

[0019] Figure 3 This is a schematic diagram of the sensing principle used in the actual sensing test of the present invention;

[0020] In the figure: 1. Input light source; 2. Detector; 3. Input optical fiber; 4. Output optical fiber; 5. Sensor chip module; 51. Input grating coupler; 52. Upper channel straight waveguide; 53. Output grating coupler; 54. Sensing ring. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] Example:

[0023] The present invention provides a technical solution: Figure 1 As shown, a slit grating-assisted high-quality factor microring resonator sensor is connected to an input light source 1 and a detector 2. The sensor chip module 5 includes an input optical fiber 3, an input grating coupler 51, a slit grating microring resonator sensor, an output grating coupler 53, and an output optical fiber 4. The input light source 1 passes through the input optical fiber 3, the input grating coupler 51, the slit grating microring resonator sensor, the output grating coupler 53, and the output optical fiber 4, before entering the detector 2. The input light source 1 is a tunable laser or a broadband light source; the detector 2 is an optical power meter or a spectrometer.

[0024] The slit grating microring resonant cavity sensor comprises an upper channel straight waveguide 52 and a sensing ring 54. The coupling mode between the upper channel straight waveguide 52 and the sensing ring 54 is end-face coupling. The upper cladding of the sensing ring 54 is the test agent, and the lower cladding is SiO2.

[0025] The slit grating is an isosceles triangle with a base length of 0.15 μm and a height of 0.4 μm. It can improve the sensitivity and quality factor of the microring resonator sensor. The grating structure is matched to the transverse magnetic mode (TM mode) to further enhance the sensing sensitivity.

[0026] The input optical fiber 3 is connected to the input light source 1 and the input grating coupler 51, so that the input light can be coupled to the slit grating micro-ring resonator sensor through the input grating coupler 51. The output grating coupler 53 is connected to the detector 2, so that the detector 2 can receive the coupled output light of the output grating coupler 53. The detector 2 transmits the received spectral image to the computer for data collection and processing, and finally calculates the sensing sensitivity and quality factor of the micro-ring resonator sensor.

[0027] The input optical fiber 3 and the input grating coupler 51 as well as the output grating coupler 53 and the output optical fiber 4 are coupled at an angle of 8 degrees. The 8-degree angle coupling allows the maximum amount of light to enter the waveguide.

[0028] During the sensing test, the testing method of the high-quality factor micro-ring resonator sensor assisted by the slit grating includes:

[0029] The light from the input light source 1 passes through the input optical fiber 3 and the input grating coupler 51, and is then coupled to the slit grating micro-ring resonator sensor.

[0030] After the light source interacts with the test solution above the sensing ring 54, it is output from the right straight-through end of the upper channel straight waveguide 52;

[0031] The light source output from the through end will be coupled to the detector 2 through the output grating coupler 53 and the output optical fiber 4. The detector 2 will pass the received spectral image to the computer to collect and process the data, and finally calculate the sensing sensitivity and quality factor of the microring resonator sensor.

[0032] like Figure 2 The figure below shows the energy field distribution at the resonant wavelength of the present invention. The horizontal and vertical axes correspond to the physical dimensions of the cavity in micrometers. The white light spot accurately maps the strongly constrained electromagnetic field intensity gradient in the resonant mode. The light energy is efficiently localized in the waveguide structure, achieving a key structure with high Q.

[0033] The Q value is defined as the ratio of the central wavelength (λ0) to the full width at half maximum (FWHM):

[0034]

[0035] Where λ0 is the center wavelength, FWHM is the full width at half maximum, which refers to the difference between two adjacent wavelengths corresponding to half the peak height of the transmission spectrum within a free spectrum range under linear coordinates;

[0036] The quality factor (Q value) is the ratio of the light field energy in the microring resonator sensor to the energy consumed by the light field during one cycle of transmission. The larger the Q value, the sharper the transmission spectrum resonance peak, which is more conducive to improving the sensing performance.

[0037] This high-gradient light field distribution provides the physical basis for single-molecule sensing: the binding of the analyte in the white area will trigger significant resonant perturbations, and the local enhancement at the submicron scale can push the sensitivity to the single-molecule detection limit.

[0038] like Figure 3The figure shows the sensor principle diagram of the present invention used in actual sensing tests. The horizontal axis corresponds to the wavelength of the input light source 1, and the vertical axis represents the transmission spectrum intensity. As can be seen in the figure, the core feature of the first curve is the sharp resonance valley at a wavelength of 1550nm, with an extinction ratio of 12.2dB. Its extremely narrow full width at half maximum (FWHM) and steep slope confirm the ultra-high quality factor (Q value) of the device, with a quality factor as high as 23000. Its depth and sharpness determine the detection limit and accuracy of the sensor. The four curves correspond to different refractive index environments (1.33 to 1.36) to simulate different concentrations of the test agent. As the refractive index increases, the resonance valley shifts toward longer wavelengths. The systematic shift of the valley values ​​and the transmittance changes of each curve intuitively reveal the strong correlation between the refractive index change of the test solution and the resonance wavelength. The uniform curve spacing verifies the linear response characteristics and sensitivity of the sensor. The sensor sensitivity is tested to be approximately 578nm / RIU. The higher sensing sensitivity provides a more reliable optical basis for detecting the concentration gradient of biochemical molecules.

[0039] The embodiments disclosed in the present invention are preferred embodiments, but are not limited to them. Ordinary technicians in this field can easily understand the spirit of the present invention based on the above embodiments and make different extensions and changes. As long as they do not deviate from the spirit of the present invention, they are all within the scope of protection of the present invention.

Claims

1. A slit grating assisted high quality factor micro-ring resonator sensor, connected to an input light source and a detector, characterized in that: include: A sensor chip module is provided with an input optical fiber, an input grating coupler, a slit grating microring resonant cavity sensor, an output grating coupler, and an output optical fiber. An input light source sequentially passes through the input optical fiber, the input grating coupler, the slit grating microring resonant cavity sensor, the output grating coupler, and the output optical fiber before finally entering the detector. The input optical fiber and the input grating coupler, as well as the output grating coupler and the output optical fiber, are coupled at an inclination angle of 8 degrees. The slit grating micro-ring resonant cavity sensor comprises an upper channel straight waveguide and a sensing ring.

2. The slit grating assisted high quality factor micro-ring resonator sensor according to claim 1, characterized in that: The coupling mode between the upper channel straight waveguide and the sensing ring is end-face coupling. The upper cladding of the sensing ring is the test agent, and the lower cladding is SiO2.

3. The slit grating assisted high quality factor micro-ring resonator sensor according to claim 1, characterized in that: The slit grating is an isosceles triangle.

4. The slit grating assisted high quality factor micro-ring resonator sensor according to claim 1, characterized in that: The input light source is a tunable laser or a broadband light source; the detector is an optical power meter or a spectrometer.

5. A method for testing a high-quality factor micro-ring resonator sensor assisted by a slit grating according to any one of claims 1 to 4, characterized in that: include: The light from the input light source passes through the input optical fiber and the input grating coupler, and is then coupled to the slit grating micro-ring resonator sensor. After the light source interacts with the test agent above the sensing ring, it is output from the right straight-through end of the upper channel straight waveguide; The light source output from the through-end will be coupled to the detector through the output grating coupler and the output optical fiber. The detector will hand over the received spectral image to the computer to collect and process the data, and finally calculate the sensing sensitivity and quality factor of the microring resonator sensor.

6. The method for testing a high-quality factor micro-ring resonator sensor assisted by a slit grating according to claim 5, characterized in that: The quality factor Q value is the ratio of the light field energy in the microring resonator sensor to the energy consumed by the light field during one cycle of transmission. The larger the Q value, the sharper the transmission spectrum resonance peak, which is more conducive to improving the sensing performance. The Q value is defined as the ratio of the central wavelength λ0 to the full width at half maximum (FWHM), that is: Where λ0 is the center wavelength and FWHM is the full width at half maximum, which refers to the difference between two adjacent wavelengths corresponding to half the peak height of the transmission spectrum within a free spectral range under linear coordinates.

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