A high-sensitivity micro-ring resonant cavity sensor based on corrugated waveguide and its testing method

Abstract

The present invention relates to a high-sensitivity micro-ring resonant cavity sensor based on a corrugated waveguide, which is connected to an input light source and a detector, and includes: a micro-ring resonant cavity, wherein the input light source is connected to an input grating coupler, wherein the input grating coupler is connected to the micro-ring resonant cavity through an input tapered waveguide, wherein the micro-ring resonant cavity is connected to an output grating coupler through an output tapered waveguide, and wherein the output grating coupler is connected to the detector. The corrugated waveguide replaces the ordinary rectangular waveguide to form the sensing ring, and the corrugated waveguide can optimize the distribution of the light field, so that the interaction between light and the detected substance is more sufficient, thereby greatly improving the sensing sensitivity of the sensor. The introduction of the corrugated waveguide can also achieve insensitivity to temperature, which greatly reduces the influence of the external environment temperature on the sensing effect of the sensor.

Description

Technical Field

[0001] The invention relates to the technical field of optical waveguide sensing and detection, and in particular to a high-sensitivity micro-ring resonant cavity sensor based on a corrugated waveguide and a testing method thereof. Background Art

[0002] With the rapid development of science and technology, sensors play an indispensable role in many fields. In the biomedical field, sensors are used to detect various physiological indicators in organisms, such as blood sugar and protein content, providing key basis for early diagnosis and treatment of diseases; in environmental monitoring, they can monitor air quality, water pollution level, etc. in real time, helping environmental protection and resource management; in industrial production, they can accurately measure parameters such as temperature, pressure, and chemical composition in the production process to ensure product quality and production safety. Therefore, the development of sensors with excellent performance has always been an important research direction in the fields of scientific research and engineering technology.

[0003] Microring resonant cavity sensors have attracted much attention due to their small size, high integration and fast response speed. However, traditional microring resonant cavity sensors have many technical problems. On the one hand, their sensing sensitivity is difficult to meet the growing demand for high-precision detection. When detecting some trace substances or small changes in physical quantities, traditional microring resonant cavity sensors often cannot provide sufficiently accurate measurement results, which leads to limitations in application scenarios with high detection accuracy requirements; on the other hand, most traditional microring resonant cavity sensors are made of two materials, silicon and silicon dioxide. Since both silicon and silicon dioxide have positive thermo-optical coefficients, this means that the waveguide structure made of them is more susceptible to changes in external temperature. Slight fluctuations in ambient temperature will cause significant changes in the optical properties of the microring resonant cavity, such as drift of the resonance peak and changes in optical loss. This temperature sensitivity makes the sensor's measurement results easily disturbed by external temperature, which seriously affects the accuracy and stability of the sensor and greatly limits its application range in actual complex environments.

[0004] In view of the above technical problems, an improved technical solution is proposed. Summary of the invention

[0005] In order to achieve the purpose of the present invention, the technical solution adopted by the present invention is: a high-sensitivity microring resonant cavity sensor based on corrugated waveguide, connected to an input light source and a detector, including: a microring resonant cavity, the input light source is connected to an input grating coupler, the input grating coupler is connected to the microring resonant cavity through an input tapered waveguide, the microring resonant cavity is connected to an output grating coupler through an output tapered waveguide, and the output grating coupler is connected to the detector.

[0006] Preferably, the micro-ring resonant cavity is composed of an upper channel waveguide and a sensing ring, the upper channel waveguide and the sensing ring are connected by gap coupling, and the sensing ring adopts a corrugated waveguide.

[0007] Preferably, the microring resonant cavity is provided with an upper cladding and a lower cladding, the upper cladding is an aqueous solution, and the lower cladding is silicon dioxide.

[0008] Preferably, the polarization mode used for sensing by the microring resonant cavity is the TM fundamental mode.

[0009] 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.

[0010] Preferably, a method for testing a high-sensitivity microring resonant cavity sensor based on a corrugated waveguide comprises:

[0011] The input light source is input into the microring resonator through a grating coupler and a tapered waveguide:

[0012] After the light interacts with the test agent, it is output to the detector through the output tapered waveguide and the grating coupler;

[0013] The spectrum near the selected wavelength is collected and extracted. When performing temperature testing or sensor testing, the peak of the output spectrum will shift. By analyzing the shift, the temperature sensitivity and sensor sensitivity can be obtained.

[0014] Preferably, when the concentration of the test agent changes, the refractive index of the upper cladding changes, thereby causing the output spectrum resonance peak to shift, and the ratio of the shift to the refractive index change of the upper cladding is the sensor sensitivity S1;

[0015] The calculation formula of the sensor sensitivity S1 is expressed as: S1=Δλ / Δnc, where Δnc represents the change in the refractive index of the upper cladding layer; Δλ represents the shift of the output spectrum resonance peak.

[0016] Preferably, the ratio of the displacement of the resonance peak of the output spectrum of the sensor due to the change of the external temperature to the change of the temperature of the waveguide structure is the temperature sensitivity S2;

[0017] The calculation formula of the temperature sensitivity S2 is expressed as: S2=Δλ / ΔT, where ΔT represents the change in the temperature of the waveguide structure, and Δλ represents the shift of the output spectrum resonance peak.

[0018] Preferably, the detection range DR of the microring resonant cavity is defined as the ratio of the free spectrum range FSR to the sensor sensitivity S. The calculation formula of the detection range DR is expressed as: DR=FSR / S, wherein FSR represents the free spectrum range within a certain wavelength range, and S represents the sensor sensitivity.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The corrugated waveguide replaces the ordinary rectangular waveguide to form the sensing ring. The corrugated waveguide can optimize the distribution of the light field, making the interaction between light and the detected substance more sufficient, thereby greatly improving the sensor's sensing sensitivity. The introduction of the corrugated waveguide can also achieve insensitivity to temperature, which greatly reduces the impact of the external ambient temperature on the sensor's sensing effect.

[0021] 2. The polarization mode used for sensing is the TM fundamental mode. This is because the upper cladding light field of the TM fundamental mode accounts for a larger proportion, making it easier to achieve higher sensing sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of a high-sensitivity micro-ring resonant cavity sensor based on a corrugated waveguide according to the present invention;

[0023] Figure 2 is the resonance peak transmission spectrum of the microring resonant cavity sensor of the present invention;

[0024] Figure 3 It is a simulation diagram of the micro-ring resonant cavity sensor of the present invention at different temperatures;

[0025] Figure 4 This is a sensing simulation diagram of the microring resonant cavity sensor of the present invention.

[0026] In the figure: 1, input light source; 2, detector; 3, microring resonant cavity; 31, upper channel waveguide; 32, sensing ring; 4, silicon dioxide substrate; 41, input grating coupler; 42, input tapered waveguide; 43, output tapered waveguide; 44, output grating coupler. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0028] Example:

[0029] like Figures 1 to 4As shown, the present invention provides a technical solution: a high-sensitivity micro-ring resonant cavity sensor based on a corrugated waveguide, connected to an input light source 1 and a detector 2, including a micro-ring resonant cavity 3. The input light source 1 is connected to an input grating coupler 41, the input grating coupler 41 is connected to an upper channel waveguide 31 in the micro-ring resonant cavity 3 through an input tapered waveguide 42, the upper channel waveguide 31 in the micro-ring resonant cavity 3 is connected to an output grating coupler 44 through an output tapered waveguide 43, and the output grating coupler 44 is connected to the detector 2.

[0030] The input light source 1 is a tunable laser or a broadband light source, and the detector 2 is an optical power meter or a spectrometer to meet different test requirements.

[0031] The microring resonant cavity 3 is composed of an upper channel waveguide 31 and a sensing ring 32. The upper channel waveguide 31 and the sensing ring 32 are connected by gap coupling. The sensing ring 32 is composed of a corrugated waveguide shown in the illustration of the schematic diagram. The microring resonant cavity 3 is provided with an upper cladding and a lower cladding. The upper cladding is an aqueous solution and the lower cladding is a silicon dioxide substrate 4.

[0032] In this embodiment, the radius of the sensing ring 32 is 10 μm, the waveguide width of the sensing ring 32 is 0.4 μm, the width of the upper channel waveguide 31 is 0.4 μm, the coupling gap between the upper channel waveguide 31 and the sensing ring 32 is 0.2 μm, the recessed depth and width on both sides of the corrugated waveguide are 0.3 μm and 0.23 μm respectively, and the number of recesses on both sides of the corrugated waveguide is 150. Different actual needs can be met by adjusting the depth, width and number of recesses on both sides of the corrugated waveguide.

[0033] During the sensing test, the testing method of the high-sensitivity micro-ring resonant cavity sensor based on the corrugated waveguide includes:

[0034] The input light source 1 is input into the upper channel waveguide 31 of the microring resonator 3 through the input grating coupler 41 and the input tapered waveguide 42;

[0035] After the light interacts with the test agent in the upper cladding, it is output to the detector 2 through the output tapered waveguide 43 and the output grating coupler 44;

[0036] The spectrum near the selected wavelength observed by the detector 2 is collected and extracted. When performing temperature testing or sensor testing, the resonance peak of the output spectrum will shift. The temperature sensitivity and sensor sensitivity can be obtained by observing the shift.

[0037] When the concentration of the test agent changes, the refractive index of the upper cladding changes, which in turn causes the output spectrum resonance peak to shift. The ratio of the shift to the refractive index change of the upper cladding is the sensor sensitivity S1. The calculation formula of the sensor sensitivity S1 is: S1 = Δλ / Δnc, where Δnc represents the refractive index change of the upper cladding, and Δλ represents the shift of the output spectrum resonance peak.

[0038] The ratio of the offset of the output spectrum resonance peak of the sensor due to the change in external temperature to the change in the temperature of the waveguide structure is the temperature sensitivity S2. The calculation formula of the temperature sensitivity S2 is: S2=Δλ / ΔT, where ΔT represents the change in the temperature of the waveguide structure, and Δλ represents the offset of the output spectrum resonance peak.

[0039] The detection range DR of the microring resonator is defined as the ratio of the free spectrum range FSR to the sensor sensitivity S. The calculation formula of the detection range DR is expressed as: DR = FSR / S, where FSR represents the free spectrum range within a certain wavelength range and S represents the sensor sensitivity. Under certain conditions, the higher the sensitivity of the microring resonator sensor, the smaller its detection range, so it is necessary to balance and reasonably set these two parameters during design.

[0040] like Figure 1 As shown, in this embodiment, the radius of the sensing ring 32 is 10 μm, the waveguide width of the sensing ring 32 is 0.4 μm, the width of the upper channel waveguide 31 is 0.4 μm, the coupling gap between the upper channel waveguide 31 and the sensing ring 32 is 0.2 μm, the recessed depth and width on both sides of the corrugated waveguide are 0.3 μm and 0.23 μm respectively, and the number of recesses on both sides of the corrugated waveguide is 150. Different actual needs can be met by adjusting the recessed depth, width and number on both sides of the corrugated waveguide.

[0041] Figure 2 The transmission spectrum around 1550nm detected by detector 2 has a good extinction ratio and quality factor.

[0042] Figure 3 This is a test of the sensor at different temperatures. When the temperature is set to 25℃, 35℃, 45℃ and 55℃, the observed output spectrum has a small resonance peak shift, and its temperature sensitivity is only 3pm / ℃. In biological detection, if the sensor is very sensitive to temperature changes, a small temperature change during the experiment will cause a large deviation in the test results.

[0043] Figure 4The figure is a graph showing the resonance peak change of the sensor corresponding to different upper cladding refractive indices, indicating that reagents with different refractive indices are used as the upper cladding of the sensing ring 32. The resonance peak shift of the output spectrum obtained by the sensor is large, and its sensing sensitivity is as high as 645nm / RIU. In many application scenarios, the concentration of the substance to be detected is extremely low, such as certain disease markers in the blood (such as tumor markers). Highly sensitive microring sensors can detect these trace changes in substances, thereby achieving early diagnosis.

[0044] By performing biomolecule modification on the microring waveguide of the microring resonant cavity 3 of the present invention, biomolecule sensing can be further realized.

[0045] The embodiments of the present invention disclose preferred embodiments, but are not limited thereto. A person skilled in the art can easily understand the spirit of the present invention based on the above embodiments and make different extensions and changes. However, as long as they do not deviate from the spirit of the present invention, they are all within the protection scope of the present invention.

Claims

1. A high-sensitivity micro-ring resonant cavity sensor based on a corrugated waveguide, connected to an input light source and a detector, characterized in that: include: The micro-ring resonant cavity, the input light source is connected to the input grating coupler, the input grating coupler is connected to the micro-ring resonant cavity through the input tapered waveguide, the micro-ring resonant cavity is connected to the output grating coupler through the output tapered waveguide, and the output grating coupler is connected to the detector.

2. The high-sensitivity micro-ring resonant cavity sensor based on corrugated waveguide according to claim 1, characterized in that: The micro-ring resonant cavity is composed of an upper channel waveguide and a sensing ring. The upper channel waveguide and the sensing ring are connected by gap coupling, and the sensing ring adopts a corrugated waveguide.

3. The high-sensitivity micro-ring resonant cavity sensor based on corrugated waveguide according to claim 1, characterized in that: The micro-ring resonant cavity is provided with an upper cladding and a lower cladding, wherein the upper cladding is an aqueous solution and the lower cladding is silicon dioxide.

4. The high-sensitivity micro-ring resonant cavity sensor based on corrugated waveguide according to claim 1, characterized in that: The polarization mode used for sensing by the micro-ring resonator is the TM fundamental mode.

5. The high-sensitivity micro-ring resonant cavity sensor based on corrugated waveguide according to claim 1, characterized in that: The input light source is a tunable laser or a broadband light source, and the detector is an optical power meter or a spectrometer.

6. A method for testing a high-sensitivity microring resonant cavity sensor based on a corrugated waveguide according to any one of claims 1 to 5, characterized in that: include: The input light source is input into the microring resonator through a grating coupler and a tapered waveguide: After the light interacts with the test agent, it is output to the detector through the output tapered waveguide and the grating coupler; The spectrum near the selected wavelength is collected and extracted. When performing temperature testing or sensor testing, the peak of the output spectrum will shift. By analyzing the shift, the temperature sensitivity and sensor sensitivity can be obtained.

7. The method for testing a high-sensitivity micro-ring resonant cavity sensor based on a corrugated waveguide according to claim 6, characterized in that: When the concentration of the test agent changes, the refractive index of the upper cladding changes, causing the output spectrum resonance peak to shift. The ratio of the shift to the refractive index change of the upper cladding is the sensor sensitivity S1. The calculation formula of the sensor sensitivity S1 is expressed as: S1=Δλ / Δnc, where Δnc represents the change in the refractive index of the upper cladding layer; Δλ represents the shift of the output spectrum resonance peak.

8. The method for testing a high-sensitivity micro-ring resonant cavity sensor based on a corrugated waveguide according to claim 6, characterized in that: The ratio of the shift of the sensor's output spectrum resonance peak due to the change in external temperature to the change in the temperature of the waveguide structure is the temperature sensitivity S2; The calculation formula of the temperature sensitivity S2 is expressed as: S2=Δλ / ΔT, where ΔT represents the change in the temperature of the waveguide structure, and Δλ represents the shift of the output spectrum resonance peak.

9. According to the test method of a high-sensitivity microring resonant cavity sensor based on a corrugated waveguide as claimed in claim 6, the detection range DR of the microring resonant cavity is defined as the ratio of the free spectrum range FSR to the sensor sensitivity S, and the calculation formula of the detection range DR is expressed as: DR = FSR / S, wherein, FSR represents the free spectral range in a certain wavelength range, and S represents the sensor sensitivity.

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