A biochemical sensor with a double-ring coupling structure

Abstract

The present invention discloses a biochemical sensor with a double-ring coupling structure, which relates to the field of photobiochemical sensing, and includes two sections of waveguides, a ring resonant cavity and an elliptical resonant cavity; the waveguide and the resonant cavity are both based on silicon, and the silicon dioxide wraps the silicon nitride structure. In this structure, due to the coupling between the waveguide and the ring resonant cavity and the coupling between the ring resonant cavity and the elliptical resonant cavity, the light wave input by the waveguide is confined in the elliptical resonant cavity via the ring resonant cavity, thereby enhancing the interaction between light and matter. At the same time, two sections of waveguides replace one section of waveguide, thereby improving the coupling efficiency between the waveguide and the ring resonant cavity. In addition, the internal area of ​​the elliptical resonant cavity is used to detect changes in the concentration of an external solution, thereby reducing changes in the outgoing waveguide light wave caused by changes in the solution concentration of the waveguide and the ring resonant cavity, thereby increasing the linear measurement range.

Description

Technical Field

[0001] The present application relates to a biochemical detection device, and in particular to an optical resonant cavity biochemical sensor. Background Art

[0002] Optical biochemical sensors use optical signals as carriers and are highly selective and sensitive detection devices that convert the signals expressed by the biochemical substances to be tested into electrical signals. They are usually used for the detection of substances such as gases, liquids and biomacromolecules. The change in the concentration of the sample to be tested causes the refractive index of the resonant cavity cladding to change, which changes the effective refractive index of the light wave mode and the transmission properties of the light wave in the resonant cavity. By measuring the change in light intensity at the output port, information about the substance to be tested can be obtained.

[0003] Optical sensing methods include scattering interferometry, photothermal microscopy, nanofiber sensors, and microcavity sensing. Optical microcavity sensing has the advantages of ultra-high quality factor, small mode volume, high sensitivity, and a small number of intracavity modes. Optical microcavity sensors can be divided into Fabry-Perot microcavity, photonic crystal microcavity, and whispering gallery microcavity according to different restriction mechanisms of the light field. The light signal resonates in the microcavity, which is equivalent to an increase in the sensor detection length, which increases the intensity or phase change of the light signal and enhances the sensor performance. Compared with other types of microcavity biochemical sensors, the whispering gallery mode microcavity has the advantages of small size, convenient chip preparation, and narrow line width.

[0004] Patent CN 203385650 U discloses an epitaxial grating FP cavity and a microring resonant cavity cascade optical biochemical sensor chip, which enhances the interaction between light and matter and has higher detection sensitivity. Under the same sensing conditions, the miniaturization of the optical biochemical sensor and the on-chip sensing system are stronger. However, the chip uses a slit-type optical waveguide structure and a convex toothed grating, which is complex in structure and difficult to process.

[0005] Patent CN 101915963 A discloses a multi-embedded micro-resonant cavity filter, which uses the filtering effect of the waveguide resonant cavity to reduce the device size, increase the free spectrum range, and has low device cost and is suitable for mass production. However, its maximum transmittance is less than 0.8, and the waveguide resonant cavity coupling efficiency is low.

[0006] Patent CN 104020137 A discloses a phase-sensitized integrated waveguide optical biochemical sensor, which uses waveguide phase sensitization to reduce the size of the sensor, and adopts the optical power ratio demodulation method to reduce the influence of the output optical power ratio, and quickly obtains information such as the concentration of the biochemical sample to be tested. However, the biochemical sensor has a small detection range, and the optical power ratio and the solution refractive index change are nonlinear, which is not conducive to accurate measurement.

[0007] Based on the existing annular microcavity biochemical sensor structure, it has low sensitivity, low coupling efficiency between the waveguide and the resonant cavity, small linear range, poor linearity, great difficulty in device manufacturing and difficulty in achieving device miniaturization and portability, which is not conducive to simple operation of various biological and chemical components. Summary of the invention

[0008] The purpose of the present invention is to solve the problem of biochemical substance detection. Based on the optical resonant cavity biochemical sensor, a micro dual-coupling structure biochemical sensor is proposed to address the problems of difficulty in manufacturing existing devices, low coupling efficiency, and poor detection linearity.

[0009] In order to achieve the above-mentioned purpose, the technical solution of the present invention is: a dual-coupling structure biochemical sensor, comprising a substrate (1) and a first waveguide (2), a second waveguide (3), a ring resonant cavity (4) and an elliptical resonant cavity (5) arranged above the substrate (1); the material of the substrate (1) is silicon; the first waveguide (2), the second waveguide (3), the ring resonant cavity (4) and the elliptical resonant cavity (5) are located in the same plane, have the same width and are all silicon dioxide wrapped silicon nitride structures. The first waveguide (2), the second waveguide (3) and the ring resonant cavity (4) are coupled and connected, and the ring resonant cavity (4) and the elliptical resonant cavity (5) are coupled and connected, and are all located in the same plane.

[0010] Preferably, the annular resonant cavity (4) is an annular waveguide, the elliptical resonant cavity (5) is an elliptical waveguide, the first waveguide (2) and the second waveguide (3) and the annular resonant cavity (4) form a first coupler, and the annular resonant cavity (4) and the elliptical resonant cavity (5) form a second coupler.

[0011] Preferably, the width structure of the first waveguide (2) and the second waveguide (3) are the same, and the vertical center lines are the same straight line. The horizontal distance between the first waveguide (2), the second waveguide (3) and the ring resonant cavity (4) is less than 0.2 times the coupling distance (incident wave wavelength).

[0012] Preferably, the centers of the annular resonant cavity (4) and the elliptical resonant cavity (5) are located at the same point.

[0013] Preferably, the vertical distances between the upper and lower sides of the annular resonant cavity (4) and the elliptical resonant cavity (5) range from 0.025 to 0.04 times the wavelength of the incident wave.

[0014] Preferably, the interior of the elliptical resonant cavity contains the solution to be tested, and the upper side of the substrate (1) except for the waveguide and the resonant cavity is a medium with the same and fixed refractive index.

[0015] The beneficial effects of the present invention are as follows: the present invention uses two sections of waveguides to replace a traditional one section of waveguide, thereby improving the absorption rate of the resonance cavity; an elliptical resonance cavity is added, so that most of the magnetic field energy of the first waveguide enters the elliptical resonance cavity, while the magnetic field strength of the second waveguide and the ring resonance cavity is weak, and the magnetic field of the elliptical resonance cavity is used for measurement, thereby reducing the influence of the second waveguide and the ring resonance cavity on the measurement result; a double coupling structure is adopted, and the light wave input by the waveguide is confined in the elliptical resonance cavity via the ring resonance cavity, thereby enhancing the light and matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a top view of a biochemical sensor with a dual coupling structure of the present invention.

[0017] Figure 2 It is a front view of a biochemical sensor with a dual coupling structure according to the present invention.

[0018] Figure 3 This is a graph of the change of the magnetic field inside the biochemical sensor of the dual-coupling structure according to the embodiment of the present invention when light waves are input.

[0019] Figure 4 This is a curve diagram of the change of magnetic field intensity at the output port of the biochemical sensor with a dual-coupling structure according to an embodiment of the present invention under different refractive index change conditions.

[0020] Explanation of the reference numerals: (1) substrate; (2) first waveguide; (3) second waveguide; (4) ring resonant cavity; (5) elliptical resonant cavity (6) silicon nitride core layer; (7) silicon base and (8) silicon dioxide cladding layer. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0022] like Figure 1 and Figure 2 As shown, the biochemical sensor with a dual-coupling structure of the present embodiment comprises a substrate (1) and a first waveguide (2), a second waveguide (3), a ring resonant cavity (4) and an elliptical resonant cavity (5) arranged above the substrate (1); the material of the substrate (1) is silicon; the first waveguide (2), the second waveguide (3), the ring resonant cavity (4) and the elliptical resonant cavity (5) are located in the same plane, have the same width and are all silicon dioxide-wrapped silicon nitride structures.

[0023] In this embodiment, the width structure of the first waveguide (2) and the second waveguide (3) are the same, and the vertical center lines are the same straight line. The horizontal distance between the first waveguide (2), the second waveguide (3) and the annular resonant cavity (4) is less than the coupling distance. The horizontal distance between the first waveguide (2), the second waveguide (3) and the annular resonant cavity (4) is less than 0.2 times the coupling distance (incident wave wavelength). The vertical distance between the upper and lower sides of the annular resonant cavity (4) and the elliptical resonant cavity (5) ranges from 0.025 to 0.04 times the incident wave wavelength. The interior of the elliptical resonant cavity is the solution to be tested, and the upper side of the substrate (1) is a medium with the same and fixed refractive index except for the waveguide and the resonant cavity. It should be noted that the resonance conditions of the first coupler and the second coupler belong to the conventional technical means of those skilled in the art and will not be repeated here.

[0024] In order to enable those skilled in the art to understand and implement the technical solution of the present invention, the biochemical sensor with the dual-ring optical resonant cavity structure will be described in detail in combination with the specific working process.

[0025] The light wave enters the second waveguide (3) from the lower left and propagates. When passing through the coupling region of the second waveguide (3), the first waveguide (2) and the annular resonant cavity (4), the light wave couples with the right annular resonant cavity (4), so that a part of the light passes through the medium region and propagates along the first waveguide (2), and another part is coupled to the annular resonant cavity (4) and propagates. A part of the light wave entering the annular resonant cavity (4) propagates along the resonant cavity, and another part is coupled to the elliptical resonant cavity (5) through the upper region. At this time, most of the magnetic field energy of the second waveguide (3) is coupled into the elliptical resonant cavity (5) to form a stable annular magnetic field. At this time, due to the change in the concentration of the substance to be measured in the second annular resonant cavity (5), the refractive index of the substance changes, causing the intensity of the light wave at the output port to change.

[0026] In this example, the waveguide cladding width is 1um, the waveguide core width is 0.75um, the outer radius of the annular resonator is 12.6um, the major axis of the elliptical resonator is 11.5um, the minor axis is 7.5um, the minimum distance between the waveguide and the annular resonator is 0.059um, and a light wave with a wavelength of 1.55um is used. The refractive index of the fixed medium is 1.3, and the refractive index range of the medium to be measured is 1.42-1.54.

[0027] Figure 3 This is a graph of the magnetic field change inside the sensor when the light wave is input into the dual-coupled biochemical sensor of the embodiment of the present invention obtained through simulation software. Figure 3As shown, at this time, the light wave enters the second waveguide (3) from the lower left incident port for transmission, the magnetic field energy is concentrated in the elliptical resonant cavity (5) and the elliptical resonant cavity is in a critical coupling state, the magnetic field intensity in the first waveguide (2) and the annular resonant cavity (4) is weak, and when the first waveguide (2) is compared with the second waveguide (3), the magnetic field intensity at the output port is much weaker than that at the input port, and at this time, the coupler resonance condition is met and the annular resonant cavity (4) has a high absorption rate.

[0028] Figure 4 The present invention is a dual-coupling structure biochemical sensor of the embodiment of the present invention. The output port magnetic field intensity change curve is different under different refractive index changes. Through the analysis of the curve, it is found that when the refractive index of the substance to be measured is 1.42 to 1.54, the magnetic field intensity change of the output port of the first waveguide (2) is approximately linear, and the sensor has good linearity. It can be used to detect changes in substance concentration.

[0029] In this embodiment, the elliptical resonant cavity (5) greatly confines the light within the region, thereby effectively enhancing the interaction between light and matter. In addition, the elliptical resonant cavity (5) can cause the light to oscillate back and forth in the resonant cavity, thereby increasing the intensity and effective length of the interaction between light and matter, thereby making the detection sensitivity higher.

[0030] The above is only a specific embodiment of the present invention. Those skilled in the art will understand that various modifications, substitutions and changes can be made to the present invention within the technical scope disclosed by the present invention. Therefore, the present invention should not be limited by the above examples, but should be limited by the protection scope of the claims.

Claims

1. A biochemical sensor with a dual-coupling structure, comprising a substrate (1), and a first waveguide (2), a second waveguide (3), a ring resonant cavity (4), and an elliptical resonant cavity (5) arranged above the substrate (1), wherein the first waveguide (2) is an upper rectangular waveguide; the second waveguide (3) is a lower rectangular waveguide; the center of the ring resonant cavity (4) is located on the perpendicular bisector of the two waveguide sections; and the elliptical resonant cavity (5) is located inside the ring resonant cavity (4); The specific working process is as follows: the light wave enters the second waveguide (3) from the lower left to propagate, and is coupled with the right side ring resonant cavity (4) when passing through the coupling area of ​​the second waveguide (3), the first waveguide (2) and the ring resonant cavity (4), so that a part of the light passes through the medium area and propagates along the first waveguide (2), and the other part is coupled to the ring resonant cavity (4) for propagation; a part of the light wave entering the ring resonant cavity (4) propagates along the resonant cavity, and the other part passes through the upper area and is coupled into the elliptical resonant cavity (5), at which time most of the magnetic field energy of the second waveguide (3) is coupled into the elliptical resonant cavity (5) to form a stable ring magnetic field; at this time, due to the change in the concentration of the substance to be measured in the second ring resonant cavity (5), the refractive index of the substance changes, so that the intensity of the light wave at the output port changes; Two waveguide sections are used instead of the traditional one waveguide to improve the absorption rate of the resonant cavity; an elliptical resonant cavity is added so that most of the magnetic field energy of the first waveguide enters the elliptical resonant cavity, while the magnetic field strength of the second waveguide and the ring resonant cavity is weak, and the magnetic field of the elliptical resonant cavity is used for measurement to reduce the influence of the second waveguide and the ring resonant cavity on the measurement results; a double coupling structure is adopted, and the light wave input by the waveguide is confined in the elliptical resonant cavity through the ring resonant cavity, thereby enhancing the interaction between light and matter.

2. A biochemical sensor with a dual coupling structure as claimed in claim 1, characterized in that The interior of the elliptical resonant cavity is the solution to be tested, and the upper side of the substrate (1) except the waveguide and the resonant cavity is a medium with the same and fixed refractive index.

3. A biochemical sensor with a dual coupling structure as claimed in claim 1, characterized in that The annular resonant cavity (4) is an annular waveguide, the elliptical resonant cavity (5) is an elliptical waveguide, the first waveguide (2), the second waveguide (3) and the annular resonant cavity (4) constitute a first coupler, and the annular resonant cavity (4) and the elliptical resonant cavity (5) constitute a second coupler.

4. A biochemical sensor with a dual coupling structure as claimed in claim 1, characterized in that The first waveguide (2) and the second waveguide (3) have the same width structure, and their vertical center lines are the same straight line. The horizontal distance between the first waveguide (2), the second waveguide (3) and the ring resonant cavity (4) is less than 0.2 times the coupling distance.

5. A biochemical sensor with a dual coupling structure as claimed in claim 1, characterized in that The centers of the annular resonant cavity (4) and the elliptical resonant cavity (5) are located at the same point and the minimum distance between the upper and lower sides is less than the wavelength of the light wave.

6. A biochemical sensor with a dual coupling structure as claimed in claim 1, characterized in that The vertical distances between the upper and lower sides of the annular resonant cavity (4) and the elliptical resonant cavity (5) range from 0.025 to 0.04 times the wavelength of the incident wave.

7. A biochemical sensor with a dual coupling structure as claimed in claim 1, characterized in that The material of the substrate (1) is silicon; the first waveguide (2), the second waveguide (3), the annular resonant cavity (4) and the elliptical resonant cavity (5) are located in the same plane, have the same width and are all silicon dioxide-wrapped silicon nitride structures.

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