A gas concentration detection device and detection method based on photon nanojet

Abstract

The present invention provides a gas concentration detection device and method based on photonic nanojet technology, relating to the field of optical sensor technology. The device comprises a DFB laser, which serves as the main light source of the gas concentration measurement device and is used to provide laser light for gas concentration measurement to other devices; and two first and second circuits, mounted on either side of one end of the DFB laser. One circuit provides the DC bias current required by the DFB laser, and the other applies a tuning voltage to the DFB laser to control its output frequency and power. By utilizing a waveguide to reduce the intersection of the waveguide and the gas, a strong localized electric field is generated at the output end. Light signals are then collected through a specially designed combined detection system. Furthermore, in photonic nanojet technology, modern optical techniques can be used to optimize the detector, further improving detection sensitivity.

Description

Technical Field

[0001] The present invention relates to the technical field of optical sensors, and in particular to a gas concentration detection device and a detection method based on photon nanojet. Background Art

[0002] Optical sensor technology is a detection system based on optical principles and physical transmission mechanisms, using light as a sensing signal. It is a device or system that uses the characteristics of the interaction between light and matter to measure physical, chemical, or biological quantities. It has become a research hotspot and one of the cutting-edge technologies in various fields. Optical sensor technology has the advantages of high sensitivity, fast response speed, good stability, and millimeter-level or even micron-level detection accuracy. Therefore, it is widely used in environmental monitoring, agriculture, food safety, biomedicine, aerospace and other fields.

[0003] At present, there is a visual irradiation type infrared gas concentration detection device. By pressing the rotating plate, the touch block presses the sensing block, thereby starting the laser and camera. The laser light will emit a laser, and the infrared laser with scanning position information will illuminate the target area. After the infrared laser is absorbed by the target gas, the infrared laser spot with the target gas absorption information is received by the photosensitive element of the focal plane infrared camera. The focal plane infrared camera outputs a high-precision gas concentration diffusion map video with seamless coupling of gas concentration and scene, and then transmits the video to the display through the sensor.

[0004] The laser and camera are activated by pressing the touch block against the sensing block by depressing the rotating plate. This mechanical operation method has instability and precision issues. Moreover, the photosensor of the focal plane infrared camera is limited by its own performance when receiving the infrared laser spot scene, such as limited dynamic range and high noise level. This will lead to inaccurate analysis of gas absorption information and affect the accuracy of the gas concentration diffusion map video. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the present invention provides a gas concentration detection device and detection method based on photon nanojet, which solves the problems of instability and low precision.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: A gas concentration detection device based on photonic nanojet, comprising:

[0007] DFB laser, which serves as the main light source of gas concentration measurement equipment and is used to provide laser for gas concentration measurement for other institutions;

[0008] Two first and second circuits are installed on both sides of one end of the DFB laser, one of which is used to provide the DC bias current required by the DFB laser, and the other is used to apply a tuning voltage to the DFB laser to control its output frequency and power;

[0009] A planar waveguide is located between the spherical lens and the photodetector, wherein the semicircular groove on the planar waveguide is located at the output end of the planar waveguide, and the edge where the diameter of the semicircular groove is located coincides with the output end of the planar waveguide and is symmetrical with the main axis of the planar waveguide;

[0010] The DFB laser is connected to the driver circuit board 2 via copper wire, and electrons are injected into the DFB laser electrodes via the driver circuit board 2;

[0011] The measurement component is installed on one side of the planar waveguide and is used to detect changes in characteristic parameters of the photonic nanojet.

[0012] Preferably, the measuring component includes a plurality of photodetectors, a driving circuit board 1, a positive electrode and a negative electrode. The top of the driving circuit board 1 is provided with a uniformly distributed P-type region and an N-type region. The positive electrode and the negative electrode are respectively installed on the P-type region and the N-type region. The photodetectors are respectively installed on the output end and the positive electrode and the negative electrode on both sides of the planar waveguide. The positive electrode is fixedly connected to the P-type region of the driving circuit board 1, and the negative electrode is fixedly connected to the N-type region of the driving circuit board 1.

[0013] Preferably, a spherical lens is provided between the DFB laser and the planar waveguide, and a bracket is fixedly connected to the bottom of the spherical lens.

[0014] Preferably, the output end of the DFB laser is an emission end, a ridge waveguide is provided inside the DFB laser, and the ridge waveguide and the emission end face the planar waveguide.

[0015] Preferably, a detection method of a gas concentration detection device based on photonic nanojet comprises the following steps:

[0016] S1: First, select an appropriate light source to emit a continuous broad spectrum beam;

[0017] S2: placing the gas sample to be detected in the gas chamber;

[0018] S3: Before the beam enters the gas chamber, an optical filter is used to filter out unwanted wavelengths.

[0019] S4: spectrally scanning the input and output optical signals through an electronic scanning device (such as a spectrometer);

[0020] S5: Detecting spectral changes by comparing the input spectrum with the output spectrum;

[0021] S6: Light source modulation and phase-locked amplification are used to improve detection accuracy; S7: The output light intensity and time are measured and processed, and the curve of light intensity change over time is recorded;

[0022] S8: Draw an absorption spectrum based on the comparison between the output spectrum and the input spectrum;

[0023] S9: Calculate the gas concentration based on the quantitative relationship between absorbance and the concentration of the gas to be detected.

[0024] Preferably, in step S2, the gas chamber should be designed to allow the light beam to pass through the entire gas sample, so as to ensure that the light beam fully interacts with the gas, thereby enabling accurate measurement of the absorption of the gas.

[0025] Preferably, step S4 specifically includes two steps: one is to record the input spectrum before entering the gas chamber, that is, the curve of the intensity of the incident light changing with the wavelength; the other is to record the output spectrum after passing through the gas chamber, that is, the curve of the intensity of the transmitted light changing with the wavelength.

[0026] Preferably, step S7 includes light source modulation and phase-locked amplification. Light source modulation is to modulate the light source by means of a mechanical chopper and an acousto-optic modulator, and the light intensity changes with time. Phase-locked amplification is to use a phase-locked amplifier to extract the modulation signal, reduce background noise interference, and enhance the signal-to-noise ratio of the signal.

[0027] The present invention provides a gas concentration detection device and method based on photon nanofluidics. It has the following beneficial effects:

[0028] The present invention utilizes a waveguide to reduce the intersection of the waveguide and the gas, thereby generating a strong local electric field at the output end and collecting optical signals through a specially designed combined detection system. At the same time, in photonic nanofluidics technology, modern optical technology can be used to better optimize the detector, thereby further improving detection sensitivity.

[0029] The present invention uses photon nanofluidics technology to perform detection in a manner based on spectral line selection, which can specifically detect the target gas and avoid interference from other gas components or impurities.

[0030] The present invention utilizes photonic nanofluidics, which is less expensive than traditional absorption spectroscopy because it requires relatively simple instrumentation and eliminates the need for expensive equipment or reagents. Furthermore, photonic nanofluidics simplifies sample preparation, eliminating the need for complex processing steps and thus reducing costs.

[0031] The present invention adopts a method of directly measuring samples through photon nanofluidics technology, does not require any sample pretreatment and pre-treatment, and is simple and convenient to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0033] Figure 2 is a schematic diagram of the bracket of the present invention;

[0034] Figure 3 is a three-dimensional schematic diagram of a planar waveguide of the present invention;

[0035] Figure 4 It is a schematic diagram of the semicircular groove of the present invention.

[0036] Among them, 1. DFB laser; 2. spherical lens; 3. planar waveguide; 4. semicircular groove; 5. driver circuit board 1; 6. photodetector; 7. first circuit; 8. second circuit; 9. driver circuit board 2; 10. DFB laser electrode; 11. ridge waveguide; 12. output end; 13. bracket; 14. positive electrode; 15. P-type region; 16. negative electrode; 17. N-type region. DETAILED DESCRIPTION

[0037] 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. Example

[0038] like Figure 1-4 As shown, an embodiment of the present invention provides a gas concentration detection device based on photonic nanojet, comprising:

[0039] DFB laser 1, which serves as the main light source of the gas concentration measurement device, is used to provide laser for gas concentration measurement for other institutions.

[0040] DFB laser: The DFB laser uses the DFB (distributed feedback) structure commonly used in optical fiber communications, and has high power stability and single-frequency characteristics. This technical solution uses a laser with dimensions of 250μm × 250μm × 250μm, a beam divergence angle of 10°, a beam diameter of 0.5mm, and an output wavelength of 1650nm as the light source;

[0041] Two first circuits 7 and second circuits 8 are installed on both sides of one end of the DFB laser 1, one of which is used to provide the DC bias current required by the DFB laser 1, and the other is used to apply a tuning voltage to the DFB laser 1 to control its output frequency and power;

[0042] The planar waveguide 3 is located between the spherical lens 2 and the photodetector 6. The semicircular groove 4 on the planar waveguide 3 is located at the output end of the planar waveguide 3. The diameter of the semicircular groove 4 coincides with the output end of the planar waveguide 3 and is symmetrical with the main axis of the planar waveguide 3.

[0043] The planar waveguide is a single-mode planar waveguide, which is mainly used to guide the laser into the semicircular groove. The advantage of the planar waveguide is that it can support high-quality factor (Q value) modes, thereby achieving high-efficiency energy transmission and sensitive detection. This technical solution uses a rectangular silicon planar waveguide with a size of 800mm×400mm×50mm, and the cladding is the gas to be measured. The refractive index contrast value is 0.35, providing stronger mode confinement capability. The bending radius is 100μm and the mode field diameter is 2.5μm. The operating wavelength is 800-1900nm, and the quality factor reaches 105. The insertion loss is 0.2dB / cm;

[0044] The semicircular grooves on the planar waveguide are important structures for generating photonic nanojets. The grooves can be adjusted as needed to achieve gas detection with different sensitivities and resolutions. This technical solution uses ultraviolet light exposure for etching, with a groove radius of 4μm and a thickness of 1μm.

[0045] The DFB laser 1 is connected to the driving circuit board 1 5 via a copper wire, and electrons are injected into the DFB laser electrode 10 via the driving circuit board 2 9;

[0046] The measurement component is installed on one side of the planar waveguide 3 and is used to detect changes in characteristic parameters of the photonic nanojet.

[0047] The measurement assembly includes multiple photodetectors 6, a driver circuit board 5, a positive electrode 14, and a negative electrode 16. The top of the driver circuit board 5 is provided with a uniformly distributed P-type region 15 and an N-type region 17. The positive electrode 14 and the negative electrode 16 are respectively mounted on the P-type region 15 and the N-type region 17. The photodetectors 6 are respectively mounted on the output end of the planar waveguide 3 and the positive electrode 14 and the negative electrode 16 on both sides. The positive electrode 14 is fixedly connected to the P-type region 15 of the driver circuit board 5, and the negative electrode 16 is fixedly connected to the N-type region 17 of the driver circuit board 5.

[0048] The photodetector 6 (PD) is a component used to detect the photonic nanofluidic signal generated by the semicircular grooves. PDs typically employ structures such as photoconductors or photodiodes, offering high response speed and low noise, enabling high-precision gas detection. They have a positive electrode and a negative electrode. This technical solution utilizes 10 PDs to achieve multi-point acquisition and analyze the characteristic changes of the photonic nanofluidic signal.

[0049] A spherical lens 2 is provided between the DFB laser 1 and the planar waveguide 3, and a bracket 13 is fixedly connected to the bottom of the spherical lens 2;

[0050] The lens uses a spherical lens, which focuses the laser into the planar waveguide. The spherical lens needs to meet requirements such as high transmittance and low scattering loss, and can be adaptively adjusted to adapt to different detection distances and detection objects. This technical solution uses a spherical lens with a focal length of 4.5mm, a radius of curvature of 4.5mm, a diameter of 1mm, a center thickness of 0.5mm, a refractive index of 1.5168, a numerical aperture of 0.12, a transmittance greater than 95%, a surface quality of 40 / 20 (scratches / pits), an anti-reflection coating of 1650nm, and an operating wavelength range of 1600-1700nm. The spherical lens is 25mm from the DFB laser 1 and 15mm from the incident end of the planar waveguide 3, located between the laser and the planar waveguide 3.

[0051] The output end of the DFB laser 1 is the output end 12. A ridge waveguide 11 is provided inside the DFB laser 1. The ridge waveguide 11 and the output end 12 face the planar waveguide 3.

[0052] The photodetector 6 is located at the emitting end of the plane waveguide, 0.2 μm away from the edge of the emitting end and symmetrical to the main axis of the plane waveguide 3;

[0053] By etching a semicircular structure on a planar waveguide and placing a photodetector where the photonic nanojet is generated, the characteristic parameters of the photonic nanojet are measured and analyzed to obtain data related to the methane gas concentration. Then, using mathematical calculations, the changes in the methane gas concentration can be obtained in real time, thereby achieving high-precision detection of the methane gas concentration.

[0054] A detection method for a gas concentration detection device based on photon nanojet comprises the following steps:

[0055] S1: First, select an appropriate light source to emit a continuous broad spectrum beam;

[0056] S2: placing the gas sample to be detected in the gas chamber;

[0057] S3: Before the beam enters the gas chamber, an optical filter is used to filter out unwanted wavelengths.

[0058] S4: spectrally scanning the input and output optical signals by an electronic scanning device such as a spectrometer;

[0059] S5: Detecting spectral changes by comparing the input spectrum with the output spectrum;

[0060] S6: Light source modulation and phase-locked amplification are used to improve detection accuracy; S7: The output light intensity and time are measured and processed, and the curve of light intensity change over time is recorded;

[0061] S8: Draw an absorption spectrum based on the comparison between the output spectrum and the input spectrum;

[0062] S9: Calculate the gas concentration based on the quantitative relationship between absorbance and the concentration of the gas to be detected.

[0063] In step S2, the gas chamber should be designed to allow the light beam to pass through the entire gas sample, so as to ensure that the light beam fully interacts with the gas and the absorption of the gas can be accurately measured.

[0064] In step S4, there are two specific steps: one is to record the input spectrum before entering the gas chamber, that is, the curve of the intensity of the incident light changing with the wavelength; the other is to record the output spectrum after passing through the gas chamber, that is, the curve of the intensity of the transmitted light changing with the wavelength.

[0065] In step S7, light source modulation and phase-locked amplification are included. Light source modulation is to modulate the light source by means of a mechanical chopper and an acousto-optic modulator, and the light intensity changes with time. Phase-locked amplification is to use a phase-locked amplifier to extract the modulated signal, reduce background noise interference, and enhance the signal-to-noise ratio. Example

[0066] Prepare a planar waveguide: This is typically made of a silicon wafer covered with an optical waveguide layer to guide the laser's incident light. It's a rectangular parallelepiped measuring 800 mm x 400 mm x 50 mm.

[0067] Etching a Semicircular Structure: During the fabrication of the optical waveguide layer, a UV exposure process is used to etch a semicircular structure with a radius of 4μm and a thickness of 1μm. Specifically, photoresist is first applied to the surface of the optical waveguide layer and exposed to incident UV light using a lens. The sample is then placed in a uranium etcher and irradiated with a uranium ion beam to remove the unexposed photoresist, ultimately resulting in the desired semicircular structure.

[0068] Coupling incident light: During the experiment, a DFB laser is used to generate an incident light beam with a central wavelength of 1650 nm, which is then coupled into the planar waveguide through a spherical lens.

[0069] Perform electron microscopy on the planar waveguide: After the planar waveguide is prepared, it needs to be processed by electron microscopy (TEM) to observe the physical structure in the waveguide area and characterize the presence of nanostructures.

[0070] Light field detection: A photodetector (PD) is a device that converts light signals into electrical signals, typically using a silicon photodiode as the detection element. When an incident photon stream strikes a PD, a photoelectric effect occurs, causing charge movement within the PD and forming a weak current signal. Multiple PDs need to be placed at equal intervals along the main axis of the planar waveguide, with the first PD 0.1μm from the output edge (to more accurately detect changes in the characteristic parameters of the photonic nanojet). PDs are spaced evenly apart, with a spacing of 0.1μm. This operation is used to achieve multi-point acquisition of nanojet properties and changes in light intensity.

[0071] Place the planar waveguide in a concentrated methane gas environment. Due to the difference in refractive index between the methane gas and the planar waveguide, the laser beam converges behind the semicircular grooves, generating a photonic nanojet. This step can be accomplished using specialized experimental equipment, such as a sample cell and gas injection system.

[0072] Detecting changes in the photon flux: When methane gas concentration changes, it affects the transmittance and phase of the photons, causing the characteristic parameters of the photonic nanojet to change. The photocurrent signal detected by the PD also changes accordingly. By amplifying, filtering, and digitizing the signal detected by the PD via a driver circuit board, the specific parameters of the photonic nanojet can be determined in real time. Using the previously obtained concentration-characteristics fitting function, data related to the methane gas concentration in the sample can be obtained.

[0073] Calculating methane concentration: Based on experimental data, methane concentration can be calculated using optical waveguide theory, photonic nanofluidics theory, Fourier transform, sliding average filtering, and peak detection. To improve detection accuracy, multiple experiments and calibration are required. Furthermore, other detection methods (such as mass spectrometry and infrared absorption spectroscopy) can be combined for verification and comparison.

[0074] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A gas concentration detection device based on photon nanojet, characterized in that: include: A DFB laser (1) serving as a light source of a gas concentration measurement device and providing laser light for gas concentration measurement to other institutions; Two first circuits (7) and second circuits (8) are installed on both sides of one end of the DFB laser (1), one of which is used to provide a DC bias current required by the DFB laser (1), and the other is used to apply a tuning voltage to the DFB laser (1) to control its output frequency and power; A planar waveguide (3) is located between the spherical lens (2) and the photodetector (6); a semicircular groove (4) on the planar waveguide (3) is located at the output end of the planar waveguide (3); and the side where the diameter of the semicircular groove (4) is located coincides with the output end of the planar waveguide (3) and is symmetrical with the main axis of the planar waveguide (3); the planar waveguide is placed in an environment of concentrated methane gas. Since the refractive index of the methane gas is different from that of the planar waveguide, the laser beam converges behind the semicircular groove to generate a photon nanojet; The DFB laser (1) is connected to the first driving circuit board (5) via a copper wire, and electrons are injected into the DFB laser electrode (10) via the second driving circuit board (9); A measuring component, which is installed on one side of the planar waveguide (3) and is used to detect changes in characteristic parameters of the photonic nanojet; The measuring component comprises a plurality of photodetectors (6), a driving circuit board (5), a positive electrode (14) and a negative electrode (16); the top of the driving circuit board (5) is provided with a uniformly distributed P-type region (15) and an N-type region (17); the positive electrode (14) and the negative electrode (16) are respectively mounted on the P-type region (15) and the N-type region (17); the photodetector (6) is respectively mounted on the output end of the planar waveguide (3) and the positive electrode (14) and the negative electrode (16) on both sides; the positive electrode (14) is fixedly connected to the P-type region (15) of the driving circuit board (5); and the negative electrode (16) is fixedly connected to the N-type region (17) of the driving circuit board (5).

2. The gas concentration detection device based on photonic nanofluidics according to claim 1, characterized in that: A spherical lens (2) is provided between the DFB laser (1) and the planar waveguide (3), and a bracket (13) is fixedly connected to the bottom of the spherical lens (2).

3. The gas concentration detection device based on photonic nanofluidics according to claim 1, characterized in that: The output end of the DFB laser (1) is an emission end (12), a ridge waveguide (11) is provided inside the DFB laser (1), and the ridge waveguide (11) and the emission end (12) face the planar waveguide (3).

4. The detection method of a gas concentration detection device based on photonic nanojet according to claim 1, characterized in that: The following steps are involved: S1: First, select an appropriate light source to emit a continuous broad spectrum beam; S2: placing the gas sample to be detected in the gas chamber; S3: Before the beam enters the gas chamber, an optical filter is used to filter out unwanted wavelengths. S4: Spectral scanning of the input and output optical signals is performed by an electronic scanning device; S5: Detecting spectral changes by comparing the input spectrum with the output spectrum; S6: Light source modulation and phase-locked amplification are used to improve detection accuracy; S7: Measure and process the output light intensity and time, and record the curve of light intensity changing with time; S8: Draw an absorption spectrum based on the comparison between the output spectrum and the input spectrum; S9: Calculate the gas concentration based on the quantitative relationship between absorbance and the concentration of the gas to be detected.

5. The detection method of a gas concentration detection device based on photonic nanofluidics according to claim 4, characterized in that: In step S2, the gas chamber should be designed to allow the light beam to pass through the entire gas sample, so as to ensure that the light beam fully interacts with the gas, thereby accurately measuring the absorption of the gas.

6. The detection method of a gas concentration detection device based on photonic nanofluidics according to claim 4, characterized in that: The step S4 specifically includes two steps: one is to record the input spectrum before entering the gas chamber, that is, the curve of the intensity of the incident light changing with the wavelength; the other is to record the output spectrum after passing through the gas chamber, that is, the curve of the intensity of the transmitted light changing with the wavelength.

7. The detection method of a gas concentration detection device based on photonic nanofluidics according to claim 4, characterized in that: Step S7 includes light source modulation and phase-locked amplification. Light source modulation is to modulate the light source by means of a mechanical chopper and an acousto-optic modulator, and the light intensity changes with time. Phase-locked amplification is to use a phase-locked amplifier to extract the modulated signal, reduce background noise interference, and enhance the signal-to-noise ratio of the signal.

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