On-chip integrated microcavity kerr frequency comb gas detection device and application thereof

Abstract

The application discloses a kind of on-chip integrated microcavity kerr frequency comb gas detection device and its application, belong to near-infrared analyte detection field, gas detection device includes pump laser generation module, on-chip microcavity frequency comb sensor and control system, the output end of pump laser generation module is coupled with the input end of upper microcavity frequency comb sensor, the output end of on-chip microcavity frequency comb sensor is coupled with control system, control system is used to control the working state of pump laser generation module and on-chip microcavity frequency comb sensor, complete the inversion and detection of the kind and concentration of multiple-component gas to be measured;The device uses the high conversion efficiency broadband coherent kerr frequency comb formed in microcavity as light source, integrated in the air with high restriction factor sensing waveguide, through back-end spectral analysis and processing, the kind and concentration of multiple-component gas can be inverted in real time, with the characteristics of detecting gas variety, system volume is small, integration is high.

Description

Technical Field

[0001] This invention relates to the field of infrared analyte detection technology, specifically to an on-chip integrated microcavity Kerr frequency comb gas detection device and its application. Background Technology

[0002] The generation of microcavity frequency combs utilizes the Kerr nonlinear effect and four-wave mixing process of waveguide materials, hence the name Kerr frequency comb. The frequency comb spectrum formed through dispersion engineering and microcavity parameter control possesses a wide span across octaves, making it an ideal broadband coherent light source for multi-component gas sensing technology. While on-chip frequency comb chips offer a compact size, currently reported sensing systems require an additional gas chamber for operation, resulting in bulky systems with low integration and insufficient portability.

[0003] Optical waveguide sensing relies on the evanescent field distribution of light propagating on the waveguide surface. This can be achieved by designing slit structures to increase the energy percentage in the air, enhancing the interaction between light and gaseous substances, or by utilizing the slow-light effect of photonic crystal slow-light waveguides to increase the optical path. However, current optical waveguide sensors generally use single-wavelength continuous-wave lasers, enabling only single-component gas detection. Integrating a microcavity frequency comb light source with an optical waveguide sensor on a single chip, and acquiring the absorption spectrum at the chip output using a spectrometer, can achieve real-time multi-component detection. However, in current technology, no sensing device has been designed that can integrate a microcavity frequency comb light source with an optical waveguide sensor on a single chip.

[0004] To address the above issues, there is an urgent need to design an on-chip integrated microcavity Kerr frequency comb gas detection device to solve the shortcomings of existing optical waveguide sensing systems, such as the limited range of detectable gases, large system size, and low integration. Summary of the Invention

[0005] To address the aforementioned problems, this invention aims to provide an on-chip integrated microcavity Kerr frequency comb gas detection device and its application. This device utilizes a high-conversion-efficiency broadband coherent Kerr frequency comb formed in a microcavity as a light source and integrates a sensing waveguide with a high confinement factor in the air. Through back-end spectral analysis and processing, it can invert the types and concentrations of multi-component gases in real time, featuring diverse gas detection capabilities, small system size, and high integration.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] An on-chip integrated microcavity Kerr frequency comb sensor includes a silicon substrate, and further includes an optical fiber coupled input inverted conical mode converter, a microcavity coupled input straight waveguide, a horizontal slit waveguide microring resonator, a back-coupled interferometer waveguide, an interferometer waveguide heater, a microcavity waveguide heater, a microcavity coupled output straight waveguide, a sensing waveguide, and an optical fiber coupled output inverted conical mode converter integrated on the silicon substrate.

[0008] The fiber-coupled input inverted conical mode converter is located at the input end of the microcavity coupled input straight waveguide. The horizontal slit waveguide microring resonator is coupled to both the microcavity coupled input straight waveguide and the microcavity coupled output straight waveguide through gaps. The back-coupled interferometer waveguide is located at the output end of the microcavity coupled input straight waveguide, the microcavity coupled output straight waveguide is located at the output end of the back-coupled interferometer waveguide, the sensing waveguide is located at the output end of the microcavity coupled output straight waveguide, and the fiber-coupled output inverted conical mode converter is located at the output end of the microcavity coupled output straight waveguide.

[0009] Preferably, the horizontal slit waveguide microring resonator and the back-coupled interferometer waveguide have the same waveguide structure; the interferometer waveguide heater is disposed on the surface of the back-coupled interferometer waveguide, and the microcavity waveguide heater is disposed on the surface of the horizontal slit waveguide microring resonator, and both are connected to the output terminal of the heater current controller; the sensing waveguide is a vertical single-air slit waveguide.

[0010] An on-chip integrated microcavity Kerr frequency comb gas detection device includes an on-chip integrated microcavity Kerr frequency comb sensor.

[0011] Preferably, the on-chip integrated microcavity Kerr frequency comb gas detection device is a gas detection device based on a back-coupled on-chip integrated microcavity Kerr frequency comb sensor.

[0012] Preferably, it includes a pump laser generation module, an on-chip microcavity frequency comb sensor, and a control system;

[0013] The pump laser generation module includes a pump laser, an optical amplifier, a polarization controller, and a tunable bandpass filter, and the tunable bandpass filter is coupled to an on-chip microcavity frequency comb sensor through an input tapered lens fiber.

[0014] The upper microcavity frequency comb sensor includes an optical fiber coupled input inverted conical mode converter, a microcavity coupled input straight waveguide, a horizontal slit waveguide microring resonator, a back-coupled interferometer waveguide, an interferometer waveguide heater, a microcavity waveguide heater, a microcavity coupled input straight waveguide, a sensing waveguide, and an optical fiber coupled output inverted conical mode converter, all integrated on the same substrate.

[0015] The control system is used to control the operating status of the pump laser generation module and the on-chip microcavity frequency comb sensor.

[0016] Preferably, the maximum wavelength adjustment range of the pump laser is greater than one free spectral range of the horizontal slit waveguide microring resonator.

[0017] Preferably, there are two coupling nodes between the horizontal slit waveguide microring resonator and the back-coupled interferometer waveguide.

[0018] Preferably, the control system includes a laser current controller, an arbitrary waveform signal generator, a high-precision servo PID controller, a heater current controller, an RF spectrum analysis module, and an absorption spectrum analysis module.

[0019] The arbitrary waveform signal generator is connected to the pump laser via a laser current controller;

[0020] The high-precision servo PID controller is connected to the microcavity waveguide heater and the interferometer arm waveguide heater through the heater current controller.

[0021] Both the radio spectrum analysis module and the absorption spectrum analysis module are connected to the inverted conical mode converter via a tapered lens fiber and a fiber optic beam splitter.

[0022] An application of an on-chip integrated microcavity Kerr frequency comb gas detection device is disclosed, which is used to invert and detect the type and concentration of multi-component analytes.

[0023] Preferably, the process of using an on-chip integrated microcavity Kerr frequency comb gas detection device to invert and detect the type and concentration of multi-component analytes includes:

[0024] Step 1: Connect all optical and electrical devices of the gas detection sensing system;

[0025] Step 2: Finely adjust the input and output coupling lens fiber to align it with the center of the frequency comb sensor input / output mode converter;

[0026] Step 3: Set the laser's amplification factor and output polarization state;

[0027] Step 4: Set the drive current of the laser so that its output wavelength sweeps across a certain resonant peak of the microcavity from small to large.

[0028] Step 5: Observe the repetition frequency and spectrum of the output frequency comb, and collect the thermally stable Kerr frequency comb spectrum under background atmosphere and sample composition.

[0029] Step 6: Process the spectral data before and after absorption, and invert the gas type and concentration by comparing with a standard database.

[0030] The beneficial effects of this invention are: This invention discloses an on-chip integrated microcavity Kerr frequency comb gas detection device and its application. Compared with the prior art, the improvement of this invention lies in:

[0031] This invention designs an on-chip integrated microcavity Kerr frequency comb gas detection device and its application.

[0032] 1. This invention designs an on-chip integrated microcavity Kerr frequency comb sensor, comprising an optical fiber coupled input inverted conical mode converter, a microcavity coupled input straight waveguide, a horizontal slit waveguide microring resonator, a back-coupled interferometric arm waveguide, an interferometric arm waveguide heater, a microcavity waveguide heater, a microcavity coupled input straight waveguide, a sensing waveguide, and an optical fiber coupled output inverted conical mode converter. This back-coupled on-chip integrated microcavity Kerr frequency comb sensor adopts an interferometric structure, resulting in high output power and high pump power conversion efficiency. Furthermore, this sensor integrates the sensing waveguide and the microcavity waveguide used for frequency comb generation on the same substrate, exhibiting high integration and compactness.

[0033] 2. This invention designs an on-chip integrated microcavity Kerr frequency comb gas detection device, including a pump laser generation module, an on-chip microcavity frequency comb sensor, and a control system. This device utilizes a high-conversion-efficiency broadband coherent Kerr frequency comb formed in the microcavity as a light source, integrated into a sensing waveguide with a high confinement factor in air. Through back-end spectral analysis and processing, it can invert the types and concentrations of multi-component gases in real time. At the same time, this device adopts a back-coupled feedback interferometer arm structure, and the formed soliton crystal comb or multi-pulse frequency comb (the spectral morphology is determined by the pump power of the injected microring and the microcavity coupling state) can well cover the fingerprint absorption region of various gases. It has the advantages of detecting a variety of gases, small system size, and high integration. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the on-chip integrated microcavity Kerr frequency comb sensor structure of the present invention.

[0035] Figure 2 This is a schematic diagram illustrating the working principle of the on-chip integrated microcavity Kerr frequency comb gas detection device of the present invention.

[0036] Figure 3 The flowchart illustrates the operation of measuring the gas to be tested using the on-chip integrated microcavity Kerr frequency comb gas detection device of this invention.

[0037] Figure 4 The diagram shows the group velocity dispersion plot and waveguide cross-section of the sensor microcavity waveguide in Embodiment 4 of the present invention.

[0038] Figure 5 This is the output frequency domain spectrum of the sensor in Embodiment 4 of the present invention at a repetition frequency of 10 GHz under a pump power of 1 W.

[0039] Figure 6 This is a time-domain pulse diagram of the sensor output at a repetition frequency of 10 GHz under a pump power of 1W in Embodiment 4 of the present invention (partial time is shown).

[0040] The system comprises: 1. Pump laser generation module, 11. Pump laser, 12. Optical amplifier, 13. Polarization controller, 14. Tunable bandpass filter; 2. On-chip microcavity frequency comb sensor, 21. Fiber-coupled input inverted conical mode converter, 22. Microcavity coupled input straight waveguide, 23. Horizontal slit waveguide microring resonator, 24. Back-coupled interferometer waveguide, 25. Interferometer waveguide heater, 26. Microcavity waveguide heater, 27. Microcavity coupled output straight waveguide, 28. Sensing waveguide, 29. Fiber-coupled output inverted conical mode converter; 3. Control system, 31. Laser current controller, 32. Arbitrary waveform signal generator, 33. High-precision servo PID controller, 34. Heater current controller, 35. RF spectrum analysis module, 36. Absorption spectrum analysis module. Detailed Implementation

[0041] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0042] Example 1: Refer to Appendix Figure 1 As shown, this embodiment designs an on-chip integrated microcavity Kerr frequency comb sensor, including an optical fiber coupled input inverted conical mode converter 21, a microcavity coupled input straight waveguide 22, a horizontal slit waveguide microring resonator 23, a back-coupled interferometer waveguide 24, an interferometer waveguide heater 25, a microcavity waveguide heater 26, a microcavity coupled input straight waveguide 27, a sensing waveguide 28, and an optical fiber coupled output inverted conical mode converter 29. All of the above on-chip sensors are grown and fabricated on a silicon substrate, forming an integrated chip and improving the integration effect.

[0043] Specifically, the fiber-coupled input inverted conical mode converter 21 and the fiber-coupled output inverted conical mode converter 29 have the function of coupling and connecting the pump laser generation module 1, the on-chip microcavity frequency comb sensor 2 and the control system 3. At the same time, during the coupling process, the multi-dimensional adjustment frame can be finely adjusted to change the position and angle of the large numerical aperture conical lens fiber, so that it is aligned with the center of the inverted conical waveguide mode converter, thereby achieving maximum coupling efficiency.

[0044] Specifically, the microcavity coupled input straight waveguide 22 is used to split the optical field coupled into the fiber coupled input inverted conical mode converter 21 into the horizontal slit waveguide microring resonator 23 and the back-coupled interferometer waveguide 24. The splitting ratio is determined by the distance between the microcavity coupled input straight waveguide 22 and the horizontal slit waveguide microring resonator 23.

[0045] Specifically, the horizontal slit waveguide microring resonator 23 is formed by chemical vapor deposition on a silicon substrate. The lower and upper cladding layers are silicon nitride, and the core layer is silicon dioxide. The optimized thickness and large width of each layer make the waveguide dispersion relatively flat; the small mode area makes the photon density relatively large; and the strong Kerr effect makes the light field undergo four-wave mixing to form a frequency comb.

[0046] Specifically, the back-coupled interferometer waveguide 24 has the same waveguide structure as the micro-ring resonator 23, which feeds back the pump light field energy that is not coupled into the micro-ring resonator 23 into the micro-cavity, where it coherently cancels out the pump wavelength component in the frequency comb inside the cavity, thereby increasing the conversion efficiency of the pump energy.

[0047] Specifically, the interferometer waveguide heater 25 is attached to the surface of the interferometer waveguide 24, and the electrode is connected to the output terminal of the heater current controller 34. By changing the driving current to heat the interferometer waveguide 24, the thermal tuning phase is changed, and the phase difference between the pump light field in the microcavity and the interferometer is adjusted, thereby controlling the pump depletion degree.

[0048] Specifically, the microcavity waveguide heater 26 is attached to the surface of the microring resonant cavity 23, and the electrode is connected to the output terminal of the heater current controller 34; the high-precision servo PID controller 33 performs proportional-integral-differential calculations based on the collected temperature information, generates a feedback signal, and loads it onto the heater current controller 34 to change the current, which is used to heat the microring resonant cavity 23 to achieve constant temperature, so that the generated frequency comb achieves thermal locking under thermal tuning.

[0049] Specifically, the microcavity coupled output straight waveguide 27 combines the coupled energy of the horizontal slit waveguide microring resonator 23 with the back-coupled interferometer waveguide 24 to form an optical frequency comb for gas sensing; the coupling ratio of microcavity energy and the transmission ratio of interferometer energy are determined by the distance between the microcavity coupled output straight waveguide 27 and the horizontal slit waveguide microring resonator 23.

[0050] Specifically, the sensing waveguide 28 is a vertical single-air slit waveguide, which can increase the energy distribution ratio of the light field in the air, thereby improving the sensitivity of the gas detection device.

[0051] Example 2: Reference Figure 2-3As shown, unlike Embodiment 1, the on-chip integrated microcavity Kerr frequency comb sensor described in Embodiment 1 is applied to an on-chip integrated microcavity Kerr frequency comb gas detection device, resulting in a back-coupled on-chip integrated microcavity Kerr frequency comb sensor gas detection device capable of detecting various gases. The detection device includes a pump laser generation module 1, an on-chip microcavity frequency comb sensor 2, and a control system 3; wherein...

[0052] The output end of the pump laser generation module 1 is coupled to the input end of the upper microcavity frequency comb sensor 2 to generate a pump laser with specific polarization characteristics and output a quasi-TE mode laser that meets the optical parametric oscillation threshold power.

[0053] The on-chip microcavity frequency comb sensor 2 achieves long-term, efficient, and stable operation under the drive of the control system 3. As the core unit of the back-coupled on-chip integrated microcavity Kerr frequency comb gas detection device, it has the function of generating a broadband Kerr optical frequency comb for multi-gas sensing and interacting with the gas to be measured.

[0054] The control system 3 is used to control the working status of the pump laser generation module 1 and the on-chip microcavity frequency comb sensor 2, and to complete the inversion and detection of the types and concentrations of multi-component analytes by collecting spectral information.

[0055] The coupling between the output of the pump laser generation module 1 and the input of the on-chip microcavity frequency comb sensor 2, and the coupling between the output of the on-chip microcavity frequency comb sensor 2 and the RF spectrum analysis module and the absorption spectrum analysis module in the control system 3, are all achieved through a tapered lens fiber. The output of the on-chip microcavity frequency comb sensor 2 can be connected to the tapered lens fiber using an on-chip inverted tapered mode converter or a grating coupler structure.

[0056] Preferably, to generate pump lasers with specific polarization characteristics, the pump laser generation module 1 is designed to include a pump laser 11, an optical amplifier 12, a polarization controller 13, and a tunable bandpass filter 14; wherein...

[0057] The pump laser 11 is a wavelength-tunable continuous wave laser for emitting laser light. The pump wavelength is not limited to near-infrared, mid-infrared and other bands, and the laser type is not limited to semiconductor laser, gas laser or fiber laser.

[0058] The optical amplifier 12 has the function of increasing optical power and is used to increase the power of the laser emitted by the pump laser 11. In use, it can be achieved by a rare earth-doped fiber amplifier or waveguide amplifier.

[0059] The polarization controller 13 is used to change the polarization state of the pump light output by the optical amplifier 12, and usually adjusts the polarization state to quasi-TE mode.

[0060] The tunable bandpass filter 14 is used to filter out spontaneous emission noise generated during the amplification process of the optical amplifier 12, so as to obtain a seed light source for frequency comb generation.

[0061] Preferably, to facilitate coupling of quasi-TE light that meets the optical parametric oscillation threshold power using a mode coupler, the microcavity frequency comb sensor 2 is designed to include an fiber-coupled input inverted conical mode converter 21, a microcavity coupled input straight waveguide 22, a horizontal slit waveguide microring resonator 23, a back-coupled interferometer waveguide 24, an interferometer waveguide heater 25, a microcavity waveguide heater 26, a microcavity coupled output straight waveguide 27, a sensing waveguide 28, and a fiber-coupled output inverted conical mode converter 29; and the above-mentioned components for microcavity frequency comb generation and on-chip gas sensing are all integrated on the same substrate; wherein

[0062] The horizontal slit waveguide microring resonator 23 is used to generate a Kerr frequency comb with the output light of the pump laser generation module 1 as the seed source. In use, it can be made of materials such as silicon nitride, aluminum nitride, silicon, aluminum gallium arsenide and lithium niobate. Its cavity structure can be in the shape of ring cavity, polygonal cavity, etc., such as micro disk, micro ring, micro sphere, micro column.

[0063] The back-coupled interferometer waveguide 24 is used to feed back the pump light that is not coupled to the horizontal slit waveguide microring resonator 23 at the microcavity coupled input straight waveguide 22 to the horizontal slit waveguide microring resonator 23. The feedback coupling position is at the microcavity coupled output straight waveguide 27.

[0064] The microcavity coupled output straight waveguide 27 is used to combine the horizontal slit waveguide microring resonator 23 with the Kerr optical frequency comb in the back-coupled interferometer arm waveguide 24, and the output end is connected to the input end of the sensing waveguide 28.

[0065] The sensing waveguide 28 is used to increase the interaction distance between the generated frequency comb and the multi-gas analyte to be measured, and to load the type and concentration information of gas absorption onto the spectral intensity of the optical comb. In use, it can be implemented using rectangular, ridge-shaped, slit waveguides with different numbers of horizontal or vertical slits, or photonic crystal waveguides. The output is coupled to the tapered lens fiber via the inverted conical mode converter 29 through fiber coupling, and after beam splitting, it is connected to the radio spectrum analysis module 35 and the absorption spectrum analysis module 36.

[0066] The microcavity waveguide heater 26 is used to receive the control of the heater current controller 34 to heat the horizontal slit waveguide microring resonator 23, so that the cavity length of the horizontal slit waveguide microring resonator 23 will not drift due to ambient temperature fluctuations, and the frequency and intensity of the generated Kerr optical frequency comb can remain stable for a long time. When the spectral line shape reaches the preset state, the high-precision servo PID controller 33 generates a feedback signal and loads it to the heater current controller 34 to change the current, which is used to heat the microring resonator 23 to achieve constant temperature.

[0067] The interferometric arm waveguide heater 25 is used to receive the control of the heater current controller 34 to heat the back-coupled interferometric arm waveguide 24, so that the length of the back-coupled interferometric arm waveguide 24 will not drift due to ambient temperature fluctuations, and the feedback optical field of the back-coupled interferometric arm waveguide has a constant thermally tuned phase; when the spectral line shape reaches the preset state, the high-precision servo PID controller 33 generates a feedback signal and loads it to the heater current controller 34 to change the current, which is used to back-couple the interferometric arm waveguide 24 to achieve constant temperature.

[0068] Preferably, in order to control the operation of the pump laser generation module 1 and the on-chip microcavity frequency comb sensor 2,

[0069] The control system 3 is designed to control and provide feedback on the operating state of the pump laser 11, the operating temperature of the on-chip microcavity frequency comb sensor 2, and the thermally tuned phase of the back-coupled interferometer waveguide 24, ensuring that the generated frequency comb is thermally stable and has high pump conversion efficiency, and is used as a broadband light source for gas detection in the sensing waveguide 28; it includes a laser current controller 31, an arbitrary waveform signal generator 32, a high-precision servo PID controller 33, a heater current controller 34, an emission spectrum analysis module 35, and an absorption spectrum analysis module 36; wherein

[0070] In use, the control system 3 uses the output signal of the arbitrary waveform signal generator 32 to control the laser current controller 31. The laser current controller 31 controls the tunable continuous wave pump laser 11 to emit laser light. The initial optical signal passes through the optical amplifier 12, polarization controller 13, and tunable bandpass filter 14, and is coupled to the fiber-coupled input inverted conical mode converter 21 through the conical lens fiber. It is then coupled to the horizontal slit waveguide microring resonator 23 and the back-coupled interferometer waveguide 24 through the microcavity coupled input straight waveguide 22. After frequency combing, the beam reaches the sensing waveguide 28 through the microcavity coupled output straight waveguide 27, and is coupled to the conical lens fiber through the conical mode converter. The beam is then split into the emission spectrum analysis module 35 and the absorption spectrum analysis module 36. When the spectral line shape reaches the preset state, the high-precision servo PID controller 33 generates a feedback signal and loads it to the heater current controller 34 to change the current, so that the on-chip microcavity frequency comb sensor 2 remains thermally stable.

[0071] The arbitrary waveform signal generator 32 can emit arbitrary waveform signals and output triangular wave scanning signals to the control terminal of the laser current controller 31;

[0072] The high-precision servo PID controller 33 is connected to the microcavity waveguide heater 26 and the horizontal slit waveguide microring resonant cavity 23, and is connected to the back-coupled interferometric arm waveguide 24 through the interferometric arm waveguide heater 25, and is used to control the temperature of the on-chip microcavity frequency comb sensor 2.

[0073] Preferably, in order to generate a pump laser with specific polarization characteristics, the maximum wavelength adjustment range of the pump laser 11 is designed to be greater than a free spectral range of the horizontal slit waveguide microring resonator 23.

[0074] Preferably, there are two coupling nodes between the horizontal slit waveguide microring resonator 23 and the back-coupled interferometer waveguide 24, so that the optical field can propagate between the horizontal slit waveguide microring resonator 23 and the back-coupled interferometer waveguide 24.

[0075] Preferably, the control system 3 is used for driving and wavelength fine-tuning of the pump laser 11, controlling the waveguide temperature of the Kerr horizontal slit waveguide microring resonator 23, and the resonant peak position and center frequency of the frequency comb of the Kerr horizontal slit waveguide microring resonator 23 on the tuning plate; and these parameters are controlled by analog signals from the hardware circuit or digital signals from the virtual instrument.

[0076] Example 3: Unlike the above examples, the on-chip integrated microcavity Kerr frequency comb gas detection device described in Example 2 is applied to the inversion and detection of the type and concentration of multi-component analyte gases. The application process includes:

[0077] Step 1: Adjust the output laser of the tunable continuous wave pump laser 11, adjust the optical amplifier 12 and polarization controller 13 so that the intensity and polarization state of the pump laser meet the power requirements and quasi-phase matching conditions of four-wave mixing, and use the tunable bandpass filter 14 to filter out the spontaneous emission noise generated during the amplification process, which is used as a seed light source for frequency comb generation.

[0078] Step 2: The quasi-TE light that meets the optical parametric oscillation threshold power is coupled to the inverted conical mode converter 21 through a tapered lens fiber with a large numerical aperture and the fiber optic coupling of the on-chip microcavity frequency comb sensor 2, and the coupling efficiency is optimized by adjusting the multi-dimensional adjustment frame; the beam after passing through the on-chip microcavity frequency comb sensor 2 is coupled to the mode coupler at the end of the sensing waveguide 28 using a tapered lens fiber with a large numerical aperture, and the coupling efficiency is optimized by adjusting the multi-dimensional adjustment frame.

[0079] Step 3: According to the pre-determined relationship between the heater drive current and the thermal tuning phase, set the operating temperature of the heater current controller 34 to ensure that the phase difference between the interferometer arm and the optical field in the microcavity is constant.

[0080] Step 4: Generate a triangular wave scanning signal through the arbitrary waveform signal generator 32 and output it to the control terminal of the laser current controller 31 so that the output wavelength of the pump laser 11 can sweep through a certain resonance peak of the Kerr horizontal slit waveguide microring resonator 23, transition from the blue detuned region of the microcavity resonator region to the red detuned region, and excite the four-wave mixing effect in the cavity.

[0081] Step 5: The output of the on-chip microcavity frequency comb sensor 2 is split into an absorption spectral analysis module 36 via a conical lens fiber for real-time spectral observation and soliton state detection. When the spectrum reaches a preset state, the scanning of the arbitrary waveform signal generator 32 is stopped. The high-precision servo PID controller 33 is used to feedback control the interferometer waveguide heater 25 and the microcavity waveguide heater 26, so that the frequency comb is in a thermally locked temperature state. After the beam is split, the pump light component is filtered out, and the repetition frequency is observed through the RF spectrum analysis module 35 connected to the detector. Alternatively, it can be directly connected to a power meter to observe the power and calculate the pump conversion efficiency.

[0082] Step 6: Export the output spectra measured in nitrogen background atmosphere and the gas atmosphere to be tested to the computer for absorbance spectrum calculation. By comparing with the absorption spectra in the standard high-resolution absorption database of the convolutional spectrometer instrument function, the concentration and type of the sample to be tested are obtained by fitting using the least squares method or by using machine learning methods such as neural networks, extreme learning machines, support vector machines, etc., thus completing the detection of gas concentration and type.

[0083] Example 4: Unlike the above examples, a specific application example is given here: the pump laser generation module 1 injects a forward-scanning quasi-TE mode seed light source with a wavelength of 1554nm and a power of 1000mW into the on-chip microcavity frequency comb sensor 2 through a tapered lens fiber. The horizontal slit waveguide microring resonator 23 and the back-coupled interferometer waveguide 24 have the following characteristics: Figure 4 The same horizontal single-slit structure shown, comprising bottom and top silicon nitride layers and a central horizontal silicon dioxide slit layer, exhibits near-zero flat dispersion in the broadband near-infrared region near the pump wavelength. The horizontal slit waveguide microring resonator 23 operates in a near-critical coupling state. The horizontal slit waveguide microring resonator 23 has a cavity length of approximately 14.6 mm, corresponding to... Figure 5 The diagram shows the approximately 10 GHz mode spacing (i.e., repetition frequency) of the generated Kerr frequency comb. At this point, the frequency comb is a multi-soliton comb, and a cavity is formed as shown... Figure 6 The large number of pulses shown.

[0084] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. An on-chip integrated microcavity Kerr frequency comb gas detection device, characterized in that: It includes an on-chip integrated microcavity Kerr frequency comb sensor, a pump laser generation module (1), and a control system (3). The pump laser generation module (1) includes a pump laser (11), an optical amplifier (12), a polarization controller (13), and a tunable bandpass filter (14), and the tunable bandpass filter (14) is coupled to the on-chip microcavity frequency comb sensor (2) through an input tapered lens fiber. The on-chip integrated microcavity Kerr frequency comb sensor includes a silicon substrate and also includes an optical fiber coupled input inverted conical mode converter (21), a microcavity coupled input straight waveguide (22), a horizontal slit waveguide microring resonator (23), a back-coupled interferometer waveguide (24), an interferometer waveguide heater (25), a microcavity waveguide heater (26), a microcavity coupled output straight waveguide (27), a sensing waveguide (28), and an optical fiber coupled output inverted conical mode converter (29) integrated on the silicon substrate. The fiber-coupled input inverted conical mode converter (21) is located at the input end of the microcavity coupled input straight waveguide (22). The horizontal slit waveguide microring resonator (23) is coupled to the microcavity coupled input straight waveguide (22) and the microcavity coupled output straight waveguide (27) through gaps. The back-coupled interferometer waveguide (24) is located at the output end of the microcavity coupled input straight waveguide (22). The microcavity coupled output straight waveguide (27) is located at the output end of the back-coupled interferometer waveguide (24). The sensing waveguide (28) is located at the output end of the microcavity coupled output straight waveguide (27). The fiber-coupled output inverted conical mode converter (29) is located at the output end of the microcavity coupled output straight waveguide (27). The horizontal slit waveguide microring resonator (23) and the back-coupled interferometer waveguide (24) have the same waveguide structure; the interferometer waveguide heater (25) is disposed on the surface of the back-coupled interferometer waveguide (24), and the microcavity waveguide heater (26) is disposed on the surface of the horizontal slit waveguide microring resonator (23), and both are connected to the output terminal of the heater current controller; the sensing waveguide (28) is a vertical single-air slit waveguide; The control system (3) is used to control the working state of the pump laser generation module (1) and the on-chip microcavity frequency comb sensor (2); the control system (3) includes a laser current controller (31), an arbitrary waveform signal generator (32), a high-precision servo PID controller (33), a heater current controller (34), a radio spectrum analysis module (35), and an absorption spectrum analysis module (36). The arbitrary waveform signal generator (32) is connected to the pump laser (11) through the laser current controller (31); The high-precision servo PID controller (33) is connected to the microcavity waveguide heater (26) and the interferometer waveguide heater (25) through the heater current controller (34). The high-precision servo PID controller (33) performs proportional-integral-differential operations based on the collected temperature information, generates a feedback signal, loads it onto the heater current controller (34), changes the current, and heats the horizontal slit waveguide microring resonant cavity (23) to achieve constant temperature, so that the generated frequency comb achieves thermal locking under thermal tuning. Both the radio spectrum analysis module (35) and the absorption spectrum analysis module (36) are connected to the fiber-coupled output inverted conical mode converter (29) through a tapered lens fiber and a fiber beam splitter.

2. The on-chip integrated microcavity Kerr frequency comb gas detection device according to claim 1, characterized in that: The on-chip integrated microcavity Kerr frequency comb gas detection device is a gas detection device based on a back-coupled on-chip integrated microcavity Kerr frequency comb sensor.

3. The on-chip integrated microcavity Kerr frequency comb gas detection device according to claim 2, characterized in that: The maximum wavelength adjustment range of the pump laser (11) is greater than one free spectral range of the horizontal slit waveguide microring resonator (23).

4. The on-chip integrated microcavity Kerr frequency comb gas detection device according to claim 3, characterized in that: There are two coupling nodes between the horizontal slit waveguide microring resonator (23) and the back-coupled interferometer waveguide (24).

5. The on-chip integrated microcavity Kerr frequency comb gas detection device according to claim 4, characterized in that: The control system (3) includes a laser current controller (31), an arbitrary waveform signal generator (32), a high-precision servo PID controller (33), a heater current controller (34), an RF spectrum analysis module (35), and an absorption spectrum analysis module (36). The arbitrary waveform signal generator (32) is connected to the pump laser (11) through the laser current controller (31); The high-precision servo PID controller (33) is connected to the microcavity waveguide heater (26) and the interferometer waveguide heater (25) through the heater current controller (34); Both the radio spectrum analysis module (35) and the absorption spectrum analysis module (36) are connected to the fiber-coupled output inverted conical mode converter (29) through a tapered lens fiber and a fiber beam splitter.

6. The application of the on-chip integrated microcavity Kerr frequency comb gas detection device as described in any one of claims 1-5, characterized in that: An on-chip integrated microcavity Kerr frequency comb gas detection device is used to invert and detect the types and concentrations of multi-component analytes.

7. The application of the on-chip integrated microcavity Kerr frequency comb gas detection device according to claim 6, characterized in that: The process of inverting and detecting the type and concentration of multi-component analytes using an on-chip integrated microcavity Kerr frequency comb gas detection device includes: Step 1: Connect all optical and electrical devices of the gas detection sensing system; Step 2: Finely adjust the input and output coupling lens fiber to align it with the center of the frequency comb sensor input / output mode converter; Step 3: Set the laser's amplification factor and output polarization state; Step 4: Set the drive current of the laser so that its output wavelength sweeps across a certain resonant peak of the microcavity from small to large. Step 5: Observe the repetition frequency and spectrum of the output frequency comb, and collect the thermally stable Kerr frequency comb spectrum under background atmosphere and sample composition. Step 6: Process the spectral data before and after absorption, and invert the gas type and concentration by comparing with a standard database.

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