Dual-channel on-chip mid-infrared and near-infrared frequency comb generation device and method

Abstract

The application discloses a double-channel on-chip mid-infrared and near-infrared frequency comb generating device and method, comprising sequentially arranged pump light source modules, double-channel frequency comb generating modules, frequency comb output modules and state monitoring modules; a high-performance near-infrared narrow-linewidth tunable continuous laser is used as a pump source, which breaks the bondage of a low-performance mid-infrared pump light source to a mid-infrared Kerr microcavity frequency comb, simultaneously generates a near-infrared and mid-infrared double-channel frequency comb, and the generated mid-infrared soliton frequency comb has no strong continuous wave background, thereby solving the problem that the mid-infrared Kerr microcavity frequency comb is difficult to generate a mid-infrared soliton frequency comb due to the influence of a low-performance mid-infrared pump source in the prior art. The micro-ring resonant cavity has high second-order and third-order nonlinear coefficients and a wide transparent window, has high energy conversion efficiency, and further obtains a double-channel frequency comb with low threshold, large bandwidth and low phase noise, thereby solving the problem that the soliton frequency comb has small bandwidth due to low energy conversion efficiency of the Kerr microcavity frequency comb in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of mid-infrared and near-infrared frequency comb generation, and relates to a mid-infrared and near-infrared frequency comb generation device, specifically a dual-channel on-chip mid-infrared and near-infrared frequency comb generation device and method. Background Technology

[0002] The mid-infrared band (2–20 μm) covers the fundamental absorption peaks of numerous atoms and molecules, with absorption intensities one to two orders of magnitude higher than those in the near-infrared band, and includes three atmospheric windows. Therefore, mid-infrared spectroscopy has important applications in industrial safety, environmental monitoring, medical diagnosis, and biochemical sensing.

[0003] Mid-infrared frequency combs, as a novel broadband multi-wavelength coherent light source, are of great significance to the development of mid-infrared spectroscopy. Traditional mid-infrared frequency combs based on solid-state mode-locked lasers, fiber mode-locked lasers, and optical parametric oscillators have large SWaP (size, weight, power consumption) and large cavity lengths, resulting in low repetition rates (<10 GHz). In recent years, microcavity optical frequency combs developed based on photonic integration technology have advantages such as small size, high Q value, low threshold, compact structure, and ease of integration, and are expected to overcome the limitations of large SWaP and low repetition rates.

[0004] Typical microcavity optical frequency combs are mostly based on the Kerr effect (FWM process) in third-order nonlinearity. On the one hand, because the third-order nonlinear coefficient of the material is usually very small, the nonlinear wavelength conversion efficiency is very low, making it difficult to realize ultra-octave broadband mid-infrared soliton frequency combs. On the other hand, because the performance of pump sources, waveguides, couplers, and other devices in the mid-infrared band is far inferior to that of near-infrared devices, the maturity of mid-infrared Kerr microcavity frequency comb technology is far lower than that of near-infrared Kerr microcavity frequency combs. These problems restrict the development and practical application of on-chip mid-infrared frequency comb technology.

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a dual-channel on-chip mid-infrared and near-infrared frequency comb generation device and method, thereby solving the technical problems in the prior art where traditional mid-infrared Kerr microcavity frequency combs are difficult to generate mid-infrared soliton frequency combs due to the influence of low-performance mid-infrared pump sources, and where the low conversion efficiency of Kerr microcavity frequency combs results in small soliton frequency comb bandwidth.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A dual-channel on-chip mid-infrared and near-infrared frequency comb generating device includes a pump light source module, a dual-channel frequency comb generating module, a frequency comb output module, and a status monitoring module arranged sequentially.

[0008] The pump light source module is used to provide continuous pump laser;

[0009] The dual-channel frequency comb generation module is used to receive near-infrared pump laser from the pump laser and simultaneously generate near-infrared and mid-infrared frequency combs.

[0010] The frequency comb output module is used to output near-infrared frequency combs and mid-infrared frequency combs;

[0011] The status monitoring module is used to determine the status of the near-infrared and mid-infrared frequency combs by analyzing the power and spectral characteristics of the output near-infrared and mid-infrared frequency combs.

[0012] This invention also includes the following technical features:

[0013] The pump source module includes a near-infrared narrow linewidth tunable continuous laser, an optical fiber amplifier, an optical fiber polarization controller, and a first lens optical fiber arranged in sequence. A signal generator is also connected to the near-infrared narrow linewidth tunable continuous laser.

[0014] The near-infrared narrow-linewidth tunable continuous laser is used to emit continuous pump laser.

[0015] The signal generator is used to change the pump laser wavelength;

[0016] The fiber amplifier is used to amplify the pump laser power;

[0017] The fiber polarization controller is used to adjust the polarization state of the pump laser;

[0018] The first lens fiber is used to compress the diameter of the pump laser spot and couple it into the dual-channel frequency comb generation module.

[0019] The dual-channel frequency comb generation module includes a thermoelectric cooler, on which a micro-ring resonant cavity is provided; the micro-ring resonant cavity is made of a material that simultaneously possesses high second-order nonlinear coefficients, high third-order nonlinear coefficients, and a wide transparent window.

[0020] The thermoelectric cooler is used to support and heat the micro-ring resonant cavity chip and maintain its temperature at a constant value.

[0021] The input port of the micro-ring resonator is connected to the lens end of the first lens fiber of the pump light source module, and is used to receive pump laser and generate dual-channel frequency comb.

[0022] The through port of the micro-ring resonant cavity is used to output a near-infrared frequency comb;

[0023] The drop port of the micro-ring resonator is used to output a mid-infrared frequency comb.

[0024] The microring resonant cavity is made of a material that simultaneously possesses a high second-order nonlinear coefficient, a high third-order nonlinear coefficient, and a wide transparent window; and the second-order nonlinear coefficient of the microring resonant cavity is higher than the third-order nonlinear coefficient.

[0025] The second-order nonlinear coefficient is not less than 1×10. -12 m / V; the third-order nonlinear coefficient is not less than 1×10 -19 m 2 / W; The transparent window covers the band range of the generated near-infrared and mid-infrared frequency comb.

[0026] The materials of the microring resonator include, but are not limited to, lithium niobate, aluminum nitride, gallium arsenide, aluminum gallium arsenide, or gallium phosphide.

[0027] The frequency comb output module includes a near-infrared output channel and a mid-infrared output channel;

[0028] The near-infrared output channel includes a second lens fiber, the lens end of which is connected to the through port of the micro-ring resonator; the second lens fiber is used to output the near-infrared frequency comb and filter out the mid-infrared frequency comb remaining in the through port.

[0029] The mid-infrared output channel includes an aspherical mirror and a long-pass filter arranged in sequence; the aspherical mirror is connected to the Drop port of the micro-ring resonator; the aspherical mirror is used to receive and collimate the mid-infrared frequency comb; the long-pass filter is used to filter out the near-infrared frequency comb remaining at the Drop port.

[0030] The status monitoring module includes a near-infrared monitoring unit and a mid-infrared monitoring unit.

[0031] The near-infrared monitoring unit includes a near-infrared spectrometer, which is connected to the lensless end of the second lens fiber to receive and monitor the spectrum of the near-infrared frequency comb.

[0032] The mid-infrared monitoring unit includes a beam splitter, wherein the rotational symmetry axis of the aspherical mirror, the normal of the long-pass filter, and the normal of the beam splitter are coplanar; a high-speed photodetector and an oscilloscope are arranged sequentially in the transmission light direction of the beam splitter, and a mid-infrared spectrometer is arranged in the reflection light direction of the beam splitter.

[0033] The beam splitter is used to split the mid-infrared frequency comb that has passed through the long-pass filter into two paths;

[0034] The high-speed photodetector is used to receive one of the channels and detect its power.

[0035] The oscilloscope is used to display the power of the mid-infrared frequency comb received by the high-speed photodetector in real time.

[0036] The mid-infrared spectrometer is used to receive another mid-infrared frequency comb and monitor its spectrum.

[0037] A method for generating dual-channel on-chip mid-infrared and near-infrared frequency combs, employing the aforementioned dual-channel on-chip mid-infrared and near-infrared frequency comb generating device, specifically includes the following steps:

[0038] Step 1: Adjust the power and polarization state of the near-infrared narrow-linewidth tunable continuous laser so that its polarization state matches that of the pump light polarization state of the OPO in the microring resonator, and its power meets the required threshold power; and use a thermoelectric cooler to heat the microring resonator so that its temperature is the same as the temperature required for phase matching of the low-power degenerate OPO.

[0039] Step 2: Use a signal generator to adjust the wavelength of the near-infrared narrow-linewidth tunable continuous laser until the mid-infrared spectrometer begins to detect spectral lines, then stop adjusting.

[0040] Step 3: Increase the power of the near-infrared narrow-linewidth tunable continuous laser so that it exceeds both the OPO threshold and the FWM threshold simultaneously, causing a synergistic second- and third-order nonlinear process to occur within the microring resonator.

[0041] Step 4: Gradually increase the wavelength of the near-infrared narrow-linewidth tunable continuous laser. Observe the power and spectral morphology of the mid-infrared frequency comb using an oscilloscope and a mid-infrared spectrometer, respectively. Observe the spectral morphology of the near-infrared frequency comb using a near-infrared spectrometer until a stable mid-infrared and near-infrared frequency comb is generated.

[0042] Step four specifically includes the following:

[0043] Step 4.1: Gradually increase the emitted laser wavelength of the near-infrared narrow-linewidth tunable continuous laser. When the mid-infrared power evolution curve displayed on the oscilloscope first increases and then decreases overall, followed by a significant step, and the spectral envelope measured by the mid-infrared spectrometer exhibits a smooth, sech-like pattern... 2 When the morphology is such that the output mid-infrared frequency comb is in a single soliton state;

[0044] Step 4.2: Reduce the tuning speed to keep the power evolution curve stable and the mid-infrared comb spectral envelope shape unchanged. When the mid-infrared comb spectral width and the near-infrared comb spectral width measured by the near-infrared spectrometer are both at their maximum, tune in the opposite direction to the middle of the step, and then stop tuning to obtain a stable mid-infrared and near-infrared comb.

[0045] Compared with the prior art, the beneficial technical effects of this invention are:

[0046] (I) This invention uses a high-performance near-infrared narrow-linewidth tunable continuous laser as the pump source, which gets rid of the constraints of low-performance mid-infrared pump sources on mid-infrared Kerr microcavity frequency combs. At the same time, it generates dual-channel frequency combs for near-infrared and mid-infrared, and the obtained mid-infrared soliton frequency comb has no strong continuous wave background. This solves the technical problem that traditional mid-infrared Kerr microcavity frequency combs are difficult to generate mid-infrared soliton frequency combs due to the influence of low-performance mid-infrared pump sources in the prior art.

[0047] (II) The micro-ring resonator used in this invention has both high second-order and third-order nonlinear coefficients and a wide transparent window. With appropriate dispersion design, phase matching and high conversion efficiency can be easily achieved, thereby obtaining a dual-channel frequency comb with low threshold, large bandwidth and low phase noise. This solves the technical problem of low conversion efficiency of Kerr micro-cavity frequency combs in the prior art, which results in small bandwidth of soliton frequency combs.

[0048] (III) The dual-channel frequency comb realized by the present invention is less affected by the thermal effect during the tuning process, and the power evolution is relatively smooth. It only needs to slowly tune the wavelength of the pump laser. The tuning scheme is simple and easy to operate.

[0049] (IV) The overall spectral range of the mid-infrared and near-infrared frequency comb achieved by this invention exceeds one octave, and f can be achieved using 1f-2f technology. CEO locking.

[0050] (V) The system of the present invention has low cost, is easy to integrate, is conducive to practical application, and has the characteristics of large bandwidth, low noise and high stability. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the system structure in an embodiment of the present invention;

[0052] Figure 2(a) is a schematic diagram of the degenerate OPO process in an embodiment of the present invention;

[0053] Figure 2(b) is a schematic diagram of the principle of the cooperative second- to third-order nonlinear process in an embodiment of the present invention;

[0054] Figure 2(c) is a schematic diagram of energy conversion for each parameter process involved;

[0055] Figure 3 The result is a graph showing the power evolution process of the mid-infrared comb monitored by an oscilloscope.

[0056] Figure 4(a) shows the final output mid-infrared frequency comb spectrum.

[0057] Figure 4(b) shows the final output near-infrared frequency comb spectrum.

[0058] The labels in the diagram represent the following: 1-Near-infrared narrow-linewidth tunable continuous laser, 2-Signal generator, 3-Fiber optic amplifier, 4-Fiber optic polarization controller, 5-First lens fiber, 6-Micro-ring resonator, 7-Thermoelectric cooler, 8-Second lens fiber, 9-Near-infrared spectrometer, 10-Aspherical mirror, 11-Long-pass filter, 13-High-speed photodetector, 14-Oscilloscope, 15-Mid-infrared spectrometer.

[0059] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0060] It should be noted that OPO stands for Optical Parametric Oscillation; FWM stands for Four-Wave Mixing.

[0061] It should be noted that, unless otherwise specified, all components in this invention are those known in the art.

[0062] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0063] This invention provides a dual-channel on-chip mid-infrared and near-infrared frequency comb generating device, comprising a pump light source module, a dual-channel frequency comb generating module, a frequency comb output module, and a status monitoring module arranged sequentially.

[0064] The pump source module is used to provide continuous pump laser;

[0065] The dual-channel frequency comb generation module is used to receive the near-infrared pump laser in the pump laser and simultaneously generate the near-infrared frequency comb and the mid-infrared frequency comb.

[0066] The frequency comb output module is used to output near-infrared and mid-infrared frequency combs;

[0067] The status monitoring module is used to determine the status of the near-infrared and mid-infrared frequency combs by analyzing the power and spectral characteristics of the output near-infrared and mid-infrared frequency combs.

[0068] In the above technical solution, a high-performance near-infrared narrow-linewidth tunable continuous laser is used as the pump source, which breaks away from the constraints of low-performance mid-infrared pump sources on mid-infrared Kerr microcavity frequency combs. At the same time, a dual-channel frequency comb with near-infrared and mid-infrared characteristics is generated, and the obtained mid-infrared soliton frequency comb has no strong continuous wave background. This solves the problem that traditional mid-infrared Kerr microcavity frequency combs are difficult to generate mid-infrared soliton frequency combs due to the influence of low-performance mid-infrared pump sources in the prior art. The micro-ring resonator has high second- and third-order nonlinear coefficients and a wide transparent window. With appropriate dispersion design, phase matching and high conversion efficiency can be easily achieved, resulting in a low threshold, large bandwidth and low phase noise dual-channel frequency comb. This solves the technical problem of low conversion efficiency of existing Kerr microcavity frequency combs, which leads to small soliton frequency comb bandwidth.

[0069] Specifically, the pump source module includes a near-infrared narrow linewidth tunable continuous laser 1, an optical fiber amplifier 3, an optical fiber polarization controller 4, and a first lens optical fiber 5 arranged in sequence. A signal generator 2 is also connected to the near-infrared narrow linewidth tunable continuous laser 1.

[0070] Near-infrared narrow-linewidth tunable continuous laser 1 is used to emit continuous pump laser;

[0071] Signal generator 2 is used to change the pump laser wavelength;

[0072] Fiber amplifier 3 is used to amplify the pump laser power;

[0073] Fiber polarization controller 4 is used to adjust the polarization state of the pump laser;

[0074] The first lens fiber 5 is used to compress the diameter of the pump laser pattern and couple it into the dual-channel frequency comb generation module.

[0075] Specifically, the dual-channel frequency comb generation module includes a thermoelectric cooler 7, on which a micro-ring resonant cavity 6 is provided; the micro-ring resonant cavity 6 is made of a material that simultaneously possesses high second-order nonlinear coefficients, high third-order nonlinear coefficients, and a wide transparent window.

[0076] Thermoelectric cooler 7 is used to support and heat the micro-ring resonant cavity 6 chip and maintain its temperature at a constant value;

[0077] The input port of the micro-ring resonator 6 is connected to the lens end of the first lens fiber 5 of the pump light source module to receive pump laser and generate dual-channel frequency comb.

[0078] The through port of the micro-ring resonator 6 is used to output the near-infrared frequency comb;

[0079] The Drop port of the micro-ring resonator 6 is used to output the mid-infrared frequency comb.

[0080] Specifically, the material of the microring resonator 6 is a material that simultaneously possesses a high second-order nonlinear coefficient, a high third-order nonlinear coefficient, and a wide transparent window; and the second-order nonlinear coefficient of the microring resonator 6 is higher than the third-order nonlinear coefficient.

[0081] The second-order nonlinear coefficient is not less than 1 × 10⁻⁶. -12 m / V; Third-order nonlinear coefficient not less than 1×10 -19 m 2 / W; The transparent window covers the band range of the near-infrared and mid-infrared frequency combs.

[0082] In the above technical solutions, the conversion efficiency of the synergistic second- to third-order microcavity frequency comb is better than that of the Kerr microcavity frequency comb, and the pump threshold is also lower.

[0083] Specifically, the materials of the micro-ring resonator 6 include, but are not limited to, lithium niobate, aluminum nitride, gallium arsenide, aluminum gallium arsenide, or gallium phosphide.

[0084] Specifically, the frequency comb output module includes a near-infrared output channel and a mid-infrared output channel;

[0085] The near-infrared output channel includes a second lens fiber 8, the lens end of which is connected to the through port of the micro-ring resonator 6; the second lens fiber 8 is used to output the near-infrared frequency comb and filter out the mid-infrared frequency comb remaining in the through port.

[0086] The mid-infrared output channel includes an aspherical mirror 10 and a long-pass filter 11 arranged sequentially; the aspherical mirror 10 is connected to the Drop port of the micro-ring resonator 6; the aspherical mirror 10 is used to receive and collimate the mid-infrared frequency comb; the long-pass filter 11 is used to filter out the near-infrared frequency comb remaining at the Drop port.

[0087] Specifically, the status monitoring module includes a near-infrared monitoring unit and a mid-infrared monitoring unit.

[0088] Specifically, the near-infrared monitoring unit includes a near-infrared spectrometer 9, which is connected to the lensless end of the second lens fiber optic cable 8 to receive and monitor the spectrum of the near-infrared frequency comb.

[0089] The mid-infrared monitoring unit includes a beam splitter 12, the rotational symmetry axis of the aspherical mirror 10, the normal of the long-pass filter 11 and the normal of the beam splitter 12 are coplanar; a high-speed photodetector 13 and an oscilloscope 14 are arranged sequentially in the direction of transmitted light of the beam splitter 12, and a mid-infrared spectrometer 15 is arranged in the direction of reflected light of the beam splitter 12.

[0090] Beam splitter 12 is used to split the mid-infrared frequency comb that has passed through long-pass filter 11 into two paths;

[0091] The high-speed photodetector 13 is used to receive one of the channels and detect its power;

[0092] The oscilloscope 14 is used to display in real time the power of the mid-infrared frequency comb received by the high-speed photodetector 13;

[0093] The mid-infrared spectrometer 15 is used to receive another mid-infrared frequency comb and monitor its spectrum.

[0094] This invention also provides a method for generating dual-channel on-chip mid-infrared and near-infrared frequency combs, employing a dual-channel on-chip mid-infrared and near-infrared frequency comb generating device, specifically including the following steps:

[0095] Step 1: Adjust the power and polarization state of the near-infrared narrow-linewidth tunable continuous laser 1 so that its polarization state is consistent with the pump light polarization state of the OPO in the micro-ring resonator 6, and its power meets the required threshold power; and use the thermoelectric cooler 7 to heat the micro-ring resonator 6 so that its temperature is the same as the temperature required for phase matching of the low-power degenerate OPO.

[0096] Step 2: Use signal generator 2 to adjust the wavelength of near-infrared narrow-linewidth tunable continuous laser 1 until mid-infrared spectrometer 15 begins to detect spectral lines, then stop adjusting.

[0097] At this time, the micro-ring resonator 6 operates in the degenerate OPO state.

[0098] Step 3: Increase the power of the near-infrared narrow-linewidth tunable continuous laser 1 so that it exceeds both the OPO threshold and the FWM threshold simultaneously, causing a synergistic second- to third-order nonlinear process to occur in the micro-ring resonator 6.

[0099] At this point, due to the thermal effect caused by high power, the micro-ring resonator deviates from the original degenerate OPO state and is in a blue detuned state.

[0100] Step 4: Gradually increase the wavelength of the near-infrared narrow-linewidth tunable continuous laser 1, and observe the power and spectral morphology of the mid-infrared frequency comb using an oscilloscope 14 and a mid-infrared spectrometer 15, respectively. Observe the spectral morphology of the near-infrared frequency comb using a near-infrared spectrometer 9, until a stable mid-infrared frequency comb and a near-infrared frequency comb are generated.

[0101] Specifically, step four includes the following:

[0102] Step 4.1: Gradually increase the emitted laser wavelength of the near-infrared narrow-linewidth tunable continuous laser 1. When the mid-infrared power evolution curve displayed on oscilloscope 14 experiences an overall increase followed by an overall decrease, and then a clear step appears, and the spectral envelope measured by mid-infrared spectrometer 15 exhibits a smooth, sech-like pattern... 2 When the morphology is such that the output mid-infrared frequency comb is in a single soliton state;

[0103] Step 4.2: Reduce the tuning speed to maintain a smooth change in the power evolution curve and keep the spectral envelope morphology of the mid-infrared comb unchanged. When the spectral width of the mid-infrared comb and the spectral width of the near-infrared comb measured by the near-infrared spectrometer 9 are both at their maximum, then tune in the opposite direction to the middle of the step, and then stop tuning to obtain a stable mid-infrared comb and near-infrared comb.

[0104] In the above technical solution, the micro-ring resonator 6 has a high thermo-optic coefficient, which makes the target temperature for degenerate OPO phase matching in step one <100℃ within the typical commercial TEC adjustment range.

[0105] Example:

[0106] This embodiment provides a dual-channel on-chip mid-infrared and near-infrared frequency comb generation device. The laser used in this embodiment is an external cavity semiconductor laser operating near 1550nm. Other types of near-infrared narrow linewidth tunable continuous lasers operating at other wavelengths can also be used, such as a DFB tunable laser operating near 1350nm.

[0107] In this embodiment, the microring resonator material is lithium niobate. Alternatively, it can be a III-V compound such as aluminum nitride, gallium arsenide, aluminum gallium arsenide, or gallium phosphide, which simultaneously possess high second-order and third-order nonlinearity, as long as its transparent window can cover the mid-infrared and near-infrared frequency comb spectrum range of the dual channels.

[0108] The near-infrared spectrometer used in this embodiment is a fiber-optic coupled spectrometer, such as an OSA spectrometer; the mid-infrared spectrometer used in this embodiment is a spatial optical coupled spectrometer, such as a Fourier transform spectrometer (FTIR).

[0109] Specifically, the dual-channel mid-infrared and near-infrared frequency combs are generated through the following process:

[0110] Step 1: Use fiber amplifier 3 and fiber polarizer 4 to adjust the polarization state and power of near-infrared narrow linewidth tunable continuous laser 1 so that its polarization state is consistent with the pump light polarization state of OPO in microring resonator 6 and its power meets the required threshold power; and use thermoelectric cooler 7 to heat microring resonator 6 so that its temperature is the same as the temperature required for phase matching of low power degenerate OPO.

[0111] Step 2: Use signal generator 2 to adjust the wavelength of near-infrared narrow linewidth tunable continuous laser 1 until the mid-infrared spectrometer 15 begins to detect spectral lines, then stop adjusting. At this time, the degenerate OPO that occurs in the cavity is shown in Figure 2(a).

[0112] Step 3: The power of the near-infrared narrow-linewidth tunable continuous laser 1 is increased by using fiber amplifier 3, so that it exceeds both the OPO threshold and the FWM threshold at the same time, and a synergistic second- and third-order nonlinear process occurs in the micro-ring resonator 6.

[0113] Step 4: Gradually increase the wavelength of the near-infrared narrow-linewidth tunable continuous laser 1, and observe the power and spectral morphology of the mid-infrared frequency comb using an oscilloscope 14 and a mid-infrared spectrometer 15, respectively. Observe the spectral morphology of the near-infrared frequency comb using a near-infrared spectrometer 9, until a stable mid-infrared frequency comb and a near-infrared frequency comb are generated.

[0114] During the tuning process, second-order nonlinear processes such as OPO, second harmonic generation (SHG), and sum-frequency generation (SFG) first occur in the micro-ring resonant cavity. Because the second-order nonlinear coefficient is usually higher than the third-order nonlinear coefficient, as the comb power in the mid-infrared band exceeds the FWM threshold, the FWM effect gradually broadens the mid-infrared comb. The complete synergistic second-order to third-order nonlinear process is shown in Figure 2(b), and the parameter processes involved are shown in Figure 2(c).

[0115] The specific tuning process of the pump laser wavelength is as follows:

[0116] Step 4.1: Gradually increase the emitted laser wavelength of the near-infrared narrow-linewidth tunable continuous laser 1. When the mid-infrared power evolution curve displayed on oscilloscope 14 experiences an overall increase followed by an overall decrease, and then a clear step appears, and the spectral envelope measured by mid-infrared spectrometer 15 exhibits a smooth, sech-like pattern... 2 When the morphology is such that the output mid-infrared frequency comb is in a single soliton state;

[0117] Step 4.2: Reduce the tuning speed to maintain a smooth change in the power evolution curve and keep the mid-infrared comb spectral envelope morphology unchanged. When both the mid-infrared comb spectral width and the near-infrared comb spectral width measured by the near-infrared spectrometer 9 are at their maximum, reverse the tuning to the middle of the step, and then stop tuning to obtain a stable mid-infrared and near-infrared comb. At this time, the mid-infrared comb spectrum output by the mid-infrared spectrometer 15 is shown in Figure 4(a), and the near-infrared comb output by the near-infrared spectrometer 9 is shown in Figure 4(b).

[0118] In this embodiment, the pump wavelength is around 1550 nm. When the pump power is 200 mW, a mid-infrared soliton frequency comb with a bandwidth exceeding 700 nm near 3100 nm and a near-infrared frequency comb with a bandwidth of approximately 100 nm near 1550 nm are finally obtained. This invention utilizes the synergistic second- and third-order nonlinear effects in a microcavity optical frequency comb that simultaneously possesses high second- and third-order nonlinearities. By using a near-infrared laser to pump the mid-infrared frequency comb, it solves the problem of mid-infrared Kerr microcavity frequency combs being limited by low-performance mid-infrared lasers. Furthermore, since the second-order nonlinear coefficient is typically much larger than the third-order nonlinear coefficient, the conversion efficiency of the synergistic second- and third-order microcavity frequency comb is superior to that of a Kerr microcavity frequency comb, and the pump threshold is also lower. Additionally, by slowly tuning the pump wavelength, the mid-infrared frequency comb generated by the micro-ring resonator smoothly enters the single soliton state, solving the problem of the difficulty in deterministic soliton generation in Kerr microcavity frequency combs. This device is easy to operate, highly stable, and practical. This method is universal and can be applied to other microcavity frequency combs made of materials with strong second- to third-order nonlinear effects.

Claims

1. A dual-channel on-chip mid-infrared and near-infrared frequency comb generating device, characterized in that, It includes a pump light source module, a dual-channel frequency comb generation module, a frequency comb output module, and a status monitoring module arranged sequentially. The pump light source module is used to provide continuous pump laser; The dual-channel frequency comb generation module is used to receive the near-infrared pump laser in the pump laser and simultaneously generate the near-infrared frequency comb and the mid-infrared frequency comb. The frequency comb output module is used to output near-infrared frequency comb and mid-infrared frequency comb; The status monitoring module is used to determine the status of the near-infrared and mid-infrared frequency combs by analyzing the power and spectral characteristics of the output near-infrared and mid-infrared frequency combs. The pump light source module includes a near-infrared narrow linewidth tunable continuous laser (1), an optical fiber amplifier (3), an optical fiber polarization controller (4) and a first lens fiber (5) arranged in sequence. A signal generator (2) is also connected to the near-infrared narrow linewidth tunable continuous laser (1). The near-infrared narrow linewidth tunable continuous laser (1) is used to emit a continuous pump laser. The signal generator (2) is used to change the pump laser wavelength; The fiber amplifier (3) is used to amplify the pump laser power; The fiber polarization controller (4) is used to adjust the polarization state of the pump laser; The first lens fiber (5) is used to compress the diameter of the pump laser pattern and couple it into the dual-channel frequency comb generation module; The dual-channel frequency comb generation module includes a thermoelectric cooler (7), and a micro-ring resonant cavity (6) is provided on the thermoelectric cooler (7). The thermoelectric cooler (7) is used to support and heat the micro-ring resonant cavity (6) chip and maintain its temperature at a constant value; The input port of the micro-ring resonator (6) is connected to the lens end of the first lens fiber (5) of the pump light source module to receive pump laser and generate dual-channel frequency comb. The through port of the micro-ring resonator (6) is used to output near-infrared frequency comb; The Drop port of the micro-ring resonator (6) is used to output a mid-infrared frequency comb.

2. The dual-channel on-chip mid-infrared and near-infrared frequency comb generating device as described in claim 1, characterized in that, The material of the micro-ring resonator (6) is a material that simultaneously possesses a high second-order nonlinear coefficient, a high third-order nonlinear coefficient, and a wide transparent window; and the second-order nonlinear coefficient of the micro-ring resonator (6) is higher than the third-order nonlinear coefficient; The second-order nonlinear coefficient is not less than 1×10. -12 m / V; the third-order nonlinear coefficient is not less than 1×10 -19 m 2 / W; The transparent window covers the band range of the generated near-infrared and mid-infrared frequency comb.

3. The dual-channel on-chip mid-infrared and near-infrared frequency comb generating device as described in claim 1 or 2, characterized in that, The materials of the micro-ring resonator (6) include lithium niobate, aluminum nitride, gallium arsenide, aluminum gallium arsenide, or gallium phosphide.

4. The dual-channel on-chip mid-infrared and near-infrared frequency comb generating device as described in claim 1, characterized in that, The frequency comb output module includes a near-infrared output channel and a mid-infrared output channel; The near-infrared output channel includes a second lens fiber (8), the lens end of which is connected to the through port of the micro-ring resonator (6); the second lens fiber (8) is used to output the near-infrared frequency comb and filter out the mid-infrared frequency comb remaining in the through port. The mid-infrared output channel includes an aspherical mirror (10) and a long-pass filter (11) arranged in sequence; the aspherical mirror (10) is connected to the Drop port of the micro-ring resonator (6); the aspherical mirror (10) is used to receive and collimate the mid-infrared frequency comb; the long-pass filter (11) is used to filter out the near-infrared frequency comb remaining at the Drop port.

5. The dual-channel on-chip mid-infrared and near-infrared frequency comb generating device as described in claim 4, characterized in that, The status monitoring module includes a near-infrared monitoring unit and a mid-infrared monitoring unit.

6. The dual-channel on-chip mid-infrared and near-infrared frequency comb generating device as described in claim 5, characterized in that, The near-infrared monitoring unit includes a near-infrared spectrometer (9), which is connected to the lensless end of the second lens fiber (8) for receiving and monitoring the spectrum of the near-infrared comb. The mid-infrared monitoring unit includes a beam splitter (12), the rotational symmetry axis of the aspherical mirror (10), the normal of the long-pass filter (11) and the normal of the beam splitter (12) are coplanar; a high-speed photodetector (13) and an oscilloscope (14) are arranged sequentially in the direction of transmitted light of the beam splitter (12), and a mid-infrared spectrometer (15) is arranged in the direction of reflected light of the beam splitter (12). The beam splitter (12) is used to split the mid-infrared frequency comb that has passed through the long-pass filter (11) into two paths; The high-speed photodetector (13) is used to receive one of the channels and detect its power; The oscilloscope (14) is used to display the power of the mid-infrared frequency comb received by the high-speed photodetector (13) in real time; The mid-infrared spectrometer (15) is used to receive another mid-infrared frequency comb and monitor its spectrum.

7. A method for generating dual-channel on-chip mid-infrared and near-infrared frequency combs, characterized in that, The dual-channel on-chip mid-infrared and near-infrared frequency comb generating device as described in claim 6 specifically includes the following steps: Step 1: Adjust the power and polarization state of the near-infrared narrow-linewidth tunable continuous laser (1) so that its polarization state is consistent with the polarization state of the pump light of the OPO in the micro-ring resonator (6) and its power meets the required threshold power; and use the thermoelectric cooler (7) to heat the micro-ring resonator (6) so that its temperature is the same as the temperature required for phase matching of the low-power degenerate OPO. Step 2: Use the signal generator (2) to adjust the wavelength of the near-infrared narrow-linewidth tunable continuous laser (1) until the mid-infrared spectrometer (15) begins to detect spectral lines, then stop adjusting. Step 3: Increase the power of the near-infrared narrow-linewidth tunable continuous laser (1) so that it exceeds both the OPO threshold and the FWM threshold at the same time, and a synergistic second- to third-order nonlinear process occurs in the micro-ring resonator (6); Step 4: Gradually increase the wavelength of the near-infrared narrow-linewidth tunable continuous laser (1), observe the power and spectral morphology of the mid-infrared comb using an oscilloscope (14) and a mid-infrared spectrometer (15), and observe the spectral morphology of the near-infrared comb using a near-infrared spectrometer (9) until a stable mid-infrared and near-infrared combs are generated.

8. The method for generating dual-channel on-chip mid-infrared and near-infrared frequency combs as described in claim 7, characterized in that, Step four specifically includes the following: Step 4.1: Gradually increase the output laser wavelength of the near-infrared narrow-linewidth tunable continuous laser (1). When the mid-infrared power evolution curve displayed on the oscilloscope (14) first increases and then decreases, and then shows a clear step, and the spectral envelope measured by the mid-infrared spectrometer (15) shows a smooth sech-like curve... 2 When the morphology is such that the output mid-infrared frequency comb is in a single soliton state; Step 4.2, reduce the tuning speed, keep the power evolution curve stable and the mid-infrared comb spectral envelope shape unchanged. When the mid-infrared comb spectral width and the near-infrared comb spectral width measured by the near-infrared spectrometer (9) are both at their maximum, then tune in the opposite direction to the middle of the step, and then stop tuning to obtain a stable mid-infrared comb and near-infrared comb.

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