High-power microcavity optical frequency comb generation device and method

Abstract

The invention discloses a high-power micro-cavity optical frequency comb generation device and method, and solves the problems that an existing optical frequency comb system needs to adopt a high-speed tunable laser to carry out precise scanning locking on micro-cavity resonance, or depends on distributed feedback type semiconductor laser with extremely narrow linewidth to carry out optical injection feedback on an ultra-high-quality micro-cavity; in order to solve the problems of complex system structure and operation due to the fact that the existing optical frequency comb has the advantages of high repetition frequency, high comb power and wide spectral range, pumping is carried out by a pumping unit, optical frequency comb generation and synchronous power amplification are carried out through an active gain microcavity, and the channel interval (100GHz) of the optical frequency comb meets the international communication standard. The power of a single comb tooth reaches a hundred mu W level and is improved by 2-3 orders of magnitude compared with a common Kerr microcavity optical frequency comb scheme (a typical value is a hundred nW level), so that weak signal power amplification is not needed, and the Kerr microcavity optical frequency comb has important application value in the field of optical communication.

Description

Technical Field

[0001] This invention relates to an optical frequency comb generating device and method, specifically to a high-power microcavity optical frequency comb generating device and method. Background Technology

[0002] Microcavity-based optical frequency combs (hereinafter referred to as microcavity optical frequency combs) benefit from the ultra-strong optical field confinement, ultra-low loss transmission, and ultra-high nonlinear enhancement capability of micro-nano scale photonic chips. Compared with traditional optical systems using solid or fiber media, they have significant advantages in repetition frequency, excitation threshold, and volumetric power consumption. They are a new generation of light source technology in many fields such as high-speed communication, microwave photonics, and atomic optical clocks, and can provide fundamental support for significant improvements in core performance such as bandwidth, speed, and accuracy in communication networks, time and frequency transmission, and all-optical processing.

[0003] Low-noise, stable mode-locked pulse states (also known as soliton pulse states) are crucial for the practical application of microcavity optical frequency combs. Due to the extremely small size of the microcavity, significant photothermal effects occur within the cavity, making it quite difficult to establish stable mode-locked pulse states. Typically, high-speed tunable lasers are used for precise scanning and locking of the microcavity resonance (i.e., frequency sweeping), or ultra-narrow linewidth distributed feedback semiconductor lasers are used for optical injection feedback into ultra-high-quality (typically >10⁷) microcavities (i.e., self-injection). This results in extremely stringent requirements for the pump source and microcavity performance, complex system structures, and high overall costs. In most cases, precise frequency sweep control circuits are needed, or extensive trials are conducted among multiple pump laser and microcavity chip combinations to select the combination with matching wavelength and resonance. On the other hand, due to limitations in soliton energy conversion efficiency and the upper limit of pump power tolerance for stable mode-locked pulse states, the direct output power (typically <5mW) and single-tooth power (typically hundreds of nW to tens of μW) of microcavity optical frequency combs are relatively low. Applications such as coherent communication require single-channel optical power to reach the mW level, so they cannot be used directly. The power of the comb teeth can only be increased by an optical fiber amplifier (such as EDFA) after the optical frequency comb is generated in order to meet the requirements. Summary of the Invention

[0004] To address the technical challenges of existing optical frequency comb systems that require either high-speed tunable lasers for precise scanning and locking of microcavity resonances or reliance on ultra-narrow linewidth distributed feedback semiconductor lasers for optical injection feedback of ultra-high quality (typical value >107) microcavities, resulting in complex system structures and operations, as well as limited comb power requiring additional amplification to meet application requirements, this invention provides a high-power microcavity optical frequency comb generation device and method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A high-power microcavity optical frequency comb generating device, characterized by: It includes a pump unit, a microcavity unit, an output unit, and a state determination unit arranged sequentially from the input end to the output end; The pumping unit is used to generate continuous pump laser; The microcavity unit includes a microcavity chip and a DC power supply; the microcavity chip includes a common waveguide, an active gain microcavity, a passive auxiliary microcavity, and a metal thermoelectrode; the waveguide input end of the common waveguide corresponds to the output end of the pump unit; the waveguide coupling region of the common waveguide is arranged around the outer wall of the active gain microcavity and maintains a first preset gap with the outer wall of the active gain microcavity; the waveguide output end of the common waveguide corresponds to the input end of the output unit; both the active gain microcavity and the passive auxiliary microcavity are annular, with equal cavity lengths and waveguide widths, and are coupled at a single point, maintaining a second preset gap at the coupling point; the metal thermoelectrode is disposed on one side or above the passive auxiliary microcavity; the positive and negative terminals of the DC power supply are respectively connected to the two ends of the metal thermoelectrode; The output unit is used to receive the beam output from the waveguide output end, split it, and inject it into the state determination unit. The state determination unit is used to monitor the spectral intensity, wavelength, and pulse sequence waveform of the corresponding light beam, providing feedback for the operation state control of the pump unit and the microcavity unit.

[0006] Furthermore, the active gain microcavity is an Er3+-doped silicon nitride ring waveguide; The passive auxiliary microcavity is an undoped silicon nitride ring waveguide; The range of the first preset gap is 200nm~1000nm; The range of the second preset gap is 200nm~1000nm.

[0007] Furthermore, the output unit includes a lens fiber and a fiber beam splitter; The input end of the lens fiber corresponds to the waveguide output end of the common waveguide, and the output end of the lens fiber is connected to the input end of the fiber beam splitter. The fiber optic beam splitter is used to split the beam output from the lens fiber into a first beam and a second beam.

[0008] Furthermore, the state determination unit includes a spectrometer, a photodetector, and an oscilloscope; The input end of the spectrometer is connected to the first output end of the fiber optic beam splitter via an optical fiber. The input end of the photodetector is connected to the second output end of the fiber optic beam splitter via an optical fiber, and the output end of the photodetector is electrically connected to the oscilloscope.

[0009] Furthermore, the pumping unit includes a semiconductor laser with an operating wavelength range of 975nm-985nm; The output terminal of the semiconductor laser corresponds to the waveguide input terminal of the common waveguide.

[0010] A method for generating a high-power microcavity optical frequency comb, employing the aforementioned high-power microcavity optical frequency comb generating device, is characterized by comprising the following steps: Step 1: Start the pump unit to emit continuous pump laser to the waveguide input end of the common waveguide; after being processed by the microcavity unit, the pump laser enters the state determination unit through the output unit. Step 2: Adjust the output power of the pump unit based on the spectral intensity monitored by the state determination unit until the active gain microcavity completes wavelength conversion and achieves the initial excitation of the preset resonant mode through intracavity circulation; Step 3: Adjust the output current or voltage of the DC power supply so that the metal thermoelectrode can adjust the working temperature of the passive auxiliary microcavity, thereby changing the repetition frequency of the passive auxiliary microcavity. The state determination unit makes a determination until the determination result shows that comb teeth have been generated in the passive auxiliary microcavity. Step 4: Keep all operating parameters unchanged, increase the output power of the pump unit until the judgment result obtained by the state judgment unit shows that a uniform and continuous optical frequency comb tooth and a stable pulse sequence waveform have been obtained, thus completing the generation of the high-power microcavity optical frequency comb.

[0011] Furthermore, step 1 specifically includes: The semiconductor laser is activated, causing it to emit a continuous pump laser into the waveguide input of the common waveguide; after passing through the microcavity unit, the pump laser enters the state determination unit through the output unit.

[0012] Furthermore, step 2 specifically involves: The output power of the semiconductor laser is gradually increased, and the spectrum of the output beam at the waveguide output end of the common waveguide is measured by the spectrometer in the state determination unit until a laser wavelength is generated on the spectrometer, indicating that the wavelength conversion has been completed inside the active gain microcavity and the initial excitation of the preset resonant mode has been achieved through intracavity circulation.

[0013] Furthermore, step 3 specifically involves: Adjusting the output current or voltage of the DC power supply allows the metal thermoelectrode to regulate the operating temperature of the passively assisted microcavity, thereby changing the repetition frequency of the passively assisted microcavity. When multiple discrete frequency wavelengths can be observed on the spectrometer, it indicates that optical frequency combs have been generated in the passively assisted microcavity.

[0014] Furthermore, step 4 specifically involves: Keeping all operating parameters constant, increase the output power of the semiconductor laser until a uniformly distributed optical frequency comb can be observed on the spectrometer and a stable pulse sequence waveform can be observed on the oscilloscope, thus completing the generation of a high-power microcavity optical frequency comb.

[0015] The beneficial effects of this invention are: 1. The present invention provides a high-power microcavity optical frequency comb generation device and method, which uses a pump unit for pumping and an active gain microcavity for optical frequency comb generation and synchronous power amplification. It has the advantages of high repetition frequency, high comb power and wide spectral range. Its channel spacing (100GHz) conforms to international communication standards. The power of a single comb tooth reaches the level of hundreds of μW, which is 2 to 3 orders of magnitude higher than the common Kerr microcavity optical frequency comb scheme (typical value of hundreds of nW). Therefore, there is no need for weak signal power amplification, which has important application value in the field of optical communication.

[0016] 2. The present invention provides a high-power microcavity optical frequency comb generation device and method, which utilizes a 980nm band semiconductor laser as a pump and generates the comb by doping with Er. 3+ The active gain microcavity amplifies the spontaneous emission process to complete wavelength conversion, and based on the ring cavity resonance principle, it realizes 1550nm laser generation and simultaneously completes automatic resonant mode selection. It can solve the problems of other 1550nm light source direct pumping schemes that require high-performance high-speed frequency sweeping or precise tabletop ultra-narrow linewidth light sources, resulting in complex system structure and operation, as well as the problem of the pump wavelength and resonant frequency detuning and difficulty in stabilizing the mode-locked pulse state caused by the thermal effect in the microcavity. Furthermore, this invention does not require pump and microcavity wavelength matching selection, and can be used for light sources of various wavelengths in this band. Therefore, it has the characteristics of compact structure, low cost and easy construction.

[0017] 3. The high-power microcavity optical frequency comb generation device and method provided by the present invention utilizes a dual micro-ring cavity coupling architecture with extremely small spacing and combines it with temperature control to achieve fine tuning of the repetition frequency. This solves the problem that the resonant modes of the dual microcavities cannot be matched due to actual processing errors. Moreover, the two microcavities (i.e., the active gain microcavity and the passive auxiliary microcavity) have the same cavity length and structure, which facilitates production and supports monolithic integration. It has the characteristics of small size, easy fabrication and low power consumption.

[0018] 4. The high-power microcavity optical frequency comb generation device and method provided by the present invention, by cleverly utilizing waveguide coupling (the common waveguide and the active gain microcavity are coupled by a wide-band pulley, which can transmit 980nm and 1550nm wavelengths, while the active gain microcavity and the passive auxiliary microcavity are coupled by a narrow-band single-point, which only supports the 1550nm wavelength), achieves efficient transmission of light waves between devices and simultaneously completes the pump laser transmission or suppression function. Therefore, there is no need to introduce additional filtering devices to eliminate residual pump lasers, and it has the characteristics of simple structure and low background noise.

[0019] 5. The high-power microcavity optical frequency comb generation device and method provided by this invention employs a ring resonant structure active gain microcavity, which can realize optical wave cyclic amplification, thus eliminating the need for high concentrations of Er. 3+ Doping can significantly improve the gain effect, which can significantly reduce the processing requirements and fabrication difficulty of microcavity doped waveguides, while also achieving higher conversion efficiency and stronger output power.

[0020] 6. The high-power microcavity optical frequency comb generation device and method provided by this invention fully integrates the actual performance of various devices at present, such as those doped with Er. 3+ An active gain microcavity constructed from silicon nitride ring waveguides has a quality factor (typically ~10). 5 (on the order of magnitude) compared to undoped passively assisted microcavities (typically ~10) 6 -10 7 The laser power threshold required is one order of magnitude lower than that of conventional single-frequency laser direct pumping schemes, which would result in excessively high laser power thresholds (in the W range). By cleverly utilizing parametric oscillations with a low threshold to generate the initial comb teeth, and then initiating a non-degenerate four-wave mixing process, while simultaneously completing the optical wave cyclic amplification, the stringent requirements for microcavity quality are reduced, making it easy to manufacture and implement.

[0021] 7. The high-power microcavity optical frequency comb generation device and method provided by the present invention can realize the synchronous integration and automatic cascading generation of optical frequency comb and power amplification process by scientifically controlling the conditions for the occurrence of various optical effects and the operation process. It does not require complicated electrical control programs or the delicate and tedious operation of professional personnel, and has the characteristics of flexible control and simple operation.

[0022] 8. The high-power microcavity optical frequency comb generation device and method provided by the present invention can achieve flexible adjustment of the repetition frequency (e.g., set to 10GHz, 50GHz, 200GHz, etc.) by changing the cavity length of the active gain microcavity and the passive auxiliary microcavity. At the same time, it has the advantages of high integration and low power consumption. It can be used as a high-performance, multi-carrier coherent light source in the fields of communication networks, precision measurement, microwave photonics, etc. Therefore, it has the characteristics of high scalability and strong versatility, and has a wide range of applications in information technology. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of an embodiment of a high-power microcavity optical frequency comb generating device according to the present invention; Figure 2 This is a schematic diagram of the optical frequency comb generation process corresponding to steps 2-4 in the embodiment of the present invention; wherein, (a) corresponds to step 2, (b) corresponds to step 3, and (c) corresponds to step 4; Figure 3This is a schematic diagram of the spectral results corresponding to step 2 in this embodiment of the invention; Figure 4 This is a schematic diagram of the spectral results corresponding to step 3 in this embodiment of the invention, where the horizontal axis represents wavelength and the vertical axis represents light intensity; Figure 5 This is a schematic diagram of the optical frequency comb spectrum results corresponding to step 4 in this embodiment of the invention, where the horizontal axis represents wavelength and the vertical axis represents optical power; Figure 6 This is a schematic diagram of the optical frequency comb pulse sequence waveform corresponding to step 4 in this embodiment of the invention. The horizontal axis represents time, and the vertical axis represents the optical pulse intensity.

[0024] The attached figures are labeled as follows: 1. Semiconductor laser; 2. Microcavity chip; 21. Waveguide input terminal; 22. Waveguide coupling region; 23. Waveguide output terminal; 24. Active gain microcavity; 25. Passive auxiliary microcavity; 26. Metal thermoelectrode; 3. DC power supply; 4. Lens fiber; 5. Fiber optic beam splitter; 6. Spectrometer; 7. Photodetector; 8. Oscilloscope. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] This invention provides a high-power microcavity optical frequency comb generating device, such as... Figure 1 As shown, it includes a pumping unit, a microcavity unit, an output unit, and a state determination unit arranged sequentially from the input end to the output end; The pump unit is used to generate continuous pump laser; specifically, the pump unit includes a semiconductor laser 1 with an operating wavelength range of 975nm to 985nm; the output terminal of the semiconductor laser 1 corresponds to the waveguide input terminal 21 of the common waveguide. In this embodiment, the semiconductor laser 1 used has an operating wavelength of 980nm.

[0027] The microcavity unit is used to receive the pump laser. After spontaneous emission from the doped waveguide microcavity, a single-frequency laser is excited under resonant conditions. Subsequently, parametric oscillation is generated using an undoped waveguide microcavity, and mode matching selection is performed. Then, cascaded four-wave mixing and synchronous cyclic amplification are performed using the doped waveguide microcavity, thereby realizing optical frequency comb generation and power amplification. Specifically, the microcavity unit includes a microcavity chip 2 and a DC power supply 3. The microcavity chip 2 includes a common waveguide, an active gain microcavity 24, a passive auxiliary microcavity 25, and a metal thermoelectric electrode 26. The waveguide input end 21 of the common waveguide corresponds to the output end of the pump unit. The waveguide coupling region 22 of the common waveguide surrounds the outer wall of the active gain microcavity 24. The waveguide coupling region 22 is positioned and maintains a first preset gap with the outer wall of the active gain microcavity 24 (i.e., the waveguide coupling region 22 is coupled to the active gain microcavity 24 in a close-range non-contact pulley manner); the range of the first preset gap is 200nm~1000nm; the waveguide output end 23 of the common waveguide corresponds to the input end of the output unit; both the active gain microcavity 24 and the passive auxiliary microcavity 25 are annular, and their cavity lengths and waveguide widths are equal, and they are coupled at a single point, maintaining a second preset gap at the coupling point; the range of the second preset gap is 200nm~1000nm; the metal hot electrode 26 is disposed on one side or above the passive auxiliary microcavity 25; the active gain microcavity 24 is doped with Er 3+ The passive auxiliary microcavity 25 is an undoped silicon nitride ring waveguide; the positive and negative terminals of the DC power supply 3 are connected to the two ends of the metal thermoelectric electrode 26, respectively; the DC power supply 3 is used to change the operating temperature of the passive auxiliary microcavity 25 to tune its actual cavity length.

[0028] The output unit is used to receive the output beam from the waveguide output end 23, split it, and inject it into the state determination unit. The output unit includes a lens fiber 4 and a fiber beam splitter 5. The input end of the lens fiber 4 corresponds to the waveguide output end 23 of the common waveguide, and the output end of the lens fiber 4 is connected to the input end of the fiber beam splitter 5. The fiber beam splitter 5 is used to split the beam output from the lens fiber 4 into a first beam and a second beam, and then input them into the state determination unit.

[0029] The state determination unit is used to monitor the spectral intensity, wavelength, and pulse sequence waveform of the corresponding light beam, providing feedback for the operation and control of the pump unit and microcavity unit. The state determination unit includes a spectrometer 6, a photodetector 7, and an oscilloscope 8. The input end of the spectrometer 6 is connected to the first output end of the fiber optic beam splitter 5 via an optical fiber, used to receive the first light beam to analyze its spectral characteristics. The input end of the photodetector 7 is connected to the second output end of the fiber optic beam splitter 5 via an optical fiber, and the output end of the photodetector 7 is electrically connected to the oscilloscope 8. The photodetector 7 is used to receive the second light beam and convert the optical signal into an electrical signal. The oscilloscope 8 is used to receive the corresponding electrical signal to monitor its pulse sequence waveform.

[0030] A method for generating a high-power microcavity optical frequency comb, using the aforementioned high-power microcavity optical frequency comb generating device, specifically includes the following steps: Step 1: Start the pump unit to emit continuous pump laser light into the waveguide input terminal 21 of the common waveguide; after passing through the microcavity unit, the pump laser light enters the state determination unit through the output unit; specifically: Start the semiconductor laser 1 and finely adjust the spatial position of the semiconductor laser 1 and the common waveguide so that the pump laser emitted from the semiconductor laser 1 is incident at close range (tens of micrometers) at the waveguide input end 21 of the common waveguide; Step 2: Adjust the output power of the pump unit based on the spectral intensity monitored by the state determination unit until the active gain microcavity 24 completes wavelength conversion and achieves initial excitation of the preset resonant mode through intracavity circulation; specifically: The output power of semiconductor laser 1 is gradually increased, and the spectrum of the output beam at the waveguide output terminal 23 of the common waveguide is measured by the spectrometer 6 in the state determination unit. When the pump laser intensity is higher than the spectral intensity threshold of the active gain microcavity 24 in the optical microcavity unit for amplified spontaneous emission (at this time, the surface of the active gain microcavity 24 shows visible green fluorescence), a narrow linewidth laser wavelength (i.e., a narrow spectral line) can be observed on the spectrometer 6 near 1550nm. This indicates that the wavelength conversion from 980nm to 1550nm has been completed inside the active gain microcavity 24, and the initial excitation of the preset resonant mode has been achieved through intracavity circulation.

[0031] like Figure 2 As shown in (a), a high-power semiconductor laser 1 in the 980nm band is pumped by an Er-doped laser. 3+ When the pump laser power exceeds the threshold for amplified spontaneous emission of the active gain microcavity 24 formed by the waveguide, it will first generate broadband spontaneous emission in the 1550nm band. At the same time, under the condition of ring cavity resonance, it will automatically achieve the excitation of a certain random wavelength component (i.e., random resonant frequency excitation) at a certain number of microcavity resonant frequencies through a cyclic oscillation process. Meanwhile, other resonant frequencies will be suppressed due to the loss of gain and failure to meet the oscillation conditions, and will not be generated.

[0032] like Figure 3 As shown, when step 2 of this embodiment is completed, the pump laser power is 80mW, and the spectrometer 6 can observe that there is only one laser wavelength component at the 1550nm band, indicating that the initial excitation of the preset resonant mode has been achieved at this time.

[0033] Step 3: Adjust the output current or voltage of the DC power supply 3 to regulate the operating temperature of the passive auxiliary microcavity 25 by the metal thermoelectrode 26, thereby changing the repetition frequency of the passive auxiliary microcavity 25. The state determination unit then determines the result until the determination indicates that comb teeth have been initially generated within the passive auxiliary microcavity 25. Specifically: Adjusting the output current or voltage of the DC power supply 3 causes the metal thermoelectrode 26 to regulate the operating temperature of the passive auxiliary microcavity 25, thereby changing the actual repetition frequency of the passive auxiliary microcavity 25. When the repetition frequency of the passive auxiliary microcavity 25 is tuned to be exactly the same as that of the active gain microcavity 24, multiple discrete frequency wavelengths can be observed on the spectrometer 6, indicating that the passive auxiliary microcavity 25 has initially generated optical frequency combs through a parametric oscillation process, and the repetition frequency of the passive auxiliary microcavity 25 is strictly the same as that of the active gain microcavity 24.

[0034] like Figure 2 As shown in (b), the active gain microcavity 24 and the passive auxiliary microcavity 25 have the same cavity length and waveguide width, but due to actual manufacturing errors, there is usually a very small deviation between them (e.g., tens of nanometers). By changing the current or voltage of the DC power supply 3 and the metal thermoelectric electrode 26, the operating temperature of the passive auxiliary microcavity 25 is adjusted to tune its actual cavity length. When its repetition frequency is tuned to be exactly the same as the repetition frequency of the active gain microcavity 24, their transmission and resonance modes will strictly coincide and match. Therefore, the initial resonance frequency generated in step 2 will couple into the passive auxiliary microcavity 25 to resonate, and through the parametric oscillation process, a small number of discrete comb teeth will be generated, with the interval being an integer multiple of the microcavity repetition frequency.

[0035] like Figure 4 As shown, in this embodiment, the cavity lengths of both the active gain microcavity 24 and the passive auxiliary microcavity 25 are 1518 μm, and the repetition frequency is 100 GHz. After completing the mode matching selection by tuning the operating temperature, the spectrometer 6 can observe two new discrete comb teeth generated through the parametric oscillation process, in addition to the initial 1550 nm wavelength component. Their wavelengths are 1537.6 nm and 1562.6 nm, respectively.

[0036] Step 4: Keeping all operating parameters constant, increase the output power of the pump unit until the judgment result obtained by the state determination unit shows that a uniformly distributed optical frequency comb and a stable pulse sequence waveform have been obtained, thus completing the generation of the high-power microcavity optical frequency comb. Specifically: Keeping all operating parameters constant, the output power of semiconductor laser 1 is increased. When the pump laser intensity exceeds the threshold condition for cascaded four-wave mixing of active gain microcavity 24, a uniformly distributed optical frequency comb can be observed on spectrometer 6, and a stable pulse sequence waveform can be observed on oscilloscope 8. This indicates that the optical frequency comb has been generated through the cascaded four-wave mixing process, thus completing the generation of high-power microcavity optical frequency comb.

[0037] like Figure 2 As shown in (c), after step 4 is completed, the active gain microcavity 24 and the passive auxiliary microcavity 25 have the same resonant mode. The small number of comb teeth generated in the passive auxiliary microcavity 25 can all be coupled into the active gain microcavity 24. At this time, the pump laser power is increased. When the comb tooth power is increased to exceed the threshold of the four-wave mixing effect of the active gain microcavity 24, a cascaded four-wave mixing process will occur, forming a mode-locked optical frequency comb with uniformly distributed comb teeth and strictly equal spacing. At the same time, the cyclic amplification is completed synchronously in the doped waveguide, thereby achieving a further increase in the output power of the optical frequency comb.

[0038] like Figure 5 As shown, when step 4 of this embodiment is completed, the pump power is 550 mW, the spacing between the comb teeth of the generated optical frequency comb is 0.8 nm, the spectrum covers 1500-1600 nm, and there are 98 optical frequency comb teeth with a power exceeding -30 dBm (the response threshold of a common amplifier). Figure 6 As shown, the optical frequency comb exhibits a stable pulse sequence in the time domain with an interval of 10 ps and a corresponding repetition frequency of 100 GHz.

[0039] The principle of this invention is as follows: By employing a 980nm semiconductor laser to directly pump Er-doped materials... 3+An active gain microcavity constructed from waveguides, when its power is low but just above the amplified spontaneous emission threshold, will first generate broadband spontaneous emission in the 1550nm band. Simultaneously, under ring cavity resonance, it will automatically undergo a cyclic oscillation process, exciting a random wavelength component at one of the many resonant frequencies of the microcavity. Other resonant frequencies will be suppressed and unable to be generated due to gain loss and failure to meet the oscillation conditions. The active gain microcavity and the passive auxiliary microcavity use the same cavity length and waveguide width structure, theoretically they should have the same resonant modes. However, errors in the actual manufacturing process will cause slight deviations between them, preventing good overlap and matching of the resonant modes between the active gain microcavity and the passive auxiliary microcavity. This can be addressed by employing a dual-micro-ring cavity coupling architecture with extremely small spacing. Combined with temperature control, the repetition frequency of the passive-assisted microcavity can be finely tuned. When it is exactly equal to that of the active-gain microcavity, their transmission and resonance modes will be strictly matched. At the same time, since the passive-assisted microcavity composed of undoped waveguides has higher quality characteristics, it can achieve a low-threshold parametric oscillation process and generate a small number of discrete comb teeth under low pump power. Then, by further increasing the pump power, when the power of the small number of comb teeth generated by the parametric oscillation is enhanced to exceed the threshold for the non-degenerate four-wave mixing effect of the active-gain microcavity, a mode-locked optical frequency comb with uniform comb teeth will be formed through a cascaded four-wave mixing process. At the same time, cyclic amplification is completed synchronously in the active-gain microcavity composed of doped waveguides, thereby realizing the stable excitation of a high-power, high-repetition-frequency, mode-locked pulse state microcavity optical frequency comb.

[0040] Based on the current performance level and operating characteristics of various devices, this invention, through the ingenious construction of each unit structure and the scientific control of the conditions and operation process for the occurrence of various optical effects, can perfectly solve the problems of pump wavelength and resonant frequency detuning caused by microcavity thermal effects, the inability of dual microcavity resonant modes to coincide due to actual processing errors, the high threshold of degenerate four-wave mixing effect leading to extremely high pump power and stringent requirements for microcavity quality factor, and the need for additional amplification due to insufficient comb power to meet application requirements. It achieves synchronous fusion and cascade generation of optical frequency comb generation and power amplification process, breaks through the existing technical bottlenecks, and provides a microcavity optical frequency comb generation device that is compact in structure, easy to operate, economical in cost, and has the advantage of high comb power.

[0041] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present invention should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high-power microcavity optical frequency comb generating device, characterized in that: It includes a pump unit, a microcavity unit, an output unit, and a state determination unit arranged sequentially from the input end to the output end; The pumping unit is used to generate continuous pump laser; The microcavity unit includes a microcavity chip (2) and a DC power supply (3); the microcavity chip (2) includes a common waveguide, an active gain microcavity (24), a passive auxiliary microcavity (25), and a metal thermoelectrode (26); the waveguide input end (21) of the common waveguide corresponds to the output end of the pump unit; the waveguide coupling region (22) of the common waveguide is arranged around the outer wall of the active gain microcavity (24) and maintains a first preset gap with the outer wall of the active gain microcavity (24); the waveguide output end (23) of the common waveguide corresponds to the input end of the output unit; the active gain microcavity (24) and the passive auxiliary microcavity (25) are both annular, and their cavity lengths and waveguide widths are equal, and they are coupled at a single point, maintaining a second preset gap at the coupling point; the metal thermoelectrode (26) is arranged on one side or above the passive auxiliary microcavity (25); the positive and negative terminals of the DC power supply (3) are respectively connected to the two ends of the metal thermoelectrode (26); The output unit is used to receive the beam output from the waveguide output end (23), split it, and inject it into the state determination unit. The state determination unit is used to monitor the spectral intensity, wavelength, and pulse sequence waveform of the corresponding light beam, providing feedback for the operation state control of the pump unit and the microcavity unit.

2. The high-power microcavity optical frequency comb generating device according to claim 1, characterized in that: The active gain microcavity (24) is doped with Er. 3+ Silicon nitride ring waveguide; The passive auxiliary microcavity (25) is an undoped silicon nitride ring waveguide; The range of the first preset gap is 200nm~1000nm; The range of the second preset gap is 200nm~1000nm.

3. The high-power microcavity optical frequency comb generating device according to claim 1 or 2, characterized in that: The output unit includes a lens fiber (4) and a fiber beam splitter (5). The input end of the lens fiber (4) corresponds to the waveguide output end (23) of the common waveguide, and the output end of the lens fiber (4) is connected to the input end of the fiber beam splitter (5). The fiber beam splitter (5) is used to split the beam output from the lens fiber (4) into a first beam and a second beam.

4. The high-power microcavity optical frequency comb generating device according to claim 3, characterized in that: The state determination unit includes a spectrometer (6), a photodetector (7), and an oscilloscope (8). The input end of the spectrometer (6) is optically connected to the first output end of the fiber optic beam splitter (5); The input end of the photodetector (7) is optically connected to the second output end of the optical fiber splitter (5), and the output end of the photodetector (7) is electrically connected to the oscilloscope (8).

5. The high-power microcavity optical frequency comb generating device according to claim 4, characterized in that: The pumping unit includes a semiconductor laser (1) with a working wavelength range of 975nm-985nm. The output end of the semiconductor laser (1) corresponds to the waveguide input end (21) of the common waveguide.

6. A method for generating a high-power microcavity optical frequency comb, employing the high-power microcavity optical frequency comb generating device according to any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Start the pump unit to emit continuous pump laser to the waveguide input end (21) of the common waveguide; after the pump laser is acted upon by the microcavity unit, it enters the state determination unit through the output unit. Step 2: Adjust the output power of the pump unit based on the spectral intensity monitored by the state determination unit until the active gain microcavity (24) completes wavelength conversion and achieves the initial excitation of the preset resonance mode through cavity circulation; Step 3: Adjust the output current or voltage of the DC power supply (3) so that the metal thermoelectrode (26) adjusts the working temperature of the passive auxiliary microcavity (25), thereby changing the repetition frequency of the passive auxiliary microcavity (25). The state determination unit makes a determination until the determination result shows that comb teeth have been generated in the passive auxiliary microcavity (25). Step 4: Keep all operating parameters unchanged, increase the output power of the pump unit until the judgment result obtained by the state judgment unit shows that a uniform and continuous optical frequency comb tooth and a stable pulse sequence waveform have been obtained, thus completing the generation of the high-power microcavity optical frequency comb.

7. The method for generating a high-power microcavity optical frequency comb according to claim 6, characterized in that, Step 1 is as follows: Start the semiconductor laser (1) to emit a continuous pump laser to the waveguide input end (21) of the common waveguide; after the pump laser is acted upon by the microcavity unit, it enters the state determination unit through the output unit.

8. The method for generating a high-power microcavity optical frequency comb according to claim 7, characterized in that, Step 2 is as follows: The output power of the semiconductor laser (1) is gradually increased, and the spectrum of the output beam of the waveguide output terminal (23) of the common waveguide is measured by the spectrometer (6) in the state determination unit until a laser wavelength is generated on the spectrometer (6), indicating that the wavelength conversion has been completed inside the active gain microcavity (24), and the initial excitation of the preset resonant mode is realized through the cavity circulation.

9. The method for generating a high-power microcavity optical frequency comb according to claim 8, characterized in that, Step 3 specifically involves: Adjust the output current or voltage of the DC power supply (3) so that the metal thermoelectrode (26) can adjust the working temperature of the passive auxiliary microcavity (25), thereby changing the repetition frequency of the passive auxiliary microcavity (25). When multiple discrete frequency wavelengths can be observed on the spectrometer (6), it indicates that optical frequency combs have been generated in the passive auxiliary microcavity (25).

10. The method for generating a high-power microcavity optical frequency comb according to claim 9, characterized in that, Step 4 specifically involves: Keeping all operating parameters unchanged, increase the output power of the semiconductor laser (1) until a uniformly distributed optical frequency comb can be observed on the spectrometer (6) and a stable pulse sequence waveform can be observed on the oscilloscope (8), thus completing the generation of the high-power microcavity optical frequency comb.

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