Multi-frequency microwave signal generation method based on microcavity optical frequency comb

Abstract

The invention discloses a multi-frequency microwave signal generation method based on a microcavity optical frequency comb, and the method comprises the following steps: forming an equally-spaced spectrum comb-shaped structure through the nonlinear optical effect in a micro-ring resonant cavity, generating optical signals of various frequencies, and generating a microcavity optical frequency comb signal; introducing the generated microcavity optical frequency comb signal into a modulator for modulation; the modulated microcavity optical frequency comb signal serves as a light source and is connected to a photoelectric detector for photoelectric conversion; frequency beating is carried out on all frequency components of the signal after photoelectric conversion, and a microwave signal sequence with the adjacent mode interval as the frequency interval is obtained. The optical frequency comb signals generated by the single micro-ring resonant cavity are combined with the broadband modulation technology, flexible generation of multi-frequency microwave signals is innovatively achieved, the complexity and cost of the system are reduced, and the reliability of the system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-frequency microwave signals, and in particular to a method for generating multi-frequency microwave signals based on a microcavity optical frequency comb. Background Art

[0002] Microwave signals play an important role in many fields such as wireless communications, radar detection, and precision measurement.

[0003] Common methods of microwave signal generation include:

[0004] 1. Direct oscillators: These devices generate microwave signals of fixed frequency through oscillation circuits. It is difficult to adjust the frequency and their applicability is limited.

[0005] 2. Phase-locked loop: Although the phase-locked loop can adjust the frequency within a certain range, its output frequency is usually an integer multiple of a fixed reference frequency and cannot achieve a wide frequency coverage;

[0006] 3. Digital synthesis technology: Use digital signal processing to generate microwave signals, but this type of technology often requires complex processing algorithms and hardware support, which increases the complexity of the system.

[0007] In recent years, the rapid development of photonic technology has brought new solutions to the generation of microwave signals. Microwave signal generation technology based on optical means, especially optical frequency comb technology, has received widespread attention. The optical frequency comb is a low phase noise light source with equally spaced coherent comb spectrum in the frequency domain and mode-locked optical pulses in the time domain. Its spectrum presents an equally spaced comb structure with extremely high frequency stability and broadband coverage. Using the optical frequency comb to convert optical signals into microwave signals through photoelectric conversion can not only achieve ultra-high frequency stability, but also significantly improve the frequency coverage range and the quality of the output signal. However, the generation of most optical frequency combs currently still relies on complex large-scale equipment, such as mode-locked lasers, which have high equipment costs, high energy consumption and are difficult to miniaturize, which is not conducive to practical application and promotion.

[0008] In order to further optimize the generation method of optical frequency combs, researchers have proposed a solution based on microcavity optical frequency combs. Microcavity optical frequency combs inject pump light into a microring resonator and use the nonlinear optical effects in the cavity (such as four-wave mixing and self-phase modulation) to form an equally spaced spectral comb structure. This method has the advantages of compact system, low cost, and easy integration. However, the existing microcavity optical frequency comb technology still has many shortcomings in practical applications. For example, the stability of the frequency interval of the optical frequency comb is greatly affected by the power fluctuations and temperature changes in the cavity. The generation conditions of the soliton frequency comb are harsh and the control requirements for the cavity geometric parameters are extremely high. These problems restrict its further application in the generation of multi-frequency microwave signals.

[0009] Patent CN114389698A discloses a microwave signal generating device and method based on all-optical devices, which uses Mach-Zehnder modulators for electro-optical modulation and relies on the Brillouin scattering effect in optical fibers to generate microwave signals with adjustable frequency and low phase noise. Patent CN116224678A discloses a soliton optical frequency comb and a photogenerated microwave signal generating device, which realizes the generation of high-precision microwave signals through the interaction of multiple pump lasers and microring resonators. The first pump laser generates a soliton optical frequency comb through nonlinear four-wave mixing; the second pump laser compensates for the power change caused by frequency detuning; the third pump laser uses the photomechanical cooling effect to suppress thermomechanical noise and reduce phase noise. The system can effectively generate stable photogenerated microwave signals and is suitable for high-precision frequency control and communication systems, but the structure is relatively complex. Therefore, how to provide a multi-frequency microwave signal generation method based on a microcavity optical frequency comb is a problem that technicians in this field urgently need to solve. Summary of the invention

[0010] One object of the present invention is to propose a method for generating multi-frequency microwave signals based on a microcavity optical frequency comb. The present invention makes full use of microcavity optical frequency comb technology, photoelectric conversion technology and frequency beating technology, generates high-stability optical frequency signals through nonlinear optical effects, and combines modulation with photoelectric conversion to realize the entire process of multi-frequency microwave signal output. It has the advantages of high flexibility, high frequency stability, high signal generation efficiency and easy system miniaturization and integration.

[0011] A method for generating a multi-frequency microwave signal based on a microcavity optical frequency comb according to an embodiment of the present invention comprises the following steps:

[0012] S1. Using the nonlinear optical effect in the microring resonator to form an equally spaced spectral comb structure, thereby generating optical signals of multiple frequencies and producing a microcavity optical frequency comb signal;

[0013] S2, introducing the generated microcavity optical frequency comb signal into a modulator for modulation;

[0014] S3, the modulated microcavity optical frequency comb signal is used as a light source and connected to a photodetector for photoelectric conversion;

[0015] S4. The frequency components of the signal after photoelectric conversion are beat with each other to obtain a microwave signal sequence with the frequency interval being the interval between adjacent modes.

[0016] Optionally, S1 includes: performing real-time feedback control on the temperature in the microring resonant cavity by using a thermosensitive chip; forming a stable soliton frequency comb by controlling the resonance peak of the microring resonant cavity to generate a microcavity optical frequency comb signal.

[0017] Optionally, the steps of forming a stable soliton frequency comb include:

[0018] S11, use the thermal balance scheme of auxiliary laser to maintain the stability of the power in the cavity;

[0019] S12, the auxiliary laser enters the microring resonator from the opposite direction to the pump light, and the pump light and the auxiliary light are transmitted in the microcavity in opposite directions;

[0020] S13, coupling the pump light signal into the resonance peak, and the pump light signal is always stable at the soliton step.

[0021] Optionally, the geometrical dimensions of the microring resonant cavity are used to determine the range of the free spectrum and are inversely proportional to the range of the free spectrum.

[0022] Optionally, the nonlinear optical effect includes four-wave mixing and self-phase modulation.

[0023] Optionally, the radius of the microring resonant cavity controls the repetition frequency of the generated optical frequency comb signal, and the repetition frequency is used to determine the fundamental frequency of the generated microwave signal.

[0024] Optionally, the modulator is a broadband acousto-optic modulator or an electro-optic modulator.

[0025] Optionally, the modulator generates microwave signals of different frequencies by changing the phase of the input light, thereby flexibly controlling the frequency distribution of the output microwave signal.

[0026] Optionally, according to different combinations of modulation frequency and optical frequency comb repetition frequency, a series of uniformly or non-uniformly spaced microwave signals can be obtained.

[0027] The beneficial effects of the present invention are:

[0028] By using microcavity optical frequency comb signals to generate high-precision optical frequency signals, and combining the optimized design of modulators and photodetectors, efficient generation of multi-frequency microwave signals is achieved. The beneficial effects achieved include:

[0029] The present invention overcomes the bandwidth limitation and frequency stability problems of traditional electronic methods in high-frequency signal generation, and realizes microwave signal output with high stability and low phase noise through the equally spaced characteristics of the optical frequency comb and the stable control of the nonlinear optical effect in the cavity.

[0030] By introducing precise temperature feedback control and soliton frequency comb generation technology, the generation stability of the optical frequency comb signal is effectively improved, fundamentally solving the problem of frequency instability caused by temperature fluctuations and power imbalance in the existing microcavity optical frequency comb technology.

[0031] In addition, the present invention optimizes the modulation and photoelectric conversion process of the optical frequency comb so that the output microwave signal has the characteristics of flexible and controllable frequency distribution, which can adapt to the needs of various application scenarios, thereby significantly improving the efficiency and practicality of signal generation.

[0032] Finally, the technical solution of the present invention realizes the high integration and miniaturization of the multi-frequency microwave signal generation device, greatly reduces the volume and energy consumption of the device, and simplifies the signal generation process. Through the application of broadband modulators, the frequency range of the output signal has been significantly expanded to support wider bandwidth application requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0034] Figure 1 A flow chart of a method for generating multi-frequency microwave signals based on a microcavity optical frequency comb proposed by the present invention;

[0035] Figure 2 A system diagram of a multi-frequency microwave signal generation based on a microring resonator and an acousto-optic modulator provided in Example 1 of the present invention;

[0036] Figure 3 A spectrum diagram of an output optical signal of a method for generating a multi-frequency microwave signal based on a microcavity optical frequency comb is provided for Example 1 of the present invention;

[0037] Figure 4 This is a power spectrum diagram of an output microwave signal of a method for generating multi-frequency microwave signals based on a microcavity optical frequency comb provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0038] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0039] refer to Figure 1 , a method for generating multi-frequency microwave signals based on a microcavity optical frequency comb, comprising the following steps:

[0040] S1. Using the nonlinear optical effect in the microring resonator to form an equally spaced spectral comb structure, thereby generating optical signals of multiple frequencies and producing a microcavity optical frequency comb signal;

[0041] S2, introducing the generated microcavity optical frequency comb signal into a modulator for modulation;

[0042] S3, the modulated microcavity optical frequency comb signal is used as a light source and connected to a photodetector for photoelectric conversion;

[0043] S4. The frequency components of the signal after photoelectric conversion are beat with each other to obtain a microwave signal sequence with the frequency interval being the interval between adjacent modes.

[0044] In this embodiment, S1 includes: using a thermosensitive chip to feedback control the temperature in the microring resonant cavity in real time; and controlling the resonance peak of the microring resonant cavity to form a stable soliton frequency comb and generate a microcavity optical frequency comb signal.

[0045] In this embodiment, the steps of forming a stable soliton frequency comb include:

[0046] S11, use the thermal balance scheme of auxiliary laser to maintain the stability of the power in the cavity;

[0047] S12, the auxiliary laser enters the microring resonator from the opposite direction to the pump light, and the pump light and the auxiliary light are transmitted in the microcavity in opposite directions;

[0048] S13, coupling the pump light signal into the resonance peak, and the pump light signal is always stable at the soliton step.

[0049] In this embodiment, the geometrical dimensions of the micro-ring resonant cavity are used to determine the range of the free spectrum and are inversely proportional to the range of the free spectrum.

[0050] In this implementation, the nonlinear optical effect includes four-wave mixing and self-phase modulation.

[0051] In this embodiment, the radius of the micro-ring resonant cavity controls the repetition frequency of the generated optical frequency comb signal, and the repetition frequency is used to determine the fundamental frequency of the generated microwave signal.

[0052] In this embodiment, the modulator is a broadband acousto-optic modulator or an electro-optic modulator.

[0053] In this embodiment, the modulator generates microwave signals of different frequencies by changing the phase of the input light, and flexibly controls the frequency distribution of the output microwave signal.

[0054] In this embodiment, a series of microwave signals with uniform or non-uniform intervals can be obtained according to different combinations of the modulation frequency and the repetition frequency of the optical frequency comb.

[0055] Embodiment 1:

[0056] like Figure 2 As shown in the figure, this embodiment shows a method for generating multi-frequency microwave signals based on a microring resonator and an acousto-optic modulator. The pump light passes through the microring resonator to generate a microcavity optical frequency comb, which is then connected to a photodetector for photoelectric conversion after acousto-optic modulation. The frequency components of the output signal beat each other to obtain a microwave signal. When the repetition frequency of the optical frequency comb is 50 GHz and the modulation frequency of the acousto-optic modulation is 2 GHz, the corresponding output optical signal spectrum image is as follows: Figure 3 The generated microwave signal power spectrum is shown in Figure 4As shown, the generated spectrum can be changed by changing the modulation frequency.

[0057] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for generating multi-frequency microwave signals based on a microcavity optical frequency comb, characterized in that: The steps include: S1. Using the nonlinear optical effect in the microring resonator to form an equally spaced spectral comb structure, generate optical signals of multiple frequencies, and produce a microcavity optical frequency comb signal; S2, introducing the generated microcavity optical frequency comb signal into a modulator for modulation; S3, the modulated microcavity optical frequency comb signal is used as a light source and connected to a photodetector for photoelectric conversion; S4. The frequency components of the signal after photoelectric conversion are beat with each other to obtain a microwave signal sequence with the frequency interval being the interval between adjacent modes.

2. The method for generating multi-frequency microwave signals based on a microcavity optical frequency comb according to claim 1, characterized in that: The S1 includes: using a thermosensitive chip to feedback control the temperature in the microring resonant cavity in real time; and controlling the resonance peak of the microring resonant cavity to form a stable soliton frequency comb and generate a microcavity optical frequency comb signal.

3. The method for generating multi-frequency microwave signals based on a microcavity optical frequency comb according to claim 2, characterized in that: The steps to form a stable soliton frequency comb include: S11, use the thermal balance scheme of auxiliary laser to maintain the stability of the power in the cavity; S12, the auxiliary laser enters the microring resonator from the opposite direction to the pump light, and the pump light and the auxiliary light are transmitted in the microcavity in opposite directions; S13, coupling the pump light signal into the resonance peak, and the pump light signal is always stable at the soliton step.

4. The method for generating multi-frequency microwave signals based on a microcavity optical frequency comb according to claim 1, characterized in that: The geometrical dimensions of the micro-ring resonant cavity are used to determine the range of the free spectrum and are inversely proportional to the range of the free spectrum.

5. The method for generating multi-frequency microwave signals based on a microcavity optical frequency comb according to claim 1, characterized in that: The nonlinear optical effects include four-wave mixing and self-phase modulation.

6. The method for generating multi-frequency microwave signals based on a microcavity optical frequency comb according to claim 1, characterized in that: The radius of the micro-ring resonant cavity controls the repetition frequency of the generated optical frequency comb signal, and the repetition frequency is used to determine the fundamental frequency of the generated microwave signal.

7. The method for generating multi-frequency microwave signals based on a microcavity optical frequency comb according to claim 1, characterized in that: The modulator is a broadband acousto-optic modulator or an electro-optic modulator.

8. The method for generating multi-frequency microwave signals based on a microcavity optical frequency comb according to claim 1, characterized in that: The modulator generates microwave signals of different frequencies by changing the phase of the input light, and flexibly controls the frequency distribution of the output microwave signal.

9. The method for generating multi-frequency microwave signals based on a microcavity optical frequency comb according to claim 1, characterized in that: Depending on the combination of modulation frequency and optical frequency comb repetition frequency, a series of evenly or unevenly spaced microwave signals can be obtained.

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