A microwave source

Abstract

The application discloses a microwave source, which solves the problems of phase noise and stability of the microwave source, and comprises a microwave reference source, a filter cavity, an integrator, a microwave frequency multiplication unit, a directional coupler and a microwave antenna, wherein the microwave reference source outputs a voltage control signal; the filter cavity receives the voltage control signal and filters the voltage control signal to obtain a filtered signal one; the integrator is used for integrating the received filtered signal one to obtain an integrated signal; the microwave frequency multiplication unit is used for frequency multiplying the received integrated signal to obtain a microwave frequency multiplication signal; the directional coupler is used for directionally coupling the received microwave frequency multiplication signal to obtain a microwave signal one and a microwave signal two; and the microwave antenna receives the microwave signal two to obtain an antenna signal. The application can greatly improve the frequency stability of the microwave frequency band, reduce the phase noise, and has simple circuit design, low cost and small size.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and in particular to a tunable microwave source. Background Technology

[0002] Microwave frequency sources with low phase noise and high stability are widely used in radar, communication metrology and other fields, and are core components of modern electronic devices.

[0003] There are generally three ways to obtain a microwave source. First, the standard crystal oscillator frequency doubling method is currently the most mature approach, but its phase noise and stability are relatively poor. Second, utilizing the low loss of the dielectric material, a high-Q dielectric resonant cavity is designed to construct a positive feedback amplifier circuit, and the phase and amplitude are controlled to improve the stability of the output signal. This method has extremely high stability and phase noise performance, but the equipment is large and heavy, limiting its application. Third, the optically generated microwave method mainly falls into two categories: one involves locking an ultra-stable laser onto a high-stable optical resonant cavity and converting it to the desired frequency using an optical comb. Due to laser wavelength drift and aging, this method has a short continuous operating time, a complex optical path structure, and high cost. The other category uses an optoelectronic oscillator method: it uses optical fibers or optical filters to filter the light and convert the optical signal into an electrical signal. The amplified electrical signal is then loaded onto the laser modulator to form an oscillation loop. Using optical fibers as optical energy storage devices makes them susceptible to temperature and pressure effects, affecting the overall performance and the frequency stability of the output microwave signal. Micro-nano structure optical energy storage devices are complex to fabricate, costly, and the coupling and adjustment between the laser and the micro-nano structure are complex. Summary of the Invention

[0004] In view of this, in order to solve the problems of phase noise and stability of microwave sources, this application provides a microwave source.

[0005] This application provides a microwave source, including a microwave reference source, a filter cavity, an integrator, a microwave frequency multiplier unit, a directional coupler, and a microwave antenna. The microwave reference source outputs a voltage-controlled signal for voltage-controlled frequency perturbation in the microwave frequency multiplier unit. The filter cavity receives the voltage-controlled signal and filters it to obtain a filtered signal 1, which is then output to the integrator. The integrator integrates the received filtered signal 1 to obtain an integrated signal, which is then output to the microwave frequency multiplier unit. The microwave frequency multiplier unit multiplies the received integrated signal to obtain a microwave frequency multiplied signal, which is then output to the directional coupler. The directional coupler directionally couples the received microwave frequency multiplied signal to obtain a microwave signal 1 and a microwave signal 2, which is then output to the microwave antenna. The microwave antenna receives the microwave signal 2 to obtain an antenna signal, which is then output to the microwave reference source.

[0006] Preferably, the microwave reference source includes a laser, a polarizer, an atomic gas cell, a polarizer, a beam splitter, a photodetector, a lock-in amplifier, a signal generator, a modulator, a laser, a polarization controller, and a spectral monitor. The laser outputs a laser signal to the polarizer. The polarizer polarizes the received laser signal to obtain a linearly polarized signal, which is then output to the atomic gas cell. The atomic gas cell provides a reaction chamber for the interaction between the laser and atoms, receives the linearly polarized signal, obtains a reaction signal, and outputs it to the polarizer. The polarizer receives the reaction signal, obtains a linearly polarized signal, and outputs it to the beam splitter. The beam splitter receives the linearly polarized signal, obtains a split signal and a split signal, which are output to the spectral monitor and the photodetector, respectively. The spectral monitor receives the split signal and monitors its spectral signal. The photodetector... The detector performs photoelectric conversion on the received beam-splitting signal two to obtain an electrical signal, which is then output to the lock-in amplifier. The laser two outputs laser signal two to the modulator. The signal generator generates a modulation signal and outputs it to the modulator and the lock-in amplifier. The modulator modulates the laser signal two, receives the laser signal two and the modulation signal, obtains a laser modulation signal, and outputs it to the polarization controller. The polarization controller controls the polarization state of the laser modulation signal to obtain a polarization signal, which is then output to the polarizer two. The polarizer two receives the polarization signal to obtain a linearly polarized signal three, which is then output to the atomic gas chamber. The atomic gas chamber receives the linearly polarized signal three and the antenna signal, and under the action of the antenna signal, the polarization signals one and three interact with atoms. The lock-in amplifier receives the modulation signal and the electrical signal to obtain the voltage-controlled signal.

[0007] Preferably, the microwave frequency multiplier unit includes a crystal oscillator, a power divider I, a power divider II, a frequency multiplier I, a frequency multiplier II, a filter I, a direct digital synthesizer, a mixer, and a filter II. The crystal oscillator receives the voltage-controlled signal to obtain the oscillation signal and outputs it to the power divider I. The power divider I is used for power distribution to obtain clock signal I and clock signal II, and clock signal I is output to the power divider II. The power divider II receives clock signal I to obtain frequency signal I and frequency signal II, and outputs them to frequency multiplier I and frequency multiplier II, respectively. The frequency multiplier I receives frequency signal I... A frequency-multiplied signal 1 is obtained and output to filter 1; filter 1 receives the frequency-multiplied signal 1, obtains a filtered signal 2, and outputs it to the mixer; frequency multiplier 2 receives the frequency signal 2, obtains a frequency-multiplied signal 2, and outputs it to the direct digital synthesizer; the direct digital synthesizer is used for signal synthesis, receives the frequency-multiplied signal 2, obtains a synthesized signal, and outputs it to the mixer; the mixer receives the synthesized signal and the filtered signal 2, obtains the mixed signal, and outputs it to filter 2; filter 2 receives the mixed signal, obtains the microwave frequency-multiplied signal, and outputs it to the directional coupler.

[0008] The above-described technical solutions adopted in the embodiments of this application can achieve the following beneficial effects:

[0009] The microwave source of the present invention can significantly improve the frequency stability of standard crystal oscillators and microwave bands, and reduce the phase noise of standard crystal oscillators and microwaves. Moreover, the circuit design is simple, the cost is low, and the size is small.

[0010] Unlike optically pumped rubidium, cesium optical frequency standards, and rubidium-cesium atomic clocks, which only utilize laser pumping or pumping two energy levels, this invention also involves an external electric field in stimulated transitions, resulting in four-level atomic interaction. This produces a more stable locked spectral line, thereby enhancing the stability of standard and microwave signals. Attached Figure Description

[0011] The accompanying drawings, which are provided to further illustrate this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application.

[0012] In the attached diagram:

[0013] Figure 1 This is a schematic diagram of an embodiment of a microwave source;

[0014] Figure 2 This is a schematic diagram of an embodiment of a microwave reference source;

[0015] Figure 3 This is a schematic diagram of an embodiment of a microwave frequency doubling unit. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0017] Figure 1 This is a schematic diagram of an embodiment of a first type of microwave source, including a microwave reference source 101, a filter cavity 102, an integrator 103, a microwave frequency multiplier unit 104, a directional coupler 105, and a microwave antenna 106. The microwave reference source outputs a voltage-controlled signal A1 to control the frequency disturbance in the microwave frequency multiplier unit. The filter cavity receives the voltage-controlled signal and filters it to obtain a first filtered signal A2, which is then output to the integrator. The integrator integrates the received first filtered signal to obtain an integrated signal A3, which is then output to the microwave frequency multiplier unit. The microwave frequency multiplier unit multiplies the received integrated signal to obtain a microwave frequency multiplied signal A4, which is then output to the directional coupler. The directional coupler directionally couples the received microwave frequency multiplied signal to obtain a first microwave signal A5 and a second microwave signal A6. The second microwave signal A6 is output to the microwave antenna. The microwave antenna receives the second microwave signal A7 and outputs it to the microwave reference source.

[0018] Figure 2This is a schematic diagram of an embodiment of a microwave reference source, including a laser 201, a polarizer 202, an atomic gas cell 203, a second polarizer 204, a beam splitter 205, a photodetector 206, a lock-in amplifier 207, a signal generator 208, a modulator 209, a second laser 210, a polarization controller 211, and a spectrum monitor 212. The laser 210 outputs a laser signal B1 to the first polarizer; the first polarizer is used to polarize the received laser signal to obtain a linearly polarized signal B2, which is then output to... The atomic gas chamber; the atomic gas chamber is used to provide a reaction chamber for laser and atomic interaction, receives the linearly polarized signal one, obtains reaction signal one B3, and outputs it to the polarizer two; the polarizer two receives the reaction signal one, obtains linearly polarized signal two B4, and outputs it to the beam splitter; the beam splitter receives the linearly polarized signal two, obtains beam splitting signal one B5 and beam splitting signal two B6, and outputs them to the spectrum monitor and the photodetector respectively; the spectrum monitor receives the beam splitting signal one and processes the beam splitting signal two. The spectral signal of beam signal one is monitored; the photodetector performs photoelectric conversion on the received beam signal two to obtain an electrical signal B7, which is output to the lock-in amplifier; the laser two outputs laser signal two B8 to the modulator; the signal generator generates a modulation signal B9, which is output to the modulator and the lock-in amplifier; the modulator modulates the laser signal two, receives the laser signal two and the modulation signal, obtains a laser modulation signal B10, and outputs it to the polarization controller; the polarization controller controls the polarization state of the laser modulation signal to obtain a polarization signal B11, which is output to the polarizer two; the polarizer two receives the polarization signal to obtain a linearly polarized signal three B12, which is output to the atomic gas chamber; the atomic gas chamber receives the linearly polarized signal three and the antenna signal, and under the action of the antenna signal, the polarization signals one, three and atoms interact; the lock-in amplifier receives the modulation signal and the electrical signal to obtain the voltage control signal.

[0019] Preferably, the polarization controller is a Faraday rotator or a liquid crystal polarization controller.

[0020] Preferably, the modulation signal is a square wave of 10 to 100 kHz.

[0021] Figure 3This is a schematic diagram of a microwave frequency multiplier unit embodiment, including a crystal oscillator 301, a power divider 302, a power divider 303, a frequency multiplier 304, a frequency multiplier 305, a filter 306, a direct digital synthesizer 307, a mixer 308, and a filter 309. The crystal oscillator receives the voltage-controlled signal to obtain the oscillation signal C1, which is output to the power divider 304. The power divider 304 is used for power distribution, obtaining clock signal C3 and clock signal C2, which is output to the power divider 305. The power divider 305 receives clock signal C3 to obtain frequency signal C4 and frequency signal C5, which are output to the frequency multiplier 304 and frequency multiplier 305, respectively. Frequency multiplier one receives frequency signal one, obtains frequency multiplier signal one C6, and outputs it to filter one; filter one receives frequency multiplier signal one, obtains filter signal two C7, and outputs it to mixer; frequency multiplier two receives frequency signal two, obtains frequency multiplier signal two C8, and outputs it to direct digital synthesizer; direct digital synthesizer is used for signal synthesis, receives frequency multiplier signal two, obtains synthesized signal C9, and outputs it to mixer; mixer receives synthesized signal and filter signal two, obtains mixed signal C10, and outputs it to filter two; filter two receives mixed signal, obtains microwave frequency multiplier signal, and outputs it to directional coupler.

[0022] The microwave source is based on the electric field-induced transparency (EIT) phenomenon formed by the interaction of Rydberg atomic states in a quantum field under the influence of two laser beams (linearly polarized signal one and linearly polarized signal three). Building upon this phenomenon, when an external electric field (the antenna signal) interacts with the Rydberg atoms, edge peaks appear in the EIT detection spectrum. The frequency intervals and amplitudes of these edge peaks correspond to the microwave signal at relative frequencies. Utilizing these edge peaks to voltage-control the crystal oscillator in the microwave frequency doubling unit can significantly improve the frequency stability of the standard crystal oscillator and the microwave frequency band, while reducing the phase noise of both.

[0023] This invention differs from optically pumped rubidium, cesium optical frequency standards, and CPT rubidium-cesium atomic clocks. Traditional optical pumping or CPT rubidium only utilizes laser pumping or pumping two energy levels, while in this invention, the external electric field (the antenna signal) also participates in the stimulated transition, resulting in a four-level atomic interaction. The resulting locked spectral lines are more stable, leading to higher stability of the standard signal and microwave signal.

[0024] Preferably, the oscillation signal is 10MHz or 5MHz.

[0025] Preferably, the first laser is a distributed feedback laser. The wavelength of the first laser is related to the alkali metal in the selected gas chamber. If rubidium metal is selected, the wavelength of the first laser signal is selected to be around 780nm; if cesium atom gas chamber is selected, the wavelength of the first laser signal is selected to be around 852nm. The frequency of the first laser can be tuned by 100MHz around the center wavelength.

[0026] Preferably, the second laser is a coupled laser. If a rubidium gas chamber is used, the wavelength of the second laser signal is a tunable laser of 479–485 nm; if a cesium gas chamber is used, the wavelength of the second laser signal is 794 nm.

[0027] The second clock signal is a stable standard 10MHz or 5MHz clock signal.

[0028] Preferably, the microwave source further includes a monitoring device for monitoring the received microwave signal.

[0029] The frequencies of laser one and laser two are fine-tuned. When a microwave signal is generated, the lock-in amplifier is adjusted according to the beam splitting signal to optimize the performance of the microwave signal.

[0030] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, or apparatus that includes said element.

[0031] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A microwave source, based on the electric field-induced transparent EIT phenomenon formed by the interaction of two laser beams in the Rydberg atomic state in a quantum field, and on this basis, introducing an external electric field to interact with the Rydberg atoms, and using the edge peaks in the EIT detection spectrum to voltage-control the crystal oscillator in the microwave frequency doubling unit, characterized in that, It includes a microwave reference source, filter cavity, integrator, microwave frequency multiplier, directional coupler, and microwave antenna. The microwave reference source outputs a voltage control signal, which is used to voltage control the frequency disturbance in the microwave frequency multiplier unit; The filter cavity receives the voltage control signal and filters the voltage control signal to obtain filtered signal one, which is then output to the integrator. The integrator is used to integrate the received filtered signal to obtain an integrated signal, which is then output to the microwave frequency multiplier unit. The microwave frequency multiplier unit is used to multiply the frequency of the received integrated signal to obtain a microwave frequency multiplier signal, which is then output to the directional coupler. The directional coupler is used to directionally couple the received microwave frequency-doubled signal to obtain microwave signal one and microwave signal two, and microwave signal two is output to the microwave antenna; The microwave antenna receives the second microwave signal, obtains the antenna signal, and outputs it to the microwave reference source. The microwave reference source includes laser one, polarizer one, atomic gas cell, polarizer two, beam splitter, photodetector, lock-in amplifier, signal generator, modulator, laser two, polarization controller, and spectral monitor. The laser outputs a laser signal to the polarizer. The polarizer is used to polarize the received laser signal to obtain a linearly polarized signal, which is then output to the atomic gas cell. The atomic gas chamber is used to provide a reaction chamber for laser and atomic interaction, receive the linearly polarized signal one, obtain reaction signal one, and output it to the polarizer two; The second polarizer receives the first reaction signal, obtains the second linearly polarized signal, and outputs it to the beam splitter. The beam splitter receives the second linearly polarized signal and obtains the first beam splitter signal and the second beam splitter signal, which are then output to the spectral monitor and the photodetector, respectively. The spectral monitor receives the first beam split signal and monitors the spectral signal of the first beam split signal; The photodetector is used to perform photoelectric conversion on the received beam split signal to obtain an electrical signal, which is then output to the lock-in amplifier. The laser outputs two laser signals to the modulator; The signal generator is used to generate a modulated signal, which is output to the modulator and the lock-in amplifier. The modulator is used to modulate the second laser signal, receive the second laser signal and the modulated signal to obtain a laser modulated signal, and output it to the polarization controller; The polarization controller is used to control the polarization state of the laser modulation signal to obtain a polarization signal, which is then output to the second polarizer. The second polarizer receives the polarization signal to obtain the third linearly polarized signal, which is then output to the atomic gas chamber. The atomic gas cell receives the linearly polarized signal tris and the antenna signal, and under the action of the antenna signal, the linearly polarized signal one and the linearly polarized signal tris and the atoms undergo four-level interactions, thereby generating side peaks in the EIT detection spectrum; The lock-in amplifier receives the modulation signal and the electrical signal to obtain the voltage-controlled signal, and uses the edge peak to voltage-control the crystal oscillator in the microwave frequency multiplication unit.

2. The microwave source according to claim 1, characterized in that, The microwave frequency multiplier unit includes a crystal oscillator, a power divider I, a power divider II, a frequency multiplier I, a frequency multiplier II, a filter I, a direct digital synthesizer, a mixer, and a filter II. The crystal oscillator receives the voltage-controlled signal, obtains an oscillation signal, and outputs it to the power divider. The power divider is used for power distribution to obtain clock signal one and clock signal two, and clock signal one is output to the power divider two. The power divider 2 receives the clock signal 1 and obtains frequency signal 1 and frequency signal 2, which are then output to the frequency multiplier 1 and frequency multiplier 2, respectively. The frequency multiplier one receives the frequency signal one, obtains the multiplied frequency signal one, and outputs it to the filter one; The filter one receives the frequency multiplication signal one, obtains the filtered signal two, and outputs it to the mixer; The second frequency multiplier receives the second frequency signal, obtains the second multiplied frequency signal, and outputs it to the direct digital synthesizer; The direct digital synthesizer is used for signal synthesis. It receives the second frequency-multiplied signal, obtains the synthesized signal, and outputs it to the mixer. The mixer receives the synthesized signal and the second filtered signal to obtain a mixed signal, which is then output to the second filter. The second filter receives the mixing signal, obtains the microwave frequency multiplier signal, and outputs it to the directional coupler.

3. The microwave source according to claim 2, characterized in that, The oscillation signal is 10MHz or 5MHz.

4. The microwave source according to claim 1, characterized in that, The polarization controller is a Faraday rotator or a liquid crystal polarization controller.

5. The microwave source according to claim 1, characterized in that, The modulation signal is a square wave of 10 to 100 kHz.

6. The microwave source according to any one of claims 1 to 5, characterized in that, The laser is a distributed feedback laser.

7. The microwave source according to any one of claims 1 to 5, characterized in that, The second laser is a coupled laser.

8. The microwave source according to any one of claims 1 to 5, characterized in that, The microwave source also includes a monitoring device, which is used to monitor the received microwave signal.

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