High-stability millimeter wave generation method and system

Abstract

The invention discloses a high-stability millimeter wave generation method and system. The method comprises the following steps: inputting single-frequency laser and a photo-generated microwave signal into an electro-optic phase modulator so as to modulate the single-frequency laser by using the photo-generated microwave signal; the modulated laser meeting the preset requirement is obtained by adjusting the power of the photo-generated microwave signal input to the electro-optic phase modulator; the preset requirement is that the modulated laser is represented as a plurality of single-frequency signals taking the frequency of the photo-generated microwave signal as a frequency interval in a frequency domain, and the frequency interval between two target single-frequency signals with the highest amplitude in the plurality of single-frequency signals is equal to f; f is the required millimeter wave frequency; filtering the modulated laser by using a preset filtering device to obtain filtered laser; the filtered laser is represented as a double-frequency signal composed of two target single-frequency signals in a frequency domain; and carrying out photoelectric detection on the filtered laser to obtain millimeter waves with relatively high frequency stability.

Description

[0001] The present invention claims the priority of the Chinese patent application filed with the China Patent Office on November 23, 2023, with application number "202311579421.X" and invention name "A method and device for photogenerated high-stability millimeter waves", the entire contents of which are incorporated by reference in the present invention. Technical Field

[0002] The present invention belongs to the field of millimeter waves, and in particular relates to a high-stability millimeter wave generation method and system. Background Art

[0003] Millimeter waves have extremely wide bandwidth. With the same antenna size, the beam of millimeter waves is narrower than that of microwaves. Millimeter waves have strong detection capabilities and good security and confidentiality. Compared with microwave band components, millimeter wave components are small in size, so millimeter wave systems are easier to miniaturize. The millimeter wave band has four atmospheric windows, and high-stability millimeter wave signals can be used in the field of high-speed, large-capacity wireless communications between space and ground. It can also be used in 6G optical communications, millimeter wave time synchronization, millimeter wave radar, future medical care and other fields.

[0004] In the prior art, a commonly used method for generating millimeter waves is the external modulator method. The principle of the external modulator method for generating millimeter waves is to use a microwave signal to modulate a carrier laser to generate a phase-related modulation signal, and then use a wavelength selection switch on the output side of the modulator to select the required sideband, and perform photoelectric detection on the selected sideband to obtain the required millimeter wave.

[0005] However, the sideband noise selected by the wavelength selective switch is large, resulting in poor frequency stability of the final millimeter wave signal. Summary of the invention

[0006] In order to solve the above problems existing in the prior art, the present invention provides a high-stability millimeter wave generation method and system.

[0007] The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0008] A highly stable millimeter wave generation method, comprising:

[0009] Inputting the single-frequency laser and the optically generated microwave signal into an electro-optical phase modulator to modulate the single-frequency laser using the optically generated microwave signal;

[0010] By adjusting the power of the optically generated microwave signal input to the electro-optical phase modulator, a modulated laser that meets preset requirements is obtained; the preset requirements are: the modulated laser is expressed in the frequency domain as a plurality of single-frequency signals with the frequency of the optically generated microwave signal as a frequency interval, and the frequency interval between the two target single-frequency signals with the highest amplitude in the plurality of single-frequency signals is equal to f; f is the required millimeter wave frequency;

[0011] The modulated laser is filtered using a preset filtering device to obtain a filtered laser; wherein the filtered laser appears as a dual-frequency signal composed of the two target single-frequency signals in the frequency domain; the filtering device filters the modulated laser based on an FP etalon; the center frequency of the FP etalon is the same as the frequency of the single-frequency laser, and the filtering bandwidth corresponding to the fineness of the FP etalon is less than half of the frequency interval;

[0012] The filtered laser light is subjected to photoelectric detection to obtain the required millimeter wave.

[0013] Optionally, the filtering device comprises: a first fiber collimator, a 1 / 2 wave plate, a polarization beam splitter, an FP etalon, a 1 / 4 wave plate, a reflector and a second fiber collimator;

[0014] The modulated laser passes through the first fiber collimator, the 1 / 2 wave plate and the polarization beam splitter prism in sequence and enters the FP etalon for the first filtering; the laser after the first filtering passes through the 1 / 4 wave plate and is reflected by the reflector, passes through the 1 / 4 wave plate again and re-enters the FP etalon for the second filtering; the laser after the second filtering is totally reflected by the polarization beam splitter prism and output through the second fiber collimator.

[0015] Optionally, the modulation power of the electro-optical phase modulator is not less than 2W.

[0016] Optionally, the frequency of the optically generated microwave signal is 10 GHz, and the two target single-frequency signals are a +5th-order sideband and a -5th-order sideband in the multiple single-frequency signals.

[0017] The present invention also provides a high-stability millimeter wave generation system, comprising: a laser generating device, a photogenerated microwave device, an electro-optical phase modulator, a filtering device and a photoelectric detection device;

[0018] The laser generating device is used to generate single-frequency laser;

[0019] The photogenerated microwave device is used to generate a photogenerated microwave signal;

[0020] The electro-optic phase modulator is used to modulate the single-frequency laser using the optically generated microwave signal;

[0021] Wherein, by adjusting the power of the optically generated microwave signal input to the electro-optical phase modulator, a modulated laser that meets the preset requirements is obtained; the preset requirements are: the modulated laser is expressed in the frequency domain as a plurality of single-frequency signals with the frequency of the optically generated microwave signal as the frequency interval, and the frequency interval between the two target single-frequency signals with the highest amplitude in the plurality of single-frequency signals is equal to f; f is the required millimeter wave frequency;

[0022] The filtering device is used to filter the modulated laser based on the FP etalon to obtain a filtered laser; the filtered laser appears as a dual-frequency signal composed of the two target single-frequency signals in the frequency domain; the center frequency of the FP etalon is the same as the frequency of the single-frequency laser, and the filtering bandwidth corresponding to the fineness of the FP etalon is less than half of the frequency interval;

[0023] The photoelectric detection device is used to perform photoelectric detection on the filtered laser to obtain the required millimeter wave.

[0024] Optionally, the filtering device comprises: a first fiber collimator, a 1 / 2 wave plate, a polarization beam splitter, an FP etalon, a 1 / 4 wave plate, a reflector and a second fiber collimator;

[0025] The modulated laser passes through the first fiber collimator, the 1 / 2 wave plate and the polarization beam splitter prism in sequence and enters the FP etalon for the first filtering; the laser after the first filtering passes through the 1 / 4 wave plate and is reflected by the reflector, passes through the 1 / 4 wave plate again and re-enters the FP etalon for the second filtering; the laser after the second filtering is totally reflected by the polarization beam splitter prism and output through the second fiber collimator.

[0026] Optionally, the optical microwave device comprises: a single-frequency ultra-stable laser generating device, a femtosecond pulse laser, a locking device, a photodetector, a bandpass filter and a power amplifier;

[0027] Among them, the single-frequency ultra-stable laser generating device is used to output a single-frequency ultra-stable laser, and the femtosecond pulse laser is used to output a femtosecond optical comb signal; the locking device is used to lock a comb tooth of the femtosecond optical comb signal on the single-frequency ultra-stable laser, and lock the carrier-envelope phase shift frequency of the femtosecond optical comb signal to obtain a femtosecond optical comb signal with ultra-stable laser frequency stability; the photodetector is used to detect the femtosecond optical comb signal with ultra-stable laser frequency stability to obtain a detection microwave electrical signal; the bandpass filter is used to bandpass filter the detection microwave electrical signal to obtain a filtered microwave electrical signal; the power amplifier is used to amplify the filtered microwave electrical signal to obtain the photogenerated microwave signal.

[0028] Optionally, the power of the optically generated microwave signal input to the electro-optical phase modulator is adjusted by adjusting the gain of the power amplifier.

[0029] In the high-stability millimeter wave generation method provided by the present invention, a single-frequency laser is modulated by a photogenerated microwave signal, and the modulated laser is expressed as a plurality of single-frequency signals with the frequency of the photogenerated microwave signal as the frequency interval in the frequency domain, and the frequency interval between the two target single-frequency signals with the highest amplitude in the plurality of single-frequency signals is equal to f; f is the required millimeter wave frequency. Then, the modulated laser is filtered based on the FP etalon; since the transmission spectrum of the FP etalon is expressed as a plurality of interval-arranged passbands with the free spectrum region (FSR) as the frequency interval in the frequency domain, the present invention customizes the FP etalon to make its center frequency the same as the frequency of the single-frequency laser, and makes the filtering bandwidth corresponding to its fineness as small as possible as small as half of the frequency interval between the two target single-frequency signals, so that the FP etalon can be used to effectively filter out the single-frequency signals between and outside the two target single-frequency signals from the plurality of single-frequency signals, thereby extracting two target single-frequency signals from the plurality of single-frequency signals at one time, which greatly improves the filtering effect compared with the filtering method using a wavelength selective switch in the prior art, and can filter out dual-frequency signals at one time. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a flow chart of a highly stable millimeter wave generating method provided by an embodiment of the present invention;

[0031] Figure 2 is a schematic structural diagram of a photogenerated microwave device provided in an embodiment of the present invention;

[0032] Figure 3 is a schematic diagram of generating a light-generated microwave signal in an embodiment of the present invention;

[0033] Figure 4 is a schematic structural diagram of another photogenerated microwave device provided in an embodiment of the present invention;

[0034] Figure 5 It is a structural schematic diagram of a high-stability millimeter wave generating system provided by an embodiment of the present invention;

[0035] Figure 6 is a structural schematic diagram of a filtering device provided by an embodiment of the present invention;

[0036] Figure 7 This is a diagram showing the effect of using a single FP etalon to filter the modulated laser.

[0037] Figure 8 is to use Figure 6The effect diagram of the filtering device filtering the modulated laser;

[0038] Fig. 9 The frequency stability of a millimeter wave generated by the method of the embodiment of the present invention is exemplarily shown;

[0039] Fig.10 is produced Fig. 9 Additional frequency stability for mid-millimeter wave systems. DETAILED DESCRIPTION

[0040] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0041] In order to obtain a millimeter wave with high frequency stability, the embodiment of the present invention provides a method for generating a high-stability millimeter wave, see Figure 1 As shown, the method comprises the following steps:

[0042] S10, inputting the single-frequency laser and the photogenerated microwave signal into the electro-optic phase modulator to modulate the single-frequency ultra-stable laser using the photogenerated microwave signal.

[0043] Among them, see Figure 5 The single-frequency laser is generated by a laser generating device 1, which includes a single-frequency laser and a fiber amplifier. The single-frequency laser generates a single-frequency laser, and the fiber amplifier (such as an erbium-doped fiber amplifier) ​​amplifies the single-frequency laser to obtain a single-frequency laser that can be input into an electro-optic phase modulator.

[0044] The photogenerated microwave signal is generated by the photogenerated microwave device 2. For example, see Figure 2 As shown, the photogenerated microwave device 2 may include: a single-frequency ultra-stable laser generating device, a femtosecond pulse laser, a locking device and a photodetector.

[0045] Among them, the single-frequency ultra-stable laser generating device is used to output a single-frequency ultra-stable laser, and the femtosecond pulse laser is used to output a femtosecond optical comb signal; the locking device is used to lock a comb tooth of the femtosecond optical comb signal on the ultra-stable laser, and lock the carrier-envelope phase shift frequency of the femtosecond optical comb signal to obtain a femtosecond optical comb signal with ultra-stable laser frequency stability; the photodetector is used to detect the femtosecond optical comb signal with ultra-stable laser frequency stability to obtain a detection microwave electrical signal, the frequency of which is in the microwave frequency band, so that the detection microwave electrical signal can be directly used as a photogenerated microwave signal input to the electro-optical phase modulator.

[0046] Specifically, in a single-frequency ultrastable laser generating device, a single-frequency ultrastable laser with ultrastable cavity length stability is obtained by locking the single-frequency laser on an ultrastable cavity and taking the ultrastable optical cavity as a frequency reference; then, a locking device locks a certain optical comb tooth of a femtosecond optical comb on the single-frequency ultrastable laser, such as Figure 3 As shown, the carrier-envelope phase shift frequency of the femtosecond optical comb is locked at the same time, and a comb tooth frequency with ultra-stable laser frequency stability is obtained, that is, a femtosecond optical comb signal with ultra-stable laser frequency stability. The comb tooth frequency of the locked femtosecond optical comb inherits the frequency stability of a single-frequency ultra-stable laser. Among them, regarding the locking method of the optical frequency comb and the locking device used therewith, reference can be made to the relevant prior art, and the embodiment of the present invention does not limit this. After the femtosecond optical comb signal with ultra-stable laser frequency stability is generated, the repetition frequency of the femtosecond optical comb signal is detected by a low-noise photodetector, and a detection microwave electrical signal with ultra-stable laser frequency stability can be detected, so that the detection microwave electrical signal can be used as a photogenerated microwave signal input to the electro-optical phase modulator. Therefore, the embodiment of the present invention adopts a single-frequency ultra-stable laser as a frequency reference, and transmits the frequency stability of the ultra-stable laser to the microwave frequency band through the femtosecond optical comb, thereby obtaining a microwave signal with ultra-stable laser frequency stability.

[0047] In another implementation, Figure 4 As shown, the photogenerated microwave device 2 may include: a single-frequency ultra-stable laser generating device, a femtosecond pulse laser, a locking device, a photodetector, a bandpass filter and a power amplifier.

[0048] Among them, the functions of the single-frequency ultra-stable laser generating device, the femtosecond pulse laser, the locking device, and the photodetector are the same as those of the aforementioned photogenerated microwave device. The bandpass filter is used to bandpass filter the detection microwave electrical signal obtained by the photodetector to obtain a filtered microwave electrical signal; the power amplifier is used to amplify the filtered microwave electrical signal, thereby using the amplified microwave electrical signal as the photogenerated microwave signal input to the electro-optical phase modulator.

[0049] Here, filtering the detection microwave electrical signal can filter out other undesirable repetitive frequency components of the femtosecond light comb, improve the frequency stability of the photogenerated microwave signal, and amplify the filtered microwave electrical signal to facilitate the subsequent modulation of the single-frequency laser generated by the laser generating device 1. In addition, the power of the photogenerated microwave signal input to the electro-optical phase modulator can be flexibly adjusted by adjusting the gain of the power amplifier.

[0050] See also Figure 5 , the photogenerated microwave signal with ultra-stable laser frequency stability and the single-frequency laser are input into the electro-optic phase modulator (EOM) 3, and the photogenerated microwave signal is used as a modulation signal to modulate the single-frequency laser, so that the modulated laser generates multiple single-frequency signals in the frequency domain.

[0051] In the embodiment of the present invention, in order to enable the modulated laser to generate more single-frequency signals in the frequency domain, the single-frequency laser can be over-modulated by adjusting the power of the photogenerated microwave signal. The greater the power of the photogenerated microwave signal, the greater the number of single-frequency signals in the frequency domain of the modulated signal output by the electro-optical phase modulator 3.

[0052] In addition, in order to support overmodulation, the modulation power of the electro-optic phase modulator 3 used in the embodiment of the present invention needs to be greater than 1W, that is, an optoelectronic phase modulator with high modulation power (that is, low half-wave voltage) is used in the embodiment of the present invention. Preferably, in order to obtain a better modulation effect, the modulation power of the electro-optic phase modulator 3 is not less than 2W.

[0053] S20. By adjusting the power of the photogenerated microwave signal input to the electro-optic phase modulator, a modulated laser that meets the preset requirements is obtained; the preset requirements are: the modulated laser appears in the frequency domain as a plurality of single-frequency signals with the frequency of the photogenerated microwave signal as the frequency interval, and the frequency interval between the two target single-frequency signals with the highest amplitude in the plurality of single-frequency signals is equal to f; f is the required millimeter wave frequency.

[0054] Here, by continuously adjusting the power of the optically generated microwave signal input to the electro-optic phase modulator 3 and observing the spectrum of the modulated laser output by the electro-optic phase modulator 3, the number of modulation sidebands is made greater than the number of required sidebands. When the frequency interval between two sidebands in the spectrum is equal to the required millimeter wave frequency and their amplitudes show the highest trend among all the modulation sidebands, the modulation purpose is achieved, and these two sidebands are the two required target single-frequency signals. Since microwave signals have ultra-stable laser frequency stability, using microwave signals as modulation signals can make the modulated signal have ultra-stable laser frequency stability.

[0055] S30. Use a preset filtering device to filter the modulated laser to obtain a filtered laser; wherein the filtered laser exhibits a dual-frequency signal composed of two target single-frequency signals in the frequency domain; the filtering device filters the modulated laser based on an FP standard tool, the center frequency of the FP standard tool is the same as the frequency of the single-frequency laser, and the filtering bandwidth corresponding to the fineness of the FP standard tool is less than half of the frequency interval between the two target single-frequency signals.

[0056] Specifically, by customizing the FP etalon so that its center frequency is the same as the frequency of the single-frequency laser, thereby matching the intermediate frequency of the two target single-frequency signals, and making the filtering bandwidth corresponding to its fineness as small as possible as small as half of the frequency interval between the two target single-frequency signals, the single-frequency signals between and outside the two target single-frequency signals can be effectively filtered out from multiple single-frequency signals based on the FP etalon, thereby filtering out two target single-frequency signals from the above multiple single-frequency signals at one time. Among them, the filtering bandwidth corresponding to the fineness of the FP etalon is roughly equal to the free spectral range of the FP etalon divided by its fineness, so the higher the fineness of the FP etalon, the narrower its filtering bandwidth. For example, if f is equal to 100 GHz and the modulation signal frequency is 10 GHz, the filtering bandwidth of the FP etalon should be as small as possible below 5 GHz.

[0057] like Figure 7 As shown in the figure, the green spectral line is the spectrum of the modulated laser, and the blue spectral line is the transmission output spectrum after filtering the modulated laser using a single FP etalon, wherein the two highest peaks are two target single-frequency signals. In the embodiment of the present invention, single-frequency signals of +5-order sideband and -5-order sideband are exemplarily selected as target single-frequency signals. The center frequency of the FP etalon is exactly in the middle of the +5-order and -5-order single-frequency signals (that is, the frequency of the modulated single-frequency laser), and the filtering bandwidth corresponding to the fineness of the FP etalon can just allow a single target single-frequency signal to pass through.

[0058] In the process of implementing the present invention, the inventors found that although using a single FP etalon to filter the modulated laser can filter out the single-frequency signals between and outside two target single-frequency signals from multiple single-frequency signals, if the fineness of the single FP etalon is not enough, it may also cause the presence of undesired single-frequency signals near the target single-frequency signal, thereby affecting the frequency stability of the millimeter wave finally generated. For example, there will be single-frequency signals with +4th and +6th order sidebands of certain power next to the screened target single-frequency signal with +5th order sideband, and there will be single-frequency signals with -4th and -6th order sidebands of certain power next to the screened target single-frequency signal with -5th order sideband.

[0059] Although the above problem can be solved by optimizing the fineness of a single FP etalon, a high-fineness optical FP etalon has high requirements on the optical path, is expensive, and is not conducive to engineering. Figure 6 The filter device shown filters the modulated laser light.

[0060] like Figure 6As shown, the filtering device includes: a first fiber collimator, a 1 / 2 wave plate, a polarization beam splitter, an FP etalon, a 1 / 4 wave plate, a reflector and a second fiber collimator; wherein the modulated laser passes through the first fiber collimator, the 1 / 2 wave plate and the polarization beam splitter in sequence and enters the FP etalon for the first filtering; the laser after the first filtering passes through the 1 / 4 wave plate and is reflected by the reflector, passes through the 1 / 4 wave plate again and re-enters the FP etalon for the second filtering; the laser after the second filtering is totally reflected by the polarization beam splitter and output through the second fiber collimator.

[0061] Among them, the laser enters the 1 / 2 wave plate from the first fiber collimator and rotates into horizontal polarized light, is fully transmitted through the polarization beam splitter prism, and is normally incident into the FP etalon for the first filtering; the laser emitted from the FP etalon then passes through the 1 / 4 wave plate and becomes circularly polarized light, and is reflected into the FP etalon by the original path through the reflector for the second filtering. Since it passes through the 1 / 4 wave plate twice, the laser entering the FP etalon is vertically polarized light. Therefore, after being emitted from the FP etalon, it passes through the polarization beam splitter prism and is fully reflected into the second fiber collimator. The other end of the second fiber collimator can be connected to the optical fiber, so that the laser after the two filtering is output through the optical fiber to complete the filtering.

[0062] In the embodiment of the present invention, by allowing the modulated laser to pass through the FP etalon twice, the fineness of a single FP etalon is improved, so that the single-frequency signals between and outside the two target single-frequency signals are further suppressed, thereby improving the filtering effect. Figure 6 In FIG. 1 , the green line represents the dual-frequency signal obtained by filtering the modulated laser using a single FP etalon, and the yellow line represents the dual-frequency signal obtained by filtering the modulated laser using the above filtering device.

[0063] Figure 8 The schematic diagram shows the use of Figure 6 The effect diagram of the filter device filtering the modulated laser is shown, where the black spectrum line is the spectrum of the modulated laser, and the red spectrum line is the transmission output spectrum after the filter device filters the modulated laser. Figure 7 It can be seen that after the modulated laser is filtered by the filtering device, the filtering effect is greatly improved. In addition, since the first fiber collimator, 1 / 2 wave plate, polarization beam splitter, 1 / 4 wave plate, reflector and second fiber collimator are low in cost and can be mass-produced, the cost can be effectively reduced.

[0064] S40, performing photoelectric detection on the filtered laser to obtain the required millimeter wave.

[0065] Here, photoelectric detection of the filtered laser is achieved by a photoelectric detection device, which can be a photodetector or a single-travel carrier (UTC) photoelectric mixer, but is not limited thereto. It should be noted that the bandwidth of the photoelectric detection device is greater than the millimeter wave frequency. Therefore, by photoelectrically detecting the filtered laser, the ultra-stable photogenerated microwave signal is frequency-multiplied to the millimeter wave band with low additional noise, and a millimeter wave with ultra-stable laser frequency stability can be obtained.

[0066] The high-stability millimeter wave generation method of the embodiment of the present invention uses a photogenerated microwave signal to modulate a single-frequency laser, and filters the modulated laser based on the FP etalon; since the free spectral range (FSR) of the FP etalon is manifested as a plurality of spaced-apart passbands, the FP etalon is customized to make its center frequency the same as the frequency of the single-frequency laser, and the bandwidth corresponding to its fineness much smaller than half of the frequency interval (e.g., 10 GHz) of the two target single-frequency signals, the FP etalon can be used to effectively filter out the single-frequency signals between and outside the two target single-frequency signals from the multiple single-frequency signals, thereby screening out the two target single-frequency signals from the multiple single-frequency signals. Compared with the method of using a wavelength selective switch to achieve filtering in the prior art, the filtering effect is greatly improved, and the dual-frequency signals can be screened out at one time.

[0067] The high-stability millimeter wave generation method of the embodiment of the present invention adopts the photoelectric frequency doubling technology to generate millimeter waves. Compared with the prior art adopting the multi-step electrical frequency doubling method, the millimeter wave generated by the embodiment of the present invention has higher frequency stability and lower phase noise, and uses fewer devices and is easy to integrate. It can be more widely used in systems requiring high-stability and low-noise frequency doubling, such as in millimeter wave radar systems to improve the test accuracy of radars; and in terahertz communications to improve communication capacity and communication rate.

[0068] In a specific example, a high-stability millimeter wave generation system was built based on the relevant components mentioned in the above high-stability millimeter wave generation method. The system uses a single-frequency laser to generate a single-frequency laser with a wavelength of 1556nm and a power of 16mW, which is amplified to 200mW by an erbium-doped fiber amplifier. Figure 4 The photogenerated microwave device shown generates a photogenerated microwave signal with a frequency of 10 GHz, which is amplified to about 1 W by a microwave power amplifier. Then, a 200 mW single-frequency laser and a 1 W photogenerated microwave signal are input into an electro-optic phase modulation to generate a modulated laser, which includes multiple single-frequency signals in the frequency domain. The modulated laser is then used to Figure 6The filter device shown in the figure is used for filtering to obtain a filtered laser containing +5th and -5th order sidebands in the frequency domain. Then, a single-line carrier (UTC) optoelectronic mixer with a bandwidth of 110 GHz is used to perform photoelectric detection on the filtered laser to obtain a 100 GHz millimeter wave with high frequency stability. The frequency stability of the millimeter wave is tested, and the test results are shown in FIG. Fig. 9 As shown in the figure, it can be seen that the frequency stability of the millimeter wave generated by this system can reach 5.2×10 -15 , reaching the E-15@1s level, and reaching 2.1×10 -15 .

[0069] In addition, the inventors also tested the additional frequency stability of the above system. The specific test method includes: replicating a set of identical systems, using an electric power divider to split the 10GHz optical microwave signal into two paths and send them to the two systems respectively, mixing the filtered lasers in the two systems and testing the frequency stability, and dividing the measured frequency stability by That is, the additional frequency stability of a single system is obtained. The test results are as follows: Fig.10 As shown in the figure, it can be seen that the additional frequency stability of the system reaches 2.3×10 -15 , reaching 5.1×10 -16 , and then dropped to 1.6×10 at 8192 seconds. -17 .

[0070] based on Fig. 9 and Fig.10 It can be seen from the test results that the embodiments of the present invention, based on the use of a photogenerated microwave signal with ultra-stable laser frequency stability as a modulation signal, and in combination with a system with an additional frequency stability comparable to or even higher than the ultra-stable laser frequency stability, can make the modulated laser have ultra-stable laser frequency stability.

[0071] Based on the same inventive concept, the embodiment of the present invention also provides a high-stability millimeter wave generation system, see Figure 5 As shown, it includes: a laser generating device 1, a photogenerated microwave device 2, an electro-optical phase modulator 3, a filtering device 4 and a photoelectric detection device 5;

[0072] A laser generating device 1, used for generating single-frequency laser;

[0073] A photogenerated microwave device 2, used for generating a photogenerated microwave signal;

[0074] An electro-optic phase modulator 3, used to modulate the single-frequency laser using a light-generated microwave signal; wherein the modulation power of the electro-optic phase modulator is preferably greater than 1W;

[0075] By adjusting the power of the photogenerated microwave signal input to the electro-optic phase modulator 3, a modulated laser that meets the preset requirements is obtained; the preset requirements are: the modulated laser is expressed in the frequency domain as a plurality of single-frequency signals with the frequency of the photogenerated microwave signal as the frequency interval, and the frequency interval between the two target single-frequency signals with the highest amplitude among the plurality of single-frequency signals is equal to f; f is the required millimeter wave frequency;

[0076] A filtering device 4 is used to filter the modulated laser based on the FP etalon to obtain a filtered laser; wherein the filtered laser is presented as a dual-frequency signal composed of two target single-frequency signals in the frequency domain; the center frequency of the FP etalon is the same as the frequency of the single-frequency laser, and the filtering bandwidth corresponding to the fineness of the FP etalon is less than half of the frequency interval;

[0077] The photoelectric detection device 5 is used to perform photoelectric detection on the filtered laser to obtain the required millimeter wave.

[0078] In one embodiment, see Figure 6 , the filtering device 4 includes: a first fiber collimator, a 1 / 2 wave plate, a polarization beam splitter, an FP etalon, a 1 / 4 wave plate, a reflector, and a second fiber collimator;

[0079] Among them, the modulated laser passes through the first fiber collimator, 1 / 2 wave plate and polarization beam splitter prism in sequence and enters the FP etalon for the first filtering; the laser after the first filtering passes through the 1 / 4 wave plate and is reflected by the reflector, passes through the 1 / 4 wave plate again and re-enters the FP etalon for the second filtering; the laser after the second filtering is totally reflected by the polarization beam splitter prism and output through the second fiber collimator.

[0080] In one embodiment, see Figure 4 , the optical microwave device 2 includes: a single-frequency ultra-stable laser generating device, a femtosecond pulse laser, a locking device, a photodetector, a bandpass filter and a power amplifier;

[0081] Among them, the single-frequency ultra-stable laser generating device is used to output single-frequency ultra-stable laser, and the femtosecond pulse laser is used to output a femtosecond optical comb signal; the locking device is used to lock one comb tooth of the femtosecond optical comb signal on the single-frequency ultra-stable laser, and lock the carrier-envelope phase shift frequency of the femtosecond optical comb to obtain a femtosecond optical comb signal with ultra-stable laser frequency stability; the photodetector is used to detect the femtosecond optical comb signal with ultra-stable laser frequency stability to obtain a detection microwave electrical signal; the bandpass filter is used to bandpass filter the detection microwave electrical signal to obtain a filtered microwave electrical signal; the power amplifier is used to amplify the filtered microwave electrical signal to obtain the above-mentioned photogenerated microwave signal.

[0082] In one embodiment, the power of the optically generated microwave signal input to the electro-optic phase modulator 3 can be adjusted by adjusting the gain of the power amplifier.

[0083] The system provided by the embodiment of the present invention can be used in a ground-based timing system, and cooperated with a fiber-optic timing system to build a fiber-optic millimeter wave communication network. Through the combination of wireless communication and wired fiber-optic communication, a three-dimensional, no-dead-angle timing and communication network can be realized.

[0084] The system provided by the embodiment of the present invention can be applied to the field of terahertz communication to improve channel capacity and rate; applied to space communication to improve air-to-ground communication rate and communication capacity; applied to high-precision millimeter-wave radar to improve radar detection accuracy and the number of detected targets; in conjunction with a high-precision ground-based timing system, an optical fiber timing network is installed to realize optical wireless communication, thereby realizing all-round and three-dimensional timing.

[0085] It should be noted that, for the system embodiment, the components involved have been illustrated in the method embodiment, so the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0086] It should be noted that the terms "first", "second", etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples of devices and methods consistent with some aspects of the present invention.

[0087] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0088] Although the present invention is described herein in conjunction with various embodiments, in the process of implementing the claimed invention, those skilled in the art can understand and implement other changes to the disclosed embodiments by viewing the drawings and the disclosed content. In the description of the present invention, the term "comprising" does not exclude other components or steps, "one" or "an" does not exclude multiple situations, and "multiple" means two or more, unless otherwise clearly and specifically limited. In addition, certain measures are recorded in different embodiments, but this does not mean that these measures cannot be combined to produce good results.

[0089] As for the device / electronic device / storage medium embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0090] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A high-stability millimeter wave generation method, characterized in that: include: Inputting the single-frequency laser and the optically generated microwave signal into an electro-optical phase modulator to modulate the single-frequency laser using the optically generated microwave signal; By adjusting the power of the optically generated microwave signal input to the electro-optical phase modulator, a modulated laser that meets preset requirements is obtained; the preset requirements are: the modulated laser is expressed in the frequency domain as a plurality of single-frequency signals with the frequency of the optically generated microwave signal as a frequency interval, and the frequency interval between the two target single-frequency signals with the highest amplitude in the plurality of single-frequency signals is equal to f; f is the required millimeter wave frequency; The modulated laser is filtered using a preset filtering device to obtain a filtered laser; wherein the filtered laser appears as a dual-frequency signal composed of the two target single-frequency signals in the frequency domain; the filtering device filters the modulated laser based on an FP etalon; the center frequency of the FP etalon is the same as the frequency of the single-frequency laser, and the filtering bandwidth corresponding to the fineness of the FP etalon is less than half of the frequency interval; The filtered laser light is subjected to photoelectric detection to obtain the required millimeter wave.

2. According to the high-stability millimeter wave generation method of claim 1, the filtering device comprises: A first fiber collimator, a half wave plate, a polarization beam splitter, an FP etalon, a quarter wave plate, a reflector, and a second fiber collimator; The modulated laser passes through the first fiber collimator, the 1 / 2 wave plate and the polarization beam splitter prism in sequence and enters the FP etalon for the first filtering; the laser after the first filtering passes through the 1 / 4 wave plate and is reflected by the reflector, passes through the 1 / 4 wave plate again and re-enters the FP etalon for the second filtering; the laser after the second filtering is totally reflected by the polarization beam splitter prism and output through the second fiber collimator.

3. The high-stability millimeter wave generation method according to claim 1, characterized in that: The modulation power of the electro-optic phase modulator is not less than 2W.

4. The high-stability millimeter wave generation method according to claim 1, characterized in that: The frequency of the optically generated microwave signal is 10 GHz, and the two target single-frequency signals are a +5th-order sideband and a -5th-order sideband in the multiple single-frequency signals.

5. A highly stable millimeter wave generating system, characterized in that: include: Laser generating devices, photogenerated microwave devices, electro-optic phase modulators, filtering devices and photoelectric detection devices; The laser generating device is used to generate single-frequency laser; The photogenerated microwave device is used to generate a photogenerated microwave signal; The electro-optic phase modulator is used to modulate the single-frequency laser using the optically generated microwave signal; Wherein, by adjusting the power of the optically generated microwave signal input to the electro-optical phase modulator, a modulated laser that meets the preset requirements is obtained; the preset requirements are: the modulated laser is expressed in the frequency domain as a plurality of single-frequency signals with the frequency of the optically generated microwave signal as the frequency interval, and the frequency interval between the two target single-frequency signals with the highest amplitude in the plurality of single-frequency signals is equal to f; f is the required millimeter wave frequency; The filtering device is used to filter the modulated laser based on the FP etalon to obtain a filtered laser; the filtered laser appears as a dual-frequency signal composed of the two target single-frequency signals in the frequency domain; the center frequency of the FP etalon is the same as the frequency of the single-frequency laser, and the filtering bandwidth corresponding to the fineness of the FP etalon is less than half of the frequency interval; The photoelectric detection device is used to perform photoelectric detection on the filtered laser to obtain the required millimeter wave.

6. The high stability millimeter wave generating system according to claim 5, characterized in that: The filtering device comprises: a first optical fiber collimator, a 1 / 2 wave plate, a polarization beam splitter prism, an FP etalon, a 1 / 4 wave plate, a reflector and a second optical fiber collimator; The modulated laser passes through the first fiber collimator, the 1 / 2 wave plate and the polarization beam splitter prism in sequence and enters the FP etalon for the first filtering; the laser after the first filtering passes through the 1 / 4 wave plate and is reflected by the reflector, passes through the 1 / 4 wave plate again and re-enters the FP etalon for the second filtering; the laser after the second filtering is totally reflected by the polarization beam splitter prism and output through the second fiber collimator.

7. The high stability millimeter wave generating system according to claim 5, characterized in that: The optical microwave device comprises: a single-frequency ultra-stable laser generating device, a femtosecond pulse laser, a locking device, a photodetector, a bandpass filter and a power amplifier; Among them, the single-frequency ultra-stable laser generating device is used to output a single-frequency ultra-stable laser, and the femtosecond pulse laser is used to output a femtosecond optical comb signal; the locking device is used to lock a comb tooth of the femtosecond optical comb signal on the single-frequency ultra-stable laser, and lock the carrier-envelope phase shift frequency of the femtosecond optical comb signal to obtain a femtosecond optical comb signal with ultra-stable laser frequency stability; the photodetector is used to detect the femtosecond optical comb signal with ultra-stable laser frequency stability to obtain a detection microwave electrical signal; the bandpass filter is used to bandpass filter the detection microwave electrical signal to obtain a filtered microwave electrical signal; the power amplifier is used to amplify the filtered microwave electrical signal to obtain the photogenerated microwave signal.

8. The high stability millimeter wave generating system according to claim 7, characterized in that: The power of the optically generated microwave signal input to the electro-optical phase modulator is adjusted by adjusting the gain of the power amplifier.

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