Microwave source omnidirectional positioning measurement device and method

Abstract

The invention belongs to the technical field of quantum precision measurement, and discloses a microwave source omnidirectional positioning measurement device and method. The device comprises a light source assembly, a signal generator, an atomic gas chamber and a signal detection module, the signal generator is used for emitting local oscillation microwaves to the atomic gas chamber; the light source assembly comprises a detection laser, an EIT module, a coupling laser, a coupling beam array editor, a detection beam array editor and a phase shifter; the detection light array and the coupling light array formed by the detection light beam array editor and the coupling light beam array editor are utilized to form the atom sensor atom receiver array in the atom gas chamber, omnidirectional detection is carried out on an unknown microwave source, the detection sensitivity can be greatly improved, and omnidirectional detection of the unknown microwave source can be realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of quantum precision measurement, and particularly relates to a microwave source omnidirectional positioning measurement device and method. BACKGROUND

[0002] Microwave electric field measurement technology is the basis for the realization of functions of electronic information systems such as radar, communication, navigation, and electromagnetic spectrum monitoring, and plays an irreplaceable important role in the current information age. Rydberg atoms show strong response to weak electric fields, have high sensitivity, small system size, and hidden anti-damage detection, and are considered as a kind of atomic receiver that is expected to surpass the sensitivity of traditional receivers.

[0003] In classical radio science, aperture refers to the effective receiving area of a radio receiving system, which is used to characterize its ability to receive radio waves. In the application process of atomic receivers, the laser beam is the basis for the preparation of Rydberg states and the basis for further photoelectric conversion measurement. Its physical properties determine the sensitivity of the atomic receiver, and thus affect the size of the quantum aperture. At present, for a wide area of to-be-received and to-be-measured microwave electric field, the quantum aperture of a single Rydberg atom receiver is usually limited, which greatly reduces the induction and reception ability of the Rydberg atom receiver to radio waves, and the measurement sensitivity of the system is strongly limited by noise from the classical and quantum levels; the microwave signal contains its own phase information, and omnidirectional positioning requires accurate and unique phase capture. Therefore, in order to realize omnidirectional positioning and accurate measurement of the microwave source, the measurement device in the prior art needs to be improved. SUMMARY

[0004] In order to solve the problem that the induction and reception ability of a single Rydberg atom receiver to radio waves is limited, the measurement accuracy of the system is limited by noise, omnidirectional positioning cannot be realized, and the sensitivity of the measurement system is difficult to improve, the present application provides a microwave source omnidirectional positioning measurement device and method to realize omnidirectional positioning and accurate measurement of an unknown microwave source.

[0005] In order to solve the above technical problems, the technical scheme adopted by the present application is as follows: a microwave source omnidirectional positioning measurement device, comprising: a light source assembly, a signal generator, an atomic cell, and a signal detection module; the signal generator is used to send a local microwave to the atomic cell; The light source assembly comprises a probe laser, an EIT module, a coupling laser, a coupling beam array editor, a probe beam array editor, and a phase shifter. The probe light emitted by the probe laser passes through the probe beam array editor to form a probe light array, and the probe light array is phase-adjusted by the phase shifter and then divided into two probe light arrays by the first light guide unit and incident on the atomic cell from two mutually perpendicular directions; the phase shifter is used to change the phase of each probe light in the probe light array so that it is located on the phase plane of the microwave to be measured; The coupling light emitted by the coupling laser passes through the second light splitting component to form a coupling light array with the same arrangement as the probe light array, and the coupling light array is divided into two coupling light arrays by the second light guide unit and then incident on the atomic cell in reverse coincidence with the two probe light arrays, so that the atoms in the atomic cell produce an electromagnetically induced transparency effect and then form an atomic receiver array; the two probe light arrays after passing through the atomic cell are focused by the lens and then incident on the signal detection module; The signal detection module is used to detect the signals of the two probe light arrays respectively to obtain the omnidirectional parameters of the microwave source to be measured.

[0006] The microwave source omnidirectional positioning measurement device also includes an EIT module, a first light splitting component, and a second light splitting component. A portion of the probe light emitted by the probe laser passes through the first light splitting component and is incident on the EIT module, and a portion of the coupling light emitted by the coupling laser passes through the second light splitting component and is incident on the EIT detection module in reverse coincidence with the probe light incident on the EIT module; The EIT module is used to assist the frequency tuning of the probe laser and the coupling laser so that they can interact with the atoms in the atomic cell to produce a stable electromagnetically induced transparency effect.

[0007] The light source component also includes a saturated absorption spectrum device, which is used to lock the frequency of the probe laser at the center of the atomic absorption peak.

[0008] The signal detection module includes two photodetectors, a spectrum analyzer, a lock-in amplifier, an oscilloscope, and a signal processing terminal, the two probe light arrays after passing through the atomic cell are focused by the lens and then detected by one photodetector respectively, the detection signals are sent to the spectrum analyzer, the lock-in amplifier, and the oscilloscope, and the oscilloscope is used to output the double-peak frequency difference in the ATS spectrum ∆f， The lock-in amplifier is used to output the phase of the microwave to be measured at each receiving point; the spectrum analyzer is used to perform frequency spectrum analysis to obtain the frequency difference between the microwave to be measured and the local oscillator; and the signal processing terminal is used to calculate the frequency, intensity, and direction of the microwave to be measured according to the outputs of the spectrum analyzer, the lock-in amplifier, and the oscilloscope.

[0009] The microwave source omnidirectional positioning measurement device also includes a first beam splitter, a second beam splitter and a performance evaluation module, the performance evaluation module includes a noise detection module, a thermal noise detection module and a line width detection module; the probe light array after the atomic gas chamber is split by the first beam splitter to form a part of light to the second beam splitter, then enters the noise detection module, the thermal noise detection module and the line width detection module after being split by the second beam splitter; the noise detection module is used for determining the noise characteristics of the measurement signal by single photon counting; the thermal noise detection module is used for determining the thermal noise of the measurement signal by single photon counting after the FP cavity reduces the noise of the probe light array signal, and the line width detection module is used for acquiring the line width of the beat frequency signal and analyzing the laser noise.

[0010] In addition, the application also provides a microwave source omnidirectional positioning measurement method, which is realized based on the device and includes the following steps: Step one: introduce reference light with the same frequency as the probe light, so that the reference light and each laser in the probe light array interfere with each other, the shape, spacing and stability of each interference fringe are observed, and the phases of each laser in the probe light array are adjusted by the phase shifter to make each interference fringe the same; Step two: the probe light array passing through the atomic gas chamber is measured by the signal detection module to obtain the preliminary information of the to-be-measured microwave at the receiving point position of each probe light in the probe light array; Step three: the frequency and amplitude parameters of the local oscillator microwave electric field are optimized, the measurement is repeated, and the final information of the to-be-measured microwave at the receiving point position of each probe light in the probe light array is measured by the signal detection module.

[0011] The step one also includes the following steps: The beam spacing in the probe light array and the coupling light array is changed by the probe beam array editor and the coupling beam array editor, the EIT-AT split spectrum is obtained by measuring the probe light array by the signal detection module, the beam spacing with the strongest EIT-AT split spectrum signal is screened out, and the probe light array and the coupling light array are controlled to have the corresponding beam spacing.

[0012] The microwave source omnidirectional positioning measurement method, the information of the to-be-measured microwave includes intensity, frequency and direction; wherein, the specific method for determining the direction of the to-be-measured microwave is: The phase information corresponding to each receiving point of the probe light is obtained; The included angle between the receiving point of each probe light in the probe light array and the to-be-measured microwave source is calculated, and the calculation formula is: ; Wherein, represents the phase difference of the to-be-measured microwave at the positions of two receiving points, is the wavelength of the microwave, is the distance between two receiving points, is the angle between the microwave source to be measured and the two receiving points; Through the angle intersection positioning algorithm, the positions of the receiving points and the multiple angles are combined to determine the position of the microwave source to be measured.

[0013] The microwave source omnidirectional positioning measurement method also includes the following steps: Step four: The performance evaluation module measures the noise characteristics, thermal noise characteristics and signal line width of the measurement signal, optimizes the device performance according to the measurement results, and improves the measurement accuracy.

[0014] Compared with the prior art, the present application has the following advantages: the present application provides a microwave source omnidirectional positioning measurement device and method, which adopts a spatial laser splitting scheme, outputs an editable and combined laser array through a beam array editor, and approximately uniformly transforms the laser array power in real time. The detection light array is placed on the equal phase surface of the incident wave, so that the noise level of each channel is guaranteed, the EIT spectrum with higher signal strength is generated, and the EIT-AT splitting is more easily realized, thereby improving the accuracy of the microwave intensity measurement. Moreover, the microwave signal phase capture at different positions is realized by using multiple receiving points, the position measurement of the microwave to be measured is realized by the triangulation method, the microwave omnidirectional positioning is realized, and the performance evaluation module is used to evaluate the noise characteristics, thermal noise characteristics and line width of the measurement signal, which can provide a reference for the parameter optimization of the device and further improve the accuracy of the microwave source omnidirectional positioning. Therefore, the present application has the advantages of high measurement sensitivity, high accuracy, and omnidirectional positioning measurement. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 Fig. 1 is a structural schematic diagram of a microwave source omnidirectional positioning measurement device according to an embodiment of the present application; Figure 2 Fig. 2 is a schematic diagram of the optical path structure of the microwave source omnidirectional positioning measurement device according to the embodiment of the present application; Figure 3 Fig. 3 is a flowchart of a microwave source omnidirectional positioning measurement method according to an embodiment of the present application; Figure 4 Fig. 4 is a flowchart of the performance evaluation module in the embodiment of the present application; In the figure, 2: signal generator; 3: light source assembly; 4: atomic cell; 5: photodetector; 6: first beam splitter; 7: performance evaluation module; 9: spectrum analyzer; 10: lock-in amplifier; 11: oscilloscope; 12: information processing terminal; 13: second beam splitter; 14: signal detection module; ​301: probe laser; 302: first half-wave plate; 303: first polarization beam splitter prism; 304: saturated absorption spectrum; 305: EIT module; 306: probe beam array editor; 307: phase shifter; 308: first mirror; 309: second mirror; 311: coupling laser; 312: second half-wave plate; 313: second polarization beam splitter prism; 314: coupling beam array editor; 315: second dichroic mirror; 316: lens; 317: first beam splitter; 318: second beam splitter; 319: first dichroic mirror. DETAILED DESCRIPTION

[0016] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0017] Embodiment one As shown in the figure, the embodiment one of the present application provides a microwave source omnidirectional positioning measurement device, comprising: a light source assembly 3, a signal generator 2, an atomic gas chamber 4 and a signal detection module 14; the signal generator 2 is used to send a local microwave to the atomic gas chamber 4. Figure 1 As shown in the figure, in the embodiment, the light source assembly 3 comprises a probe laser 301, an EIT module 305, a coupling laser 311, a coupling beam array editor 314, a probe beam array editor 306 and a phase shifter 307.

[0018] Figure 2 Among them, the probe light emitted by the probe laser 301 forms a probe light array after the probe beam array editor 306, and the probe light array is adjusted in phase by the phase shifter 307, then is divided into two probe light arrays by the first light guide unit and is incident to the atomic gas chamber 4 from two mutually perpendicular directions; the phase shifter 307 is used to change the phase of each probe light in the probe light array, so that it is located on the equal phase plane of the microwave to be measured.

[0019]

[0020] ​​Among them, the coupling light emitted by the coupling laser 311 is separated by the second splitting component, and a portion of it is incident on the EIT detection module 305 in the opposite direction and overlaps with the first detection signal; the remaining laser light is formed into a coupling light array with the same arrangement as the detection light array after passing through the coupling beam array editor 314. After the coupling light array is divided into two coupling light arrays by the second light guide unit, they are respectively incident on the atomic gas chamber 4 in the opposite direction and overlap with the two detection light arrays, causing the atoms in the atomic gas chamber 4 to produce an electromagnetically induced transparency effect; the two detection light arrays after passing through the atomic gas chamber 4 are respectively focused by lenses and incident on the signal detection module 14. Among them, the beams of light in the coupling light array and the detection light array respectively overlap, and can cause the atoms on the overlapping path to produce an electromagnetically induced transparency effect. Each pair of light beams in the array forms an atomic receiver, thereby forming an atomic receiver array.

[0021] In this embodiment, the signal detection module 14 is used to detect the signals of the two detection light arrays respectively to obtain the omnidirectional parameters of the microwave source to be measured.

[0022] Among them, such as Figure 2 As shown, the first light guiding unit includes a first beam splitter 317, a first reflector 308, and a second reflector 309. After passing through the phase shifter, the detection light array is split into two beams by the first beam splitter 317. One beam is transmitted light and is incident on the atomic gas cell 4 along the X direction. The other beam is reflected light and is reflected by the first reflector 308 and the second reflector 309 respectively and is incident on the atomic gas cell 4 along the Y direction. The second light guiding unit includes a second beam splitter 318, a first dichroic mirror 319, and a second dichroic mirror 315. The coupled light array formed by the coupled light array editor 314 is split into two beams after passing through the second beam splitter 318. One beam is reflected light and is reflected by the first dichroic mirror 319 and is incident on the atomic gas cell 4 along the -Y direction. The other beam is transmitted light and is reflected by the second dichroic mirror 315 and is incident on the atomic gas cell 4 along the -X direction. The detection light array in the X direction after passing through the atomic gas chamber 4 is transmitted through the second dichroic mirror 315, and then is focused by the lens and incident on the signal detection module 14; the detection light array in the Y direction after passing through the atomic gas chamber 4 is transmitted through the first dichroic mirror 319, and then is focused by another lens and incident on the signal detection module 14.

[0023] Specifically, the first beam splitter 317 and the second beam splitter 318 are polarization beam splitting prisms, and a half-wave plate is arranged in front of the polarization beam splitter prisms to adjust the splitting ratio of the transmitted light and the reflected light.

[0024] Specifically, in this embodiment, the detection beam array editor 306 and the coupling beam array editor 314 are used to edit the corresponding lasers into a laser array formed by multiple parallel laser beams with uniform success rate. The arrangement of the laser array can be a one-dimensional linear arrangement or a two-dimensional triangular arrangement, a square arrangement, etc.

[0025] It should be noted that in the atomic cell 4, each of the probe light in the probe light array is reversely coincided with one of the coupling light in the coupling light array to prepare the atoms at the corresponding position to the Rydberg state.

[0026] Further, the microwave source omnidirectional positioning measurement device of the embodiment further comprises an EIT module 305, a first light splitting component and a second light splitting component; a part of the probe light emitted by the probe laser 301 is split by the first light splitting component and then incident to the EIT module 305, a part of the coupling light emitted by the coupling laser 311 is split by the second light splitting component and then incident to the EIT module 305, and the incident direction is reversely coincided with the incident direction of the probe light to the EIT module; the EIT module 305 is used to assist the frequency tuning of the probe laser 301 and the coupling laser 311 to make the atoms in the atomic cell 4 produce stable electromagnetic induced transparency effect. Specifically, whether the frequency of the probe light and the coupling light is tuned to the right position can be determined by observing whether the EIT effect of the atoms in the EIT module is stable.

[0027] The first light splitting component comprises a first half-wave plate 302 with a wavelength equal to that of the probe light and a first polarization light splitting prism 303, and the second light splitting component comprises a second half-wave plate 312 with a wavelength equal to that of the coupling light and a second polarization light splitting prism 313. Through the combination of the half-wave plate and the polarization light splitting prism, the continuous adjustment of the light intensity can be realized.

[0028] Further, as shown in Figure 1 and 2 The light source component 3 of the microwave source omnidirectional positioning measurement device of the embodiment further comprises a third light splitting component and a saturated absorption spectrum device 304, and a part of the probe light emitted by the probe laser 301 is split by the third light splitting component and then incident to the saturated absorption spectrum device 304, and the saturated absorption spectrum device is used to obtain the saturated absorption spectrum and then lock the frequency of the probe laser 301 at the center of the atomic absorption peak.

[0029] Specifically, as shown in Figure 1 In the embodiment, the signal detection module 14 comprises two photodetectors 5, a spectrum analyzer 9, a lock-in amplifier 10, an oscilloscope 11 and a signal processing terminal 12. After passing through the atomic cell 4, the two probe light arrays are respectively focused by a lens and then detected by one photodetector 5, and the detection signal is sent to the spectrum analyzer 9, the lock-in amplifier 10 and the oscilloscope 11. The oscilloscope 11 is used to output the double-peak frequency difference value in the ATS spectrum. ∆f，The phase-locked amplifier 10 is used to output the phase of the to-be-detected microwave at each receiving point; the spectrum analyzer 9 is used to perform spectrum analysis to obtain the frequency difference between the to-be-detected microwave and the local microwave; and the signal processing terminal 12 is used to calculate the frequency, intensity and direction of the to-be-detected microwave according to the output of the spectrum analyzer 9, the phase-locked amplifier 10 and the oscilloscope 11.

[0030] Specifically, the intensity of the to-be-detected microwave and the double-peak frequency difference value in the ATS spectrum Delta f correlation, The frequency of the to-be-detected microwave can be obtained from the frequency of the beat signal obtained by the spectrum analyzer and the frequency of the local microwave, and the direction of the to-be-detected microwave can be obtained according to the phase information of the to-be-detected microwave at each receiving point.

[0031] In addition, in the embodiment, the spectrum analyzer 9 performs spectrum analysis on the output signal of the photodetector 5 to obtain the frequency component and the power distribution; in addition, the noise floor power and the beat signal power amplitude of the to-be-detected microwave electrical signal can also be obtained, and the signal-to-noise ratio (SNR) can be calculated by taking the ratio of the two, while constantly optimizing the local microwave parameters, recording the change of the corresponding beat signal power value and establishing a linear relationship, obtaining the optimal signal-to-noise ratio (SNR) according to the ratio, determining the local microwave frequency, and finally combining the linear relationship with the minimum beat signal power (just above the noise floor power) detected by the spectrum analyzer 9, the corresponding electric field intensity, and the minimum detectable intensity (sensitivity) of the to-be-detected microwave electric field can be obtained; in addition, the electrical signal output by the photodetector 5 is output to the oscilloscope 11, and the time-domain waveform of the electrical signal can also be observed to confirm the frequency and amplitude stability of the beat signal, and the electric field intensity of the to-be-detected microwave can be calculated according to the double-peak frequency difference value ∆f， in the ATS spectrum; on the other hand, the electrical signal output by the photodetector 5 is output to the phase-locked amplifier 10, and through the phase-locked amplifier 10, signals of a specific frequency can be extracted from noise, and the phase information of the signals is extracted by using the phase-sensitive detection technology, that is, the phase information of each laser beam in the laser array is obtained, and the omnidirectional measurement of the to-be-detected microwave is realized through the phase difference. In the signal detection module 14, the measurement results of the phase-locked amplifier 10 and the spectrum analyzer 9 are both sent to the signal processing terminal 12 for further processing.

[0032] The photodetector 5 includes a plurality of probes arranged in the same manner as the detection light array to realize the detection of each detection light beam in each detection light array.

[0033] Further, the microwave source omnidirectional positioning measurement device in the embodiment further comprises a first beam splitter 6, a second beam splitter 13 and a performance evaluation module, the performance evaluation module comprises a noise detection module, a thermal noise detection module and a line width detection module; the probe light array after the atomic gas chamber 4 is split by the first beam splitter 6 to form a part of light incident to the second beam splitter 13, and then enters the noise detection module, the thermal noise detection module and the line width detection module after being split by the second beam splitter 13; the noise detection module is used for determining the noise characteristics of the measurement signal by single photon counting; the cavity filtering detection module is used for determining the thermal noise of the measurement signal by single photon counting after the probe light array signal is denoised by the FP cavity, and the line width detection module is used for obtaining the line width of the beat frequency signal and analyzing the laser noise.

[0034] Specifically, the noise detection module counts and measures the probe light array after the atomic gas chamber 4 by the single photon detector to determine the noise characteristics of the measurement signal; the thermal noise detection module is used for denoising the probe light array signal by the FP cavity, and inputting the denoised light signal to the single photon detector for counting measurement, so as to remove the non-thermal noise in the system, obtain the thermal noise, and evaluate the performance of the measurement device; the line width detection module is used for obtaining the line width of the beat frequency signal and analyzing that the laser phase noise is dominant; the detection signals of the noise detection module, the thermal noise detection module and the line width detection module are all sent to the signal processing terminal 12 for processing, the signal processing terminal 12 comprehensively processes all the measurement signals, and finally obtains the performance of the measurement device, which provides a direction for subsequent measurement result optimization.

[0035] Further, in the embodiment, the performance evaluation module 7 further comprises a self-defined detection module, and the probe light array after the first beam splitter 6 is split by the second beam splitter 13 into a plurality of beams, one of which enters the self-defined detection module for other types of detection.

[0036] Specifically, in the embodiment, the wavelength of the probe laser 301 is 852 nm, and the wavelength of the coupling laser 311 is 510 nm. The atoms in the atomic gas chamber 4 are cesium atoms.

[0037] Further, in the embodiment, the probe laser 301 uses a semiconductor laser of Toptica SHG Pro from Toptica, and the coupling laser 311 uses an external cavity semiconductor laser of Toptica SHG Pro from Toptica; the signal generator 2 uses N5183B from Keysight; the photodetector 5 uses DET-10A from Thorlabs; the lock-in amplifier uses Model SR830 from STANFORD; and the oscilloscope uses MDO34 from Tektronix.

[0038] The embodiment utilizes the atomic receiver array formed by the probe light array and the coupling light array in the atomic cell, and can realize omnidirectional measurement of a microwave source, and has high measurement accuracy and sensitivity. The measurement principle of the embodiment is introduced below.

[0039] (1) Measurement efficiency (sensitivity) of a single atomic receiver.

[0040] The effective value E of the electric field intensity at the target position is estimated according to the standard antenna formula (IEEE Std 1309-2013). cal The effective value E of the electric field intensity at the target position can be represented as: ; (1) Wherein, d is the distance from the antenna to the target position (in m), g is the directional gain of the antenna (dimensionless linear unit), η is the wave impedance in free space (η = 377 Ω in air), P MW is the set power of the signal source, α l is the insertion loss from the signal source to the antenna (dimensionless linear unit), and is in units of V·m −1 1 V·m −1 = 0.01 V·cm −1 .

[0041] In an embodiment of the present invention, a typical quantum coherence effect, the electromagnetically induced transparency effect (EIT), is used to realize the preparation of the Rydberg state of the atom. The energy level frequency shift of the Rydberg atom can be read out all-optically through the electromagnetically induced transparency (EIT) spectrum, and the microwave information will eventually be reflected in the absorption change of the detection laser. By introducing a microwave field corresponding to a specific frequency, the adjacent Rydberg states are coupled to form a resonant bright state. In the Rydberg EIT spectrum, the spectrum at the resonant position will be split into two transmission peaks, which is the Autler-Townes Splitting (ATS) effect. The double-peak frequency difference Δf in the ATS spectrum is closely related to the field intensity of the microwave field and the transition dipole moment of the Rydberg state, and is described by the following mathematical formula: ; (2) ; (3) Among them, the coefficient k Characterizes the Doppler mismatch between the probe light and the coupled light. k When the detection light is scanned k for . and are the wavelengths of pump light and probe light, Ω MW represents the Rabi frequency of the microwave field, Mu MW is expressed as the transition dipole moment, E mea represents the intensity of the microwave field, represents the simplified Planck constant. In summary, the double peak frequency difference in the ATS spectrum can be obtained ∆f The relationship between it and the microwave electric field intensity is: ; (4) Therefore, the double peak frequency difference in the ATS spectrum is obtained by measuring ∆f， The measured value of microwave electric field strength can be calculated By performing a series of measurements corresponding to different microwave field intensities, the measurement efficiency of the Rydberg atomic receiver can be evaluated. , and its calculation formula is: ; (5) (2) The influence of the atomic receiver array formed by arranging the detection light array and the coupling light array in the atomic gas chamber on the sensitivity.

[0042] In the process of arranging the atomic receivers into an array, there are two factors that have a significant impact on the measurement sensitivity: the number of atoms participating in the measurement process and the total power of the probe light. The number of atoms participating in the measurement process increases linearly with the number of atomic receivers , and the receiving area, and the final gain effect can be represented as: ; (6) where , , are the number of atoms participating in the measurement in a single receiver, the beam diameter, and the cell length, respectively. , and represent the number of atoms participating in the measurement, the beam diameter, and the cell length of the reference standard atomic receiver, respectively.

[0043] The total power of the probe light is converted into an output voltage by the photodetector, which can be calculated by the detector gain formula: ; (7) where is the wavelength response coefficient of the detector, is the corresponding photoelectric conversion factor of the detector, is the load resistance, is the intrinsic resistance of the photodiode, is the corresponding probe light power of the reference standard atomic receiver. Based on the Fourier transform principle, the voltage growth has a nearly linear growth contribution to the total output power of the spectrometer.

[0044] Therefore, the ratio of the sensitivity of a single atomic receiver to the total sensitivity of the array can be calculated by the following formula: ; (8) That is, the measurement device of the present embodiment can effectively improve the induction and reception capability of the atomic receiver for radio waves by constructing a Rydberg atomic receiver array and arranging and nesting the Rydberg atomic receivers, thereby greatly improving the sensitivity of the system measurement.

[0045] Embodiment Two As shown in Figures 3-4 , the present application is a microwave source omnidirectional positioning measurement method based on the device described in Embodiment One, which includes the following steps: Step one: introduce a reference light with the same frequency as the probe light, make the reference light interfere with each laser beam in the probe light array respectively, observe the shape, spacing and stability of each interference fringe, and adjust the phase of each laser beam in the probe light array through the phase shifter (307) to make each interference fringe the same; through the above steps, the equal phase surface of each laser beam in the probe light array can be located on the equal phase surface of the incident wave, the wavefront phase difference can be reduced, and then the laser array can realize coherent superposition, and the system measurement sensitivity can be improved.

[0046] In this embodiment, if each laser beam in the probe light array is not on the equal phase surface, there will be a wavefront phase difference when the microwave signal reaches different beam positions, which will cause the coherence of each channel signal to decrease and the signal-to-noise ratio (SNR) to decrease. Each beam of the probe array needs to maintain coherent superposition with the microwave signal to maximize the signal strength and suppress noise. If the phase difference is too large (such as > 90 degrees), the signals of each channel may be weakened due to phase cancellation, or even cause the array enhancement effect to fail. By adjusting the equal phase surface of each laser beam in the probe light array through the phase shifter, the equal phase surface of the microwave can be placed on the equal phase surface of the microwave, the wavefront phase difference can be minimized, the signal coherent superposition effect can be enhanced, and thus the sensitivity and signal-to-noise ratio of the Rydberg atom receiver can be improved.

[0047] Step two: the signal detection module 14 measures the probe light array passing through the atomic gas chamber 4 to obtain the preliminary information of the to-be-measured microwave at the receiving point position of each probe light in the probe light array; The preliminary information of the to-be-measured microwave includes: the intensity, frequency information and direction information of the to-be-measured microwave. Among them, the field strength of the to-be-measured microwave can be obtained according to the double-peak frequency difference Δf of the ATS spectrum displayed on the oscilloscope. f The calculation result is ， Since the frequency of the local microwave is different from that of the to-be-measured microwave, the frequency information of the to-be-measured microwave can be obtained by analyzing the beat frequency signal in the electrical signal output by the optical-electrical detector 5 through the spectrum analyzer 9; and the direction information of the target microwave can be obtained by combining the phase information of each atomic receiver obtained through the phase-locked amplifier 10 with the triangulation method.

[0048] In addition, in this embodiment, the noise floor of the electrical signal, the signal-to-noise ratio (SNR), and the sensitivity (the minimum detectable intensity of the microwave electric field) can also be obtained through the signal detection module 14; among them, the noise floor of the electrical signal, the signal-to-noise ratio, the frequency information and the sensitivity can be obtained through the spectrum analyzer 9.

[0049] Step three: optimize the frequency and amplitude parameters of the local microwave electric field, and repeat the measurement to obtain the final information of the to-be-measured microwave at the receiving point position of each probe light in the probe light array.

[0050] Specifically, the optimization method is: changing the frequency and amplitude of the local microwave electric field, observing the trend of the amplitude of the beat frequency signal in the electric signal detected by the photodetector 5 with the local microwave parameters through the oscilloscope 11, and observing the trend of the noise floor with the local microwave parameters through the spectrum analyzer 9; finding the local microwave parameters (frequency and amplitude) that maximize the amplitude of the beat frequency signal and minimize the noise impact, to maximize the response sensitivity and signal-to-noise ratio (SNR) of each atomic receiver.

[0051] Further, the step one further comprises the following steps: changing the beam spacing in the probe light array and the coupling light array through the probe light beam array editor 306 and the coupling light beam array editor 314, measuring the EIT-AT split spectrum of the probe light array through the signal detection module 14, screening out the light beam spacing with the strongest EIT-AT split spectrum signal, and controlling the probe light array and the coupling light array to be the corresponding light beam spacing. At this time, the probe array in the photodetector 5 should be arranged in accordance with the arrangement of the probe light beam array.

[0052] Specifically, in the embodiment, the specific method for determining the orientation of the to-be-measured microwave is as follows: Obtaining the phase information of the to-be-measured microwave at the receiving point position of each probe light in the probe light array; Calculating the angle between the receiving point and the to-be-measured microwave source in the probe light array according to the phase difference; Determining the orientation of the to-be-measured microwave through triangulation combined with the positions of the receiving points and the multiple angles .

[0053] Specifically, based on the positioning principle of triangulation, the embodiment can realize the specific position positioning of the microwave source. When the laser array interacts with the atomic cell, it is equivalent to that there are multiple microwave receiving points, and the phase difference of the signal phase received from the unknown microwave source at each receiving point will be different. The phase information of the microwave signal carried in the probe light at each receiving point can be extracted through the phase-locked amplifier 10. According to the principle of triangulation, when the position coordinates of two receiving points and the phase difference of the microwave signals received by them are known, the angle of the microwave source relative to the two receiving points can be calculated. For example, if there are receiving points A and B, and the phase difference of the signal from the microwave source reaching A and B is Δφ, then the calculation formula of the angle between the A and B receiving points and the to-be-measured microwave source is: ; (8) Where Δφ represents the phase difference of the to-be-measured microwave at the positions of the two receiving points, is the wavelength of the microwave, is the distance between the two receiving points, is the angle between the microwave source and the two receiving points.

[0054] Therefore, if there are three or more receiving points, the specific position of the microwave source can be determined through the intersection positioning of multiple angles. In the embodiment, the detection light array formed after passing through the detection light beam array editor (306) includes at least 3 parallel laser beams.

[0055] Further, the microwave source omnidirectional positioning measurement method of the embodiment further includes the following steps: Step four: measure the noise characteristics, thermal noise characteristics and signal linewidth of the measurement signal through the performance evaluation module, optimize the device performance according to the measurement results, and improve the measurement accuracy.

[0056] Specifically, in the embodiment, as shown in Figure 4 The performance evaluation module can realize multi-parameter evaluation of the device, which specifically includes: (1) Noise detection module: The noise detection module performs photon counting on the detection light array through a single-photon detector and records data to determine the noise characteristics of the measurement signal. During detection, first record the total photon rate when the microwave field is turned on, then turn off the microwave field and record the total noise photon rate; during measurement, if the photon rate that the detector can respond reliably is greater than 10 7 phot / s, use a calibrated neutral density filter to attenuate to ensure accurate counting.

[0057] Specifically, a superconducting nanowire single-photon detector with a quantum efficiency of 85%, a dark count rate of less than 1 Hz and a recovery time of 35 ns is used for photon counting. The high quantum efficiency of the detector ensures high sensitivity of photon detection, the low dark count rate reduces the interference of background noise on the measurement results, and the appropriate recovery time ensures that the detector can respond to subsequent photon signals in time.

[0058] Specifically, since the upper limit of the photon rate that the detector can respond reliably is about 10 7 phot / s, for signals higher than this value, a calibrated neutral density filter is needed to attenuate to ensure that the detector accurately counts photons within its effective working range, avoiding inaccurate measurement results caused by detector saturation due to too strong signals.

[0059] (2) Thermal noise detection module: The thermal noise detection module uses an optical cavity with a specific spectral width and fineness as a filtering device. The signal to be detected is input into the optical cavity, and the signal undergoes interference and resonance in the cavity. According to the design of the optical cavity structure, only the signal components matching the resonance frequency of the cavity can form a stable standing wave in the cavity, thereby smoothly passing through the optical cavity, while other frequency components will rapidly attenuate in the cavity and cannot pass through, enabling frequency-selective filtering of the input signal. In addition, after filtering by the optical cavity, a superconducting nanowire single-photon detector is used for photon counting and data recording to obtain the thermal noise of the measurement signal. The measurement results are compared with the noise detection module, and it is found that the total photon number decreases. Due to the narrowband characteristics of the optical cavity, the non-thermal noise photons (such as broadband noise such as laser scattering photons) in the system can be significantly reduced through cavity filtering, making the noise measurement results more accurate, the non-thermal noise suppression efficiency improved, and the signal purity improved, providing more reliable data support for further research on the performance improvement of the system.

[0060] (3) Line width detection module: The line width detection module performs photoelectric conversion through a photodetector to obtain an electrical signal input to a spectrum analyzer 9. The line width (frequency width when the power spectral density decreases to half of the peak value) of the beat frequency signal of the atomic gas chamber at low temperature and room temperature is measured by the spectrum analyzer 9 to analyze the factors affecting the line width. First, the temperature of the atomic gas chamber is lowered below room temperature, making the atomic density in the atomic gas chamber extremely low, and the line width of the beat frequency signal is measured which can be regarded as pure laser phase noise; second, the room temperature is restored, and the line width of the beat frequency signal is measured (including laser phase noise and atomic noise); since the two types of noise are independent and unrelated, the total line width satisfies: , and the difference can be calculated as . By comparing the numerical values in the experiment, it is found that , and it is analyzed that the signal line width is mainly dominated by the laser phase noise, which indicates the direction for subsequent optimization, and the frequency locking accuracy needs to be further improved.

[0061] (4) Custom detection module: The custom detection module is an additional detection port of the multi-parameter detection module, which has no specific limit and can define related quantity detection according to actual needs.

[0062] Therefore, in the embodiment of the present application, the noise characteristics of the measurement signal, the thermal noise characteristics and the signal line width are measured by the performance evaluation module, which is beneficial to optimizing the device performance according to the measurement results, such as improving the frequency locking accuracy, removing non-thermal noise, and improving the accuracy of the microwave omnidirectional measurement.

[0063] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A microwave source omnidirectional positioning measurement device, characterized in that: include: A light source assembly (3), a signal generator (2), an atomic gas chamber (4), and a signal detection module (14); the signal generator (2) is used to emit local oscillation microwaves to the atomic gas chamber (4); The light source assembly (3) includes a detection laser (301), an EIT module (305), a coupling laser (311), a coupling beam array editor (314), a detection beam array editor (306), and a phase shifter (307); The detection light emitted by the detection laser (301) is formed into a detection light array after passing through the detection beam array editor (306). The detection light array is phase-adjusted by the phase shifter (307), and then divided into two detection light arrays by the first light guide unit and incident on the atomic gas chamber (4) from two mutually perpendicular directions. The phase shifter (307) is used to change the phase of each detection light in the detection light array so that it is located on the phase plane of the microwave to be measured. The coupling light emitted by the coupling laser (311) is separated by a second light splitting component, and a portion of the light is incident on the EIT detection module (305) in an opposite direction and overlaps with the first detection signal; the remaining laser light is formed into a coupling light array with the same arrangement as the detection light array after passing through a coupling light array editor (314); the coupling light array is divided into two coupling light arrays by a second light guide unit, and the two coupling light arrays are respectively incident on the atomic gas chamber (4) in an opposite direction and overlap with the two detection light arrays, so that the atoms in the atomic gas chamber (4) produce an electromagnetically induced transparency effect, thereby forming an atomic receiver array; The two detection light arrays after passing through the atomic gas chamber (4) are respectively focused by lenses and then incident on the signal detection module (14); The signal detection module (14) is used to detect the signals of the two detection light arrays respectively, and obtain the omnidirectional parameters of the microwave source to be measured.

2. The microwave source omnidirectional positioning measurement device according to claim 1, characterized in that: Also included is an EIT module (305), a first light splitting component, and a second light splitting component; The detection light emitted by the detection laser (301) is split into a portion incident on the EIT module (305) after passing through the first light splitting component, and the coupling light emitted by the coupling laser (311) is split into a portion incident on the EIT detection module (305) after passing through the second light splitting component, and the incident direction is opposite to that of the detection light incident on the EIT module; The EIT module (305) is used to assist in frequency tuning of the detection laser (301) and the coupling laser (311), so that they can interact with atoms in the atomic gas chamber (4) to generate a stable electromagnetically induced transparency effect.

3. The microwave source omnidirectional positioning measurement device according to claim 1, characterized in that: The light source assembly (3) further comprises a saturation absorption spectrum device (304), and the saturation absorption spectrum device (304) is used to lock the frequency of the detection laser (301) at the center of the atomic absorption peak.

4. The microwave source omnidirectional positioning measurement device according to claim 1, characterized in that: The signal detection module (14) includes two photodetectors (5), a spectrum analyzer (9), a phase-locked amplifier (10), an oscilloscope (11) and a signal processing terminal (12). The two detection light arrays after passing through the atomic gas chamber (4) are respectively focused by a lens and detected by a photodetector (5). The detection signal is sent to the spectrum analyzer (9), the phase-locked amplifier (10) and the oscilloscope (11). The oscilloscope (11) is used to output the double peak frequency difference in the ATS spectrum. ∆f， The phase-locked amplifier (10) is used to output the phase of the microwave to be measured at each receiving point; the spectrum analyzer (9) is used to perform spectrum analysis to obtain the frequency difference between the microwave to be measured and the local oscillator microwave; and the signal processing terminal (12) is used to calculate the frequency, intensity and direction of the microwave to be measured based on the outputs of the spectrum analyzer (9), the phase-locked amplifier (10) and the oscilloscope (11).

5. The microwave source omnidirectional positioning measurement device according to claim 1, characterized in that: The invention also includes a first beam splitter (6), a second beam splitter (13) and a performance evaluation module, wherein the performance evaluation module includes: a noise detection module, a thermal noise detection module and a line width detection module; the detection light array after passing through the atomic gas chamber (4) splits a portion of light through the first beam splitter (6) and enters the second beam splitter (13), and then enters the noise detection module, the thermal noise detection module and the line width detection module respectively after being split by the second beam splitter (13); the noise detection module is used to determine the noise characteristics of the measurement signal through single photon counting; the thermal noise detection module is used to reduce the noise of the detection light array signal through the FP cavity and then determine the thermal noise of the measurement signal through single photon counting; the line width detection module is used to obtain the line width of the beat frequency signal and analyze the laser noise.

6. A microwave source omnidirectional positioning measurement method, implemented based on a microwave source omnidirectional positioning measurement device according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: Introduce reference light with the same frequency as the detection light, make the reference light interfere with each laser beam in the detection light array, observe the shape, spacing and stability of each interference fringes, and adjust the phase of each laser beam in the detection light array through the phase shifter (307) to make each interference fringes the same; Step 2: measuring the detection light array passing through the atomic gas chamber (4) through the signal detection module (14) to obtain preliminary information of the microwave to be measured at the receiving point position of each detection light in the detection light array; Step three: Optimize the frequency and amplitude parameters of the local oscillator microwave electric field, repeat the measurement, and obtain the final information of the microwave to be measured at the receiving point position of each detection light in the detection light array through the signal detection module (14).

7. The microwave source omnidirectional positioning measurement method according to claim 6, characterized in that: The step 1 further comprises the following steps: The beam spacing in the detection light array and the coupling light array is changed by using a detection beam array editor (306) and a coupling beam array editor (314), the detection light array is measured by using a signal detection module (14) to obtain an EIT-AT splitting spectrum, the beam spacing with the strongest EIT-AT splitting spectrum signal is screened out, and the detection light array and the coupling light array are controlled to have the corresponding beam spacing.

8. The microwave source omnidirectional positioning measurement method according to claim 6, characterized in that: The information of the microwave to be measured includes intensity, frequency and direction. The specific method for determining the direction of the microwave to be measured is: Obtaining the phase information corresponding to the receiving point of each detection light; Calculate the angle between the receiving point of each detection light in the detection light array and the line connecting the microwave source to be measured. The calculation formula is: ； in, Indicates the phase difference of the microwave to be measured at the two receiving points. is the microwave wavelength, is the distance between the two receiving points, is the angle between the microwave source to be measured and the two receiving points; Through the angle cross positioning algorithm, the positions of each receiving point and multiple angles are combined , determine the direction of the microwave to be measured.

9. The microwave source omnidirectional positioning measurement method according to claim 6, characterized in that: The following steps are also included: Step 4: Use the performance evaluation module to measure the noise characteristics, thermal noise characteristics, and signal linewidth of the measurement signal. Optimize device performance based on the measurement results to improve measurement accuracy.

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