A frequency spectrum monitoring device for a scanning atomic heterodyne receiver

Abstract

The application provides a spectrum monitoring device of a scanning atomic heterodyne receiver, comprising a Rydberg module, a radio frequency module and a spectrum module in communication connection with the Rydberg module, the radio frequency module inputs a first local oscillation signal into an atomic chamber and inputs a signal to be measured into the atomic chamber along a direction parallel to a laser propagation direction in the atomic chamber; the Rydberg module comprises a resonant cavity and a photoelectric detector, the resonant cavity prepares first high excited state Rydberg atoms in the atomic chamber; the resonant cavity prepares second high excited state Rydberg atoms through the atomic chamber, and the photoelectric detector outputs a beat frequency signal between the signal to be measured and a second local oscillation signal to the spectrum module; the spectrum module performs fast Fourier transform processing on the beat frequency signal to obtain spectrum information of the signal to be measured. The application can produce high sensitivity and fast response to multiple discrete frequency point signals, and realizes continuous seamless spectrum monitoring without the need to separately construct a complex multi-stage frequency conversion link for a low frequency band.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic spectrum monitoring, and more specifically to a spectrum monitoring device for a scanning atomic heterodyne receiver. Background Technology

[0002] In the field of electromagnetic spectrum monitoring, achieving high-resolution, wide-bandwidth signal reception and processing has long been a technical challenge. Traditional solutions mostly rely on a scanning heterodyne receiver architecture with multi-stage mixing and segmented filtering. This approach not only results in a complex, lengthy, bulky, and costly system, but also makes it difficult to achieve seamless wideband continuous coverage while maintaining high sensitivity when extending from high frequencies to low frequencies, due to limitations in the local oscillator tuning range, link noise accumulation, and the frequency response characteristics of each component.

[0003] Traditional scanning heterodyne receivers, in order to analyze high-frequency signals, typically employ a multi-stage mixer structure to convert the radio frequency signal to an intermediate frequency (IF), and then use a narrowband filter to extract the spectral information. (See attached image) Figure 1 As shown, a traditional scanning heterodyne receiver receives a signal through an antenna, which is then sequentially processed by a multi-stage pre-selective filter, a multi-stage mixer, and corresponding sweep-frequency mixing local oscillator signal sources. The local oscillator tuning is coordinated by a sweep generator, and the final signal is output to a spectrum display unit after intermediate frequency (IF) filtering and envelope detection, achieving high-resolution monitoring of high-frequency signals. However, this approach has significant limitations: First, traditional scanning heterodyne receivers rely on multi-stage frequency conversion and filtering, resulting in inherent limitations such as complex system structure, large size, significant noise accumulation, and difficulty in high-frequency extension. Second, the spectral resolution of this approach depends on the IF filter bandwidth. Since IF filters cannot achieve narrowband filtering at higher frequencies, traditional monitoring methods often require multi-stage mixing to convert the target frequency to a lower "IF" to achieve high-resolution monitoring of the target signal spectrum in order to maintain spectral resolution.

[0004] In recent years, quantum sensing technology based on Rydberg atoms has provided a new approach to overcoming the aforementioned bottlenecks. This technology utilizes the extremely high inherent sensitivity and naturally narrow linewidth of atoms to specific resonance frequencies, potentially significantly simplifying the receiving link. However, a fundamental contradiction remains in achieving continuous wideband monitoring, especially in low-frequency coverage: if Rydberg states with extremely high principal quantum numbers are used to directly respond to low frequencies, the sensitivity advantage is lost due to difficulties in state preparation and spectral broadening; if external field modulation is used to broaden the response bandwidth, such as the AC-Stark effect, it comes at the cost of sacrificing quality factors such as Q-value and sensitivity. Therefore, developing a spectrum monitoring method or system that can simultaneously achieve continuity, high sensitivity, and high resolution across the entire frequency band, especially in the low-frequency band, remains a core technical problem that urgently needs to be solved.

[0005] The patent document with publication number CN118707188A discloses a signal spectrum monitoring system based on Rydberg atoms. This scheme uses a first signal processing device and a second signal processing device to perform multiple frequency conversions on external broadband radio signals. Then, it uses the frequency conversion of the Rydberg atom device and the spectrum processor to collect spectrum information and splice the spectrum, thereby realizing the spectrum monitoring and output of external broadband radio signals. However, although this scheme provides more accurate frequency control through a two-stage mixing link of step sweep frequency and fixed frequency conversion, it has the following defects: (1) It is difficult to achieve fast response and cannot adapt to capturing transient signals, monitoring rapidly changing and low-frequency electromagnetic environments; (2) A large number of filtering and amplification modules need to be introduced during mixing, resulting in redundant equipment, large size, and increased cost; the multi-stage mixing process is prone to introducing additional noise, degrading the system signal-to-noise ratio and restricting the detection sensitivity of weak signals; (3) High-frequency monitoring has strict requirements on the tuning range and stability of the local oscillator signal, resulting in a complex system architecture and high implementation difficulty. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a spectrum monitoring device for a scanning atomic heterodyne receiver, which can generate a high-sensitivity and fast response to multiple discrete frequency signals distributed across a wide frequency band, including low-frequency electric fields of 10-50MHz. This effectively overcomes the problem of low-frequency signal coverage in existing technologies, and achieves continuous and seamless spectrum monitoring from 10MHz to 40GHz without the need to construct complex multi-stage frequency conversion links separately for low-frequency bands.

[0007] A spectrum monitoring device for a scanning atomic heterodyne receiver includes a Rydberg module, an RF module and a spectrum module that are communicatively connected to the Rydberg module.

[0008] The radio frequency module inputs the first local oscillator signal into the atomic gas chamber along the direction perpendicular to the laser propagation inside the atomic gas chamber, and inputs the signal to be measured into the atomic gas chamber along the direction parallel to the laser propagation inside the atomic gas chamber. The signal frequency of the signal to be measured is equal to the resonance frequency of the Rydberg atom in the atomic gas chamber transitioning from the first highly excited state to the second highly excited state.

[0009] The Rydberg module includes a resonant cavity with a built-in atomic gas chamber and a photodetector. The resonant cavity prepares first highly excited Rydberg atoms within the atomic gas chamber, wherein the energy levels of the first highly excited Rydberg atoms are... n D 5 / 2 , principal quantum number n For any integer value between 30 and 120; the resonant cavity prepares the second highly excited Rydberg atom through the atomic gas cell; the photodetector outputs the difference frequency signal between the signal to be measured and the first local oscillator signal to the spectrum module, wherein the energy level of the second highly excited Rydberg atom is ( n+ 1) P3 / 2 .

[0010] The spectrum module performs a fast Fourier transform on the difference frequency signal to obtain the spectrum information of the signal under test.

[0011] Furthermore, the radio frequency module includes:

[0012] The pre-selection frequency filtering component includes multiple pre-selection filters arranged in parallel. After receiving the first gating signal, it selects one pre-selection filter to conduct, filters the first signal received from the outside, and outputs the second signal.

[0013] The gating mixer assembly is communicatively connected to the gating pre-selection filter assembly. It includes two mixers arranged in parallel. After receiving the second gating signal, it selects one of the mixers to conduct, mixes the second signal and the second local oscillator signal, and outputs the signal to be measured to the atomic gas cell.

[0014] A frequency sweeping component, which is communicatively connected to a gating mixer component, includes a frequency sweeping mixer local oscillator signal source and a sweep generator communicatively connected to both the frequency sweeping mixer local oscillator signal source and a spectrum module. The frequency sweeping component sends a frequency sweeping control signal to the frequency sweeping mixer local oscillator signal source, which outputs a second local oscillator signal with a continuously and progressively changing frequency to the gating mixer component. The gating mixer component performs segment-by-segment mixing of the second signal using the second local oscillator signal and outputs the signal to be measured to the atomic gas cell.

[0015] The selected mixed-frequency local oscillator component is communicatively connected to the atomic gas cell. It includes multiple mixed-frequency local oscillator signal sources with different signal frequencies. After receiving the third selection signal, it selects one of the mixed-frequency local oscillator signal sources to conduct and outputs a first local oscillator signal with a fixed frequency to the atomic gas cell.

[0016] Furthermore, the Ridgeburg module also includes:

[0017] The probe light introduction component emits 852nm probe light into the resonant cavity from one end of the resonant cavity, causing cesium atoms in the atomic gas cell inside the resonant cavity to transition from the ground state to a low excited state.

[0018] The coupling light introduction component emits 509nm coupled light into the resonant cavity from the other end. Cesium atoms in the atomic gas cell within the resonant cavity are excited from a low-excited state (6D). 3 / 2 Transition to the first highly excited state n D 5 / 2 ;

[0019] The radio frequency signal introduction component outputs the signal to be measured and the first local oscillator signal to the resonant cavity. Cesium atoms in the atomic gas cell within the resonant cavity are in a first highly excited state. nD 5 / 2 Transition to the second most excited state ( n+ 1) P 3 / 2 .

[0020] Furthermore, the probe light introduction component includes a third half-wave plate, a second polarization beam splitter, a fourth half-wave plate, and a second high-reflectivity mirror connected sequentially by optical fibers. After the 852nm probe light is frequency-locked, it is incident on the probe light introduction component and passes sequentially through the third half-wave plate, the second polarization beam splitter, the fourth half-wave plate, and the second high-reflectivity mirror before exiting into the resonant cavity.

[0021] The coupling light introduction component includes a first high reflectivity mirror, a first half-wave plate, a first polarization beam splitter, and a second half-wave plate connected sequentially by optical fibers. After frequency locking, the 509nm coupling light is incident on the coupling light introduction component, passes sequentially through the first high reflectivity mirror, the first half-wave plate, the first polarization beam splitter, and the second half-wave plate, and then exits into the resonant cavity.

[0022] The resonant cavity also includes a second dichroic mirror connected to the second high-reflectivity mirror via an optical fiber and a first dichroic mirror connected to the second half-wave plate via an optical fiber. The probe light incident into the resonant cavity is reflected by the second dichroic mirror and then incident horizontally and parallel to the atomic gas cell on one side. The cesium atoms in the atomic gas cell are in their ground state 6S... 1 / 2 Transition to the low-excited state 6P 2 / 3 The coupled light incident into the resonant cavity is reflected by the first dichroic mirror and then incident horizontally and parallel to the direction opposite to the probe light into the atomic gas cell. The cesium atoms in the atomic gas cell are in the low-high excited state 6P. 2 / 3 Transition to the first highly excited state nD 5 / 2 The electromagnetically induced transparent spectral signal emitted from the atomic gas cell is transmitted through the first dichroic mirror and then emitted to the photodetector.

[0023] Furthermore, the radio frequency signal introduction component outputs the signal to be measured to the atomic gas cell along the direction of the coupled light emission on one side of the atomic gas cell, and outputs the first local oscillator signal to the atomic gas cell above the atomic gas cell in a direction perpendicular to the coupled light or the probe light. The cesium atoms in the atomic gas cell are in the first highly excited state nD. 5 / 2 Transition to the first highly excited state (n+1)P 3 / 2 The electromagnetically induced transparent spectrum signal under the influence of the test signal and the first local oscillator signal is emitted from the atomic gas cell to the photodetector. The photodetector outputs the difference frequency signal between the test signal and the first local oscillator signal to the spectrum module.

[0024] Furthermore, the principal quantum number n It can be any integer value between 50 and 100.

[0025] Furthermore, the principal quantum number n It is 58 or 90.

[0026] Furthermore, the radio frequency module also includes:

[0027] The first power module is communicatively connected to the pre-selection frequency filter component. It is used to generate a first gating control signal according to the signal frequency band corresponding to the signal frequency of the externally received first signal, turn on the pre-selection frequency filter of the corresponding frequency band and filter the first signal, and output a second signal. The signal frequency band corresponding to the signal frequency of the first signal includes 10MHz to 50MHz and 50MHz to 40GHz.

[0028] The second power module is communicatively connected to the gating mixer component. It is used to generate a second gating control signal based on the signal frequency band corresponding to the received second signal frequency and the received sweeping second local oscillator signal. This signal controls the gating mixer component to turn on the mixer in the corresponding frequency band and perform mixing processing on the second signal and the second local oscillator signal, outputting the signal to be measured.

[0029] The third power module is communicatively connected to the selected mixed-frequency local oscillator component. It is used to generate a third gating control signal according to the signal frequency band corresponding to the received signal under test, and control the selected mixed-frequency local oscillator component to turn on the mixed-frequency local oscillator signal source of the corresponding frequency band, and output the first local oscillator signal to the atomic gas cell.

[0030] The beneficial effects of this invention are as follows:

[0031] 1. The spectrum monitoring device of the present invention directly converts the frequency to the atomic resonance frequency by using a pre-selection filter component and a pre-selection mixer component. Then, it prepares first and second Rydberg atoms from cesium atoms by using probe light and coupling light to reach specific Rydberg energy levels. Then, it utilizes the natural resonance characteristic of cesium atoms to signal frequencies that match their energy level differences to achieve high-sensitivity detection of the signal to be measured. The measured sensitivity is better than -150dBm / Hz, and the dynamic range reaches 65dB.

[0032] 2. Compared to the complex two-stage frequency conversion and multi-channel parallel processing of existing technologies, where each channel includes devices such as limiters, digitally controlled attenuators, signal amplifiers, and complex control switching systems, the spectrum monitoring device of the scanning atomic heterodyne receiver described in this invention achieves single-stage frequency conversion through a pre-selective filter component and a gating mixer component. This not only significantly reduces the size of the equipment, the number of electronic components, and noise accumulation, but also achieves a scanning rate ≥1GHz / s, enabling rapid response. This allows it to adapt to capturing transient signals and monitoring rapidly changing electromagnetic environments. It solves the technical problems of needing to introduce a large number of filtering and amplification modules during mixing, resulting in redundant equipment, large size, and increased costs; and the fact that multi-stage mixing processes easily introduce additional noise, degrading the system's signal-to-noise ratio and limiting the sensitivity to weak signals.

[0033] 3. This invention synchronously excites and utilizes multiple Rydberg levels using a Rydberg module, enabling it to simultaneously generate a highly sensitive response to multiple discrete frequency signals distributed across a wide frequency band, including low-frequency electric fields ranging from 10-50MHz. This effectively overcomes the problem of insufficient low-frequency signal coverage in existing technologies. It achieves continuous and seamless spectrum monitoring from 10MHz to 40GHz without requiring the construction of complex multi-stage frequency conversion links for the low-frequency band. Therefore, this invention fundamentally avoids the inherent frequency response limitations and blind spots of traditional solutions that rely on segmented processing. It also solves the technical defects of existing technologies, such as complex system architecture, high cost, low integration, and limited overall performance, which require independent filtering, amplification, and mixing links for different frequency bands. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of a traditional scanning heterodyne receiver;

[0035] Figure 2 This is a schematic diagram of the spectrum monitoring device of a scanning atomic heterodyne receiver according to an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of the structure of the Rydberg atom module according to an embodiment of the present invention;

[0037] Figure 4 This is the energy level diagram corresponding to the preparation of the first Rydberg atom and the preparation of the second Rydberg atom as described in the embodiments of the present invention;

[0038] Figure 5 This is a schematic diagram of continuous spectrum monitoring as described in an embodiment of the present invention;

[0039] Figure 6 This is the spectrum monitoring waterfall diagram described in the embodiments of the present invention;

[0040] Among them, 1-first high-reflectivity mirror, 2-first half-wave plate, 3-first polarization beam splitter, 4-second half-wave plate, 5-third half-wave plate, 6-second polarization beam splitter, 7-fourth half-wave plate, 8-second high-reflectivity mirror, 9-first dichroic mirror, 10-second dichroic mirror, 11-photodetector, 12-mixer, 13-sweep frequency mixing local oscillator signal source, 14-mix fixed frequency local oscillator signal source. Detailed Implementation

[0041] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0042] As attached Figure 2 As shown, this embodiment of the invention provides a spectrum monitoring device for a scanning atomic heterodyne receiver, including a Rydberg module, a radio frequency module and a spectrum module communicatively connected to the Rydberg module. The Rydberg module includes a probe light introduction component, a resonant cavity, a photodetector, a coupling light introduction component, and a radio frequency signal introduction component.

[0043] The radio frequency module inputs the first local oscillator signal into the atomic gas chamber along the direction perpendicular to the laser propagation inside the atomic gas chamber, and inputs the signal to be measured into the atomic gas chamber along the direction parallel to the laser propagation inside the atomic gas chamber. The signal frequency of the signal to be measured is equal to the resonance frequency of the Rydberg atom in the atomic gas chamber transitioning from the first highly excited state to the second highly excited state.

[0044] The first highly excited Rydberg atom was prepared in the resonant cavity within the atomic gas chamber. The energy level of the first highly excited Rydberg atom was... n D 5 / 2 , principal quantum number n The principal quantum number can be any integer value between 30 and 120, such as 30, 31, 32...120. A higher principal quantum number results in higher measured sensitivity and greater sensitivity to weak signals. In this embodiment, to obtain higher detection sensitivity, the principal quantum number... n The value is 58. The resonant cavity prepares the second highly excited Rydberg atom through an atomic gas cell. The energy level of the second highly excited Rydberg atom is ( n+ 1) P 3 / 2 In this embodiment, in order to obtain higher detection sensitivity, the principal quantum number... n+ The value of 1 is 59.

[0045] The photodetector outputs the difference frequency signal between the signal to be measured and the first local oscillator signal to the spectrum module. The spectrum module performs a fast Fourier transform on the difference frequency signal to obtain the spectrum information of the signal to be measured.

[0046] Preferably, the radio frequency module includes a gating pre-selective filter component, a gating mixer component, a sweep frequency component, and a gating mixed-frequency local oscillator component. The gating mixer component is communicatively connected to the gating pre-selective filter component, the sweep frequency component is communicatively connected to the gating mixer component, and the gating mixed-frequency local oscillator component is communicatively connected to the atomic gas cell. The gating pre-selective filter component includes multiple pre-selective filters arranged in parallel, the gating mixer component includes two mixers arranged in parallel, the sweep frequency component includes a sweep mixed-frequency local oscillator signal source and a sweep generator that is communicatively connected to the sweep mixed-frequency local oscillator signal source and the spectrum module, respectively, and the gating mixed-frequency local oscillator component includes multiple mixed-frequency local oscillator signal sources with different signal frequencies.

[0047] The pre-selection filter in the pre-selection filter assembly receives the first gating signal and selects one to conduct the pre-selection filter, filtering the first radio frequency signal to be tested and outputting the second signal; the mixer in the selection mixer assembly receives the second gating signal and selects one to conduct the mixer, mixing the second signal and the second local oscillator signal and outputting the signal to be tested to the atomic gas cell; the sweep generator in the sweep frequency assembly outputs the second gating signal to the selection mixer assembly and sends a sweep frequency control signal to the sweep frequency mixing local oscillator signal source, controlling the sweep frequency mixing local oscillator signal source to output second local oscillator signals of different frequencies to the selection mixer assembly; the mixed fixed frequency local oscillator signal source in the selection mixed fixed frequency local oscillator assembly receives the second gating signal and selects one to conduct the mixed fixed frequency local oscillator signal source, outputting the first local oscillator signal to the atomic gas cell.

[0048] In this embodiment, the pre-selective frequency filtering component is a bandpass or bandstop filter used to pre-select the desired signal frequency and suppress interference from other frequencies before the signal enters the mixer of the receiver. Its main functions are to reduce image frequency interference, reduce noise and spurious signals entering subsequent circuits, and protect the subsequent circuits from being damaged by strong signals. At the same time, the pre-selective frequency filtering component has a switching action that allows the signal to pass only at a specific time or under specific conditions. For example, in this embodiment, a gating signal is used to control the on / off state of the filter, and the signal can only pass when the gating signal is active.

[0049] In this embodiment, the gating mixer component converts the frequency of the input signal to the target frequency band. It uses nonlinear devices to make the input signal "mix" with the second local oscillator signal of different frequencies generated by the system, generating new frequency components. At the same time, the gating control signal controls the mixer to work when the gating signal is valid and to shut down when the gating signal is invalid, so as to avoid interference signals from non-target time periods from entering the processing flow, reduce noise interference, and improve the accuracy of signal processing.

[0050] The core purpose of a sweep generator is to generate a sweep frequency control signal, providing a drive command for the sweep frequency mixing local oscillator signal source to sweep the frequency continuously from low to high frequency by outputting a voltage that rises linearly from low to high. The sweep speed can be changed by adjusting the rate of voltage change. The sweep frequency control signal is a linearly changing voltage signal, such as a sawtooth wave signal or a triangular wave signal.

[0051] A swept-frequency mixer local oscillator signal source is used to generate a local oscillator signal whose frequency can be swept according to a control signal. In conjunction with a gating mixer assembly, it converts a wide-band radio frequency signal (i.e., the second signal) into a frequency band suitable for Rydberg atomic cell detection. Since the frequency range of the radio frequency signal received by the antenna is extremely wide, covering 10MHz to 40GHz, it is impossible to process all frequencies at once using a fixed local oscillator. Therefore, by sweeping the frequency of the swept-frequency mixer local oscillator signal source, the mixer can progressively convert the second signal of different frequencies into a frequency band suitable for Rydberg atomic cell detection. Through this frequency sweeping method, the entire target frequency band of 10MHz to 40GHz is covered, enabling the acquisition and analysis of a wide range of electromagnetic signals.

[0052] Preferably, as shown in the appendix Figure 3 and attached Figure 4 As shown, a resonant cavity is provided, containing an atomic gas cell, a first dichroic mirror 9 located on one side of the atomic gas cell and connected to the atomic gas cell and photodetector via optical fiber, and a second dichroic mirror 10 located on the other side of the atomic gas cell and connected to the atomic gas cell via optical fiber. The probe light introduction assembly includes a third half-wave plate 5, a second polarizing beam splitter 6, a fourth half-wave plate 7, and a second high-reflectivity mirror 8 connected sequentially via optical fiber. The coupling light introduction assembly includes a first high-reflectivity mirror 1, a first half-wave plate 2, a first polarizing beam splitter 3, and a second half-wave plate 4 connected sequentially via optical fiber. The second dichroic mirror 10 and the second high-reflectivity mirror 8 are connected via optical fiber, and the first dichroic mirror 9 and the second half-wave plate 4 are connected via optical fiber.

[0053] Preferably, the method for preparing first highly excited Rydberg atoms in an atomic gas chamber specifically includes:

[0054] After the probe light is emitted from one end of the resonant cavity by the probe light introduction component, producing an 852nm probe light, the cesium atoms in the atomic gas cell inside the resonant cavity change from the ground state 6S. 1 / 2 Transition to the low-excited state 6P 3 / 2 At the other end of the resonant cavity, a 509nm coupled light is emitted from the coupling light introduction component and enters the resonant cavity. Cesium atoms in the atomic gas cell within the resonant cavity are excited from a low-excited state (6D). 3 / 2 Transition to the first highly excited state n D 5 / 2 .

[0055] Specifically, the frequency-locked 852nm probe light, after being incident on the probe light introduction component, passes sequentially through the third half-wave plate 5, the second polarizing beam splitter 6, the fourth half-wave plate 7, and the second high-reflectivity mirror 8 before exiting into the resonant cavity. Similarly, the frequency-locked 509nm coupling light, after being incident on the coupling light introduction component, passes sequentially through the first high-reflectivity mirror 1, the first half-wave plate 2, the first polarizing beam splitter 3, and the second half-wave plate 4 before exiting into the resonant cavity. In this embodiment, the frequency of the 852nm probe light corresponds to the transition of the cesium atom from the ground state 6S1 / 2 to the first excited state 6P3 / 2. It first passes through the fourth half-wave plate 7 and the second polarizing beam splitter 6, adjusting its polarization state to the desired horizontally polarized linearly polarized light.

[0056] The probe light incident into the resonant cavity is reflected by the second dichroic mirror 10 and then incident horizontally and parallel to one side of the atomic gas cell. The cesium atoms in the atomic gas cell change from the ground state 6S... 1 / 2 Transition to the low-excited state 6P 2 / 3 The coupled light incident into the resonant cavity is reflected by the first dichroic mirror 9 and then incident horizontally and parallel to the direction opposite to the probe light into the atomic gas cell. The cesium atoms in the atomic gas cell are in the low-high excited state 6P. 2 / 3 Transition to the first highly excited state nD 5 / 2 The electromagnetically induced transparent spectral signal emitted from the atomic gas cell is transmitted through the first dichroic mirror 9 and then emitted to the photodetector 11. In this embodiment, the frequency of the 509nm coupling light corresponds to the excitation of the atom from the 6P3 / 2 state to the first highly excited state. n D 5 / 2 The transition occurs. It also undergoes polarization adjustment via the first half-wave plate 2 and the first polarization beam splitter 3.

[0057] In this embodiment, two beams of light, precisely polarized, are combined using a first dichroic mirror 9. The first dichroic mirror 9 reflects the 509nm wavelength coupling light while transmitting the 852nm wavelength probe light, thus causing the two beams to coincide spatially. The combined light paths both pass through an atomic gas cell containing cesium atom vapor. When the frequencies of the two beams resonate with the corresponding energy level transitions of the atoms, an electromagnetically induced transparency effect occurs: under the influence of the coupling light, the originally opaque gas cell becomes transparent to the probe light.

[0058] Preferably, the resonant cavity, used to prepare a second highly excited Rydberg atom in an atomic gas chamber, comprises:

[0059] After the radio frequency signal introduction component outputs the signal under test and the first local oscillator signal to the resonant cavity, the cesium atoms in the atomic gas cell inside the resonant cavity are in the first highly excited state. n D 5 / 2 Transition to the second most excited state ( n+ 1) P 3 / 2 .

[0060] Specifically, after the radio frequency signal introduction component outputs the signal to be measured to the atomic gas cell along the direction of the coupled light emission on one side of the atomic gas cell, and outputs the first local oscillator signal to the atomic gas cell above the atomic gas cell in a direction perpendicular to the coupled light or the probe light, the cesium atoms in the atomic gas cell within the resonant cavity are in the first highly excited state nD. 5 / 2 Transition to the first highly excited state (n+1)P 3 / 2 The atomic gas cell emits an electromagnetically induced transparent spectral signal influenced by the measured signal and the first local oscillator signal to a photodetector. The photodetector outputs the difference frequency signal between the measured signal and the first local oscillator signal to the spectrum module. The master quantum number... n The value can be any integer between 50 and 100. In this embodiment, if the signal to be measured is a mid-to-high frequency signal, for example, 500MHz to 40GHz, the principal quantum number is... n The value is 58; if the signal to be measured is a low-frequency signal, for example, 10MHz to 500MHz, then the principal quantum number is 58. n Set to any one of 90, 100, 110, and 120.

[0061] In this embodiment, the signal to be measured is an unknown signal, while the first and second local oscillator signals are reference signals generated internally by the system, with known and precisely controllable frequencies. Electric fields of these two frequencies are jointly applied to the atomic gas cell, interacting with the atoms in the Rydberg state. Due to the nonlinear response of the atoms, a "mixing" effect occurs within the atoms. The new frequency component generated by the mixing, i.e., the difference frequency signal, modulates the polarization state information of the probe light. The modulated probe light is ultimately received by the photodetector, which converts the optical information it carries back into an intermediate frequency signal, thus completing the detection.

[0062] An actual spectrum monitoring experiment was conducted on a spectrum monitoring device for a scanning atomic heterodyne receiver according to an embodiment of the present invention, as shown in the attached figure. Figure 5 The continuous spectrum monitoring graph shown indicates that the horizontal axis covers a frequency range from 0 GHz to 40 GHz, encompassing the range from microwaves to millimeter waves. At most frequencies, the system's noise floor, or baseline, is below -170 dBm / Hz, even reaching the level of -180 dBm / Hz, better than -150 dBm / Hz. This means the receiver can detect extremely weak electromagnetic signals. There is a gap of over 20 dB between the strongest signal (around -150 dBm) and the weakest identifiable signal (around -170 dBm) and the noise floor. Although no extremely strong signals appear in the graph, the vertical axis starting from -145 dBm indicates the system's ability to process stronger signals, meaning the receiver can simultaneously monitor signals with vastly different intensities without saturating strong signals or overwhelming weak signals.

[0063] The spectrum waterfall diagram is attached. Figure 6As shown, firstly, during the 410 scans, the dark, thick spectral lines at 54.5MHz and 67.5MHz represent signals with high power. Around these strong signals and in the frequency gaps, numerous lighter-colored fine spectral lines are visible. This demonstrates that the spectrum monitoring device of this embodiment possesses a high dynamic range, capable of detecting much weaker signals without being overwhelmed by strong signals. Secondly, multiple signals with very close frequencies are clearly distinguished. For example, near 54.5MHz, a strong signal is adjacent to a clearly distinguishable, independent fine spectral line. This demonstrates that the spectrum monitoring device of this embodiment has a frequency resolution superior to that of conventional receiver spectrum monitoring devices. Furthermore, although the spectrum graph cannot directly display "speed," it can capture and clearly present the complete historical record of up to 410 scans. This relies on an extremely high scan rate, ensuring that the system can quickly capture transient signals and accurately reflect the dynamic changes in the electromagnetic environment, avoiding the loss of important information due to slow scanning.

[0064] Regarding the spectrum monitoring range, this embodiment of the invention first obtains the test signal with the same resonant frequency as the atomic gas chamber by filtering the signal frequency band from 10MHz to 40GHz in the pre-selection filter component and mixing the signal in the mixer component. Then, the test signal is detected by the Rydberg module. Compared with the existing technology's detection range of 50MHz to 40GHz, this embodiment of the invention also realizes the acquisition and analysis of electromagnetic signals in the 10MHz to 40GHz frequency band, thus expanding the frequency coverage capability.

[0065] In terms of signal detection, this embodiment of the invention first directly converts the first signal to the target signal at the atomic sensitive frequency through a single mixing. Then, by preparing a first highly excited Rydberg atom and a second highly excited Rydberg atom in an atomic gas chamber, the target signal is used to induce a Stark shift or transition in the energy level of the Rydberg atom, which destroys the previous electromagnetically induced transparency condition, resulting in a decrease in the transmittance of the gas chamber to the probe light. The photodetector converts this small change in light intensity into an electrical signal, thereby achieving high-sensitivity measurement of the microwave electric field. The measured signal sensitivity is better than -150dBm / Hz, and the signal dynamic range reaches 65dB.

[0066] Regarding the scanning rate, the embodiments of the present invention achieve a single-stage frequency conversion through a pre-selective frequency filter component and a mixer component, which can convert the externally received first signal to the test signal at the atomic sensitive frequency point. Compared with the prior art, it not only significantly reduces the number of electronic components and reduces noise accumulation, but also achieves a continuous scanning rate of not less than 1 GHz / s and a spectral resolution of more than 1 kHz. It can present the dynamic changes of the spectrum in near real-time, which is suitable for dynamic monitoring. It solves the technical problem in the prior art that the step scanning method easily misses the signal occurring between two step points in order to monitor transient or rapidly changing signals.

Claims

1. A spectrum monitoring device for a scanning atomic heterodyne receiver, comprising a Rydberg module, a radio frequency module communicatively connected to the Rydberg module, and a spectrum module, characterized in that: The radio frequency module inputs a first local oscillator signal into the atomic gas chamber along a direction perpendicular to the laser propagation direction within the atomic gas chamber, and inputs a signal to be measured into the atomic gas chamber along a direction parallel to the laser propagation direction within the atomic gas chamber. The signal frequency of the signal to be measured is equal to the resonance frequency of the Rydberg atom in the atomic gas chamber transitioning from a first highly excited state to a second highly excited state. The Rydberg module includes a resonant cavity with a built-in atomic gas chamber and a photodetector. The resonant cavity prepares a first highly excited Rydberg atom within the atomic gas chamber, wherein the energy level of the first highly excited Rydberg atom is... n D 5 / 2 , principal quantum number n The value is any integer between 30 and 120; the resonant cavity prepares a second highly excited Rydberg atom through an atomic gas cell; the photodetector outputs the difference frequency signal between the signal to be measured and the first local oscillator signal to the spectrum module, wherein the energy level of the second highly excited Rydberg atom is ( n+ 1) P 3 / 2 ; The spectrum module performs a fast Fourier transform on the difference frequency signal to obtain the spectrum information of the signal under test. The radio frequency module includes: A pre-selective frequency filtering component is provided, which includes multiple pre-selective frequency filters arranged in parallel. After receiving the first gating signal, one pre-selective frequency filter is selected to be turned on, and the second signal is output after filtering the first signal received from the outside. A gating mixer assembly is communicatively connected to a gating pre-selection filter assembly. It includes two mixers arranged in parallel. After receiving a second gating signal, it selects one of the mixers to conduct, mixes the second signal and the second local oscillator signal, and outputs the signal to be measured to the atomic gas cell. A frequency sweeping component, communicatively connected to a gating mixer component, includes a frequency sweeping mixer local oscillator signal source and a sweep generator communicatively connected to both the frequency sweeping mixer local oscillator signal source and a spectrum module. The frequency sweeping component sends a frequency sweeping control signal to the frequency sweeping mixer local oscillator signal source, which outputs a second local oscillator signal with a continuously and progressively changing frequency to the gating mixer component. The gating mixer component performs segment-by-segment mixing of the second signal using the second local oscillator signal and outputs the signal to be measured to the atomic gas cell. A gated mixed-frequency local oscillator component is communicatively connected to the atomic gas cell. It includes multiple mixed-frequency local oscillator signal sources with different signal frequencies. After receiving a third gate signal, it selects one of the mixed-frequency local oscillator signal sources to conduct and outputs a first local oscillator signal of a fixed frequency to the atomic gas cell.

2. The spectrum monitoring device for a scanning atomic heterodyne receiver as described in claim 1, characterized in that, The Rydberg module also includes: A probe light introduction component emits 852nm probe light into the resonant cavity from one end of the resonant cavity, causing cesium atoms in the atomic gas cell within the resonant cavity to transition from the ground state to a low excited state. A coupling light introduction component emits 509nm coupling light into the resonant cavity from the other end of the resonant cavity, causing cesium atoms in the atomic gas cell within the resonant cavity to transition from a low excited state 6D. 3 / 2 Transition to the first highly excited state n D 5 / 2 ; The radio frequency signal introduction component outputs the signal to be measured and the first local oscillator signal to the resonant cavity, where cesium atoms in the atomic gas cell of the resonant cavity are in a first highly excited state. n D 5 / 2 Transition to the second most excited state ( n+ 1) P 3 / 2 .

3. The spectrum monitoring device for a scanning atomic heterodyne receiver as described in claim 2, characterized in that, The probe light introduction component includes a third half-wave plate, a second polarizing beam splitter, a fourth half-wave plate, and a second high-reflectivity mirror connected sequentially by optical fibers. After the 852nm probe light is frequency-locked, it is incident on the probe light introduction component, passes sequentially through the third half-wave plate, the second polarizing beam splitter, the fourth half-wave plate, and the second high-reflectivity mirror, and then exits into the resonant cavity. The coupled light introduction component includes a first high-reflectivity mirror, a first half-wave plate, a first polarizing beam splitter, and a second half-wave plate connected in sequence by optical fibers. The 509nm coupled light after frequency locking is incident on the coupled light introduction component, passes through the first high-reflectivity mirror, the first half-wave plate, the first polarizing beam splitter, and the second half-wave plate in sequence, and then exits into the resonant cavity. The resonant cavity further includes a second dichroic mirror connected to the second high-reflectivity mirror via an optical fiber and a first dichroic mirror connected to the second half-wave plate via an optical fiber. Probe light incident into the resonant cavity is reflected by the second dichroic mirror and then incident horizontally and parallel to one side of the atomic gas cell. The cesium atoms in the atomic gas cell are in their ground state 6S... 1 / 2 Transition to the low-excited state 6P 2 / 3 The coupled light incident into the resonant cavity is reflected by the first dichroic mirror and then incident horizontally and parallel to the probe light into the atomic gas cell. The cesium atoms in the atomic gas cell are in the low-high excited state 6P. 2 / 3 Transition to the first highly excited state nD 5 / 2 The electromagnetically induced transparent spectral signal emitted from the atomic gas cell is transmitted through the first dichroic mirror and then emitted to the photodetector.

4. The spectrum monitoring device for a scanning atomic heterodyne receiver as described in claim 2, characterized in that, The radio frequency signal introduction component outputs the signal to be measured to the atomic gas cell from one side along the direction of the coupled light emission, and outputs a first local oscillator signal to the atomic gas cell from above the atomic gas cell in a direction perpendicular to the coupled light or the probe light. The cesium atoms in the atomic gas cell are in a first highly excited state nD. 5 / 2 Transition to the first highly excited state (n+1)P 3 / 2 The electromagnetically induced transparent spectrum signal under the influence of the test signal and the first local oscillator signal is emitted from the atomic gas cell to the photodetector. The photodetector outputs the difference frequency signal between the test signal and the first local oscillator signal to the spectrum module.

5. A spectrum monitoring device for a scanning atomic heterodyne receiver as described in claim 3 or 4, characterized in that, principal quantum number n It can be any integer value between 50 and 100.

6. The spectrum monitoring device for a scanning atomic heterodyne receiver as described in claim 5, characterized in that, principal quantum number n It is 58 or 90.

7. The spectrum monitoring device for a scanning atomic heterodyne receiver as described in claim 1, characterized in that, The radio frequency module also includes: The first power module is communicatively connected to the pre-selection frequency filter component. It is used to generate a first gating control signal according to the signal frequency band corresponding to the signal frequency of the externally received first signal, turn on the pre-selection frequency filter of the corresponding frequency band and filter the first signal, and output a second signal. The signal frequency band corresponding to the signal frequency of the first signal includes 10MHz to 50MHz and 50MHz to 40GHz. The second power module is communicatively connected to the gating mixer component. It is used to generate a second gating control signal based on the signal frequency band corresponding to the received second signal frequency and the received sweeping second local oscillator signal. This signal controls the gating mixer component to turn on the mixer in the corresponding frequency band and perform mixing processing on the second signal and the second local oscillator signal, outputting the signal to be measured. The third power module is communicatively connected to the selected mixed-frequency local oscillator component. It is used to generate a third gating control signal according to the signal frequency band corresponding to the received signal under test, and control the selected mixed-frequency local oscillator component to turn on the mixed-frequency local oscillator signal source of the corresponding frequency band, and output the first local oscillator signal to the atomic gas cell.

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