A color center heterodyne microwave detection device and method based on master clock cooperative triggering

Abstract

The application discloses a color center heterodyne microwave detection device and method based on master clock cooperative triggering, belongs to the technical field of microwave quantum detection, and aims at solving the problems of reference field phase drift, sampling point misplacement and incoherent accumulation of heterodyne signals caused by independent operation of multiple devices. The application is based on master clock cooperative triggering laser excitation, reference field phase resetting, microwave signal gating, microwave beam combination and coupling, photoelectric detection and data acquisition, so that the whole heterodyne detection system has unified cycle starting point, phase and sampling. After the start of each measurement cycle, when the measured microwave signal is a controlled source or has a determined phase relationship with the master clock, the initial phase of the reference field is reset to a preset value, so that the phase repeatability of the difference frequency signal across cycles is ensured. The sampling clock is locked with the cycle starting point, so that the same physical time is ensured for the sampling points with the same serial number in different cycles. Compared with the prior art, the application significantly improves the signal-to-noise ratio and phase stability of long-time accumulated detection of weak microwave signals.

Description

Technical Field

[0001] This invention belongs to the field of microwave quantum detection technology, and particularly relates to a color center heterodyne microwave detection device and method based on master clock coordinated triggering. Background Technology

[0002] Silicon carbide (SiC) is a wide-bandgap semiconductor material with mature wafer-level fabrication, ion implantation, epitaxial growth, and micro / nano fabrication processes, making it compatible with existing power electronics, microwave devices, and integrated photonics technologies. Silicon vacancies, double vacancies, carbon vacancy-related defects, nitrogen vacancy-type defects, and other optically readout point defects in SiC can exhibit the optical and spin properties of solid-state color centers. Its energy level structure, fluorescence intensity, photocharge conversion behavior, and spin resonance frequency are affected by external electric fields, magnetic fields, temperature, stress, pressure, or microwave fields, thus making it suitable as a quantum sensing unit for micro / nano-scale, high-temperature, high-pressure, or on-chip integrated environments.

[0003] For the microwave signal under test, directly reading weak signals at the microwave frequency is often limited by detector bandwidth, instrument phase drift, environmental noise, and multi-cycle averaging efficiency. Heterodyne detection introduces a reference microwave signal, causing the microwave signal under test and the reference microwave signal to act simultaneously in the region where the silicon carbide color center is located. By utilizing the nonlinear term, coherence term, or photocharge conversion term of the color center response to generate a difference frequency component in the readout signal, the high-frequency microwave information under test is converted into a lower-frequency beat frequency or intermediate frequency signal, reducing the requirement for detector bandwidth and improving the signal-to-noise ratio through coherent detection.

[0004] However, existing solutions typically have the following shortcomings: Current technologies do not use a single master clock to uniformly control the phase and sampling of the entire microwave heterodyne detection link; instead, each component operates based on its own clock or software commands. In practical silicon carbide color center heterodyne microwave detection systems, if the laser, the microwave source under test, the reference source, the data acquisition card, the detector, and the digital demodulation unit are started up using their own clocks or software commands, problems such as inconsistent cycle start points, initial phase drift of the reference field, mismatch between the gate edge of the microwave under test and the readout window, and misalignment of sampling points across cycles will occur.

[0005] Existing technologies do not provide specific methods for controlling the reference field phase reset, co-exposure of the microwave under test and the reference field, laser initialization and readout, detector integration, fixed sampling point numbering, and digital heterodyne demodulation simultaneously by the master clock within each measurement cycle. Especially in the detection of weak microwave signals and long-term accumulation, the above problems may lead to widening of the difference frequency signal, ineffective phase cancellation, or background drift, which severely restricts the detection sensitivity and phase stability.

[0006] While existing technologies have achieved synchronization between solid-state spin and external perturbation, they do not address the active reset of the reference field phase in each measurement cycle, nor do they solve the problem of heterodyne signals being unable to coherently accumulate across cycles due to reference field phase drift. Summary of the Invention

[0007] Based on the above analysis, the present invention aims to provide a color center heterodyne microwave detection device and method based on master clock coordinated triggering, in order to solve the problems of reference field phase drift, sampling point misalignment, and inability to coherently accumulate heterodyne signals caused by the independent operation of multiple devices in the present invention.

[0008] In a first aspect, embodiments of the present invention provide a color center heterodyne microwave detection device based on master clock coordinated triggering, the device comprising: The system includes a master clock generation unit, a silicon carbide color center sensing unit, a laser excitation unit, a reference field application unit, a microwave receiving unit under test, a microwave coupling unit, a photoelectric detection and data acquisition unit, and a data processing unit. The laser excitation unit is used to emit a laser under the control of the master clock generation unit to excite the silicon carbide color center sensing unit. The reference field application unit is used to reset the initial phase of the reference microwave signal to a preset phase under the control of the master clock generation unit, and send the phase-reset reference microwave signal to the microwave coupling unit. The microwave receiving unit under test is used to transmit the microwave signal under test to the microwave coupling unit under the control of the master clock generating unit; the reference microwave signal after phase reset and the microwave signal under test are transmitted synchronously. The microwave coupling unit is used to combine the microwave signal to be measured and the reference microwave signal after phase reset and couple them to the silicon carbide color center sensing unit. The silicon carbide color center sensing unit is used to perform heterodyne sensing under the combined action of the microwave signal to be measured and the reference microwave signal after phase reset, and generate a heterodyne signal containing a difference frequency component. The photoelectric detection and data acquisition unit is used to acquire the heterodyne signal under the control of the master clock generation unit; The data processing unit is used to demodulate the heterodyne signal to obtain the amplitude and phase of the microwave signal under test.

[0009] Based on the above solution, the present invention also makes the following improvements: The master clock generating unit generates a cycle start trigger signal according to a preset cycle period and sends it to each unit. It also generates a laser gating signal, a microwave gating signal under test, a reference field phase reset signal, a reference field output gating signal, and a data acquisition sampling clock according to a pre-calibrated delay compensation table and sends them to the corresponding units. The laser excitation unit synchronously receives the cycle start trigger signal and the laser gating signal to ensure that the laser illuminates the silicon carbide color center sensing unit at the beginning of each measurement cycle. The reference field application unit receives the reference field phase reset signal in front of the preset microwave exposure window to reset the initial phase of the reference microwave signal, and receives the reference field output gate signal to output the phase-reset reference microwave signal to the microwave coupling unit. The microwave receiving unit under test receives the microwave gating signal under test in front of a preset microwave exposure window and outputs the microwave signal under test to the microwave coupling unit. At the start of the preset microwave exposure window, the microwave coupling unit transmits the coupled signal after beam combining to the silicon carbide color center sensing unit. The photoelectric detection and data acquisition unit synchronously receives the cycle start trigger signal and the data acquisition sampling clock to ensure that the heterodyne signal is acquired at the beginning of each measurement cycle.

[0010] Furthermore, the silicon carbide color center sensing unit includes a silicon carbide color center, which includes at least a silicon vacancy color center, a double vacancy color center, a carbon vacancy-related defect, a nitrogen vacancy-type defect, or other optically readable point defects in 4H-SiC, 6H-SiC, or 3C-SiC.

[0011] Furthermore, the delay compensation table at least includes the optical path delay of the laser reaching the silicon carbide color center. The propagation delay of the microwave signal to be measured to the silicon carbide color center. The propagation delay of the reference microwave signal to the silicon carbide color center. Phase stabilization time of the reference field application unit and the delay triggered by data acquisition ; Phase stabilization time of the reference field application unit This represents the time required from the moment the reference field application unit receives the reference field phase reset signal until the output reference microwave signal reaches the preset phase and stabilizes.

[0012] Furthermore, the master clock generating unit calculates the advance output amount of the laser gating signal, the microwave gating signal under test, the reference field output gating signal, the reference field phase reset signal, and the data acquisition sampling clock relative to the start time of the microwave exposure window, based on the delay parameters in the delay compensation table. The laser gating signal is advanced Output, the microwave gating signal to be tested is advanced The reference field output gating signal is advanced. The output, the reference field phase reset signal is advanced. End, the data acquisition sampling clock is advanced. Output.

[0013] Furthermore, the master clock generating unit establishes a phase stability based on the phase stability settling time of the reference field applying unit. The time interval between the end time of the reference field phase reset signal and the start time of the preset microwave exposure window is greater than or equal to the specified time. This ensures that the initial phase of the reference microwave signal has been reset to the preset phase of the current cycle before the start of the preset microwave exposure window in each measurement cycle.

[0014] Furthermore, the preset phase adopts any of the following modes: A phase pair mode that alternates between 0° and 180°; or A four-phase sequence mode that cycles through 0°, 90°, 180° and 270°; When the phase pair mode is used, the data processing unit subtracts the heterodyne signals corresponding to the phase pair to eliminate the common-mode background that does not change with the phase of the reference field and enhance the heterodyne signal, thereby obtaining the in-phase component of the microwave signal under test and thus obtaining the amplitude of the microwave signal under test. When the four-phase sequence mode is used, the data processing unit reconstructs the in-phase and quadrature components of the microwave signal under test based on the heterodyne signal corresponding to the four-phase sequence, thereby obtaining the amplitude and phase of the microwave signal under test.

[0015] Furthermore, the master clock generating unit locks the cycle start trigger signal and the data acquisition sampling clock; the sampling points with the same sequence number in different measurement cycles correspond to the same physical time within the cycle, and this correspondence covers all sampling points, ensuring that the phase of the heterodyne signal containing the difference frequency component acquired within the preset microwave exposure window is repeatable between different cycles.

[0016] Furthermore, the amplitude and phase of the microwave signal under test are expressed by the following formula:

[0017] In the formula, This represents the in-phase component of the microwave signal under test. This represents the orthogonal components of the microwave signal under test. This indicates the amplitude of the microwave signal under test. Indicates the phase of the microwave signal under test. Indicates the first measurement cycle in a single measurement cycle The serial number of each sampling point Indicates the first The average value of multiple measurement cycles at a sampling point. This represents the frequency difference between the reference microwave signal and the microwave signal under test. Indicates the sampling frequency. This indicates the number of sampling points in a single measurement cycle.

[0018] In a second aspect, embodiments of the present invention provide a method for color center heterodyne microwave detection based on master clock coordinated triggering using the apparatus described in any one of the first aspects, characterized in that the method includes the following steps: The master clock generation unit outputs a cycle start trigger signal to each unit according to a preset cycle period, which serves as the start time of each measurement cycle; According to the pre-calibrated delay compensation table, the master clock generation unit outputs a laser gating signal to the laser excitation unit and a data acquisition sampling clock to the photoelectric detection and data acquisition unit at the same time as outputting the cycle start trigger signal; the laser excitation unit synchronously receives the cycle start trigger signal and the laser gating signal and irradiates the silicon carbide color center sensing unit with laser. According to the pre-calibrated delay compensation table, the master clock generation unit outputs a reference field phase reset signal to the reference field application unit before the start of the preset microwave exposure window, so as to reset the initial phase of the reference microwave signal to the preset phase. According to the pre-calibrated delay compensation table, the master clock generating unit synchronously outputs the microwave gate signal to be tested to the microwave receiving unit before the preset microwave exposure window, sends the microwave signal to be tested to the microwave coupling unit, outputs the reference field gate signal to the reference field application unit, and sends the phase-reset reference microwave signal to the microwave coupling unit, so that the microwave signal to be tested and the phase-reset reference microwave signal are synchronously sent to the microwave coupling unit. At the start of the preset microwave exposure window, the microwave coupling unit combines the microwave signal to be measured and the reference microwave signal and couples them together to the silicon carbide color center sensing unit, so that the silicon carbide color center sensing unit generates a heterodyne signal containing a difference frequency component. The photoelectric detection and data acquisition unit synchronously receives the cycle start trigger signal and the data acquisition sampling clock to acquire the heterodyne signal; The data processing unit performs heterodyne demodulation on the heterodyne signal of each measurement cycle to obtain the amplitude and phase of the microwave signal under test.

[0019] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: 1. This invention, through a master clock generation unit, ensures that the entire microwave heterodyne detection link has a unified cycle start point, phase, and sampling. Compared with existing technologies where each module relies on its own clock or software commands to start, this invention fundamentally solves the problems of inconsistent cycle start points and misaligned sampling points across cycles, enabling precise coherent accumulation of data from thousands of cycles.

[0020] 2. Before the start of the microwave exposure window in each measurement cycle, this invention forcibly resets the initial phase of the reference field application unit to a preset phase using a reference field phase reset signal, ensuring that the reference field is output from a determined initial phase in each cycle. Compared to existing technologies where the reference field operates freely and phase drift is uncontrollable, this invention guarantees the repeatability of the phase of the heterodyne difference frequency signal between different cycles, avoids signal averaging cancellation caused by phase drift, and significantly improves the signal-to-noise ratio of long-term cumulative detection.

[0021] 3. This invention derives the sampling clock from the master clock and locks it to the loop start trigger signal. Sampling points with the same sequence number in different measurement loops correspond to the same physical time within that loop, and this correspondence covers all sampling points. Compared to existing technologies where the sampling clock operates independently and sampling points are misaligned across loops, this invention ensures that the phase of the heterodyne difference frequency signal acquired within the microwave exposure window remains consistent across different loops. This provides a timing basis for the point-by-point coherent accumulation and averaging of the heterodyne signal, reducing waveform broadening caused by internal crystal oscillator frequency offset and software startup delay.

[0022] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0023] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0024] Figure 1 A schematic diagram of the structure of a color center heterodyne microwave detection device based on master clock coordinated triggering provided in an embodiment of the present invention; Figure 2 The diagram shows the correspondence between the measurement cycle timing and sampling points provided in the embodiments of the present invention. Detailed Implementation

[0025] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0026] Example 1 A specific embodiment of the present invention discloses a color center heterodyne microwave detection device based on master clock coordinated triggering, the schematic diagram of which is shown below. Figure 1 As shown, the device includes: The system includes a master clock generation unit, a silicon carbide color center sensing unit, a laser excitation unit, a reference field application unit, a microwave receiving unit under test, a microwave coupling unit, a photoelectric detection and data acquisition unit, and a data processing unit. The laser excitation unit is used to emit a laser under the control of the master clock generation unit to excite the silicon carbide color center sensing unit. The reference field application unit is used to reset the initial phase of the reference microwave signal to a preset phase under the control of the master clock generation unit, and send the phase-reset reference microwave signal to the microwave coupling unit. The microwave receiving unit under test is used to transmit the microwave signal under test to the microwave coupling unit under the control of the master clock generating unit; the reference microwave signal after phase reset and the microwave signal under test are transmitted synchronously. The microwave coupling unit is used to combine the microwave signal to be measured and the reference microwave signal after phase reset and couple them to the silicon carbide color center sensing unit. The silicon carbide color center sensing unit is used to perform heterodyne sensing under the combined action of the microwave signal to be measured and the reference microwave signal after phase reset, and generate a heterodyne signal containing a difference frequency component. The photoelectric detection and data acquisition unit is used to acquire the heterodyne signal under the control of the master clock generation unit; The data processing unit is used to demodulate the heterodyne signal to obtain the amplitude and phase of the microwave signal under test.

[0027] It should be noted that the above units do not work in isolation, but are unified under the same cycle generated by the master clock generation unit, forming a complete closed loop from color center initialization, microwave exposure, heterodyne response formation to data acquisition and demodulation.

[0028] In the specific implementation process, the specific structure and connection relationship of each unit are as follows: 1) The master clock generation unit includes a master clock source and an FPGA-based multi-channel master timing generator. The reference output of the master clock source is connected to the reference clock input of the FPGA master timing generator via a coaxial cable. The FPGA master timing generator is configured through multiple channels to generate the following synchronization signals: Channel CH0 (output cycle start trigger signal): connected to each unit via a coaxial line. When connected to the start trigger terminal of the data acquisition card in the photoelectric detection and data acquisition unit, it generates the start time for defining each measurement cycle according to a preset cycle period. Preferably, the preset cycle period is set to 20ms.

[0029] Channel CH1 (output laser gating signal): connected to the control terminal of the acousto-optic modulator in the laser excitation unit via a coaxial cable.

[0030] Channel CH2 (outputs the gated signal of the microwave under test): connected to the TTL control terminal of the RF switch in the microwave receiver unit under test via a coaxial cable.

[0031] Channel CH3 (output reference field phase reset signal): connected to the DDS phase reset terminal in the reference field application unit via a coaxial line.

[0032] Channel CH4 (output reference field output gate signal): connected to the TTL control terminal of the RF switch in the reference field application unit via a coaxial line.

[0033] Channel CH5 (Output Data Acquisition Sampling Clock): Connected to the external sampling clock input of the data acquisition unit via a coaxial cable.

[0034] 2) The laser excitation unit includes at least a laser, an optical isolator, an acousto-optic modulator, a fiber optic coupler, a dichroic mirror, an objective lens, a filter, and an optical path shaping device. The laser is a 785nm continuous laser, and its output is connected in sequence to the optical isolator, the acousto-optic modulator, and the fiber optic coupler.

[0035] The TTL control terminal of the acousto-optic modulator is connected to the CH0 and CH1 output terminals of the FPGA. The active levels of CH0 and CH1 turn on the acousto-optic modulator at the beginning of each measurement cycle, and the laser is focused onto the silicon carbide color center sensing unit after passing through the fiber coupler, dichroic mirror and objective lens; the inactive level of CH1 turns off the acousto-optic modulator and stops the laser irradiation.

[0036] 3) The silicon carbide color center sensing unit includes a silicon carbide color center, which includes at least a silicon vacancy color center, a double vacancy color center, a carbon vacancy-related defect, a nitrogen vacancy-type defect, or other optically readable point defects in 4H-SiC, 6H-SiC, or 3C-SiC. Preferably, a silicon vacancy color center in a 4H-SiC crystal is used. This crystal is fixed on a sample stage above the coplanar waveguide, positioned such that the focused spot of the objective lens coincides with the region of maximum microwave field strength of the coplanar waveguide.

[0037] The silicon vacancy color centers in 4H-SiC crystals emit fluorescence around 916nm when excited by a 785nm laser. Their fluorescence intensity, photocharge conversion behavior, or spin resonance frequency are affected by the local microwave field, and they can be used as sensitive units for microwave sensing.

[0038] 4) The reference field application unit includes a DDS microwave source, a reference field RF switch, an attenuator, and an amplifier. The external reference input of the DDS microwave source is connected to the reference output of the master clock source, so that its output frequency is locked to the master clock.

[0039] The phase reset terminal of the DDS microwave source is connected to the CH3 output terminal of the FPGA to receive the reference field phase reset signal. In each measurement cycle, the phase reset terminal of the DDS microwave source receives the reference field phase reset signal and clears the phase accumulator of the DDS to zero, so that the initial phase of the reference microwave signal is reset to the preset phase of this cycle.

[0040] It should be noted that the preset phase adopts any of the following modes: A phase pair mode that alternates between 0° and 180°; or A four-phase sequence mode that cycles through 0°, 90°, 180° and 270°; When the phase pair mode is used, the data processing unit subtracts the heterodyne signals corresponding to the phase pair to eliminate the common-mode background that does not change with the phase of the reference field and enhance the heterodyne signal, thereby obtaining the in-phase component of the microwave signal under test and thus obtaining the amplitude of the microwave signal under test. When the four-phase sequence mode is used, the data processing unit reconstructs the in-phase and quadrature components of the microwave signal under test based on the heterodyne signal corresponding to the four-phase sequence, thereby obtaining the amplitude and phase of the microwave signal under test.

[0041] The RF output of the DDS microwave source is sequentially connected to the RF input of the reference field RF switch, an attenuator, and an amplifier to attenuate and amplify the phase-reset reference microwave signal. The amplifier's output is connected to the second input of the microwave coupling unit. The TTL control terminal of the reference field RF switch is connected to the CH4 output of the FPGA to control the output of the phase-reset reference microwave signal to the microwave coupling unit.

[0042] 5) The microwave receiver under test (DUT) includes a DUT input terminal, a protection limiter, a low-noise amplifier, an adjustable attenuator, and a DUT RF switch. The DUT signal is connected to the DUT input terminal via an SMA connector, and passes sequentially through the protection limiter, low-noise amplifier, adjustable attenuator, and DUT RF switch. The RF output terminal of the DUT RF switch is connected to the first input terminal of the microwave coupling unit. The TTL control terminal of the DUT RF switch is connected to the CH2 output terminal of the FPGA to control the output of the DUT microwave signal to the microwave coupling unit.

[0043] 6) The microwave coupling unit includes a power combiner, an isolator, an attenuator, a coplanar waveguide, and a near-field probe. The first input of the power combiner is connected to the output of the microwave RF switch under test, and the second input is connected to the output of the reference field RF switch.

[0044] The output of the power combiner is connected sequentially to an isolator and an attenuator, and then to the input of the coplanar waveguide via an SMA connector. The coplanar waveguide is positioned close to the silicon carbide color center sensing unit, and a load is connected to the end of the coplanar waveguide to absorb reflections. Above the coplanar waveguide, a near-field probe is placed to further concentrate and couple the microwave field resulting from combining the measured microwave signal with the phase-reset reference microwave signal to the region where the silicon carbide color center is located.

[0045] In this process, the microwave field resulting from the combination of the measured microwave signal and the phase-reset reference microwave signal, along with the laser emitted from the laser excitation unit, acts on the silicon vacancy color center in the 4H-SiC crystal to perform heterodyne sensing, generating a heterodyne signal containing a difference frequency component. Specifically, the measured microwave signal and the reference microwave signal act on the same spin transition or overlapping effective response frequency band of the silicon vacancy color center. The frequency difference between the two signals lies within the fluorescence, population, or charge state readout response bandwidth of the silicon vacancy color center, resulting in a heterodyne signal in the readout signal containing a beat frequency component.

[0046] 7) The photoelectric detection and data acquisition unit includes a photodetector, a transimpedance amplifier, an analog-to-digital converter, and a data acquisition card. The 916nm fluorescence emitted by the silicon carbide color center sensing unit is collected by the same objective lens in the laser excitation unit, and then filtered by a dichroic mirror and a bandpass filter to remove the 785nm excitation light before sequentially entering the photosensitive surface of the photodetector, the transimpedance amplifier, the analog-to-digital converter, and the data acquisition card.

[0047] The data acquisition card's start trigger is connected to the FPGA's CH0 output; the external sampling clock is connected to the FPGA's CH5 output. The data acquisition card begins acquisition at the CH0 trigger of each measurement cycle and, driven by the CH5 sampling clock, acquires a fixed number of sampling points at a preset sampling rate.

[0048] Preferably, the preset sampling frequency is 10kHz, and the fixed number of sampling points is 200.

[0049] It should be noted that the master clock generation unit locks the cycle start trigger signal (CH0) and the data acquisition sampling clock (CH5); the sampling points with the same sequence number in different measurement cycles correspond to the same physical time within the cycle, and this correspondence covers all sampling points, ensuring that the phase of the heterodyne signal containing the difference frequency component acquired within the preset microwave exposure window is repeatable between different cycles.

[0050] 8) The data processing unit is a computer running data acquisition and processing software. The computer connects to the data acquisition card via a PCIe interface and reads a fixed number of sampling points collected in each cycle.

[0051] The data processing unit is configured to: buffer the data according to the cycle number k and the sampling point number i; perform point-by-point coherent averaging of the data with the same sampling point number in different cycles; and perform digital I / Q heterodyne demodulation to obtain the amplitude and phase of the microwave signal under test.

[0052] Specifically, the amplitude and phase of the microwave signal under test are expressed by the following formula:

[0053] In the formula, This represents the in-phase component of the microwave signal under test. This represents the orthogonal components of the microwave signal under test. This indicates the amplitude of the microwave signal under test. Indicates the phase of the microwave signal under test. Indicates the first measurement cycle in a single measurement cycle The serial number of each sampling point Indicates the first The average value of multiple measurement cycles at a sampling point. This represents the frequency difference between the reference microwave signal and the microwave signal under test. Indicates the sampling frequency. This indicates the number of sampling points in a single measurement cycle.

[0054] Preferably, the frequency difference between the reference microwave signal and the microwave signal under test does not exceed 5 kHz.

[0055] Furthermore, the process of implementing master clock-based coordinated triggering in this device includes: The master clock generation unit generates a cycle start trigger signal according to a preset cycle period and sends it to each unit. According to the pre-calibrated delay compensation table, it generates a laser gating signal, a microwave gating signal under test, a reference field phase reset signal, a reference field output gating signal, and a data acquisition sampling clock and sends them to the corresponding units. The laser excitation unit synchronously receives the cycle start trigger signal and the laser gating signal to ensure that the laser illuminates the silicon carbide color center sensing unit at the beginning of each measurement cycle. The reference field application unit receives the reference field phase reset signal in front of the preset microwave exposure window to reset the initial phase of the reference microwave signal, and receives the reference field output gate signal to output the phase-reset reference microwave signal to the microwave coupling unit. The microwave receiving unit under test receives the microwave gating signal under test in front of the preset microwave exposure window and outputs the microwave signal under test to the microwave coupling unit. At the start of the preset microwave exposure window, the microwave coupling unit transmits the coupled signal, which is the result of combining the phase-reset reference microwave signal and the microwave signal to be measured, to the silicon carbide color center sensing unit. The photoelectric detection and data acquisition unit synchronously receives the cycle start trigger signal and the data acquisition sampling clock to ensure that the heterodyne signal is acquired at the beginning of each measurement cycle.

[0056] Preferably, the preset microwave exposure window is set to 5-15ms.

[0057] It should be noted that the delay compensation table includes at least the optical path delay from the output of the CH1 gated signal to the arrival of the laser at the silicon carbide color center. The propagation delay from the CH2 gated signal output to the arrival of the microwave signal under test at the silicon carbide color center. The propagation delay from the CH4 gated signal output to the reference microwave signal reaching the silicon carbide color center. Phase stabilization time from the CH3 phase reset signal to the reference field application unit And the delay in data acquisition from the output of the trigger signal at the start of the CH0 trigger cycle to the photoelectric detection and data acquisition unit. .

[0058] Among them, the phase stabilization time of the reference field application unit This represents the time required from the moment the reference field application unit receives the reference field phase reset signal until the output reference microwave signal reaches the preset phase and stabilizes.

[0059] Furthermore, the master clock generation unit calculates the advance output amount of the laser gating signal, the microwave gating signal under test, the reference field output gating signal, the reference field phase reset signal, and the data acquisition sampling clock relative to the start time of the microwave exposure window, based on the delay parameters in the delay compensation table: The laser gating signal is advanced Output, the microwave gating signal to be tested is advanced The reference field output gating signal is advanced. The output, the reference field phase reset signal is advanced. End, the data acquisition sampling clock is advanced. Output.

[0060] It should be noted that the master clock generation unit is based on the phase stabilization time of the reference field application unit. The time interval between the end time of the reference field phase reset signal and the start time of the preset microwave exposure window is greater than or equal to the specified time. This ensures that the initial phase of the reference microwave signal has been reset to the preset phase of the current cycle before the start of the preset microwave exposure window in each measurement cycle.

[0061] Preferably, the laser optical path delay The microwave transmission delay to be measured is 10ns to 100ns. The reference field propagation delay is 50 ns to 2 μs. The reference field phase stabilization time is 50 ns to 2 μs. The data acquisition trigger delay is 100ns~20μs. The time ranges from 10 μs to 1 ms.

[0062] It should be noted that the above values ​​are merely preferred examples based on typical hardware selections and do not constitute a limitation on the scope of protection of this invention. In practical applications, the specific values ​​of the delay compensation table should be determined after actual measurement and calibration of each channel using an oscilloscope or time-to-digital converter.

[0063] Example 2 In a typical measurement cycle, the measurement cycle timing and sampling point correspondence diagram is as follows: Figure 2 As shown, the working process of this device is as follows: Cycle start trigger: At time T0, the FPGA triggers the data acquisition card via CH0 to mark the start of a new cycle. The cycle period of each measurement cycle is 20ms.

[0064] Laser initialization and continuous readout: The FPGA, based on the delay compensation table, in The CH1 laser gating signal is output continuously to turn on the acousto-optic modulator, so that the 785nm laser continuously irradiates the silicon carbide color center, completing the initialization of the color center and exciting the 916nm fluorescence.

[0065] Reference field phase reset: Before the start of the preset microwave exposure window (5ms to 15ms), the FPGA performs a phase reset. The CH3 phase reset pulse is output at all times to clear the phase accumulator of the DDS to zero, so that the initial phase of the reference microwave signal in this cycle is reset to 0° (reset cyclically according to the selected preset phase mode).

[0066] Simultaneous exposure of the microwave under test and the reference field: The FPGA, according to the delay compensation table, in The CH2 gate signal is output continuously to turn on the microwave RF switch under test; simultaneously, The CH4 gated signal is output continuously to turn on the reference field RF switch. The two microwave signals are combined in the power combiner and coupled to the silicon carbide color center through a coplanar waveguide and a near-field probe, where they work together within a 5ms-15ms window.

[0067] Heterodyne response generated by silicon carbide color centers: microwave under test (frequency) ) and reference microwave (frequency) ( ) together act on silicon vacancy color centers, and the fluorescence response of the color centers contains frequencies of The difference frequency component.

[0068] Fixed sampling point acquisition: The photodetector converts fluorescence into an analog voltage. The data acquisition card, after being triggered by CH0, [is used for data acquisition]. The time output uses the 10kHz sampling clock provided by CH5 to collect 200 sampling points within 0-20ms, with each sampling point corresponding to a fixed physical time within the loop.

[0069] Data processing and heterodyne demodulation: The computer reads 200 sampling points, averages the sampling points with the same index i in different cycles, and then performs digital I / Q demodulation on the averaged sequence to obtain the amplitude and phase of the microwave signal under test.

[0070] The above is a detailed description of the embodiments of the device of the present invention. Those skilled in the art should understand that the specific values ​​in the above embodiments are merely illustrative examples, and in practical applications, they can be adaptively adjusted according to the type of silicon carbide color center, the microwave frequency band to be measured, and the system performance requirements, without departing from the protection scope of the present invention.

[0071] Example 3 A specific embodiment of the present invention discloses a color center heterodyne microwave detection method based on master clock coordinated triggering, the method comprising the following steps: The master clock generation unit outputs a cycle start trigger signal to each unit according to a preset cycle period, which serves as the time start point for each measurement cycle; According to the pre-calibrated delay compensation table, the master clock generation unit outputs a laser gating signal to the laser excitation unit and a data acquisition sampling clock to the photoelectric detection and data acquisition unit at the same time as outputting the cycle start trigger signal; the laser excitation unit synchronously receives the cycle start trigger signal and the laser gating signal and irradiates the silicon carbide color center sensing unit with laser. According to the pre-calibrated delay compensation table, the master clock generation unit outputs a reference field phase reset signal to the reference field application unit before the start of the preset microwave exposure window, so as to reset the initial phase of the reference microwave signal to the preset phase. According to the pre-calibrated delay compensation table, the master clock generating unit synchronously outputs the microwave gate signal to be tested to the microwave receiving unit before the preset microwave exposure window, sends the microwave signal to be tested to the microwave coupling unit, outputs the reference field gate signal to the reference field application unit, and sends the phase-reset reference microwave signal to the microwave coupling unit, so that the microwave signal to be tested and the phase-reset reference microwave signal are synchronously sent to the microwave coupling unit. At the start of the preset microwave exposure window, the microwave coupling unit combines the microwave signal to be measured and the reference microwave signal and couples them together to the silicon carbide color center sensing unit, so that the silicon carbide color center sensing unit generates a heterodyne signal containing a difference frequency component. The photoelectric detection and data acquisition unit synchronously receives the cycle start trigger signal and the data acquisition sampling clock to acquire the heterodyne signal; The data processing unit performs heterodyne demodulation on the heterodyne signal of each measurement cycle to obtain the amplitude and phase of the microwave signal under test.

[0072] The working principle of the method is the same as that in Example 1, and will not be repeated here.

[0073] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware, and the program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0074] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A color center heterodyne microwave detection device based on master clock coordinated triggering, characterized in that, The device includes: a master clock generating unit, a silicon carbide color center sensing unit, a laser excitation unit, a reference field application unit, a microwave receiving unit under test, a microwave coupling unit, a photoelectric detection and data acquisition unit, and a data processing unit. The laser excitation unit is used to emit a laser under the control of the master clock generation unit to excite the silicon carbide color center sensing unit. The reference field application unit is used to reset the initial phase of the reference microwave signal to a preset phase under the control of the master clock generation unit, and send the phase-reset reference microwave signal to the microwave coupling unit. The microwave receiving unit under test is used to transmit the microwave signal under test to the microwave coupling unit under the control of the master clock generating unit; the reference microwave signal after phase reset and the microwave signal under test are transmitted synchronously. The microwave coupling unit is used to combine the microwave signal to be measured and the reference microwave signal after phase reset and couple them to the silicon carbide color center sensing unit. The silicon carbide color center sensing unit is used to perform heterodyne sensing under the combined action of the microwave signal to be measured and the reference microwave signal after phase reset, and generate a heterodyne signal containing a difference frequency component. The photoelectric detection and data acquisition unit is used to acquire the heterodyne signal under the control of the master clock generation unit; The data processing unit is used to demodulate the heterodyne signal to obtain the amplitude and phase of the microwave signal under test.

2. The apparatus according to claim 1, characterized in that, The master clock generating unit generates a cycle start trigger signal according to a preset cycle period and sends it to each unit. It also generates a laser gating signal, a microwave gating signal under test, a reference field phase reset signal, a reference field output gating signal, and a data acquisition sampling clock according to a pre-calibrated delay compensation table and sends them to the corresponding units. The laser excitation unit synchronously receives the cycle start trigger signal and the laser gating signal to ensure that the laser illuminates the silicon carbide color center sensing unit at the beginning of each measurement cycle. The reference field application unit receives the reference field phase reset signal in front of the preset microwave exposure window to reset the initial phase of the reference microwave signal, and receives the reference field output gate signal to output the phase-reset reference microwave signal to the microwave coupling unit. The microwave receiving unit under test receives the microwave gating signal under test in front of a preset microwave exposure window and outputs the microwave signal under test to the microwave coupling unit. At the start of the preset microwave exposure window, the microwave coupling unit transmits the coupled signal after beam combining to the silicon carbide color center sensing unit. The photoelectric detection and data acquisition unit synchronously receives the cycle start trigger signal and the data acquisition sampling clock to ensure that the heterodyne signal is acquired at the beginning of each measurement cycle.

3. The apparatus according to claim 1, characterized in that, The silicon carbide color center sensing unit includes a silicon carbide color center, which includes at least a silicon vacancy color center, a double vacancy color center, a carbon vacancy-related defect, a nitrogen vacancy-type defect, or other optically readable point defects in 4H-SiC, 6H-SiC, or 3C-SiC.

4. The apparatus according to claim 2, characterized in that, The delay compensation table includes at least the optical path delay of the laser reaching the silicon carbide color center. The propagation delay of the microwave signal to be measured to the silicon carbide color center. The propagation delay of the reference microwave signal to the silicon carbide color center. Phase stabilization time of the reference field application unit and the delay triggered by data acquisition ; Phase stabilization time of the reference field application unit This represents the time required from the moment the reference field application unit receives the reference field phase reset signal until the output reference microwave signal reaches the preset phase and stabilizes.

5. The apparatus according to claim 4, characterized in that, The master clock generating unit calculates the advance output amount of the laser gating signal, the microwave gating signal under test, the reference field output gating signal, the reference field phase reset signal, and the data acquisition sampling clock relative to the start time of the microwave exposure window, based on the delay parameters in the delay compensation table. The laser gating signal is advanced Output, the microwave gate signal to be tested is advanced The reference field output gating signal is advanced. The output, the reference field phase reset signal is advanced. End, the data acquisition sampling clock is advanced. Output.

6. The apparatus according to claim 4, characterized in that, The master clock generating unit establishes a phase stabilization time based on the reference field applying unit. The time interval between the end time of the reference field phase reset signal and the start time of the preset microwave exposure window is greater than or equal to the specified time. This ensures that the initial phase of the reference microwave signal has been reset to the preset phase of the current cycle before the start of the preset microwave exposure window in each measurement cycle.

7. The apparatus according to claim 4, characterized in that, The preset phase adopts any of the following modes: A phase pair mode that alternates between 0° and 180°; or A four-phase sequence mode that cycles through 0°, 90°, 180° and 270°; When the phase pair mode is used, the data processing unit subtracts the heterodyne signals corresponding to the phase pair to eliminate the common-mode background that does not change with the phase of the reference field and enhance the heterodyne signal, thereby obtaining the in-phase component of the microwave signal under test and thus obtaining the amplitude of the microwave signal under test. When the four-phase sequence mode is used, the data processing unit reconstructs the in-phase and quadrature components of the microwave signal under test based on the heterodyne signal corresponding to the four-phase sequence, thereby obtaining the amplitude and phase of the microwave signal under test.

8. The apparatus according to claim 1, characterized in that, The master clock generating unit locks the cycle start trigger signal and the data acquisition sampling clock; the sampling points with the same sequence number in different measurement cycles correspond to the same physical time in the cycle, and this correspondence covers all sampling points, ensuring that the phase of the heterodyne signal containing the difference frequency component acquired within the preset microwave exposure window is repeatable between different cycles.

9. The apparatus according to claim 1, characterized in that, The amplitude and phase of the microwave signal under test are expressed by the following formula: In the formula, This represents the in-phase component of the microwave signal under test. This represents the orthogonal components of the microwave signal under test. This indicates the amplitude of the microwave signal under test. Indicates the phase of the microwave signal under test. Indicates the first measurement cycle in a single measurement cycle The serial number of each sampling point Indicates the first The average value of multiple measurement cycles at a sampling point. This represents the frequency difference between the reference microwave signal and the microwave signal under test. Indicates the sampling frequency. This indicates the number of sampling points in a single measurement cycle.

10. A method for heterodyne microwave detection of color centers based on master clock coordinated triggering using the apparatus of any one of claims 1-9, characterized in that, The method includes the following steps: The master clock generation unit outputs a cycle start trigger signal to each unit according to a preset cycle period, which serves as the start time of each measurement cycle; According to the pre-calibrated delay compensation table, the master clock generation unit outputs a laser gating signal to the laser excitation unit and a data acquisition sampling clock to the photoelectric detection and data acquisition unit at the same time as outputting the cycle start trigger signal; the laser excitation unit synchronously receives the cycle start trigger signal and the laser gating signal and irradiates the silicon carbide color center sensing unit with laser. According to the pre-calibrated delay compensation table, the master clock generation unit outputs a reference field phase reset signal to the reference field application unit before the start of the preset microwave exposure window, so as to reset the initial phase of the reference microwave signal to the preset phase. According to the pre-calibrated delay compensation table, the master clock generating unit synchronously outputs the microwave gate signal to be tested to the microwave receiving unit before the preset microwave exposure window, sends the microwave signal to be tested to the microwave coupling unit, outputs the reference field gate signal to the reference field application unit, and sends the phase-reset reference microwave signal to the microwave coupling unit, so that the microwave signal to be tested and the phase-reset reference microwave signal are synchronously sent to the microwave coupling unit. At the start of the preset microwave exposure window, the microwave coupling unit combines the microwave signal to be measured and the reference microwave signal and couples them together to the silicon carbide color center sensing unit, so that the silicon carbide color center sensing unit generates a heterodyne signal containing a difference frequency component. The photoelectric detection and data acquisition unit synchronously receives the cycle start trigger signal and the data acquisition sampling clock to acquire the heterodyne signal; The data processing unit performs heterodyne demodulation on the heterodyne signal of each measurement cycle to obtain the amplitude and phase of the microwave signal under test.

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