A terahertz superconducting array detector characteristic measurement device and measurement method

Abstract

The present invention proposes a novel terahertz superconducting array detector characteristic measurement device and measurement method, which mainly controls the switching of microwave switches by electrical signals to put the measurement device in different measurement states, and completes the integration method of the measurement system by sharing the same system link, and the method of the back-end automatic calibration program to complete the corresponding functions. The measurement device and measurement method of the present invention can achieve: measuring the noise readout of the KIDs detector, measuring the imbalance correction parameters of the readout circuit system, and reading the S21 parameters of the KIDs detector, and are easy to implement, reduce unnecessary system operations, improve the stability of the system, and effectively reduce the measurement error.

Description

Technical Field

[0001] The invention relates to a frequency response measurement method for a terahertz detector and a readout circuit system, and belongs to the field of terahertz technology research. Background Art

[0002] Kinetic Inductance Detectors (KIDs) are a new type of low-temperature and high-sensitivity detectors that can be used for target imaging observations from millimeter waves to terahertz, optical / ultraviolet, X-ray, and gamma frequency bands.

[0003] The core circuit of KIDs detector is mainly composed of two parts: photon signal receiver and microwave resonator. According to the working principle of KIDs, when the external RF signal irradiates the KIDs detector, the receiver receives the photon energy and the superconducting Cooper pair breaks, which will cause the dynamic resistance and dynamic inductance of the microwave resonator to change, thereby causing the microwave resonator characteristics (Q factor, amplitude, phase, etc.) to change. By obtaining the amplitude (which can be characterized by the S21 parameter) or phase change information of the microwave resonator through the readout circuit, the information characteristics of the incident photon signal can be indirectly detected. Since the microwave resonator of KIDs detector can achieve a high Q value design of more than 104, it is possible to couple multiple (>1000) KIDs detectors with different resonant frequencies on a single transmission line. If a comb signal generator is used to add an excitation signal corresponding to the resonant frequency of the KIDs detector array unit on the transmission line, all output signals of the KIDs detector array can be read simultaneously through the frequency division multiplexing FDM (Frequency Division Multiplexing) technology.

[0004] Phase noise is one of the main parameters that characterizes the performance of KIDs detectors and directly affects the overall sensitivity of the terahertz imaging system. Its importance is beyond doubt. At present, the KIDs phase noise measurement hardware system generally uses microwave orthogonal mixers, combined with auxiliary circuit modules such as low-noise amplifiers, power dividers, adjustable attenuators, fixed attenuators, bandpass filters, and low-pass filters, and measures phase noise through homodyne mixing. By processing the data of the I and Q orthogonal intermediate frequency output signals, the phase noise θ(f) and amplitude noise A(f) of the KIDs detector can be obtained simultaneously. The calculation formula can be as follows:

[0005]

[0006] θ(f)=FFT(tan -1 (I(t) / Q(t))) (2)

[0007] Both theoretical and measured results confirm that phase noise plays a dominant role in these two types of noise, and its magnitude is usually one to two orders of magnitude higher than amplitude noise. The general principle of a broadband quadrature mixer is mainly composed of two double-balanced mixers, a 3dB equal-phase equal-power divider, and a 3dB equal-power directional coupler with an orthogonal (90°) phase difference. After the RF signal with equal phase and the local oscillator signal with a 90° phase difference are down-mixed in two double-balanced mixers, two intermediate frequency signals I and Q with an orthogonal phase difference are output.

[0008] The existing KIDs readout circuit has the following problems:

[0009] 1) Due to the existing circuit design methods and processing technology, it is still difficult to realize a power divider and directional coupler with perfect equal power division, 90° phase difference and high isolation in a broadband, so the two orthogonal intermediate frequency output ends I and Q of the orthogonal mixer microwave generally have amplitude and phase imbalance, and the specific values ​​change with frequency. This makes the calibration of the orthogonal mixer a complicated and demanding process in the phase noise measurement of superconducting KIDs detectors.

[0010] 2) At the same time, as mentioned above, the information characteristics of the incident photon signal can be indirectly detected by obtaining the amplitude of the microwave resonator (which can be characterized by the S21 parameter) through the readout circuit. It takes a lot of time to obtain the amplitude of the KIDs resonator by ADC sampling and computer data software processing, so a vector network analyzer is often used to quickly scan the S21 parameters of the resonator. However, the existing solution uses a vector network analyzer to measure the S21 parameters of the resonator, which requires an amplification circuit. During the noise readout and S21 parameter acquisition test, two sets of circuit systems need to be switched back and forth, which increases the instability of the system and the complexity of the operation. Summary of the invention

[0011] In view of the deficiencies of the prior art, the present invention proposes a terahertz superconducting array detector characteristic measurement device and a measurement method to improve the deficiencies of the prior art.

[0012] The technical solution provided by the present invention is:

[0013] A terahertz superconducting array detector characteristic measurement device, comprising a frequency signal source, a clock signal synchronization device, a vector network analyzer, a readout circuit system, an ADC data acquisition module, a control computer and a refrigerator for installing a KIDs detector, characterized in that:

[0014] The readout circuit system includes a directional coupler, a microwave switch A, a microwave switch B and a mixer, wherein:

[0015] The signal input end of the directional coupler is connected to the frequency signal source, and the two signal output ends of the directional coupler are connected to the microwave switch A and the local oscillator signal input end of the mixer respectively;

[0016] The signal input end of the microwave switch A is provided with a first channel switch contact and a second channel switch contact, the first channel switch contact is connected to the directional coupler, the second channel switch contact is connected to a port of the vector network analyzer, and the signal output end of the microwave switch A is connected to the signal input end of the KIDs detector;

[0017] The signal output end of microwave switch B is provided with a first channel switch contact and a second channel switch contact, and its signal input end is connected to the signal output end of the KIDs detector, the first channel switch contact of microwave switch B is connected to the resonant signal input end of the mixer, and the second channel switch contact of microwave switch B is connected to the second port of the vector network analyzer;

[0018] The two orthogonal intermediate frequency output terminals I and Q of the mixer are respectively connected to the ADC data acquisition module;

[0019] The ADC data acquisition module is connected to the control computer to upload data to the control computer and receive control instructions from the control computer;

[0020] The control signal input ends of the frequency signal source, vector network analyzer, microwave switch A and microwave switch B are respectively connected to the control computer, and the control computer controls their operation modes according to instructions input by the user or preloaded programs.

[0021] On the basis of the above scheme, the preferred scheme also includes:

[0022] Further, the signal output end of the microwave switch A is connected to the signal input end of the KIDs detector through a first attenuator, a first DC block, and a second attenuator connected in series in sequence; the signal output end of the KIDs detector is connected to the signal input end of the microwave switch through a low-temperature amplifier, a third attenuator, a first normal temperature amplifier, a fourth attenuator, and a second normal temperature amplifier connected in series in sequence; the output end I of the mixer is connected to the ADC data acquisition module through a fifth attenuator and a low-pass filter, and the output end Q is connected to the ADC data acquisition module through a sixth attenuator and a low-pass filter; a third DC block is provided between the directional coupler and the mixer;

[0023] In the above components, the second attenuator and the low-temperature amplifier are installed together with the KIDs detector in the cold chamber of the refrigerator; the first attenuator, the fourth attenuator, the fifth and the sixth attenuator are all adjustable attenuators, and the first normal temperature amplifier and the second normal temperature amplifier are both low noise amplifiers;

[0024] The first attenuator is used to adjust the input power of the KIDs detector to prevent the detector power from being saturated;

[0025] The fourth attenuator is used to adjust the power of the amplifier input mixer resonant port to ensure that the dynamic range of the KIDs detector is consistent with the RF dynamic range of the mixer;

[0026] The fifth and sixth attenuators are used to adjust the imbalance of the amplitudes of the I and Q output signals of the mixer.

[0027] Furthermore, the first attenuator is an adjustable attenuator of 0-60dB, the second attenuator is a 30dB attenuator, the third attenuator is a 3dB attenuator, the fourth attenuator is an adjustable attenuator of 0-30dB, and the fifth and sixth attenuators are step attenuators with a step size of 0.1dB.

[0028] Furthermore, the microwave switch A and the microwave switch B are single-pole double-throw microwave switches.

[0029] A measurement method based on the terahertz superconducting array detector characteristic measurement device as described above, characterized in that it comprises the following steps:

[0030] S1. Measurement of correction parameters for system imbalance

[0031] Setting the resonant frequency to be measured, installing a KIDs detector sample having the resonant frequency in the refrigerator, connecting the frequency signal source and the vector network analyzer to a synchronous clock signal, so that the signals output by the two are synchronized;

[0032] The signal output by the frequency signal source is used as a test signal, the frequency of which is the same as the resonant frequency of the KIDs detector sample, the signal output by a port of the vector network analyzer is used as a calibration signal, and the frequency difference between the calibration signal and the test signal is controlled within a preset range;

[0033] Connecting the second channel switch contact of the microwave switch A to the signal output terminal of the microwave switch A, and connecting the signal input terminal of the microwave switch B to the first channel switch contact of the microwave switch B, to establish a calibration link;

[0034] According to the sampling value of the ADC data acquisition module, a correction parameter of the imbalance of the readout circuit system at the resonant frequency is obtained, and the readout circuit system is calibrated based on the correction parameter;

[0035] S21 parameter measurement of S2.KIDs detector

[0036] The KIDs detector to be tested is installed in the refrigerator, the second channel switch contact of microwave switch A is connected to the signal output end of microwave switch A, the signal input end of microwave switch B is connected to the second channel switch contact of microwave switch B, and the S21 parameter is selected in the vector network analyzer to measure the resonance characteristics of the KIDs detector;

[0037] S3. Noise readout of KIDs detector

[0038] The KIDs detector to be tested is installed in the refrigerator, the first channel switch contact of microwave switch A is connected to the signal output end of microwave switch A, the signal input end of microwave switch B is connected to the first channel switch contact of microwave switch B, a zero-difference frequency detection circuit is established, the output signal is read out using the calibrated readout circuit system, and the data is sampled using the ADC data acquisition module.

[0039] On the basis of the above scheme, the preferred scheme also includes:

[0040] Furthermore, in step S1, the frequency difference between the calibration signal and the test signal is between 1 and 10 kHz.

[0041] Furthermore, in step S1, the process of obtaining the correction parameter of the imbalance of the readout circuit system at the resonant frequency according to the sampling value of the ADC data acquisition module is as follows:

[0042] Using the sampling values ​​of the discrete ADC data acquisition module, a relationship curve between the output I and output Q signal values ​​of the mixer is drawn, and the relationship curve is named IQ circle. The IQ circle is represented by the following equation:

[0043] I=I0+A I cosγ

[0044] Q=Q0+A Q sinγ

[0045] Where I0 and Q0 represent the offset of I and Q channel output respectively, A I and A Q It represents the imbalance between the I and Q channel signal amplitudes, and γ represents the fixed initial phase difference;

[0046] I0, Q0, A I , A Q , γ are the correction parameters to be determined, and the IQ circle is fitted using the least squares method to determine the correction parameters.

[0047] Furthermore, in step S3, the method for calibrating the readout circuit system is:

[0048] The signal amplitude is adjusted by an adjustable attenuator arranged between the mixer output end and the ADC data acquisition module.

[0049] Beneficial effects:

[0050] 1) The terahertz superconducting array detector characteristic measurement device and measurement method of the present invention have the functions of noise reading of KIDs detector, correction parameter measurement of system imbalance, and S21 parameter reading of KIDs detector;

[0051] 2) The measuring device and the measuring method of the present invention can replace the corresponding link by controlling the switching of the microwave switch by the control computer, thereby reducing unnecessary operations of the system and improving the stability of the system;

[0052] 3) The measuring device and measuring method of the present invention use the measuring function of the vector network analyzer to accurately obtain the resonant frequency and S21 characteristics of the KIDs detector array, which is the basic measurement for the subsequent KIDs noise characteristics or sensitivity characterization. At the same time, the vector network analyzer provides a synchronous signal source for the homodyne mixer circuit, which is used for the unbalanced calibration of the homodyne mixer circuit. In the same system, the measurement error can be effectively reduced. Compared with the traditional measurement method, the method of the present invention can control the resonance depth of the KIDs detector test signal within the measurement range of the vector network analyzer by adjusting the adjustable attenuator, and the operation is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 It is a system principle diagram of the measuring device of the present invention;

[0054] Figure 2 It is the flowchart of the ADC data processing module;

[0055] Figure 3 is a schematic diagram of an IQ circle before correction in one embodiment;

[0056] Figure 4 Schematic diagram of the corrected IQ circle. DETAILED DESCRIPTION

[0057] The present invention will now be described in further detail with reference to the accompanying drawings.

[0058] like Figure 1 As shown, a terahertz superconducting array detector characteristic measurement device includes a frequency signal source, a clock signal synchronization device, a vector network analyzer, a readout circuit system, an ADC data acquisition module, a control computer and a refrigerator for installing KIDs detectors.

[0059] The readout circuit system includes a directional coupler, a microwave switch A, a microwave switch B and a mixer, wherein:

[0060] The signal input end of the directional coupler is connected to the frequency signal source, and the two signal output ends of the directional coupler are respectively connected to the microwave switch A and the local oscillator signal input end (LO) of the mixer;

[0061] The signal input end of the microwave switch A is provided with a first channel switch contact ① and a second channel switch contact ②, wherein the first channel switch contact ① is connected to the directional coupler, and the second channel switch contact ② is connected to a port (Port 1) of the vector network analyzer, and the signal output end of the microwave switch A is connected to the signal input end of the KIDs detector;

[0062] The signal output end of microwave switch B is provided with a first channel switch contact ① and a second channel switch contact ②, and its signal input end is connected to the signal output end of the KIDs detector, the first channel switch contact ① of microwave switch B is connected to the resonant signal input end (RF) of the mixer, and the second channel switch contact of microwave switch B is connected to the second port (Port2) of the vector network analyzer;

[0063] The two orthogonal intermediate frequency output terminals I and Q of the mixer are respectively connected to the terminals of the two signal acquisition channels of the ADC data acquisition module.

[0064] The ADC data acquisition module is connected to the control computer to upload data to the control computer and receive control instructions from the control computer.

[0065] The control signal input ends of the frequency signal source, vector network analyzer, microwave switch A and microwave switch B are respectively connected to the control computer, and the control computer controls the operation according to the instructions input by the user or the preloaded program, including the switching control of the microwave switch, and the adjustment of the working mode of the frequency signal source and the vector network analyzer.

[0066] The signal output end of the microwave switch A is connected to the signal input end of the KIDs detector through a first attenuator, a first DC block, and a second attenuator connected in series in sequence; the signal output end of the KIDs detector is connected to the signal input end of the microwave switch through a low-temperature amplifier, a third attenuator, a first normal temperature amplifier, a fourth attenuator, and a second normal temperature amplifier connected in series in sequence; the output end I of the mixer is connected to the ADC data acquisition module through a fifth attenuator and a low-pass filter, and the output end Q is connected to the ADC data acquisition module through a sixth attenuator and a low-pass filter; a third DC block is provided between the directional coupler and the mixer.

[0067] in:

[0068] The second attenuator and the low-temperature amplifier are installed together with the KIDs detector in the cold chamber of the refrigerator; the first attenuator, the fourth attenuator, the fifth and the sixth attenuator are all adjustable attenuators, and the first normal temperature amplifier and the second normal temperature amplifier are both low noise amplifiers.

[0069] The first attenuator is used to adjust the input power of the KIDs detector to prevent the detector power from being saturated;

[0070] The fourth attenuator is used to adjust the power of the amplifier input mixer resonant port to ensure that the dynamic range of the KIDs detector is consistent with the RF dynamic range of the mixer;

[0071] The fifth and sixth attenuators are used to adjust the imbalance of the amplitudes of the I and Q output signals of the mixer.

[0072] As a preferred implementation, in this embodiment, the first attenuator uses an adjustable attenuator of 0-60dB, the second attenuator uses a 30dB attenuator, the third attenuator is a 3dB attenuator, the fourth attenuator is an adjustable attenuator of 0-30dB, and the fifth and sixth attenuators both use step (adjustable) attenuators with a step of 0.1dB. The microwave switch A and microwave switch B use single-pole double-throw microwave switches.

[0073] The working principle and measurement method of the terahertz superconducting array detector characteristic measurement device are as follows.

[0074] (1) Noise readout of KIDs detector

[0075] The KIDs detector to be tested is installed in the refrigerator, the first channel switch contact ① of microwave switch A is connected to the signal output end of microwave switch A, and the signal input end of microwave switch B is connected to the first channel switch contact ① of microwave switch B to establish a zero-difference frequency detection circuit.

[0076] In this circuit, the frequency signal source outputs a detection signal, which is divided into two channels by a directional coupler, one as the local oscillator signal (Local-Oscillator, LO) of the IQ mixer, and the other as its radio frequency signal (Radio Frequency, RF) after modulation and multi-stage amplification by the KID detector. The two channels are simultaneously used as the input signals of the IQ mixer, and the difference frequency of the mixer is output as a DC signal. The two time domain DC signals are filtered by a step attenuator (impedance converter) and a low-pass filter (LPF) and then input to the ADC sampling module. The ADC module preferably uses a high-precision data sampling card, and the sampling values ​​are I (t) and Q (t) respectively. Finally, the two time domain signals are converted into amplitude or phase noise in the frequency domain through Fourier transform. The frequency signal source generates the frequency of the resonance point of the KIDs detector, and different input powers can be set for easy measurement.

[0077] The signal generated by the frequency signal source is divided into two signals of the same frequency through a directional coupler. After the direct-through end of the directional coupler filters out the DC signal through a DC block, it enters the local oscillator input port of the mixer; after the coupling end of the directional coupler outputs another signal, the signal passes through an adjustable attenuator to adjust the signal strength entering the detector (the saturation power of the KIDs detector is relatively low, generally lower than -60dBm), and then the signal passes through the KIDs detector in a low-temperature environment, the low-temperature amplifier HEMT and the multi-stage constant temperature amplifier, and then the signal enters the adjustable attenuator (adjusting the amplitude of the signal to adapt to the dynamic range of the RF of the mixer); after the signal is output from the adjustable attenuator, it enters the IQ mixer; the I and Q signals output by the IQ mixer pass through the next-level adjustable attenuator (adjusting the amplitude imbalance of the IQ two-way) and the low-pass filter, respectively, and enter the ADC data acquisition module to sample data, and then after being processed by the software algorithm, the amplitude and phase noise of the detector are calculated.

[0078] (2) Measurement of correction parameters for system imbalance

[0079] KIDs detectors often have the characteristics of high sensitivity and large dynamic range, which depends not only on the detector itself but also on its readout circuit. In the homodyne mixing readout system of KID detectors, the IQ mixer often has the disadvantage of unbalanced two-way output. This not only limits the dynamic range of the entire readout system, but also makes data acquisition inaccurate and affects the measurement of noise, so it is necessary to calibrate the imbalance of the readout circuit system.

[0080] The calibration process is:

[0081] Setting the resonant frequency to be measured, installing a KIDs detector sample having the resonant frequency in the refrigerator, connecting the frequency signal source and the vector network analyzer to a synchronous clock signal, so that the signals output by the two are synchronized;

[0082] The signal output by the frequency signal source is used as a test signal, the frequency of which is the same as the resonant frequency of the KIDs detector sample, the signal output by a port of the vector network analyzer is used as a calibration signal, and the frequency difference between the calibration signal and the test signal is controlled within a preset range;

[0083] Connect the second channel switch contact ② of the microwave switch A to the signal output terminal of the microwave switch A, and connect the signal input terminal of the microwave switch B to the first channel switch contact ① of the microwave switch B, so as to establish a calibration link;

[0084] According to the sampling value of the ADC data acquisition module, the correction parameter of the imbalance of the readout circuit system at the resonant frequency is obtained, which is specifically:

[0085] Using the sampling values ​​of the discrete ADC data acquisition module, a relationship curve between the output I and output Q signal values ​​of the mixer is drawn, and the relationship curve is named IQ circle. The IQ circle is represented by the following equation:

[0086] I=I0+A I cosγ

[0087] Q=Q0+A Q sinγ

[0088] Where I0 and Q0 (the center of the ellipse) represent the offset of the I and Q channel outputs, respectively. I and A Q (the major axis of the ellipse and its minor axis) represent the imbalance of the I and Q channel signal amplitudes, and γ (the tilt angle of the ellipse) represents the fixed initial phase difference;

[0089] The I0, Q0, A I , A Q , γ are the correction parameters to be determined, and the correction parameters can be obtained by fitting the IQ circle using the least squares method.

[0090] Finally, based on the correction parameters, the amplitude of the readout circuit system is calibrated by adjusting the back-end 0.1dB step attenuator, and the phase is corrected by software, so that the image of the IQ circle can be sorted out in real time, which is convenient for observation and data processing. Figure 3 , Figure 4 As shown, before calibration, the IQ circle is elliptical, and after calibration, the IQ is a standard perfect circle (the IQ amplitude is the same and the phase difference is 90°).

[0091] In the prior art, the system needs to disassemble the whole system and test the unbalanced parameters of the corresponding frequency points to obtain the correction parameters. This operation is complicated and troublesome, and increases the stability of the system and has a certain impact on the system structure. The present invention designs a single-pole double-throw microwave switch and uses an electrical signal control method to switch the corresponding path, reducing unnecessary operations of the system.

[0092] In the above process of the method of the present invention, when setting the signal source, the frequency of the signal output to one port of the vector network analyzer differs from the resonant frequency of the KIDs detector sample by several kHz, theoretically within 100kHz, and the smaller the frequency difference between the two, the better, but too small a difference is not easy to obtain the IQ circle, so the frequency difference can generally be controlled to be several kHz, for example, between 1 and 10kHz. The signal generated by the frequency signal source enters the LO (local oscillator) port of the IQ mixer through the through port; the signal generated by the vector network analyzer enters the 0-60dB adjustable attenuator and the DC isolation device through the switching of the microwave switch, and then connects the 3dB attenuator, the low noise amplifier, the 0-30dB adjustable attenuator, the secondary low noise amplifier, and then switches to the RF (radio frequency) port of the IQ mixer through the microwave switch; the mixer samples the IQ two-way signal after mixing the two-way signal through the ADC, thereby obtaining the correction parameters of the imbalance of the readout circuit system at the working resonance point of the KIDs detector.

[0093] (3) S21 parameter measurement of KIDs detector

[0094] The KIDs detector to be tested is installed in the refrigerator, the second channel switch contact of microwave switch A is connected to the signal output end of microwave switch A, the signal input end of microwave switch B is connected to the second channel switch contact of microwave switch B, the S21 parameter is selected in the vector network analyzer to measure the resonance characteristics of the KIDs detector.

[0095] The KIDs detector detects signals with high sensitivity by detecting the characteristics that the resonant frequency of the resonator changes and the amplitude of the resonance curve of the resonator becomes shallower and wider, so the S21 parameter of the detector can well characterize the detection characteristics of the detector. In this embodiment, the signal generated by one port (Port1) of the vector network analyzer is switched by a single-pole double-throw microwave switch A, and then the signal enters a 0-60dB adjustable attenuator and a DC block, passes through a low-temperature test system, connects a 3dB attenuator, a low-noise amplifier, a 0-30dB adjustable attenuator, and a secondary low-noise amplifier, and then switches to the RF (radio frequency) port of the IQ mixer through a microwave switch B; after passing through the low-temperature test system, it passes through a normal temperature amplifier and is connected to the second port (Port2) of the vector network analyzer, thereby measuring the S21 parameter of the detector.

[0096] The measurement device of this example integrates the measurement function of the vector network analyzer to accurately obtain the resonant frequency and S21 of the KIDs array, which is the basic measurement data for the noise characteristics or sensitivity characterization of the subsequent KIDs array pixel detector; the vector network analyzer provides a synchronous signal source for the homodyne mixer circuit, which is used for the unbalanced calibration of the homodyne mixer circuit. Under the same system, the measurement error can be effectively reduced. At the same time, compared with the traditional measurement method, this solution can adjust the attenuation of the two adjustable attenuators so that the resonance depth of the test signal of the KIDs detector is within the measurement range of the vector network analyzer (the measurement range of the vector network analyzer is generally -40dBm to 10dBm).

[0097] The above are only preferred embodiments of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. A terahertz superconducting array detector characteristic measurement device, comprising a frequency signal source, a clock signal synchronization device, a vector network analyzer, a readout circuit system, an ADC data acquisition module, a control computer and a refrigerator for installing KIDs detectors, characterized in that: The readout circuit system includes a directional coupler, a microwave switch A, a microwave switch B and a mixer, wherein: The signal input end of the directional coupler is connected to the frequency signal source, and the two signal output ends of the directional coupler are connected to the microwave switch A and the local oscillator signal input end of the mixer respectively; The signal input end of the microwave switch A is provided with a first channel switch contact and a second channel switch contact, the first channel switch contact is connected to the directional coupler, the second channel switch contact is connected to a port of the vector network analyzer, and the signal output end of the microwave switch A is connected to the signal input end of the KIDs detector; The signal output end of microwave switch B is provided with a first channel switch contact and a second channel switch contact, and its signal input end is connected to the signal output end of the KIDs detector, the first channel switch contact of microwave switch B is connected to the resonant signal input end of the mixer, and the second channel switch contact of microwave switch B is connected to the second port of the vector network analyzer; The two orthogonal intermediate frequency output terminals I and Q of the mixer are respectively connected to the ADC data acquisition module; The ADC data acquisition module is connected to the control computer to upload data to the control computer and receive control instructions from the control computer; The control signal input ends of the frequency signal source, vector network analyzer, microwave switch A and microwave switch B are respectively connected to the control computer, and the control computer controls their operation modes according to instructions input by the user or preloaded programs; The signal output end of the microwave switch A is connected to the signal input end of the KIDs detector through the first attenuator, the first DC block and the second attenuator connected in series in sequence; the signal output end of the KIDs detector is connected to the signal input end of the microwave switch through the low-temperature amplifier, the third attenuator, the first normal temperature amplifier, the fourth attenuator and the second normal temperature amplifier connected in series in sequence; the output end I of the mixer is connected to the ADC data acquisition module through the fifth attenuator and the low-pass filter, and the output end Q is connected to the ADC data acquisition module through the sixth attenuator and the low-pass filter; a third DC block is provided between the directional coupler and the mixer; In the above components, the second attenuator and the low-temperature amplifier are installed together with the KIDs detector in the cold chamber of the refrigerator; the first attenuator, the fourth attenuator, the fifth and the sixth attenuator are all adjustable attenuators, and the first normal temperature amplifier and the second normal temperature amplifier are both low noise amplifiers; The first attenuator is used to adjust the input power of the KIDs detector to prevent the detector power from being saturated; The fourth attenuator is used to adjust the power of the amplifier input mixer resonant port to ensure that the dynamic range of the KIDs detector is consistent with the RF dynamic range of the mixer; The fifth and sixth attenuators are used to adjust the imbalance of the amplitudes of the I and Q output signals of the mixer.

2. A terahertz superconducting array detector characteristic measurement device according to claim 1, characterized in that: The first attenuator is an adjustable attenuator of 0-60dB, the second attenuator is a 30dB attenuator, the third attenuator is a 3dB attenuator, the fourth attenuator is an adjustable attenuator of 0-30dB, and the fifth and sixth attenuators are step attenuators with a step size of 0.1dB.

3. The terahertz superconducting array detector characteristic measurement device according to claim 1, characterized in that: The microwave switch A and the microwave switch B are single-pole double-throw microwave switches.

4. A method for measuring characteristics of a terahertz superconducting array detector based on the device for measuring characteristics of a terahertz superconducting array detector according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. Measurement of correction parameters for system imbalance Setting the resonant frequency to be measured, installing a KIDs detector sample having the resonant frequency in the refrigerator, connecting the frequency signal source and the vector network analyzer to a synchronous clock signal, so that the signals output by the two are synchronized; The signal output by the frequency signal source is used as a test signal, the frequency of which is the same as the resonant frequency of the KIDs detector sample, the signal output by a port of the vector network analyzer is used as a calibration signal, and the frequency difference between the calibration signal and the test signal is controlled within a preset range; Connecting the second channel switch contact of the microwave switch A to the signal output terminal of the microwave switch A, and connecting the signal input terminal of the microwave switch B to the first channel switch contact of the microwave switch B, to establish a calibration link; According to the sampling value of the ADC data acquisition module, a correction parameter of the imbalance of the readout circuit system at the resonant frequency is obtained, and the readout circuit system is calibrated based on the correction parameter; S21 parameter measurement of S2.KIDs detector The KIDs detector to be tested is installed in the refrigerator, the second channel switch contact of microwave switch A is connected to the signal output end of microwave switch A, the signal input end of microwave switch B is connected to the second channel switch contact of microwave switch B, and the S21 parameter is selected in the vector network analyzer to measure the resonance characteristics of the KIDs detector; S3. Noise readout of KIDs detector The KIDs detector to be tested is installed in the refrigerator, the first channel switch contact of microwave switch A is connected to the signal output end of microwave switch A, the signal input end of microwave switch B is connected to the first channel switch contact of microwave switch B, a zero-difference frequency detection circuit is established, the output signal is read out using the calibrated readout circuit system, and the data is sampled using the ADC data acquisition module.

5. The measuring method according to claim 4, characterized in that: In step S1, the frequency difference between the calibration signal and the test signal is between 1 and 10 kHz.

6. The measuring method according to claim 4 or 5, characterized in that: In step S1, the process of obtaining the correction parameter of the imbalance of the readout circuit system at the resonant frequency according to the sampling value of the ADC data acquisition module is as follows: Using the sampling values ​​of the discrete ADC data acquisition module, a relationship curve between the output I and output Q signal values ​​of the mixer is drawn, and the relationship curve is named IQ circle. The IQ circle is represented by the following equation: I=I0+A I cosγ Q=Q0+A Q sinγ Where I0 and Q0 represent the offset of I and Q channel output respectively, A I and A Q It represents the imbalance between the I and Q channel signal amplitudes, and γ represents the fixed initial phase difference; I0, Q0, A I , A Q , γ are the correction parameters to be determined, and the IQ circle is fitted using the least squares method to determine the correction parameters.

7. The measuring method according to claim 6, characterized in that: In step S3, the method for calibrating the readout circuit system is: The signal amplitude is adjusted by an adjustable attenuator arranged between the mixer output end and the ADC data acquisition module.

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