Superconducting microwave dynamic inductance detector array imaging chip and detection related device

Abstract

The invention discloses a superconducting microwave dynamic inductance detector array imaging chip and a detection related device, and belongs to the field of signal detection, and the chip comprises a pixel configuration module, an experiment building module, a signal detection module, a signal processing module, a signal generation module, a data analysis module and a space imaging module. By optimizing the pixel pitch and the detector array design, the spatial resolution can be remarkably improved, high-quality imaging data can be obtained in real time by combining time domain and frequency domain signal analysis and high-speed data acquisition, and an image is optimized through an efficient signal processing algorithm. The process can quickly respond and generate a space imaging picture, so that the dynamic response capability of the imaging system is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of signal detection, and more specifically, particularly relates to a superconducting microwave dynamic inductance detector array imaging chip and detection-related devices. Background Art

[0002] The current commonly used solution for security checks is a combination of metal detection gates and manual body searches. Although this method is simple and direct, it has many limitations, such as: the inspection speed is slow, the prohibited items that can be detected are limited to metals (that is, non-metallic items carried may be missed, such as ceramic knives), it is impossible to conduct a comprehensive inspection of the human body, and contact-based manual body searches may infringe on privacy.

[0003] In the past three decades, millimeter wave technology 130~300 GHz has received extensive attention in human security applications due to its clothing penetration and radiation safety. In 2001, the Pacific Northwest National Laboratory (PNNL) of the United States first published research on 27-33GHz millimeter wave holographic imaging systems. Subsequently, PNNL proposed a cylindrical scanning holographic imaging system for human security imaging. The MKID detector is designed as a lumped structure resonator, consisting of a large area interdigital capacitor (IDC, blue line) and a thin inductor strip (Al, red line). The large area IDC (≈1.2 mm×1.0 mm) is to suppress the noise caused by the second-level impurities in the substrate. The typical line width of the IDC is ≈5μm, and the material is thick Al or TiN. The inductor strip is the light absorption area (the green circle indicates the position of the horn antenna alignment), and the material is Al film with Tc≈1.3 K-1.5 K, which is very thin ≈10~60 nm and has a typical width of ≈2μm. The feed line is designed as a 50Ohm microstrip line, with a coupling quality factor Qc≈10~20×103 with the resonator, and a resonant frequency≈0.5~1 GHz. The lower microwave frequency band is selected to reduce the cost of the circuit system. Using SOI (Silicon on Insulator) or deep silicon etching technology, the large Si substrate below the light absorption area is etched away, allowing the light absorption area to "suspend" above a thinner Si layer (thickness≈50μm), and thick Al is plated on the back. This optical cavity structure can increase the absorption rate of 600 GHz photons, while effectively utilizing thermal phonon energy to improve the detector's responsiveness to radiation energy. The lower layer of SiN is to reduce noise, and the upper layer of SiN or α-Si is to prevent the thin Al layer from oxidizing. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] In view of the above or existing problems of superconducting microwave dynamic inductance detector array imaging chips, the present invention is proposed.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: The embodiment of the present invention provides a superconducting microwave dynamic inductance detector array imaging chip, including: a pixel configuration module for selecting a substrate material, designing an inductance region of the same detector, adjusting the resonant frequency by adjusting the number and length of fingers of the IDC, and adjusting the coupling strength between the IDC and the feed line; The experimental construction module is used to build the experiment through the MKID detector. The MKID detector sample box is placed in a dilution refrigerator for cooling. When the THz photon is absorbed by the MKID detector, the impedance of the detector surface changes suddenly, causing the phase and amplitude of the microwave excitation signal to change. The signal detection module is used to generate an excitation signal from a microwave source and divide it into two signals through a power divider. One signal is input into the LO terminal of the IQ mixer as the reference signal, and the other signal is input into the sample box after attenuation, DC isolation and filtering; The signal processing module is used to couple the signal to the MKID detector through the feeder and further amplify it through the HEMT amplifier. After being amplified by the room temperature amplifier, the signal enters the RF end of the IQ mixer. The mixer outputs the in-phase voltage and quadrature voltage signals. After the output signal passes through the low-pass filter, it is collected by the A / D card and analyzed in the time domain. The signal generation module is used to introduce the signal of the THz wave source into the sample box through the THz low-pass filter. By coupling the THz signal into the inductive absorption region of the MKID detector; The data analysis module is used to analyze the collected I / Q signals through data processing algorithms. By analyzing the pixel data of multiple detectors and combining the time domain and frequency domain information, spatial imaging is achieved. Based on the responses of different frequency bands, full-band imaging data within the THz band is extracted. The spatial imaging module is used to optimize the resolution of spatial imaging by controlling the pixel pitch and the design of the detector array.

[0007] As a preferred solution of the superconducting microwave dynamic inductance detector array imaging chip of the present invention, wherein: the resonant frequency is adjusted by adjusting the number and length of fingers of the IDC, and the coupling strength between the IDC and the feed line is adjusted, including: In MKID, increasing the number or length of fingers of IDC increases the capacitance C, thereby reducing the resonant frequency f0; reducing the number or length of fingers of IDC reduces the capacitance C, thereby increasing the resonant frequency f0; Increasing the finger length or number of the IDC enhances the coupling strength between the IDC and the feed line, thereby improving the detector's response to microwave signals.

[0008] As a preferred solution of the superconducting microwave dynamic inductance detector array imaging chip of the present invention, when the THz photon is absorbed by the MKID detector, the impedance of the detector surface changes suddenly, causing the phase and amplitude of the microwave excitation signal to change, including: Assuming that the resonant circuit of the MKID detector consists of an inductor and a capacitor, the impedance of the resonator is expressed as:

[0009] Due to the change of inductance and capacitance, the resonant frequency shifts and the phase change of the microwave signal is described by the following formula:

[0010] Among them, ΔZ L is the change in the detector surface impedance, and Z0 is the characteristic impedance in the system; Assuming that there is reflection at the coupling point between the detector and the feed line, the change in amplitude is calculated by the reflection coefficient:

[0011] Among them, Z load is the impedance of the detector, Z0 is the characteristic impedance of the feed line; When the detector impedance Z load When a mutation occurs, the reflection coefficient Γ will change, and the specific amplitude is quantified by the reflection loss calculation formula:

[0012] Among them, |Γ| 2 Indicates the intensity of the reflection.

[0013] As a preferred solution of the superconducting microwave dynamic inductance detector array imaging chip of the present invention, wherein: the signal is coupled to the MKID detector through a feeder line and further amplified by a HEMT amplifier, and the signal enters the RF end of the IQ mixer after being amplified by a room temperature amplifier, including: The IQ mixer mixes the input RF signal with the local oscillator signal to generate two output signals, I signal and Q signal. The mathematical formula of the mixer is expressed as:

[0014] Among them, RF is the radio frequency signal input to the mixer, LO is the local oscillator signal from the microwave source, and IF1 and IF2 are the intermediate frequency signals obtained after mixing; The mixed I / Q signal needs to be processed by a low-pass filter to remove the high-frequency components and obtain a low-frequency intermediate frequency signal. The low-pass filter passes:

[0015] The mixed signal is downconverted and finally digitized through an A / D converter to obtain the amplitude and phase of the signal.

[0016] As a preferred solution of the superconducting microwave dynamic inductance detector array imaging chip of the present invention, the mixer outputs in-phase voltage and quadrature voltage signals, and the output signals are collected by an A / D card and analyzed in the time domain after passing through a low-pass filter, including: Assume that the signal obtained after mixing contains two frequency components, one is the low-frequency signal f IF =|f LO -f RF ∣, another high frequency component f HF , after passing through a low-pass filter, the filtered signal is:

[0017] The low-pass filter is represented by the following formula:

[0018] Among them, f c is the cutoff frequency of the low-pass filter, and H(f) is the frequency response of the filter; In the time domain, the A / D card converts the analog signal I filtered (t) and Q filtered (t) is converted into a digital signal. Assuming that the sampling rate of the A / D card is fs, the samples are obtained through the following discretization process:

[0019] The I[n] and Q[n] signals are transformed by fast Fourier transform to obtain the signal spectrum, so as to analyze its frequency domain characteristics and determine the frequency distribution and energy concentration area of ​​the signal. The spectrum after FFT conversion is expressed as:

[0020] where S(f) is the complex spectrum in the frequency domain.

[0021] As a preferred solution of the superconducting microwave dynamic inductance detector array imaging chip of the present invention, wherein: the signal of the THz wave source is introduced into the sample box through the THz low-pass filter, and the THz signal is coupled into the inductance absorption area of ​​the MKID detector, including: The THz wave source generates THz signals through a temperature-adjustable blackbody radiation source, which are filtered through a THz low-pass filter to remove unnecessary high-frequency noise. The filtered signal is effectively transmitted to the sample box through a horn antenna coupler; the superconducting inductive absorption area in the MKID detector absorbs THz photons, causing changes in its inductance value, thereby causing changes in the phase and amplitude of the microwave excitation signal.

[0022] As a preferred solution of the superconducting microwave dynamic inductance detector array imaging chip of the present invention, the collected I / Q signal is analyzed by a data processing algorithm, and spatial imaging is achieved by analyzing multiple detector pixel data and combining time domain and frequency domain information, including: By deconstructing the I and Q signals, the response of each detector pixel to the THz signal is obtained, which is further analyzed by decoding the amplitude A(t) and phase φ(t) to obtain the amplitude and phase changes of the signal; Extract the frequency domain features of the signal and perform Fourier transform to obtain frequency information from the time domain signal:

[0023] Where s(t) is the time domain signal, S(f) is the frequency domain signal, and f is the frequency; Spatial imaging uses the signal obtained by the detector to invert the electromagnetic properties of the sample surface or volume. Suppose the sample is at position r i The response at R ri , the signal I / Q collected by the detector can be used to construct the inversion formula:

[0024] Among them, H(ri,t) is the response function of the detector at position ri to the time domain signal, and R(ri) is the signal strength at the spatial position ri.

[0025] As a preferred solution of the superconducting microwave dynamic inductance detector array imaging chip of the present invention, the extraction of full-band imaging data in the THz band according to the responses of different frequency bands includes: The detector pixels record the frequency domain information of the THz signal. By gradually scanning different frequencies, the system collects the response data of the full frequency band. For each frequency band f, the spatial image R (r, f) of the sample is established through the amplitude and phase information of the signal, where r is the spatial position vector and f is the frequency, thus obtaining spectrum imaging. By collecting data from multiple frequency bands, the full-band response of the sample is obtained:

[0026] By combining the data from all frequency bands, a spatial image is constructed, which reflects the electromagnetic response characteristics of the material in the entire THz band.

[0027] As a preferred solution of the superconducting microwave dynamic inductance detector array imaging chip of the present invention, wherein: the resolution of spatial imaging is optimized by controlling the pixel spacing and the design of the detector array, including: By controlling the size, shape and coupling characteristics of the resonator, the response frequency and coupling strength of each pixel can be optimized to improve the spatial resolution of the system. By adjusting the size of the inductive coupling area and the number of IDC fingers, the resonant frequency of each pixel can be adjusted to cover the entire THz band signal.

[0028] A superconducting microwave dynamic inductance detector array imaging detection related device comprises the above-mentioned superconducting microwave dynamic inductance detector array imaging chip.

[0029] The beneficial effects of the present invention are as follows: the present invention ensures fine sampling of the imaging area through a smaller pixel pitch and a dense array layout, effectively reduces the loss of details in the imaging process, and improves the clarity and resolution of the image. Imaging within the full frequency range of the THz band can not only capture the broadband information of the THz signal, but also provide image reconstruction in different frequency bands, thereby obtaining richer imaging details. This multi-band fusion method improves the imaging performance and signal processing capabilities of the system. By combining time domain and frequency domain signal analysis with high-speed data acquisition, high-quality imaging data can be obtained in real time, and the image can be optimized through efficient signal processing algorithms. This process can quickly respond and generate spatial imaging maps, thereby improving the dynamic response capability of the imaging system. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0031] Figure 1 A schematic diagram of the structure of a superconducting microwave dynamic inductance detector array imaging chip provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0033] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0034] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0035] Example Reference below Figure 1 , which is an embodiment of the present invention.

[0036] S1: Pixel configuration module, used to select substrate materials, design the inductance area of ​​the same detector, adjust the resonant frequency by adjusting the number and length of IDC fingers, and adjust the coupling strength between IDC and feed line.

[0037] Preferably, in the MKID, the number or length of fingers of the IDC is increased, the capacitance C is increased, thereby reducing the resonant frequency f0; the number or length of fingers of the IDC is reduced, the capacitance C is reduced, thereby increasing the resonant frequency f0; Increasing the finger length or number of the IDC enhances the coupling strength between the IDC and the feed line, thereby improving the detector's response to microwave signals.

[0038] Furthermore, suppose a MKID detector is designed, using a 3-inch high-resistance silicon wafer, with 331 detector pixels in the array, the initial number of IDC fingers for each pixel is 5, the finger length is 2 mm, and the resonant frequency of the detector is 1.5 GHz. In order to reduce the resonant frequency to 1 GHz, increase the number or length of the IDC fingers: increase the number of IDC fingers to 10 and increase the finger length to 4 mm. In theory, both the inductance and capacitance will increase, and the resonant frequency will be reduced to the target frequency of 1 GHz.

[0039] S2: Experimental construction module, used to build experiments using MKID detectors. The MKID detector sample box is placed in a dilution refrigerator for cooling. When THz photons are absorbed by the MKID detector, the impedance of the detector surface changes suddenly, causing the phase and amplitude of the microwave excitation signal to change.

[0040] Preferably, assuming that the resonant circuit of the MKID detector is composed of an inductor and a capacitor, the impedance of the resonator is expressed as:

[0041] Due to the change of inductance and capacitance, the resonant frequency shifts and the phase change of the microwave signal is described by the following formula:

[0042] Among them, ΔZ L is the change in the detector surface impedance, and Z0 is the characteristic impedance in the system; Assuming that there is reflection at the coupling point between the detector and the feed line, the change in amplitude is calculated by the reflection coefficient:

[0043] Among them, Z load is the impedance of the detector, Z0 is the characteristic impedance of the feed line; When the detector impedance Z load When a mutation occurs, the reflection coefficient Γ will change, and the specific amplitude is quantified by the reflection loss calculation formula:

[0044] Among them, |Γ| 2 Indicates the intensity of the reflection.

[0045] Furthermore, assuming that the characteristic impedance of the system is Z0 = 50 Ω, when the detector surface impedance Z load Changes to ΔZ L =5 Ω, the phase change is calculated as: Δϕ=arctan(0.1)≈5.71∘ Assume that the characteristic impedance of the system is Z0 = 50 Ω, and the impedance of the detector before the change is Z load =60 Ω, the reflection coefficient is: Γ initial ≈0.0909 When the impedance of the detector changes to ΔZL=-10 Ω, that is, Z load When it becomes 50Ω, the new reflection coefficient is: Γ new =0 S3: Signal detection module, used for microwave source to generate excitation signal, and divide it into two signals through power divider. One signal is input into LO end of IQ mixer as reference signal, and the other signal is input into sample box after attenuation, DC isolation and filtering.

[0046] Preferably, one signal is input as a reference signal into the LO end of the IQ mixer without being processed, and is used to provide a local oscillator signal for the IQ mixer; the other signal is input into the sample box after attenuation, DC isolation, and filtering, and then input into the MKID detector array after additional processing for detecting THz band signals.

[0047] Furthermore, suppose we have a THz band imaging system that uses signals in the frequency range of 0.1 THz to 1 THz for detection. The signal source frequency in the system is 10 GHz.

[0048] The reference signal is directly provided to the LO end of the IQ mixer through a signal source without any processing. Assume that the output power of the signal source is 0 dBm and the frequency is 10 GHz. This signal is used as the local oscillator signal, so that the IQ mixer can mix with the input signal and finally obtain the baseband signal. Another signal with a frequency of 300 GHz (in the THz band) will be processed through the following steps: Use an attenuator to attenuate the signal by 10 dB, and the signal strength is reduced from the original 0dBm to -10dBm to avoid overloading the signal processing system due to excessive signal strength. Use a capacitor for DC isolation to filter out low-frequency interference. The cutoff frequency of this capacitor is set at several GHz to ensure that the THz band signal can pass smoothly. The signal passes through a bandpass filter with a cutoff frequency range of 0.1THz to 1THz. The bandpass filter ensures that only signals in a specific frequency band can pass, avoiding stray signals in other frequency bands from affecting the detection results.

[0049] S4: Signal processing module, used to couple the signal to the MKID detector through the feeder and further amplify it through the HEMT amplifier. The signal enters the RF end of the IQ mixer after being amplified by the room temperature amplifier. The mixer outputs in-phase voltage and quadrature voltage signals. After the output signal passes through the low-pass filter, it is collected by the A / D card and analyzed in the time domain.

[0050] Preferably, the IQ mixer mixes the input RF signal with the local oscillator signal to generate two output signals, an I signal and a Q signal. The mathematical formula of the mixer is expressed as:

[0051] Among them, RF is the radio frequency signal input to the mixer, LO is the local oscillator signal from the microwave source, and IF1 and IF2 are the intermediate frequency signals obtained after mixing; The mixed I / Q signal needs to be processed by a low-pass filter to remove the high-frequency components and obtain a low-frequency intermediate frequency signal. The low-pass filter passes:

[0052] The mixed signal is downconverted and finally digitized through an A / D converter to obtain the amplitude and phase of the signal.

[0053] Preferably, it is assumed that the signal obtained after mixing contains two frequency components, one of which is a low-frequency signal f IF =|f LO -f RF ∣, another high frequency component f HF , after passing through a low-pass filter, the filtered signal is:

[0054] The low-pass filter is represented by the following formula:

[0055] Among them, f c is the cutoff frequency of the low-pass filter, and H(f) is the frequency response of the filter; In the time domain, the A / D card converts the analog signal I filtered (t) and Q filtered (t) is converted into a digital signal. Assuming that the sampling rate of the A / D card is fs, the samples are obtained through the following discretization process:

[0056] The I[n] and Q[n] signals are transformed by fast Fourier transform to obtain the signal spectrum, so as to analyze its frequency domain characteristics and determine the frequency distribution and energy concentration area of ​​the signal. The spectrum after FFT conversion is expressed as:

[0057] where S(f) is the complex spectrum in the frequency domain.

[0058] Furthermore, assume that a 10 GHz RF signal and a 9.8 GHz LO signal are used to demonstrate the mixing process. The RF signal has a frequency of 10 GHz and an amplitude of 1 V, and the LO signal has a frequency of 9.8 GHz and an amplitude of 1 V; the IQ mixer mixes these two signals to generate two intermediate frequency signals IF1 and IF2:

[0059] The intermediate frequency parts IF1 and IF2 of the mixed signal contain a component with a frequency of 200 MHz (, and the other high-frequency parts are removed by the low-pass filter. Assuming that the cutoff frequency of the low-pass filter is 1 GHz, the high-frequency part is completely filtered out, and the retained 200 MHz intermediate frequency signal can be passed through the low-pass filter.

[0060] The low-pass filtered signal is input to the A / D converter. Assuming the resolution of the A / D converter is 12 bits and the maximum input voltage is 1 V, the A / D converter converts the analog signal into a digital signal according to the above formula.

[0061] For example, if the input signal amplitude is 0.5 V, the digital value output by the A / D converter is: ADC Output =2048.

[0062] Furthermore, the RF signal fRF = 10 GHz, the local oscillator signal fLO = 9.8 GHz, the cutoff frequency of the low-pass filter fc = 1 GHz, and the sampling rate of the A / D converter fs = 2 GHz; After mixing, we get two frequency components: Low frequency component fIF=|fLO-fRF|=|9.8 GHz-10 GHz|=200 MHz, high frequency component: fHF=19.8 GHz; Since the cutoff frequency of the low-pass filter is 1 GHz, only the low-frequency component of 200 MHz is allowed to pass. Therefore, the signal I filtered (t) and Q filtered (t) contains only a low-frequency component of 200 MHz, with a sampling rate of 2 GHz. The A / D converter discretizes the signal to obtain discrete samples I[n] and Q[n]; The discretized signals I[n] and Q[n] are input into the FFT algorithm to obtain the spectrum S(f). Assuming that the number of FFT points is 1024, the obtained spectrum can display the frequency components of the signal, as follows: S(f)=FFT(I[n],Q[n]) The FFT shows the low frequency components (200 MHz) as peaks in the spectrum, while the high frequency components are filtered out.

[0063] S5: signal generation module, used to introduce the signal of the THz wave source into the sample box through the THz low-pass filter, and enter the inductive absorption area of ​​the MKID detector by coupling the THz signal.

[0064] Preferably, the THz wave source generates a THz signal through a blackbody radiation source with adjustable temperature, which is filtered through a THz low-pass filter to remove unnecessary high-frequency noise. The filtered signal is effectively transmitted to the sample box through a horn antenna coupler; the absorption of THz photons by the superconducting inductive absorption region in the MKID detector causes a change in its inductance value, thereby causing changes in the phase and amplitude of the microwave excitation signal.

[0065] S6: Data analysis module, used to analyze the collected I / Q signals through data processing algorithms, analyze the pixel data of multiple detectors, combine time domain and frequency domain information, realize spatial imaging, and extract full-band imaging data in the THz band according to the responses of different frequency bands.

[0066] Preferably, the response of each detector pixel to the THz signal is obtained by deconstructing the I and Q signals, and further analyzed by decoding the amplitude A(t) and phase φ(t), thereby obtaining the amplitude and phase changes of the signal; Extract the frequency domain features of the signal and perform Fourier transform to obtain frequency information from the time domain signal:

[0067] Where s(t) is the time domain signal, S(f) is the frequency domain signal, and f is the frequency; Spatial imaging uses the signal obtained by the detector to invert the electromagnetic properties of the sample surface or volume. Suppose the sample is at position r i The response at R ri , the signal I / Q collected by the detector can be used to construct the inversion formula:

[0068] Among them, H(ri,t) is the response function of the detector at position ri to the time domain signal, and R(ri) is the signal strength at the spatial position ri.

[0069] Preferably, the detector pixels record the frequency domain information of the THz signal. By gradually scanning different frequencies, the system collects the response data of the full frequency band. For each frequency band f, the spatial image R (r, f) of the sample is established through the amplitude and phase information of the signal, where r is the spatial position vector and f is the frequency, and the spectrum imaging is obtained; By collecting data from multiple frequency bands, the full-band response of the sample is obtained:

[0070] By combining the data from all frequency bands, a spatial image is constructed, which reflects the electromagnetic response characteristics of the material in the entire THz band.

[0071] Further, assume that we use a MKID array with 500 detector pixels, scanning in the frequency band from 0.1 THz to 3 THz3. The positions ri of each detector are uniformly distributed in the 2D plane, and the sample is placed at z=0.

[0072] By decoding the amplitude and phase, we can construct a spatial response image R(ri,fj) for each frequency band fj, which reflects the sample response corresponding to the detector position ri at that frequency:

[0073] Combining the data of all frequency bands, we can get the full-band response of the sample in the entire THz band:

[0074] The final R total (r) is a three-dimensional data set representing the electromagnetic response of the sample in both spatial and frequency dimensions.

[0075] S7: Spatial imaging module, used to optimize the resolution of spatial imaging by controlling the pixel pitch and the design of the detector array.

[0076] Preferably, the spatial resolution of the system is improved by controlling the size, shape and coupling characteristics of the resonator to optimize the response frequency and coupling strength of each pixel; By adjusting the size of the inductive coupling area and the number of IDC fingers, the resonant frequency of each pixel can be adjusted to cover the entire THz band signal.

[0077] Furthermore, a MKID array with 500 pixels is designed for imaging in the THz band. Each pixel of the array consists of a resonator and an inductive coupling region. We adjust the resonant frequency and coupling strength of each pixel by the following method: multiple resonators of different sizes are designed, and the size of each resonator is precisely adjusted to be able to respond to THz signals of different frequencies. For example, the larger resonator size is designed to respond to low frequencies (such as 0.1THz to 0.5THz), while the smaller resonator size is designed to respond to high frequencies (such as 1.5THz to 3THz). In the array design, the size of the inductive coupling region of each pixel is adjusted to adapt to its corresponding resonant frequency. We reduce the resonant frequency of low-frequency pixels by increasing the width and number of turns of the inductor coil, and increase the resonant frequency of high-frequency pixels by reducing the inductor area. The number of IDC fingers for each pixel is adjusted to adjust the capacitance size and resonant frequency. For example, low-frequency pixels use longer IDC fingers and more fingers, while high-frequency pixels use shorter IDC fingers and fewer fingers. Through this design, the response frequency of each pixel can accurately cover the entire THz band. Through these adjustments, the entire MKID array can cover a wide frequency band from 0.1THz to 3THz, ensuring that each pixel can respond to THz signals of different frequencies. The array can ultimately capture full-band THz signals from different spatial locations and use them for imaging analysis.

[0078] In the description of the present invention, it should be noted that the terms “first”, “second” and “third” are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0079] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0080] In the several embodiments provided by the present invention, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. The device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of devices or units can be electrical, mechanical or other forms.

[0081] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0082] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0083] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

[0084] In addition, although the operations of the method of the present invention are described in a specific order in the drawings, this does not require or imply that the operations must be performed in this specific order, or that all the operations shown must be performed to achieve the desired results. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into one step, and / or one step may be decomposed into multiple steps.

Claims

1. A superconducting microwave dynamic inductance detector array imaging chip, characterized in that: include: The pixel configuration module is used to select the substrate material, design the inductive area of ​​the same detector, adjust the resonant frequency by adjusting the number and length of the IDC fingers, and adjust the coupling strength between the IDC and the feed line; The experimental construction module is used to build the experiment through the MKID detector. The MKID detector sample box is placed in a dilution refrigerator for cooling. When the THz photon is absorbed by the MKID detector, the impedance of the detector surface changes suddenly, causing the phase and amplitude of the microwave excitation signal to change. The signal detection module is used to generate an excitation signal from a microwave source and divide it into two signals through a power divider. One signal is input into the LO terminal of the IQ mixer as the reference signal, and the other signal is input into the sample box after attenuation, DC isolation and filtering; The signal processing module is used to couple the signal to the MKID detector through the feeder and further amplify it through the HEMT amplifier. After being amplified by the room temperature amplifier, the signal enters the RF end of the IQ mixer. The mixer outputs the in-phase voltage and quadrature voltage signals. After the output signal passes through the low-pass filter, it is collected by the A / D card and analyzed in the time domain. The signal generation module is used to introduce the signal of the THz wave source into the sample box through the THz low-pass filter. By coupling the THz signal into the inductive absorption region of the MKID detector; The data analysis module is used to analyze the collected I / Q signals through data processing algorithms. By analyzing the pixel data of multiple detectors and combining the time domain and frequency domain information, spatial imaging is achieved. Based on the responses of different frequency bands, full-band imaging data within the THz band is extracted. The spatial imaging module is used to optimize the resolution of spatial imaging by controlling the pixel pitch and the design of the detector array.

2. The superconducting microwave dynamic inductance detector array imaging chip according to claim 1, characterized in that: The method of adjusting the resonant frequency by adjusting the number and length of the fingers of the IDC and adjusting the coupling strength between the IDC and the feeder line comprises: In MKID, increasing the number or length of fingers of IDC increases the capacitance C, thereby reducing the resonant frequency f0; reducing the number or length of fingers of IDC reduces the capacitance C, thereby increasing the resonant frequency f0; Increasing the finger length or number of the IDC enhances the coupling strength between the IDC and the feed line, thereby improving the detector's response to microwave signals.

3. The superconducting microwave dynamic inductance detector array imaging chip according to claim 1, characterized in that: When the THz photon is absorbed by the MKID detector, the impedance of the detector surface changes suddenly, causing the phase and amplitude of the microwave excitation signal to change, including: Assuming that the resonant circuit of the MKID detector consists of an inductor and a capacitor, the impedance of the resonator is expressed as: Due to the change of inductance and capacitance, the resonant frequency shifts and the phase change of the microwave signal is described by the following formula: Among them, ΔZ L is the change in the detector surface impedance, and Z0 is the characteristic impedance in the system; Assuming that there is reflection at the coupling point between the detector and the feed line, the change in amplitude is calculated by the reflection coefficient: Among them, Z load is the impedance of the detector, Z0 is the characteristic impedance of the feed line; When the detector impedance Z load When a mutation occurs, the reflection coefficient Γ will change, and the specific amplitude is quantified by the reflection loss calculation formula: Among them, |Γ| 2 Indicates the intensity of the reflection.

4. The superconducting microwave dynamic inductance detector array imaging chip according to claim 1, characterized in that: The signal is coupled to the MKID detector through a feeder line and further amplified by a HEMT amplifier. The signal enters the RF end of the IQ mixer after being amplified by a room temperature amplifier, including: The IQ mixer mixes the input RF signal with the local oscillator signal to generate two output signals, I signal and Q signal. The mathematical formula of the mixer is expressed as: Among them, RF is the radio frequency signal input to the mixer, LO is the local oscillator signal from the microwave source, and IF1 and IF2 are the intermediate frequency signals obtained after mixing; The mixed I / Q signal needs to be processed by a low-pass filter to remove the high-frequency components and obtain a low-frequency intermediate frequency signal. The low-pass filter passes: The mixed signal is downconverted and finally digitized through an A / D converter to obtain the amplitude and phase of the signal.

5. The superconducting microwave dynamic inductance detector array imaging chip according to claim 1, characterized in that: The mixer outputs in-phase voltage and quadrature voltage signals, and the output signals are collected by an A / D card and analyzed in the time domain after passing through a low-pass filter, including: Assume that the signal obtained after mixing contains two frequency components, one is the low-frequency signal f IF =|f LO -f RF ∣, another high frequency component f HF , after passing through a low-pass filter, the filtered signal is: The low-pass filter is represented by the following formula: Among them, f c is the cutoff frequency of the low-pass filter, and H(f) is the frequency response of the filter; In the time domain, the A / D card converts the analog signal I filtered (t) and Q filtered (t) is converted into a digital signal. Assuming that the sampling rate of the A / D card is fs, the samples are obtained through the following discretization process: The I[n] and Q[n] signals are transformed by fast Fourier transform to obtain the signal spectrum, so as to analyze its frequency domain characteristics and determine the frequency distribution and energy concentration area of ​​the signal. The spectrum after FFT conversion is expressed as: where S(f) is the complex spectrum in the frequency domain.

6. The superconducting microwave dynamic inductance detector array imaging chip according to claim 1, characterized in that: The method of introducing the signal of the THz wave source into the sample box through the THz low-pass filter and coupling the THz signal into the inductive absorption area of ​​the MKID detector includes: The THz wave source generates THz signals through a temperature-adjustable blackbody radiation source, which are filtered through a THz low-pass filter to remove unnecessary high-frequency noise. The filtered signal is effectively transmitted to the sample box through a horn antenna coupler; the superconducting inductive absorption area in the MKID detector absorbs THz photons, causing changes in its inductance value, thereby causing changes in the phase and amplitude of the microwave excitation signal.

7. The superconducting microwave dynamic inductance detector array imaging chip according to claim 1, characterized in that: The collected I / Q signals are analyzed by a data processing algorithm, and spatial imaging is achieved by analyzing the pixel data of multiple detectors and combining time domain and frequency domain information, including: By deconstructing the I and Q signals, the response of each detector pixel to the THz signal is obtained, which is further analyzed by decoding the amplitude A(t) and phase φ(t) to obtain the amplitude and phase changes of the signal; Extract the frequency domain features of the signal and perform Fourier transform to obtain frequency information from the time domain signal: Where s(t) is the time domain signal, S(f) is the frequency domain signal, and f is the frequency; Spatial imaging uses the signal obtained by the detector to invert the electromagnetic properties of the sample surface or volume. Suppose the sample is at position r i The response at R ri , the signal I / Q collected by the detector can be used to construct the inversion formula: Among them, H(ri,t) is the response function of the detector at position ri to the time domain signal, and R(ri) is the signal strength at the spatial position ri.

8. The superconducting microwave dynamic inductance detector array imaging chip according to claim 1, characterized in that: The method of extracting full-band imaging data in the THz band according to responses of different frequency bands includes: The detector pixels record the frequency domain information of the THz signal. By gradually scanning different frequencies, the system collects the response data of the full frequency band. For each frequency band f, the spatial image R (r, f) of the sample is established through the amplitude and phase information of the signal, where r is the spatial position vector and f is the frequency, thus obtaining spectrum imaging. By collecting data from multiple frequency bands, the full-band response of the sample is obtained: By combining the data from all frequency bands, a spatial image is constructed, which reflects the electromagnetic response characteristics of the material in the entire THz band.

9. The superconducting microwave dynamic inductance detector array imaging chip according to claim 1, characterized in that: The resolution of spatial imaging is optimized by controlling the pixel spacing and the design of the detector array, including: By controlling the size, shape and coupling characteristics of the resonator, the response frequency and coupling strength of each pixel can be optimized to improve the spatial resolution of the system. By adjusting the size of the inductive coupling area and the number of IDC fingers, the resonant frequency of each pixel can be adjusted to cover the entire THz band signal.

10. A superconducting microwave dynamic inductance detector array imaging detection related device, comprising the superconducting microwave dynamic inductance detector array imaging chip described in claims 1-9.

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