Terahertz wave decoherence method, decoherence system and imaging system
By controlling the number of array elements and the phase change rate of terahertz waves using a reconfigurable phased array, the problem of poor imaging quality caused by stable coherence in terahertz wave imaging is solved, enabling active and controllable decoherence operation and optimizing the imaging effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SUZHOU INST OF NANO TECH & NANO BIONICS CHINESE ACEDEMY OF SCI
- Filing Date
- 2026-03-27
- Publication Date
- 2026-05-15
AI Technical Summary
In the prior art, the stable coherence of terahertz waves leads to poor imaging quality, and the untunability and uncontrollability of the random phase plate limits the effectiveness of decoherence operations.
By employing a reconfigurable phased array, active and controllable terahertz wave decoherence can be achieved by adjusting the number of effective array elements and the phase modulation rate. The variable capacitance characteristics of the SBD reconfigurable phased array can be used to change the resonant mode of the terahertz antenna for active phase modulation.
It achieves active and controllable decoherence of terahertz waves, optimizes imaging quality, improves imaging effect, and has temporal and spatial reconfigurability, enabling quantitative control of speckle characteristics.
Smart Images
Figure CN122051653A_ABST
Abstract
Description
Technical Field
[0001] This invention specifically relates to a terahertz wave decoherence method, a decoherence system, and an imaging system, belonging to the field of terahertz reconfigurable transmission metasurface technology. Background Technology
[0002] Terahertz waves lie at the boundary between microwaves and infrared radiation. They can penetrate most dielectric materials, revealing material structures with high contrast. Furthermore, their wavelength is sufficiently short compared to microwaves, providing higher image resolution, and they are widely used in imaging. However, the generation mechanism of terahertz waves results in a definite phase relationship, which is difficult to disrupt during transmission. This stable phase relationship can generate speckle noise and interference artifacts during imaging, significantly impacting image quality and degrading its quality. Therefore, for terahertz imaging, there is an urgent need for methods that can stably remove the stable coherence of terahertz waves.
[0003] However, current methods for decohering terahertz waves mainly rely on random phase plates. The surface morphology of these plates is randomly distributed. After passing through the plate, the coherent terahertz wave travels an extra optical path. Due to the random fluctuations in the surface morphology, the resulting optical path difference is random, effectively applying several random phases to the original stable phase, thus disrupting the stable phase relationship and achieving decoherence. However, once the random phase plate is fabricated, its surface morphology is unadjustable and unreconfigurable, producing only a single random mode without temporal diversity. Furthermore, the degree of randomness in its surface morphology is difficult to control. Therefore, it can only perform passive and uncontrollable terahertz decoherence operations. Summary of the Invention
[0004] The main objective of this invention is to provide a terahertz wave decoherence method, a decoherence system, and an imaging system. It utilizes a reconfigurable phased array for decoherence modulation, specifically based on an SBD reconfigurable phased array. By leveraging the variable capacitance characteristics of the SBD, different voltages received by the phased array cause changes in the junction capacitance, thereby altering the resonant mode of the terahertz antenna and achieving terahertz phase modulation. Specifically, it enables actively controllable terahertz decoherence operation, thus optimizing terahertz imaging effects and overcoming the shortcomings of existing technologies.
[0005] To achieve the aforementioned objectives, the technical solution adopted by this invention includes: The first aspect of this invention provides a terahertz wave decoherence method based on a reconfigurable phased array, comprising: Active phase modulation of coherent terahertz waves is achieved by using a reconfigurable phased array containing multiple array elements with independent terahertz wave phase modulation degrees of freedom. By adjusting the number of effective array elements and / or the phase modulation rate of the effective array elements, the magnitude of the first-order coherence function of the terahertz wave is reduced, thereby achieving decoherence of the terahertz wave without changing the intrinsic time coherence length of the terahertz source.
[0006] A second aspect of this invention provides a terahertz wave decoherence system for implementing the aforementioned terahertz wave decoherence method based on a reconfigurable phased array. The terahertz wave decoherence system includes a control module and a reconfigurable phased array comprising multiple array elements with independent terahertz wave phase modulation degrees of freedom. The control module is used to regulate the number of effective array elements and / or the phase modulation rate of the effective array elements to reduce the magnitude of the first-order coherence function of the terahertz wave, thereby achieving terahertz wave decoherence.
[0007] A third aspect of the present invention provides a terahertz wave imaging system, comprising: a terahertz source, a beamforming component, a reconfigurable phased array, an optical collection and steering component, and a terahertz detector arranged sequentially along an optical path, and a control module, wherein the control module is electrically connected to the reconfigurable phased array and configured to form the terahertz wave decoherence system. The terahertz source emits coherent terahertz waves, the terahertz wave decoherence system performs active phase modulation on the coherent terahertz waves after beamforming, and achieves decoherence, the optical collection and steering component guides the decoherent terahertz waves to the object under test, and the terahertz detector receives the terahertz waves that are transmitted through or reflected from the object under test and completes imaging.
[0008] Compared with the prior art, the advantages of the present invention include: The present invention provides a terahertz decoherence method and system based on a reconfigurable phased array. The reconfigurable phased array is used as the main device for terahertz wave decoherence. The phase of each array element can be designed by encoding, transforming the natural randomness of the random phase plate into an artificially set engineering randomness.
[0009] The present invention provides a terahertz decoherence method and system based on a reconfigurable phased array, which introduces decoherence in the time dimension. The random phase plate introduces spatial phase randomness, and the reconfigurable phased array allows the phase to be updated over time, thereby achieving time-level decoherence control.
[0010] The present invention provides a terahertz decoherence method and system based on a reconfigurable phased array, which is reconfigurable. The passive decoherence mode based on a random phase plate generates a single randomness, and the randomness is not reconfigurable and difficult to reproduce. The reconfigurable phased array decoherence method is equivalent to encoding information, which can not only be recorded but also easily reproduced. Attached Figure Description
[0011] Figure 1 This is a schematic diagram of the structure of a terahertz decoherence and imaging system based on a reconfigurable phased array provided in an embodiment of the present invention; Figure 2 This is a reconfigurable phased array image and its working principle diagram provided in the embodiments of the present invention. Detailed Implementation
[0012] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate this technical solution, its implementation process, and its principles.
[0013] The first aspect of this invention provides a terahertz wave decoherence method based on a reconfigurable phased array, comprising: Active phase modulation of coherent terahertz waves is achieved by using a reconfigurable phased array containing multiple array elements with independent terahertz wave phase modulation degrees of freedom. By adjusting the number of effective array elements and / or the phase modulation rate of the effective array elements, the magnitude of the first-order coherence function of the terahertz wave is reduced, thereby achieving decoherence of the terahertz wave without changing the intrinsic time coherence length of the terahertz source.
[0014] Furthermore, the terahertz wave decoherence method includes: when actively phase modulating the coherent terahertz wave, applying mutually independent random phases to each effective array element, breaking the stable phase relationship of the terahertz wave through random phase distribution, and reducing the first-order coherence function magnitude of the terahertz wave.
[0015] In a typical implementation, controlling the number of effective array elements of the reconfigurable phased array includes: generating coded instructions containing random phase allocation information through a control module; selectively activating the array elements in the reconfigurable phased array through the control module; outputting a bias voltage matching an independent random phase to each activated effective array element; and outputting a zero bias or cutoff voltage to the dormant array elements that are not activated, thereby simultaneously realizing programmable control of the number of effective array elements and the application of independent random phases to each effective array element.
[0016] Furthermore, when decohering terahertz waves by adjusting the number of effective array elements, the normalized spatial first-order coherence function magnitude is used to characterize the degree of decoherence, and the root mean square of the spatial first-order coherence function magnitude is used as a quantitative index. The root mean square of the spatial first-order coherence function magnitude increases with the number of effective array elements N. The scaling decay is such that the closer the root mean square of the magnitude of the first-order spatial coherence function is to 0, the better the spatial decoherence effect; the closer the root mean square of the magnitude of the first-order spatial coherence function is to 1, the worse the spatial decoherence effect.
[0017] Furthermore, the root mean square of the spatial first-order coherence function modulus is obtained by taking the square root of the squared statistical average of the spatial first-order coherence function modulus of the random phase set.
[0018] In a typical implementation, the phase modulation change rate of the effective array elements is controlled by: generating a continuous coded instruction containing dynamic random phase allocation information through the control module; updating the bias voltage corresponding to all effective array elements synchronously according to the set phase modulation change rate, keeping the number of effective array elements fixed, and switching the phase modulation state of each effective array element synchronously with the new coded instruction to achieve time dynamic modulation of the terahertz wave phase.
[0019] Furthermore, when decoherence is achieved by adjusting the phase modulation change rate of the effective array elements, the spatial phase distribution of the terahertz wave is changed by dynamically updated independent random phases, breaking the temporal stability of the terahertz wave phase, thereby reducing the magnitude of the first-order temporal coherence function of the terahertz wave. Here, the phase modulation change rate of the effective array elements is the generation rate of random codes, the random codes are digital phase modulation instruction sets generated by the control module that correspond one-to-one with the effective array elements, and the phase modulation change rate is the frequency at which the control module generates and issues new random codes.
[0020] Furthermore, when decoherence is achieved by adjusting the phase modulation rate of the effective array elements, the magnitude of the first-order time coherence function satisfying the exponential decay model is used to characterize the degree of decoherence in the time dimension. The magnitude of the first-order time coherence function is used as a quantitative indicator, and it is negatively correlated with the phase modulation rate. That is, the faster the phase modulation rate, the lower the magnitude of the first-order time coherence function, and the better the decoherence effect in the time dimension.
[0021] Furthermore, the array elements of the reconfigurable phased array are integrated with terahertz antennas and Schottky barrier diodes. The array elements change the junction capacitance by applying an external bias voltage, thereby switching the resonant mode of the terahertz antenna and realizing independent phase control of the terahertz wave.
[0022] Furthermore, the Schottky barrier diode operates in varactor diode mode, increasing the depletion layer width by applying a reverse bias voltage to reduce the junction capacitance and complete the switching of the terahertz antenna resonant mode.
[0023] A second aspect of this invention provides a terahertz wave decoherence system for implementing the aforementioned terahertz wave decoherence method based on a reconfigurable phased array. The terahertz wave decoherence system includes a control module and a reconfigurable phased array comprising multiple array elements with independent terahertz wave phase modulation degrees of freedom. The control module is used to regulate the number of effective array elements and / or the phase modulation rate of the effective array elements to reduce the magnitude of the first-order coherence function of the terahertz wave, thereby achieving terahertz wave decoherence.
[0024] Furthermore, the control module selectively electrically activates the array elements in the reconfigurable phased array by generating coded instructions containing random phase allocation information, outputting a bias voltage matching the independent random phase to each activated effective array element, and outputting a zero bias or cutoff voltage to the dormant array elements that are not activated, thereby simultaneously realizing programmable control of the number of effective array elements and the application of independent random phases to each effective array element. The control module generates continuous encoded instructions containing dynamic random phase allocation information, and synchronously updates the bias voltages corresponding to all effective array elements according to the set phase modulation change rate, keeping the number of effective array elements fixed, so that the phase modulation state of each effective array element switches synchronously with the new encoded instructions, thereby realizing the time dynamic modulation of the terahertz wave phase.
[0025] Furthermore, the array elements of the reconfigurable phased array are integrated with terahertz antennas and Schottky barrier diodes. The array elements change the junction capacitance by applying an external bias voltage, thereby switching the resonant mode of the terahertz antenna and realizing independent phase control of the terahertz wave.
[0026] Furthermore, the Schottky barrier diode operates in varactor diode mode, increasing the depletion layer width by applying a reverse bias voltage to reduce the junction capacitance and complete the switching of the terahertz antenna resonant mode.
[0027] A third aspect of the present invention provides a terahertz wave imaging system, comprising: a terahertz source, a beamforming component, a reconfigurable phased array, an optical collection and steering component, and a terahertz detector arranged sequentially along an optical path, and a control module, wherein the control module is electrically connected to the reconfigurable phased array and configured to form the terahertz wave decoherence system. The terahertz source emits coherent terahertz waves, the terahertz wave decoherence system performs active phase modulation on the coherent terahertz waves after beamforming, and achieves decoherence, the optical collection and steering component guides the decoherent terahertz waves to the object under test, and the terahertz detector receives the terahertz waves that are transmitted through or reflected from the object under test and completes imaging.
[0028] The following will further explain the technical solution, its implementation process and principle in conjunction with the accompanying drawings and specific implementation examples. Unless otherwise specified, the GaN SBD (Schottky barrier diode), terahertz antenna, terahertz source, beamforming component, off-axis parabolic mirror and terahertz detector involved in the embodiments of the present invention can all be obtained commercially. The FPGA (Field-Programmable Gate Array) chip and the circuit structure between the FPGA chip and the reconfigurable phased array involved in the embodiments of the present invention can also be implemented based on the technology known in the art, and are not limited here.
[0029] It should be noted that the decoherence of this invention refers to reducing the magnitude of the first-order coherence function by introducing controllable phase degrees of freedom in a statistical sense, rather than changing the intrinsic time coherence length of the terahertz source.
[0030] Please see Figure 1 and Figure 2 In a typical implementation, a terahertz decoherence and imaging system based on a reconfigurable phased array includes: The system includes a terahertz source, a beamforming component, a reconfigurable phased array, an off-axis parabolic mirror (a typical optical collection and steering component), and a terahertz detector arranged sequentially along the optical path, as well as a control module. The control module is electrically connected to the reconfigurable phased array and configured to form a terahertz wave decoherence system. A terahertz source emits a coherent terahertz wave. The terahertz wave decoherence system performs active phase modulation on the coherent terahertz wave after it has been shaped by the beamforming component and achieves decoherence. An off-axis parabolic mirror guides the decoherent terahertz wave to the object under test. The terahertz detector receives the terahertz wave that is transmitted through or reflected from the object under test and completes imaging.
[0031] Specifically, the process of terahertz wave decoherence modulation in this invention mainly includes: a coherent terahertz light is emitted from a terahertz source, and after beam shaping, it is incident on a reconfigurable phased array. The reconfigurable phased array is connected to the FPGA chip of the control module to achieve random decoherence effect. The emitted decoherent terahertz light is collected and redirected by an off-axis parabolic mirror, and after passing through an object, it is received and imaged by a detector.
[0032] Specifically, the principle by which the reconfigurable phased array in this invention can perform decoherence operation is as follows: when actively modulating coherent terahertz waves, each effective array element is given an independent random phase. The stable phase relationship of the terahertz waves is broken by the random phase distribution, thereby reducing the magnitude of the first-order coherence function of the terahertz waves.
[0033] The specific implementation method includes: writing a control program in the computer language of the control module, sending instructions to the FPGA chip, the FPGA chip receiving the code, performing digital-to-analog conversion, outputting a precise bias voltage that can reconfigure the number of array elements of the phased array, and then updating the array element voltage according to the set encoding rate. The voltage is input to the array element, and different voltages cause changes in the junction capacitance. Under different junction capacitances, the resonant mode of the terahertz antenna is converted, and the phase modulation capability of the terahertz wave changes, thereby realizing terahertz phase shift.
[0034] This invention performs terahertz decoherence from two levels: Firstly, at the spatial level, all array elements are given a random phase and kept unchanged. The number of effective array elements in the reconfigurable phased array is controlled. A normalized spatial first-order coherence function is used to represent the degree of decoherence, with the root mean square (RMS) of the spatial first-order coherence function's magnitude as the quantification index. The RMS of the spatial first-order coherence function's magnitude increases with the number of effective array elements N. The scaling decay of the spatial first-order coherence function modulus is such that the closer the root mean square of the modulus is to 0, the better the spatial decoherence effect; conversely, the closer the root mean square of the modulus is to 1, the worse the spatial decoherence effect. It should be noted that the scaling relationship of the spatial first-order coherence function modulus holds true under the statistical averaging of a set of random phases, where a single random phase realization corresponds to only one sample.
[0035] Secondly, at the time level, the number of effective array elements of the reconfigurable phased array is fixed. The control module generates continuous coded instructions containing dynamic random phase allocation information. According to the set phase modulation change rate, the control module synchronously updates the bias voltage corresponding to all effective array elements, so that the phase modulation state of each effective array element switches synchronously with the new coded instructions, realizing the time dynamic modulation of the terahertz wave phase. That is, the generation rate of random codes of the control module is regulated. The faster the random codes are generated, the more they can disrupt the phase stability of the terahertz wave in time.
[0036] Specifically, the reconfigurable phased array in this embodiment can also be considered as a metasurface, and the array element of the reconfigurable phased array is the metasurface unit of the metasurface. Specifically, the reconfigurable phased array in this embodiment includes multiple array elements with independent terahertz wave phase modulation degrees of freedom. The array element of the reconfigurable phased array is an integration of a terahertz antenna and a Schottky barrier diode. The array element changes the junction capacitance by applying an external bias voltage, thereby switching the resonant mode of the terahertz antenna and achieving independent phase modulation of the terahertz wave. For example, the Schottky barrier diode can be a GaN Schottky barrier diode.
[0037] Specifically, the Schottky barrier diode operates in varactor diode mode, and its junction capacitance satisfies the semiconductor depletion layer model: ; In the formula, The junction capacitance of a Schottky barrier diode. The junction capacitance at zero bias. To apply an external reverse bias voltage, As a built-in potential, an increase in reverse bias causes the depletion layer to widen, resulting in a decrease in the equivalent capacitance.
[0038] Electromagnetic response model of the array elements of the reconfigurable phased array in this embodiment of the invention: The array elements of the reconfigurable phased array in this embodiment of the invention are integrated from terahertz antennas and Schottky barrier diodes, and their electromagnetic response can be represented by equivalent surface impedance. describe: ; in, , Add contact resistance to the channel resistance. The imaginary unit represents the phase relationship. Angular frequency, This is the equivalent inductance of the terahertz antenna and the metal structure. The junction capacitance of a Schottky barrier diode. The capacitance is parasitic and determined by the physical structure of the reconfigurable phased array.
[0039] Specifically, the reflection coefficients of the elements of a reconfigurable phased array. for: Reflection phase Defined as: ,in, This is the free space impedance.
[0040] 1) Spatial phase modulation.
[0041] Specifically, the magnitude of the spatial first-order coherence function under random phase modulation conditions should be understood as a statistical quantity, and its magnitude needs to be characterized by averaging the random phase set.
[0042] More specifically, at the spatial level, to study the statistical scaling relationship between the magnitude of the first-order coherence function and the number of array elements N, firstly, the number of effective array elements N in the reconfigurable phased array is fixed. Then, M sets of mutually independent random phase distributions are generated, and the phases are kept fixed during each measurement. The corresponding first-order coherence function is measured for each set of phase distributions. The root mean square value of the spatial first-order coherence function magnitude is obtained by statistically averaging the squares of the obtained magnitudes and taking the square root. The above process is repeated, and the number of array elements N is changed, thus obtaining the statistical law of the change in the magnitude of the spatial first-order coherence function with the number of array elements. Finally, the normalized spatial first-order coherence function magnitude describes the relationship between the degree of decoherence and the number of array elements N. Ignoring the time term, the normalized spatial first-order coherence function is: .
[0043] in, , These are two different spatial locations on the imaging plane. , Represent , The instantaneous complex electric field strength at the location.
[0044] From this, we can conclude that The closer a value is to 0, the better its decoherence; the closer a value is to 1, the worse its decoherence.
[0045] Specifically, in the far-field direction, the complex electric field of the reconfigurable phased array for: .
[0046] in, For the deterministic propagation phase from the array element to the image plane, The random phase is generated from the random coding. The magnitude weight from the Nth element to the observation point. The imaginary unit is used to construct the phase factor e in exponential form. j θ , representing the phase relationship of the wave.
[0047] Specifically, the random phase of the nth element. Satisfying independence ,but , Substituting the first-order spatial coherence function into the calculation yields: .
[0048] when And if the array elements are sufficiently dispersed, then exist Approximately uniform distribution on top Its root mean square is Therefore, we can conclude that: .
[0049] That is, the root mean square scale of the magnitude of the first-order coherence function in space is This refers to the fact that, statistically, the root mean square of the magnitude of the first-order spatial coherence function increases with the number of effective independent array elements. Scale decay.
[0050] 2) Temporal phase modulation.
[0051] The change in decorrelation at the time level is determined by the coding production rate. To achieve this, with a fixed number of array elements N, the degree of decoherence and coding rate are described by the magnitude of the first-order temporal coherence function. The relationship between them: 。
[0052] Similarly, in the far-field direction, the complex electric field of the reconfigurable phased array for: ； in, The magnitude weight from the Nth element to the observation point. The phase that changes over time. For deterministic phase (similar to the spatial layer modulation mentioned above), to simplify the derivation, let... ,but, .
[0053] That is, to find the common point, the correlation between fields at two different times, then, Taking the average over time yields: .
[0054] Based on the principle of independent statistics, when At that time, the phases of different array elements are statistically independent and randomly and uniformly distributed: .
[0055] when hour, ， in The autocorrelation function of the phase of a single array element is determined by the coding modulation rate, so we can obtain... ： And the denominator .
[0056] therefore, The part that determines the coherent terms is ,so, .
[0057] Specifically, let the code update cycle be... Then when ＜ At that time, the phase was not updated. At that time, the phase has been updated, for the self-coherence function It can be approximated as an exponential decay model, meaning that due to factors such as system delay, the phase cannot be maintained. The internal is absolutely unchanged, in Everything changes. Therefore satisfy: .
[0058] Taking the exponential decay model as an example, its first-order time coherence function is: .
[0059] In summary, the theoretical derivations of the first-order coherence function at both the spatial and temporal levels can support the controllable active terahertz decoherence method based on reconfigurable phased arrays.
[0060] This invention provides a terahertz decoherence method and system based on a reconfigurable phased array. Based on a terahertz frequency band decoherence coding mechanism, for monochromatic coherent terahertz radiation, it achieves active front-end conversion from coherent light to controllable decoherent light through coding. The reconfigurable phased array has precise and adjustable decoherence characteristics. Through the reconfigurable phased array coding design, it actively achieves quantitative control of the degree of decoherence and speckle characteristics in time and / or space.
[0061] The present invention provides a terahertz decoherence method and system based on a reconfigurable phased array. The reconfigurable phased array is used as the main device for terahertz wave decoherence. The phase of each array element can be designed by encoding, transforming the natural randomness of the random phase plate into an artificially set engineering randomness.
[0062] The present invention provides a terahertz decoherence method and system based on a reconfigurable phased array, which introduces decoherence in the time dimension. The random phase plate introduces spatial phase randomness, and the reconfigurable phased array allows the phase to be updated over time, thereby achieving time-level decoherence control.
[0063] The present invention provides a terahertz decoherence based on a reconfigurable phased array and its system, which is reconfigurable. The passive decoherence mode based on a random phase plate generates a single randomness, and the randomness is not reconfigurable and difficult to reproduce. The reconfigurable phased array decoherence method is equivalent to encoding information, which can not only be recorded but also easily reproduced.
[0064] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.
Claims
1. A terahertz wave decoherence method based on a reconfigurable phased array, characterized in that, include: Active phase modulation of coherent terahertz waves is achieved by using a reconfigurable phased array containing multiple array elements with independent terahertz wave phase modulation degrees of freedom. By adjusting the number of effective array elements and / or the phase modulation rate of the effective array elements, the magnitude of the first-order coherence function of the terahertz wave is reduced, thereby achieving decoherence of the terahertz wave without changing the intrinsic time coherence length of the terahertz source.
2. The terahertz wave decoherence method based on a reconfigurable phased array according to claim 1, characterized in that: When actively phase modulating coherent terahertz waves, independent random phases are applied to each effective array element. The stable phase relationship of the terahertz waves is broken by the random phase distribution, thereby reducing the magnitude of the first-order coherent function of the terahertz waves.
3. The terahertz wave decoherence method based on a reconfigurable phased array according to claim 1 or 2, characterized in that, Adjusting the number of effective array elements of the reconfigurable phased array includes: generating coded instructions containing random phase allocation information through a control module; selectively activating the array elements in the reconfigurable phased array through the control module; outputting a bias voltage matching an independent random phase to each activated effective array element; and outputting a zero bias or cutoff voltage to the dormant array elements that are not activated, thereby simultaneously realizing programmable adjustment of the number of effective array elements and application of independent random phases to each effective array element.
4. The terahertz wave decoherence method based on a reconfigurable phased array according to claim 3, characterized in that: When decohering terahertz waves by adjusting the number of effective array elements, the normalized spatial first-order coherence function magnitude is used to characterize the degree of decoherence, and the root mean square (RMS) of the spatial first-order coherence function magnitude is used as the quantification index. The RMS of the spatial first-order coherence function magnitude increases with the number of effective array elements N. The scaling decay is such that the closer the root mean square of the magnitude of the first-order spatial coherence function is to 0, the better the spatial decoherence effect; the closer the root mean square of the magnitude of the first-order spatial coherence function is to 1, the worse the spatial decoherence effect. Preferably, the root mean square of the spatial first-order coherence function modulus is obtained by taking the square root of the squared statistical average of the spatial first-order coherence function modulus of the random phase set.
5. The terahertz wave decoherence method based on a reconfigurable phased array according to claim 1 or 2, characterized in that, The phase modulation rate of the effective array elements is controlled by: generating a continuous coded instruction containing dynamic random phase allocation information through the control module; updating the bias voltage corresponding to all effective array elements synchronously according to the set phase modulation rate; keeping the number of effective array elements fixed; and switching the phase modulation state of each effective array element synchronously with the new coded instruction to achieve time dynamic modulation of the terahertz wave phase.
6. The terahertz wave decoherence method based on a reconfigurable phased array according to claim 5, characterized in that, When decoherence is achieved by adjusting the phase modulation change rate of the effective array elements, the spatial phase distribution of the terahertz wave is changed by dynamically updated independent random phases, breaking the temporal stability of the terahertz wave phase, thereby reducing the magnitude of the first-order temporal coherence function of the terahertz wave. The phase modulation change rate of the effective array elements is the generation rate of random codes. The random codes are digital phase modulation instruction sets generated by the control module and corresponding one-to-one with the effective array elements. The phase modulation change rate is the frequency at which the control module generates and issues new random codes. Preferably, the degree of decoherence in the time dimension is characterized by a time-first coherence function that satisfies the exponential decay model, and the magnitude of the time-first coherence function is used as a quantitative indicator, wherein the magnitude of the time-first coherence function is negatively correlated with the rate of change of phase modulation.
7. The terahertz wave decoherence method based on a reconfigurable phased array according to claim 1, characterized in that: The array element of the reconfigurable phased array is an integrated terahertz antenna and a Schottky barrier diode. The array element changes the junction capacitance by applying an external bias voltage, thereby switching the resonant mode of the terahertz antenna and realizing independent phase modulation of the terahertz wave. Preferably, the Schottky barrier diode operates in varactor diode mode, increasing the depletion layer width by applying a reverse bias voltage to reduce the junction capacitance and completing the switching of the terahertz antenna resonant mode.
8. A terahertz wave decoherence system, characterized in that, The terahertz wave decoherence method based on a reconfigurable phased array, as described in any one of claims 1-7, comprises a control module and a reconfigurable phased array containing multiple array elements with independent terahertz wave phase modulation degrees of freedom. The control module is used to regulate the number of effective array elements and / or the phase modulation rate of the effective array elements to reduce the magnitude of the first-order coherence function of the terahertz wave, thereby achieving terahertz wave decoherence.
9. The terahertz wave decoherence system according to claim 8, characterized in that: The control module generates coded instructions containing random phase allocation information to selectively electrically activate the array elements in the reconfigurable phased array. It outputs a bias voltage matching the independent random phase to each activated effective array element and outputs a zero bias or cutoff voltage to the dormant array elements that are not activated, thus simultaneously realizing the programmable control of the number of effective array elements and the application of the independent random phase of each effective array element. The control module generates continuous encoded instructions containing dynamic random phase allocation information, and synchronously updates the bias voltages corresponding to all effective array elements according to the set phase modulation change rate, keeping the number of effective array elements fixed, so that the phase modulation state of each effective array element switches synchronously with the new encoded instructions, thereby realizing the time dynamic modulation of the terahertz wave phase. And / or, the array elements of the reconfigurable phased array are integrated with terahertz antennas and Schottky barrier diodes. The array elements change the junction capacitance by applying an external bias voltage, thereby switching the resonant mode of the terahertz antenna and realizing independent phase modulation of the terahertz wave. Preferably, the Schottky barrier diode operates in varactor diode mode, increasing the depletion layer width by applying a reverse bias voltage to reduce the junction capacitance and completing the switching of the terahertz antenna resonant mode.
10. A terahertz wave imaging system, characterized in that, include: The system comprises a terahertz source, a beamforming component, a reconfigurable phased array, an optical collection and steering component, and a terahertz detector arranged sequentially along the optical path, as well as a control module electrically connected to the reconfigurable phased array and configured to form the terahertz wave decoherence system as described in claim 8 or 9. The terahertz source emits coherent terahertz waves, the terahertz wave decoherence system performs active phase modulation on the coherent terahertz waves after beamforming, and achieves decoherence, the optical collection and steering component guides the decoherent terahertz waves to the object under test, and the terahertz detector receives the terahertz waves that are transmitted through or reflected from the object under test and completes imaging.