2x2 beam splitter based on an error compensation structure, interference unit, imaging system and method

Abstract

The application provides a 2*2 beam splitter based on an error compensation structure, an interference unit, an imaging system and a method, the 2*2 beam splitter comprising: a first coupler, a second coupler, a first phase shifter and a second phase shifter; wherein the first phase shifter is connected on an optical path between the first coupler and the second coupler, and the second phase shifter is connected at an input port of the first coupler; the first phase shifter is configured to compensate for a phase deviation of the first coupler caused by a process error by adjusting a phase value of the first phase shifter; and the second phase shifter is configured to compensate for a phase deviation of the second coupler caused by a process error by adjusting a phase value of the second phase shifter. The application solves the problem that a traditional multi-mode interference coupler causes a misalignment of a light splitting ratio due to a process error, and further causes a decline in imaging resolution.

Description

Technical Field

[0001] This invention belongs to the field of photonic integrated interferometric imaging technology, and particularly relates to a 2×2 beam splitter, interferometric unit, imaging system and method based on an error compensation structure. Background Technology

[0002] Photonic integrated interferometry imaging technology achieves the interference and detection of optical signals through on-chip optical paths, offering advantages such as small system size, high stability, and large-scale integration capabilities, and has broad application prospects in the field of high-resolution optical detection and imaging. For example, the segmented planar photoelectric detection imaging system (SPIDER) utilizes a lens array and a photonic integrated chip for spatial frequency sampling, and reconstructs the image through inverse Fourier transform, significantly reducing the size and power consumption of the imaging system. In such systems, the core of achieving high-precision interference lies in the performance of the optical beamsplitter; the accuracy of its splitting ratio directly determines the quality of the interference signal and the accuracy of the final image reconstruction.

[0003] Currently, multimode interference couplers (MMCPs) are commonly used as core optical beam splitting components in photonic integrated chips. MMCPs operate based on the self-image effect, achieving specific splitting ratios, such as 1×2 and 2×2, by designing the dimensions of the multimode waveguide. However, in actual manufacturing, it is difficult to achieve absolute uniformity in process parameters such as waveguide etching depth, sidewall morphology, and material refractive index, leading to unavoidable process errors in the manufactured MMCPs. These process errors cause the actual splitting ratio of the MMCP to deviate from the theoretical design value and introduce additional phase deviations. For 2×2 MMCPs, the imperfect symmetry of their structure makes them particularly sensitive to these process errors.

[0004] In interferometric units and large-scale interferometric arrays composed of multimode interferometric couplers, the splitting ratio misalignment and phase deviation of each beamsplitter are propagated and accumulated at each stage, leading to a decrease in interference fringe contrast and introducing phase noise into the system. This ultimately results in the interference signal acquired by the detector containing errors, such as in-phase and quadrature current components. Even with complex digital image processing algorithms at the back end, improvements in imaging quality (such as structural similarity index) are still limited by the accuracy of the front-end signal acquisition. Therefore, overcoming the impact of process errors on beamsplitter performance and improving the signal fidelity of the basic interferometric unit at the device level of photonic integrated chips has become a key bottleneck in improving the overall performance of photonic integrated interferometric imaging systems. Summary of the Invention

[0005] The purpose of this invention is to provide a 2×2 beam splitter, interferometric unit, imaging system and method based on an error compensation structure, to solve the problem of reduced imaging resolution caused by the inaccuracy of the splitting ratio due to process errors in traditional multimode interferometric couplers.

[0006] In a first aspect, the present invention provides a 2×2 beam splitter based on an error compensation structure, the 2×2 beam splitter comprising: a first coupler, a second coupler, a first phase shifter, and a second phase shifter;

[0007] The first phase shifter is connected to an optical path between the first coupler and the second coupler, and the second phase shifter is connected to an input port of the first coupler.

[0008] The first phase shifter is configured to compensate for the phase deviation of the first coupler caused by process error by adjusting the phase value of the first phase shifter; the second phase shifter is configured to compensate for the phase deviation of the second coupler caused by process error by adjusting the phase value of the second phase shifter.

[0009] In one embodiment, both the first coupler and the second coupler are 2×2 multimode interference couplers.

[0010] In one embodiment, the first phase shifter and the second phase shifter are thermo-optical phase shifters or electro-optical phase shifters.

[0011] Secondly, the present invention provides a 2×2 interference unit based on an error compensation structure, the 2×2 interference unit comprising:

[0012] Two 2×2 beam splitters based on the error compensation structure as described above;

[0013] Two 1×2 beam splitters are used to receive two input optical signals and perform primary beam splitting;

[0014] Two balanced detectors are respectively connected to the output ports of the two 2×2 beam splitters based on the error compensation structure;

[0015] The output ports of the two 1×2 beam splitters are connected to the input ports of the two 2×2 beam splitters based on the error compensation structure via waveguides to form two interference optical paths.

[0016] In one embodiment, the 2×2 interference unit further includes a 90° phase shifter disposed on one of the waveguides.

[0017] Thirdly, the present invention provides a photonic integrated interferometric imaging system based on an error compensation structure, comprising:

[0018] An external receiving module is used to receive the target optical signal;

[0019] A photonic integrated interference module, optically connected to the external receiving module, is used to perform interference processing on the target optical signal and convert the interference-processed optical signal into an electrical signal; the photonic integrated interference module includes at least one 2×2 interference unit based on the error compensation structure as described above;

[0020] The data processing module, connected to the photonic integrated interference module, is used to process the electrical signal to reconstruct the target image.

[0021] In one embodiment, the external receiving module includes a microlens array.

[0022] In one embodiment, the photonic integrated interferometer module further includes an input cross-waveguide array and / or a wavelength division multiplexer array for guiding and distributing the target optical signal to the at least one 2×2 interferometer unit.

[0023] In one implementation, the data processing module is configured to:

[0024] Receive the in-phase and quadrature electrical signals output by the photonic integrated interference module;

[0025] Based on the in-phase electrical signal and the quadrature electrical signal, the mutual intensity information of optical signals from different paths is recovered;

[0026] Perform an inverse Fourier transform on the cross-intensity information to reconstruct the target light intensity distribution image.

[0027] Fourthly, the present invention provides a photonic integrated interferometry imaging method based on an error compensation structure, comprising the following steps:

[0028] Provide at least one 2×2 beam splitter based on the error compensation structure as described above;

[0029] By adjusting the phase values ​​of the first phase shifter and the second phase shifter, the phase deviation introduced by the process error in the at least one 2×2 beam splitter is calibrated, thereby enabling the 2×2 beam splitter to achieve the set splitting ratio.

[0030] An interference optical path is constructed using the calibrated at least one 2×2 beam splitter to interfere with the input target optical signal, and the interfered optical signal is then converted into an electrical signal.

[0031] The electrical signals are processed to reconstruct the target image.

[0032] In one embodiment, the step of processing the electrical signal to reconstruct the target image includes:

[0033] Based on the electrical signal, obtain the mutual intensity information of at least two interfering optical signals;

[0034] Perform an inverse Fourier transform on the cross-intensity information to obtain the light intensity distribution of the target image;

[0035] The mutual strength information includes real part information and imaginary part information.

[0036] Fifthly, the present invention provides a calibration method for a 2×2 beam splitter based on an error compensation structure as described above, comprising the steps of:

[0037] Measure the actual phase deviation between the first coupler and the second coupler caused by manufacturing errors;

[0038] Based on the actual phase deviation, the required compensation phase for the first phase shifter and the second phase shifter is calculated;

[0039] The compensation phase value is applied to the corresponding first phase shifter and second phase shifter.

[0040] As described above, the 2×2 beam splitter, interferometer, imaging system, and method based on the error compensation structure of the present invention have the following beneficial effects:

[0041] This invention adds two adjustable phase shifters (a first phase shifter and a second phase shifter) to the first and second couplers. This actively compensates for phase deviations caused by manufacturing errors in the first and second couplers at the device level, stably achieving a pre-set splitting ratio of 50:50. This solves the problem of reduced imaging resolution caused by splitting ratio inaccuracies due to manufacturing errors in traditional multimode interferometric couplers. The 2×2 beam splitter of this invention has high integration and is suitable for the miniaturization requirements of photonic chips. It can output high-precision, consistent split beam signals, providing a reliable core component for the subsequent construction of high-precision interferometric units and imaging systems. This ensures the accuracy of interferometric measurements from the source and is suitable for high-precision optical detection scenarios such as super-resolution microscopy. Attached Figure Description

[0042] Figure 1 The diagram shown is a schematic diagram of a 2×2 beam splitter structure based on an error compensation structure provided in an embodiment of the present invention.

[0043] Figure 2 The diagram shows a comparison of the splitting ratio at the output port of a conventional 2×2 beam splitter and the 2×2 beam splitter of this invention.

[0044] Figure 3 The diagram shows the relationship between the output optical signal intensity and the input optical signal phase difference of a conventional 2×2 beam splitter and the 2×2 beam splitter of this invention.

[0045] Figure 4The diagram shown is a schematic diagram of a 2×2 interference unit structure based on an error compensation structure provided in an embodiment of the present invention.

[0046] Figure 5 The diagram shows the change in the output optical signal intensity as a function of the phase difference between the input optical signal and the output optical signal of a conventional 2×2 interferometer unit and the 2×2 interferometer unit of the present invention.

[0047] Figure 6 The diagram shows a comparison of the error compensation effects before and after the present invention, as provided in an embodiment of the present invention.

[0048] Figure 7 The diagram shown is a schematic diagram of a photonic integrated interferometric imaging system based on an error compensation structure provided in an embodiment of the present invention.

[0049] Figure 8 The diagram shown is a partial structural schematic of the photonic integrated interference module provided in an embodiment of the present invention.

[0050] Figure 9 The diagram shows a comparison of the light field distribution after imaging in the photonic integrated interferometric imaging system provided in an embodiment of the present invention.

[0051] Figure 10 The diagram shows a flowchart of a photonic integrated interferometric imaging method based on an error compensation structure provided in an embodiment of the present invention.

[0052] Figure 11 The diagram shown is a flowchart of a calibration method for a 2×2 beam splitter based on an error compensation structure, provided by an embodiment of the present invention.

[0053] Explanation of reference numerals in the accompanying drawings: 1. 2×2 beam splitter based on error compensation structure; 11. First coupler; 12. Second coupler; 13. First phase shifter; 14. Second phase shifter; 2. 2×2 interferometer unit based on error compensation structure; 3. 1×2 beam splitter; 4. Balanced detector; 5. 90° phase shifter; 6. External receiving module; 7. Photonic integrated interferometer module; 71. Input cross-waveguide array; 72. Wavelength division multiplexer array; 8. Data processing module. Detailed Implementation

[0054] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0055] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0056] To address the aforementioned technical problems, this invention proposes a 2×2 beam splitter, interferometric unit, imaging system, and method based on an error compensation structure. By adding two adjustable phase shifters, namely a first phase shifter and a second phase shifter, to the first and second couplers, the phase deviation introduced by the first and second couplers due to manufacturing process errors is actively compensated at the device level. This can stably achieve a pre-set beam splitting ratio, i.e., a 50:50 average beam splitting ratio, thus solving the problem of reduced imaging resolution caused by inaccurate beam splitting ratio due to manufacturing errors in traditional multimode interferometric couplers.

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

[0058] like Figure 1 As shown, this embodiment provides a 2×2 beam splitter based on an error compensation structure. The 2×2 beam splitter 1 includes: a first coupler 11, a second coupler 12, a first phase shifter 13, and a second phase shifter 14. The first phase shifter 13 is connected to an optical path between the first coupler 11 and the second coupler 12, and the second phase shifter 14 is connected to an input port of the first coupler 11. The first phase shifter 13 is configured to compensate for the phase deviation of the first coupler 11 caused by process errors by adjusting the phase value of the first phase shifter 13. The second phase shifter 14 is configured to compensate for the phase deviation of the second coupler 12 caused by process errors by adjusting the phase value of the second phase shifter 14.

[0059] In this embodiment, the first coupler 11 and the second coupler 12 are 2×2 multimode interference couplers.

[0060] In this embodiment, the first phase shifter 13 and the second phase shifter 14 are thermo-optical phase shifters or electro-optical phase shifters.

[0061] Specifically, the transfer matrix of an ideal 2×2 multimode interference coupler is: However, due to certain manufacturing errors, the actual transmission matrix of the 2×2 multimode interference coupler is... .in, This represents the phase error in a 2×2 multimode interferometric coupler. In this embodiment, a 2×2 Mach-Zehnder interferometer is used instead of the multimode interferometric coupler to realize a 2×2 beam splitter based on an error compensation structure. The transmission matrix of the 2×2 beam splitter can be obtained as follows: .in, The phase error of the first coupler 11, For the phase error of the second coupler 12, This is the first compensation phase of the first phase shifter 13. This is the second compensation phase of the second phase shifter 14.

[0062] Furthermore, when and When both are 0, that is, there is no phase error between the first coupler 11 and the second coupler 12. for , for .when and When neither is 0, , ,in, , The calculated first compensation phase Second compensation phase When applied to the phase shifter, the square root of the modulus of all elements in the transmission matrix of the 2×2 beam splitter is equal to... According to the principle of optical power calculation, that is, the output light intensity is equal to the product of the input light intensity and the square of the corresponding transmission coefficient modulus, it can be concluded that for any input light, its power will be evenly divided between the two output ports. Therefore, in this embodiment, a 2×2 Mach-Zehnder interferometer is used instead of a multimode interference coupler to obtain two output signals with the same signal intensity, that is, a 2×2 beam splitter with perfect splitting ratio is realized. In this embodiment, the 2×2 Mach-Zehnder interferometer refers to a 2×2 beam splitter.

[0063] Furthermore, such as Figure 2 A schematic diagram showing the splitting ratio at the output port of a conventional 2×2 beam splitter and the 2×2 beam splitter of this invention is displayed.

[0064] Assuming the phase error of a 2×2 beam splitter implemented using a conventional 2×2 multimode interferometric coupler is 0.2, with an input optical signal amplitude of 1 at one input port and 0 at the other, the relationship between the output splitting ratio of the two output ports and the phase difference of the input optical signals is as follows: Figure 2As shown by the midpoint and star-shaped straight lines, the output splitting ratio of the two output ports is 0.7:0.3, and the splitting ratio error is 40%. Assume the phase error of the two ordinary 2×2 multimode interference couplers in the compensated 2×2 beamsplitter is 0.2. With the same input optical signal, the output splitting ratio of the two output ports of the 2×2 beamsplitter based on the error compensation structure is... Figure 2 As shown by the solid line, the ratio is 0.5:0.5, achieving complete equalization and improving the accuracy of the splitting ratio by 40%.

[0065] Furthermore, such as Figure 3 The diagram shows the relationship between the output optical signal intensity and the phase difference between the input optical signal of a conventional 2×2 beam splitter and the 2×2 beam splitter of this invention. When the amplitude of the input optical signal at both input ports is 1, the relationship between the output optical intensity at the two output ports and the phase difference between the two input optical signals is as follows: Figure 3 As shown by the midpoint and star-shaped curves, the maximum output light intensity at the two output ports is 1.9211, and the minimum output light intensity is 0.0789, indicating a certain loss in the transmitted light intensity. Assume the phase error between the two ordinary 2×2 multimode interference couplers in the 2×2 beamsplitter based on the error compensation structure is 0.2. With an input optical signal amplitude of 1, the relationship between the output light intensity at the two output ports and the phase difference between the two input optical signals is as follows: Figure 3 As shown by the dashed and solid lines, the maximum and minimum output light intensities of the two output ports are 2 and 0, respectively, proving that the transmission loss is fully compensated and the device achieves lossless perfect interference characteristics. Figure 2 and Figure 3 The simulation data, visualized under specific parameters, intuitively demonstrates that the light intensity of the two output ports is perfectly evenly distributed after compensation. Figure 2 The 0.5:0.5 straight line and ideal interference (in the context of the problem) Figure 3 (The maximum and minimum values ​​in the equation). Therefore, the 2×2 beam splitter based on the error compensation structure has a high-accuracy splitting ratio and can achieve high-precision optical signal interference.

[0066] In this embodiment, the output light intensity refers to the output light signal intensity, and the input light intensity refers to the input light signal intensity.

[0067] In this embodiment, the splitting and phase errors of the first coupler can be initially compensated and pre-corrected by the first phase shifter 13. After passing through the second coupler, the remaining errors are then finally corrected by the second phase shifter 14. The adjustable compensation phases of the first phase shifter 13 and the second phase shifter 14 can completely compensate for the phase errors of the first and second couplers, realizing a high-precision 2×2 beam splitter based on error compensation, improving information accuracy, and reducing splitting and phase errors.

[0068] like Figure 4As shown, another exemplary embodiment of the present invention provides a 2×2 interferometer unit based on an error compensation structure. The 2×2 interferometer unit 2 includes: two 2×2 beamsplitters 1 based on an error compensation structure; two 1×2 beamsplitters 3 for receiving two input optical signals and performing primary beam splitting; and two balanced detectors 4, which are respectively connected to the output ports of the two 2×2 beamsplitters 1 based on the error compensation structure. The output ports of the two 1×2 beamsplitters 3 are respectively connected to the input ports of the two 2×2 beamsplitters 1 based on the error compensation structure via waveguides to form two interferometric optical paths.

[0069] In this embodiment, as Figure 4 As shown, the 2×2 interference unit also includes a 90° phase shifter 5, which is disposed on one of the waveguides.

[0070] This embodiment introduces a 90° phase shifter to achieve a 90° phase shift, separating the real and imaginary components with complete mutual strength, thus meeting the basic functional requirements of image restoration. The real components are analogous to the phase current. Imaginary components, such as orthogonal currents .

[0071] In some embodiments, the 2×2 interferometer unit further includes a phase modulator (not shown) disposed between the output ports of the two 1×2 beam splitters and the input ports of the two 2×2 beam splitters based on the error compensation structure. By introducing the phase modulator, additional deviations in the interferometric optical path are compensated, ensuring the accuracy of the interferometric phase and improving the final imaging accuracy.

[0072] For example, assuming the phase error between two ordinary 2×2 beam splitters is 0.2 and the photoelectric response of the balanced detector is 1 A / W, then the intensity of the two optical signals output by the balanced detector changes with the phase difference between the two input optical signals as follows: Figure 5 The midpoint and star-shaped curves are shown. When the multimode interference coupler has a phase error, the maximum and minimum values ​​of the output optical signal intensity of the interference array are approximately 0.921 and -0.921, respectively, indicating a certain loss in the output optical signal intensity. The 2×2 beam splitter based on the error compensation structure uses a 2×2 Mach-Zehnder interferometer structure instead of the 2×2 multimode interference coupler, achieving a perfect splitting ratio and thus giving the output coherent optical signal high accuracy. After passing through a 1×2 beam splitter, a cross waveguide, a phase shifter, and a 2×2 beam splitter, the two coherent input optical signals are received at the output by a balanced detector. Coherent detection of the signals is performed, and after photoelectric conversion, in-phase and quadrature currents are obtained, as shown below. Figure 5 As shown by the dashed and solid lines, the maximum and minimum values ​​of the output light signal intensity of the interference array are approximately 1 and -1, respectively, indicating that the output light signal intensity is perfectly compensated.

[0073] like Figure 6 As shown, 200 sets of input data were randomly input into the 2×2 interferometer unit using simulation software. The data before compensation was obtained using an optical power monitor, and the root mean square error was calculated to be 10. -1 The magnitude of this error, on the order of magnitude, would lead to unclear imaging in applications utilizing photonic integrated interferometry imaging. After compensation using 2×2 interferometric units, simulation results show that the root mean square error is only 10. -2 The error is reduced by an order of magnitude compared to the uncompensated structure. The 2×2 interferometer provided by this invention reduces the calculation error by an order of magnitude, significantly improving the accuracy of information processing. Reducing the calculation error by an order of magnitude is equivalent to improving the accuracy by an order of magnitude, which will further improve the reconstruction rate of the system imaging. This solves the problem that in the traditional 2×2 interferometer, the four output light signals are directly output through a 2×2 ordinary beam splitter, and the intensity information of the coherent light is affected by the phase error of the ordinary beam splitter, resulting in incomplete accuracy.

[0074] like Figure 7 As shown, another exemplary embodiment of the present invention provides a photonic integrated interferometry imaging system based on an error compensation structure. The photonic integrated interferometry imaging system includes: an external receiving module 6 for receiving a target optical signal; a photonic integrated interferometry module 7, optically connected to the external receiving module 6, for interfering the target optical signal and converting the interferometrically processed optical signal into an electrical signal; the photonic integrated interferometry module 7 includes at least one 2×2 interferometer unit 2 based on an error compensation structure; and a data processing module 8, connected to the photonic integrated interferometry module 7, for processing the electrical signal to reconstruct a target image.

[0075] In this embodiment, the external receiving module 6 includes a microlens array.

[0076] In some embodiments, the photonic integrated interference module 7 further includes an input cross waveguide array 71 and / or a wavelength division multiplexer array 72 for guiding and distributing at least one 2×2 interference unit 2 of the target optical signal.

[0077] In this embodiment, as Figure 8 As shown, the photonic integrated interferometer module 7 includes four sets of 2×2 interferometer units 2 based on error compensation structures and one set of 8×8 input cross waveguide arrays 71. The working principle of the 8×8 interferometer array architecture based on error compensation structures is similar to that of the 2×2 interferometer units based on error compensation structures, and it can realize pairwise interference of 8-channel optical signals.

[0078] It is worth noting that this invention only illustrates an 8×8 dimensional interferometric architecture, but the compensation structure beam splitter proposed in this invention is applicable to integrated photonic interferometric imaging systems of any dimension. In this invention, the input cross-waveguide array structure varies with the input waveguide structure and is not entirely fixed.

[0079] In this embodiment, as Figure 7 As shown, the input cross waveguide array 71 can be combined with the wavelength division multiplexing array 72 to form a complex interferometric imaging array with wavelength multiplexing, but the structure of the interferometric unit is consistent with the structure proposed in this invention.

[0080] In this embodiment, the data processing module 8 is configured to: receive the in-phase electrical signal and the quadrature electrical signal output by the photonic integrated interference module 7; recover the mutual intensity information of the optical signals of different paths based on the in-phase electrical signal and the quadrature electrical signal; and perform an inverse Fourier transform on the mutual intensity information to reconstruct the light intensity distribution image of the target.

[0081] The system operates by having a microlens array receive image information from the target and couple the target's optical signal onto an optical chip (e.g., ...). Figure 7 As shown, the external receiving module 6 receives the target optical signal from the target's image information. The target optical signal is transmitted via an input cross-waveguide array on the optical chip, then undergoes grating-based beam splitting and multiplexing via a wavelength division multiplexing array, and finally undergoes phase modulation of the two light waves by a phase modulator (not shown) to ensure the input target optical signal meets the interference conditions. The coherent light then enters a coherent optical interference array based on error compensation and a balanced detector for optical wave interference and signal measurement, and finally, the target image is reconstructed through digital signal processing (e.g., ...). Figure 7 As shown, data processing module 8).

[0082] For example, if the two input coherent optical signals are and The expressions for in-phase current and quadrature current are: , ,in, To balance the photoelectric response coefficient of the detector, , These represent the electric field amplitudes of the two input coherent light sources; These represent the initial phases of the two input coherent beams. In-phase current, These are orthogonal currents.

[0083] According to the van Sitter-Zenick theorem, the mutual intensity of the two input coherent beams is... ;in, , The spatial frequency corresponding to the interferometric baseline in the horizontal direction. The spatial frequency corresponding to the interferometric baseline in the vertical direction. The difference in length between the horizontal interference baselines. The difference in length between the vertical interference baselines. The wavelength of the input target optical signal. The imaging distance from the target plane to the microlens receiving array is denoted as . Let be the cross intensity at the spatial frequency domain coordinates, and be a complex quantity describing the coherence characteristics of the two coherent beams. For target plane coordinates The original light intensity distribution at the location, i.e., the light intensity distribution of the target, is then used to reconstruct the coordinates. The light intensity distribution in the image is as follows: ,in, This is a two-dimensional inverse Fourier transform operator. As shown in the equation above, the in-phase current represents the real part of the mutual intensity of the two coherent beams, while the orthogonal current represents the imaginary part. After digital signal processing and inverse Fourier transform, the target light intensity distribution image is obtained, i.e., the image light field distribution map of the photon interferometric imaging system after error compensation. This achieves higher imaging resolution and image restoration accuracy than traditional uncompensated structures.

[0084] like Figure 9 As shown, where, Figure 9 (a) is the light field distribution diagram of the target. Figure 9 (b) is the imaging light field distribution of the photonic integrated interferometry imaging system with errors, and its SSIM value is 0.09. Figure 9 (c) shows the image light field distribution of the photonic integrated interferometric imaging system after error compensation, with an SSIM value of 0.39. It can be clearly seen that the compensated image light field distribution is closer to the light field distribution of the target, enhancing the image restoration rate. The structural similarity index (SSIM) of the image has increased from 0.09 to 0.39.

[0085] like Figure 10 As shown, another exemplary embodiment of the present invention provides a photonic integrated interferometry imaging method based on an error compensation structure, comprising the following steps:

[0086] Step 100: Provide at least one 2×2 beam splitter based on an error compensation structure.

[0087] Step 200: By adjusting the phase values ​​of the first phase shifter 13 and the second phase shifter 14, at least one phase deviation introduced by process error in the 2×2 beam splitter is calibrated, thereby enabling the 2×2 beam splitter to achieve the set splitting ratio.

[0088] In this embodiment, the set splitting ratio is an equal splitting ratio, i.e., 50:50, and the output optical power of the two output ports is equal.

[0089] Step 300: Construct an interference optical path using at least one calibrated 2×2 beam splitter to interfere with the input target optical signal.

[0090] Step 400: Detect the interferometric optical signal and convert it into an electrical signal.

[0091] Step 500: Process the electrical signal to reconstruct the target image.

[0092] In this embodiment, the step of processing the electrical signal to reconstruct the target image includes: obtaining the mutual intensity information of the two interfering light signals based on the electrical signal; and performing an inverse Fourier transform on the mutual intensity information to obtain the light intensity distribution of the target image.

[0093] The mutual strength information includes real part information and imaginary part information.

[0094] like Figure 11 As shown, another exemplary embodiment of the present invention provides a calibration method for a 2×2 beam splitter based on an error compensation structure as described above, including the following steps:

[0095] Step 600: Measure the actual phase deviation between the first coupler and the second coupler caused by manufacturing errors;

[0096] Step 700: Based on the actual phase deviation, calculate the required compensation phase value for the first phase shifter 13 and the second phase shifter 14; apply the compensation phase value to the corresponding first phase shifter 13 and second phase shifter 14.

[0097] In the above embodiments, the target refers to the external object to be observed; the target light signal refers to the light emitted or reflected from the target and entering the external receiving module of this system; the target image refers to the image of the target reconstructed by processing the target light signal, and the target image is also a target light intensity distribution image.

[0098] The modules / units described as separate components may or may not be physically separate. The components shown as modules / units may or may not be physical modules; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules / units can be selected to achieve the objectives of the embodiments of the present invention, depending on actual needs. For example, the functional modules / units in the various embodiments of the present invention may be integrated into one processing module, or each module / unit may exist physically separately, or two or more modules / units may be integrated into one module / unit.

[0099] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A photonic integrated interferometric imaging system based on an error compensation structure, characterized in that, include: An external receiving module is used to receive the target optical signal; The photonic integrated interference module is optically connected to the external receiving module and is used to perform interference processing on the target optical signal and convert the interference-processed optical signal into in-phase electrical signals and quadrature electrical signals. The data processing module, connected to the photonic integrated interference module, is used to receive the in-phase and quadrature electrical signals output by the photonic integrated interference module, recover the cross-intensity information of optical signals from different paths based on the in-phase and quadrature electrical signals, and perform an inverse Fourier transform on the cross-intensity information to reconstruct the target light intensity distribution image. The photonic integrated interference module includes: At least one 2×2 interference element, the 2×2 interference element comprising: Two 1×2 beam splitters are used to receive two input target optical signals and perform primary beam splitting on the target optical signals; Two 2×2 beam splitters are provided, each comprising a first coupler, a second coupler, a first phase shifter, and a second phase shifter. The first phase shifter is connected to an optical path between the first coupler and the second coupler, and the second phase shifter is connected to an input port of the first coupler. The first phase shifter is configured to compensate for phase deviations in the first coupler caused by manufacturing errors by adjusting its phase value. The second phase shifter is configured to compensate for phase deviations in the second coupler caused by manufacturing errors by adjusting its phase value. By adjusting the phase values ​​of the first and second phase shifters, the 2×2 beam splitters can still stably achieve a 50:50 beam splitting ratio even under the condition of manufacturing errors. The output ports of the two 1×2 beam splitters are connected to the input ports of the two 2×2 beam splitters via waveguides to form two interference optical paths. A 90° phase shifter is disposed on one of the waveguides of the two 1×2 beam splitters and the two 2×2 beam splitters to perform a 90° phase shift on the electrical signal in order to separate the in-phase current and the quadrature current with complete mutual strength. Two balanced detectors are connected to the output ports of the two 2×2 beam splitters, respectively, to convert the optical signals output by the two 2×2 beam splitters into in-phase electrical signals and quadrature electrical signals.

2. The photonic integrated interferometric imaging system according to claim 1, characterized in that, The external receiving module includes a microlens array.

3. The photonic integrated interferometric imaging system according to claim 1, characterized in that, The photonic integrated interferometer module further includes an input cross waveguide array and / or a wavelength division multiplexer array for guiding and distributing the target optical signal to the at least one 2×2 interferometer unit.

4. The photonic integrated interferometric imaging system according to claim 1, characterized in that, Both the first coupler and the second coupler are 2×2 multimode interference couplers.

5. The photonic integrated interferometric imaging system according to claim 1, characterized in that, The first phase shifter and the second phase shifter are thermo-optical phase shifters or electro-optical phase shifters.

6. A photonic integrated interferometric imaging method based on an error compensation structure, characterized in that, The method is applied to the system according to any one of claims 1 to 5, and the method includes the following steps: Provide at least one 2×2 beam splitter; By adjusting the phase values ​​of the first phase shifter and the second phase shifter, the phase deviation introduced by the process error in the at least one 2×2 beam splitter is calibrated, thereby enabling the 2×2 beam splitter to achieve the set splitting ratio. An interference optical path is constructed using the calibrated at least one 2×2 beam splitter to interfere with the input target optical signal, and the interfered optical signal is converted into an electrical signal. Based on the electrical signal, obtain the mutual intensity information of at least two interfering optical signals; The cross-intensity information is subjected to inverse Fourier transform to reconstruct the target light intensity distribution image; The mutual strength information includes real part information and imaginary part information.

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