A phase-recovery-based optical phased array calibration method and device

Abstract

The application discloses an optical phased array calibration method and device based on phase recovery, which traverses each channel of the optical phased array in a voltage input range, and records far-field light intensity changes under multiple measurement angles; according to the far-field light intensity changes, initial phases and phase shifter periods of each channel under each measurement angle are fitted; by using phase relationships between different measurement angles, the initial phases of each channel under different measurement angles are converted to the same reference angle, and the phase shifter period data under different measurement angles is processed to obtain the initial phases and the phase shifter periods of each channel under the reference angle; based on the obtained initial phases and the phase shifter periods of each channel under the reference angle, the calibration voltage of any deflection angle is calculated. The calibration method can obtain accurate driving voltage by measuring the initial phase of the preset angle, realizes continuous beam scanning, and effectively improves the calibration efficiency of the optical phased array.

Description

Technical Field

[0001] This invention belongs to the field of optical phased array technology, and particularly relates to an optical phased array calibration method and apparatus based on phase recovery. Background Technology

[0002] The concept of Optical Phased Arrays (OPA) originates from traditional microwave phased arrays. As an emerging beam scanning technology, OPA controls the wavefront of the emitted beam by altering the phase delay of light within the array elements, thereby achieving beam deflection. Compared to other beam scanning technologies, OPA offers advantages such as high emitted beam quality, no need for mechanical scanning, and fast response speed, demonstrating significant application potential in fields such as lidar and space optical communication.

[0003] However, due to limitations in current chip manufacturing processes, optical phased array chips inevitably exhibit random initial phase errors between channels. These errors severely interfere with the coherent synthesis of the beam, leading to a decrease in output beam quality and an increase in sidelobe levels. Therefore, precise calibration of the optical phased array is essential before practical application to compensate for these random phase errors. Currently, the mainstream method for optical phased array calibration is based on iterative optimization algorithms for adaptive optics systems. These algorithms repeatedly search and iterate within the voltage space to find the optimal combination of driving voltages for each scanning angle. However, for large-scale arrays (such as those with thousands of channels or more), this method involves numerous iterations and an extremely time-consuming optimization process, making it difficult to meet the requirements of practical applications. Summary of the Invention

[0004] To address the above problems, this invention proposes an optical phased array calibration method and apparatus based on phase retrieval. By measuring only a small number of initial phase angles, it is possible to achieve accurate calibration and continuous beam scanning of optical phased array devices, effectively improving the calibration efficiency of optical phased arrays and laying a technical foundation for the batch testing, characterization, and application of large-scale optical phased arrays.

[0005] The technical solution adopted in this invention is as follows: In a first aspect, this invention provides an optical phased array calibration method based on phase retrieval, specifically including the following steps:

[0006] S1: Select one channel of the optical phased array, traverse within the voltage input range of that channel, record the changes in far-field light intensity at multiple preset measurement angles, and repeat the operation until all channels of the optical phased array have been traversed.

[0007] S2: Based on the recorded far-field light intensity changes, the initial phase and phase shifter period of each channel at each measurement angle are fitted.

[0008] S3: Utilize the phase relationship between different measurement angles to convert the initial phase of each channel at different measurement angles to the same reference angle, and process the phase shifter period data at different measurement angles to obtain the initial phase and phase shifter period of each channel at the reference angle;

[0009] S4: Based on the initial phase and phase shifter period of each channel at the reference angle, calculate the calibration voltage at any deflection angle.

[0010] Furthermore, the light intensity change in step S1 is the change in light intensity measured by the photodetector at a preset angle. Far-field light intensity variation , where i is the channel number currently being traversed by voltage.

[0011] Furthermore, step S2 specifically includes the following steps:

[0012] S21: For channel i and the measured angle Based on the recorded light intensity and input voltage, the initial phase and phase shifter period of the selected channel at the preset measurement angle are obtained by fitting.

[0013] S22: Repeat step S21 until the initial phase and phase shifter period of all channels at each measurement angle are obtained.

[0014] Furthermore, the type of fitting curve function is determined by the type of phase shifter. If the phase shift of the phase shifter is proportional to the input voltage, then the fitting function is: If the phase shift of the phase shifter is proportional to the input power, then the fitting function is: ;

[0015] in, For measuring far-field light intensity, Input voltage, The parameters to be fitted are... , These represent the measurement angles of channel i. The phase shifter period and initial phase;

[0016] Furthermore, step S3 specifically includes the following steps:

[0017] S31: Based on the phase relationship of the optical phased array at different far-field angles, according to the formula All measured angles Corresponding initial phase Unified into a reference angle The equivalent initial phase below ,in d is the operating wavelength, and d is the waveguide spacing.

[0018] S32: Remove outliers from the equivalent initial phase data of channel i, and average the remaining normal data. Recorded as channel i at the reference angle The initial phase;

[0019] S33: Remove outliers from the phase shifter period data of channel i, and average the remaining normal data. The phase shifter period for channel i is recorded.

[0020] S34: Repeat steps S31 to S33 until the phase shifter period and reference angle of all channels are reached. The initial phase data were all recorded.

[0021] Further, the calculation process for the calibration voltage of each channel in step S4 is as follows: Based on the initial phase of the selected channel at the reference angle and the required calibration angle, the theoretical corrected phase shift of the selected channel is calculated. Then, based on the phase shifter periodic voltage of the selected channel, the theoretical corrected phase shift is converted into the corresponding calibration voltage. The specific calculation formula for the calibration voltage is as follows:

[0022]

[0023] Where i is the channel number. The calibration voltage for channel i. This represents the mapping relationship between the phase shift of phase shifter i and the input voltage. For channel i at the reference angle The initial phase, d is the operating wavelength, and d is the waveguide spacing. For reference angle, Set the required calibration angle.

[0024] Secondly, the present invention also provides an optical phased array calibration system based on phase recovery, the calibration system comprising a laser, an optical phased array, a photodetector, a controller, an electrically controlled turntable, and a driver;

[0025] The laser is used to transmit the output light to the optical phased array;

[0026] The optical phased array is used to output the modulated beam into free space;

[0027] The photodetector is used to collect the far-field light intensity distribution of the optical phased array;

[0028] The controller is used to receive light intensity data for calculation and to control the electronically controlled turntable and the driver;

[0029] The electrically controlled turntable is used to acquire data from different angles of the optical phased array.

[0030] The driver is used to control the input voltage of each channel of the optical phased array.

[0031] Thirdly, the present invention also provides an optical phased array calibration device based on phase retrieval, including a memory and one or more processors, wherein the memory stores executable code, and when the processor executes the executable code, it implements the optical phased array calibration method based on phase retrieval.

[0032] Fourthly, the present invention also provides a computer-readable storage medium having a program stored thereon, which, when executed by a processor, implements the aforementioned optical phased array calibration method based on phase recovery.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] This invention directly calculates the calibration voltage for other angles to be calibrated by measuring the initial phase of each channel at a selected angle. Compared to traditional calibration methods that require numerous angle calibrations to achieve beam scanning, this invention only requires a single calibration to achieve scanning at any angle, effectively reducing the time required for calibrating the optical phased array drive voltage. Attached Figure Description

[0035] Figure 1 A schematic flowchart illustrating an optical phased array calibration method based on phase retrieval provided in an embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram of the structure of the optical phased array calibration system provided in an embodiment of the present invention;

[0037] Figure 3 This is a graph showing the light intensity variation when adjusting a single channel phase shifter, as provided in an embodiment of the present invention.

[0038] Figure 4 Histogram of the initial phase distribution of each channel of the optical phased array provided in an embodiment of the present invention;

[0039] Figure 5 Histogram of the period of each channel phase shifter in an optical phased array provided in an embodiment of the present invention;

[0040] Figure 6(a) is a far-field plot of an uncalibrated one-dimensional 1024-channel optical phased array provided in an embodiment of the present invention;

[0041] Figure 6(b) is a far-field plot of a calibrated one-dimensional 1024-channel optical phased array provided in an embodiment of the present invention;

[0042] Figure 7 This is a diagram showing the ±15-degree field-of-view calibration results of a one-dimensional 1024-channel optical phased array provided in an embodiment of the present invention.

[0043] Figure 8 This is a structural diagram of an optical phased array calibration device based on phase recovery, provided in an embodiment of the present invention. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and do not constitute a limitation thereof.

[0045] like Figure 1 and Figure 2 As shown, this invention provides a method for calibrating an optical phased array based on phase retrieval, specifically including the following steps:

[0046] S1: Select one channel of the optical phased array, traverse within the voltage input range of that channel, record the changes in far-field light intensity at multiple preset measurement angles, and repeat the operation until all channels of the optical phased array have been traversed.

[0047] S2: Based on the recorded far-field light intensity changes, the initial phase and phase shifter period of each channel at each measurement angle are fitted.

[0048] S3: Utilize the phase relationship between different measurement angles to convert the initial phase of each channel at different measurement angles to the same reference angle, and process the phase shifter period data at different measurement angles to obtain the initial phase and phase shifter period of each channel at the reference angle;

[0049] S4: Based on the initial phase and phase shifter period of each channel at the reference angle, calculate the calibration voltage at any deflection angle.

[0050] like Figure 3 As shown, for an optical phased array, when the phase shifter of a single channel is adjusted to change the phase, it can be considered as the beam from that channel interfering with the combined beam from other channels, at an angle. The change in far-field light intensity is represented by a cosine curve. By fitting the curve... , and The phase shifter period of this channel can be obtained by using the parameters of the fitted curve. ,angle Phase difference between the combined beam from other channels and the beam from this channel Because the amplitude of the combined beam from other channels is much larger than that of a single-channel beam, the influence of the single-channel beam on the combined beam can be ignored. Therefore, the phase difference obtained from the fitted curve can be used. We can approximate the phase difference between the beam from this channel and the combined beam from all channels. Then, by sequentially adjusting the phase shifters of each channel of the optical phased array, we can obtain the angular phase difference between each channel of the optical phased array. The relative phase difference with respect to the same combined beam.

[0051] Furthermore, for large-scale optical phased arrays (such as those with thousands of channels or more), the intensity change caused by a phase change in a single channel is relatively small, resulting in a low signal-to-noise ratio in the measurement data. To address this, we improve the robustness of the calibration algorithm by simultaneously measuring the far-field intensity changes from multiple angles.

[0052] The calibration method is illustrated below using the measurement of the initial phase of each channel in a one-dimensional 1024-channel optical phased array at 0° as an example. The specific steps include:

[0053] S1: Select a channel of the optical phased array, traverse the voltage input range of that channel, and record the angles. Far-field light intensity variation Continue in this manner until all channels of the optical phased array have been traversed;

[0054] S2: Based on the recorded far-field light intensity changes, the initial phase and phase shifter period of each channel at each measurement angle are fitted.

[0055] S2 specifically includes the following steps:

[0056] S21: For channel i and the measured angle Based on the recorded light intensity and input voltage, the initial phase and phase shifter period of the selected channel at the preset measurement angle are obtained by fitting.

[0057] The type of fitting curve function depends on the type of phase shifter. If the phase shift of the phase shifter is proportional to the input voltage, then the fitting function is: If the phase shift of the phase shifter is proportional to the input power, then the fitting function is: ;

[0058] in, For measuring far-field light intensity, Input voltage, The parameters to be fitted are... , These represent the measurement angles of channel i. The phase shifter period and initial phase;

[0059] S22: Repeat step S21 until the initial phase and phase shifter period of all channels at each measurement angle are obtained.

[0060] S3: Utilize the phase relationship between different measurement angles to convert the initial phase of each channel at different measurement angles to the same reference angle, and process the phase shifter period data at different measurement angles to obtain the initial phase and phase shifter period of each channel at the reference angle;

[0061] S3 specifically includes the following steps:

[0062] S31: According to the formula All measured angles Corresponding initial phase Unified conversion to equivalent initial phase at a reference angle of 0° ,in d is the operating wavelength, and d is the waveguide spacing.

[0063] S32: Remove outliers from the equivalent initial phase data of channel i, and average the remaining normal data. Record the initial phase of channel i at the reference angle 0°;

[0064] S33: Remove outliers from the phase shifter period data of channel i, and average the remaining normal data. The phase shifter period for channel i is recorded.

[0065] S34: Repeat steps S31 to S33 until the phase shifter period and initial phase data at the reference angle of 0° for all channels are recorded.

[0066] like Figure 4 The image shows an optical phased array in... Initial phase distribution of each channel in the direction, Figure 5 This refers to the phase shifter period of each channel in an optical phased array. Due to limitations in current manufacturing processes, a small number of phase shifters in optical phased arrays malfunction, making it impossible to obtain the initial phase and phase shifter period for these channels.

[0067] S4: Based on the initial phase and phase shifter period of each channel at the reference angle, calculate the calibration voltage at any deflection angle.

[0068] The formula for calculating the calibration voltage of each channel in step S6 is as follows:

[0069]

[0070] Where i is the channel number. The calibration voltage for channel i. This represents the mapping relationship between the input voltage and phase shift of channel i. Let i be the initial phase of channel i at 0°. d is the operating wavelength, and d is the waveguide spacing. Set the required calibration angle.

[0071] Figure 6(a) shows the far-field diagram of the uncalibrated optical phased array, and Figure 6(b) shows the far-field diagram of the calibrated optical phased array. It can be seen that the output beam quality of the optical phased array is significantly improved.

[0072] like Figure 7 The diagram shows the calibration results of the optical phased array within a ±15° field of view, at 0.5° intervals, based on the initial phase measured at 0°. Traditional calibration methods require calibrating each of the 61 angles individually, while the method provided by this invention only requires a single calibration, effectively reducing the time required for optical phased array calibration.

[0073] Corresponding to the aforementioned embodiment of an optical phased array calibration method based on phase retrieval, this invention also provides an embodiment of an optical phased array calibration system based on phase retrieval. This system includes a laser, an optical phased array, a photodetector, a controller, an electrically controlled turntable, and a driver. The output light of the laser is transmitted to the optical phased array; the optical phased array outputs a modulated beam into free space; the photodetector is used to collect the far-field light intensity distribution of the optical phased array; the controller receives the light intensity data, performs calculations, and controls the electrically controlled turntable and the driver; the electrically controlled turntable is used to acquire data from different angles of the optical phased array; and the driver is used to control the input voltage of each channel of the optical phased array.

[0074] Corresponding to the aforementioned embodiment of an optical phased array calibration method based on phase recovery, the present invention also provides an embodiment of an optical phased array calibration device based on phase recovery.

[0075] See Figure 8 The present invention provides an optical phased array calibration device based on phase retrieval, comprising a memory and one or more processors. The memory stores executable code, and when the processor executes the executable code, it is used to implement an optical phased array calibration method based on phase retrieval in the above embodiment.

[0076] An embodiment of the phase-recovery-based optical phased array calibration device provided by this invention can be applied to any device with data processing capabilities, such as a computer. The device embodiment can be implemented in software, hardware, or a combination of both. Taking software implementation as an example, as a logical device, it is formed by the processor of any data-processing device loading the corresponding computer program instructions from non-volatile memory into memory for execution. From a hardware perspective, such as... Figure 8The diagram shown is a hardware structure diagram of any data processing-capable device, including the phase retrieval-based optical phased array calibration device provided by this invention. (Except for...) Figure 8 In addition to the processor, memory, network interface, and non-volatile memory shown, any data processing device in the embodiment may also include other hardware depending on the actual function of the data processing device, which will not be described in detail here.

[0077] The specific implementation process of the functions and roles of each unit in the above device can be found in the implementation process of the corresponding steps in the above method, and will not be repeated here.

[0078] For the device embodiments, since they basically correspond to the method embodiments, the relevant parts can be referred to in the description of the method embodiments. The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of the present invention according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0079] This invention also provides a computer-readable storage medium storing a program thereon, which, when executed by a processor, implements an optical phased array calibration method based on phase recovery as described in the above embodiments.

[0080] The computer-readable storage medium can be an internal storage unit of any data processing device described in any of the foregoing embodiments, such as a hard disk or memory. The computer-readable storage medium can also be an external storage device of any data processing device, such as a plug-in hard disk, smart media card (SMC), SD card, flash card, etc., equipped on the device. Furthermore, the computer-readable storage medium can include both internal storage units and external storage devices of any data processing device. The computer-readable storage medium is used to store the computer program and other programs and data required by the data processing device, and can also be used to temporarily store data that has been output or will be output.

[0081] The present invention also provides a computer program product, including a computer program, which, when executed by a processor, implements the aforementioned optical phased array calibration method based on phase retrieval.

[0082] This invention is not limited to the specific embodiments described above. Any modifications and alterations to this invention that are within the spirit and principles of this invention should also fall within the scope of protection of the claims of this invention.

Claims

1. A calibration method for an optical phased array based on phase retrieval, characterized in that: The calibration method specifically includes the following steps: S1: Select one channel of the optical phased array, traverse within the voltage input range of that channel, record the changes in far-field light intensity at multiple preset measurement angles, and repeat the operation until all channels of the optical phased array have been traversed. S2: Based on the recorded far-field light intensity changes, the initial phase and phase shifter period of each channel at each measurement angle are fitted. S3: Utilize the phase relationship between different measurement angles to convert the initial phase of each channel at different measurement angles to the same reference angle, and process the phase shifter period data at different measurement angles to obtain the initial phase and phase shifter period of each channel at the reference angle; S4: Based on the initial phase and phase shifter period of each channel at the reference angle, calculate the calibration voltage at any deflection angle.

2. The optical phased array calibration method based on phase retrieval according to claim 1, characterized in that: Step S2 specifically includes the following steps: S21: For the selected channel and the preset measurement angle, based on the recorded far-field light intensity and input voltage, the initial phase and phase shifter period of the selected channel at the preset measurement angle are fitted. S22: Repeat step S21 until the initial phase and phase shifter period of all channels at each measurement angle are obtained.

3. The optical phased array calibration method based on phase retrieval according to claim 2, characterized in that: The function type of the fitted curve is determined by the phase shifter type. If the phase shifter phase shift is proportional to the input voltage, then the change in far-field light intensity and the input voltage satisfy a cosine curve relationship. If the phase shifter phase shift is proportional to the input power, then the change in far-field light intensity and the square of the input voltage satisfy a cosine curve relationship.

4. The optical phased array calibration method based on phase retrieval according to claim 1, characterized in that: Step S3 specifically includes the following steps: S31: Based on the phase relationship of optical phased array at different far-field angles, the initial phases corresponding to all measurement angles are uniformly transformed into equivalent initial phases under the reference angles; S32: Remove outliers from the equivalent initial phase data of the selected channel and record the mean of the remaining normal data as the initial phase of the selected channel at the reference angle. S33: Remove outliers from the phase shifter cycle data of the selected channel and record the average of the remaining normal data as the phase shifter cycle of the selected channel. S34: Repeat steps S31 to S33 until the initial phase data of the phase shifter period and reference angle of all channels are recorded.

5. The optical phased array calibration method based on phase retrieval according to claim 4, characterized in that: The calculation process for the calibration voltage of each channel in step S4 is as follows: based on the initial phase of the selected channel at the reference angle and the required calibration angle, the theoretical correction phase shift of the selected channel is calculated, and the theoretical correction phase shift is converted into the corresponding calibration voltage according to the phase shifter period voltage of the selected channel.

6. A calibration system for implementing the phase retrieval-based optical phased array calibration method according to any one of claims 1-5, characterized in that: The calibration system includes a laser, an optical phased array, a photodetector, a controller, an electrically controlled turntable, and a driver; The laser is used to transmit the output light to the optical phased array; The optical phased array is used to output the modulated beam into free space; The photodetector is used to collect the far-field light intensity distribution of the optical phased array; The controller is used to receive light intensity data for calculation and to control the electronically controlled turntable and the driver; The electrically controlled turntable is used to acquire data from different angles of the optical phased array. The driver is used to control the input voltage of each channel of the optical phased array.

7. A phase-recovery-based optical phased array calibration device, comprising a memory and one or more processors, wherein the memory stores executable code, characterized in that, When the processor executes the executable code, it implements an optical phased array calibration method based on phase recovery as described in any one of claims 1-5.

8. A computer-readable storage medium having a program stored thereon, characterized in that, When the program is executed by the processor, it implements the optical phased array calibration method based on phase recovery as described in any one of claims 1-5.

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