A method and system for calibration and attenuation control of a variable optical attenuator

Abstract

This invention provides a method and system for calibration and attenuation control of a variable optical attenuator. The method acquires multiple data points of the variable optical attenuator at different temperatures; fits the data acquired at the corresponding temperatures to obtain polynomial curve formulas, and stores the parameters of each curve formula; during operation, the method obtains the parameters of the corresponding curves based on the current ambient temperature, calculates the voltage for controlling the variable optical attenuator according to the formulas corresponding to the calibration curve parameters, and sends it down to achieve attenuation control of the output light intensity. This invention achieves fast and high-precision calibration of the variable optical attenuator without changing the existing system hardware and firmware interface, only by optimizing the software algorithm. It effectively reduces the number of parameters collected and can store multiple calibration parameters at different temperatures, which also contributes to the high-precision and high-reliability control of the output light intensity of the quantum key distribution system.

Description

Technical Field

[0001] This invention belongs to the field of quantum communication technology and relates to a method and system for calibration and attenuation control of a variable optical attenuator. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] In quantum key distribution (QKD) systems, voltage-controlled variable optical attenuators are required to attenuate the light and maintain the output light intensity at the single-photon level. Before use, the variable optical attenuator needs to be calibrated to establish the relationship between the attenuation value (dB value) and the voltage value (DAC value).

[0004] Taking a microelectromechanical system-type variable optical attenuator (MEMS VOA) as an example, the calibration process of commonly used calibration methods is explained below:

[0005] 1) Scan the voltage value in a certain step (e.g., 100) until the maximum voltage value range is reached to obtain a set of data (DAC value, optical power value);

[0006] 2) Based on the data obtained from scanning in 1), calculate the corresponding voltage value.<DAC_0> Attenuation value <0dB>), (voltage value)<DAC_1> Attenuation value <1dB>), (voltage value)<DAC_2> (Attenuation value <2dB>), ..., (voltage value)<DAC_n> Attenuation value <ndb>);

[0007] 3) Store the (voltage value, attenuation value) data of the above n points in the QKD system. When using the QKD system, select the DAC value corresponding to two adjacent integer attenuation values ​​according to the required attenuation value, and calculate the corresponding voltage value according to the linear interpolation method for transmission.

[0008] According to the inventor, the above calibration and usage methods have the following drawbacks:

[0009] (1) The calibration process requires scanning a large number of points (generally more than 200 points: the scanning range of the digital-to-analog converter (DAC) is 0-40000, and considering the calibration accuracy, the adjustment step of the DAC is <200), so the calibration is time-consuming.

[0010] (2) (Voltage value, attenuation value) requires a lot of storage space in the QKD system. For example, 41 parameters (DAC values ​​corresponding to 0~40dB) need to be stored at a temperature point.

[0011] (3) Calibration is generally performed only at room temperature, without considering different temperature ranges, and the calibration parameters are not adjusted according to the actual ambient temperature, resulting in a certain deviation.

[0012] (4) When using the QKD system, the voltage value calculated by linear interpolation based on the required attenuation value differs from the actual voltage value of the system. Some errors are between 0.1 and 0.2 dB, which is not accurate enough. Summary of the Invention

[0013] To address the aforementioned problems, this invention proposes a method and system for calibration and attenuation control of a variable optical attenuator. Without altering the existing system hardware and firmware interface, this invention achieves fast and high-precision calibration of the variable optical attenuator solely through optimized software algorithms. This effectively reduces the number of parameters collected and allows for the storage of multiple calibration parameters at different temperatures. It also contributes to the high-precision and high-reliability control of the output light intensity of the quantum key distribution system.

[0014] According to some embodiments, the present invention adopts the following technical solution:

[0015] A method for calibrating and controlling the attenuation of a variable optical attenuator includes the following steps:

[0016] Acquire multiple data points for the variable optical attenuator at different temperatures;

[0017] The data collected at the corresponding temperature are fitted to obtain the curve formula of the polynomial, and the parameters of each curve formula are stored.

[0018] During operation, the parameters of the corresponding curve are obtained based on the current ambient temperature. The voltage for controlling the variable optical attenuator is calculated according to the formula corresponding to the calibration curve parameters and then sent out to achieve attenuation control of the output light intensity.

[0019] As an alternative implementation, each data point in the acquired data includes both an attenuation value and a voltage value.

[0020] As an alternative implementation, the number of data points acquired is at least greater than the number of levels in the fitted curve formula.

[0021] As an alternative implementation, the temperature is equidistantly distributed, and data is collected at set temperature intervals.

[0022] As an alternative implementation, the temperature distribution range covers the operating temperature range of the quantum key distribution system / variable optical attenuator.

[0023] As an alternative implementation method, Taylor's formula is used for fitting.

[0024] As an alternative implementation, the parameters of each curve formula are stored in a quantum key distribution system.

[0025] A variable optical attenuator calibration and attenuation control system, comprising:

[0026] The data acquisition module is configured to acquire multiple data points from the variable optical attenuator at different temperatures;

[0027] The curve fitting module is configured to fit the data collected at the corresponding temperature to obtain the curve formula of the polynomial and store the parameters of each curve formula.

[0028] The attenuation control module is configured to obtain the parameters of the corresponding curve based on the current ambient temperature during operation, calculate the voltage to control the variable optical attenuator according to the formula corresponding to the calibration curve parameters, and send it down to achieve attenuation control of the output light intensity.

[0029] A computer-readable storage medium storing a plurality of instructions adapted for loading by a processor of a terminal device and executing steps in the method.

[0030] A terminal device includes a processor and a computer-readable storage medium, the processor being configured to implement instructions; the computer-readable storage medium being configured to store a plurality of instructions adapted to be loaded by the processor and executed in accordance with the steps of the method described therein.

[0031] A quantum key distribution system, controlled by the above method, or comprising the above system, a computer-readable storage medium, or a terminal device.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] This invention uses Taylor's formula to quickly and accurately calibrate a variable optical attenuator. It only requires determining the number of data points to be acquired according to the order of the polynomial in the fitted curve formula, reducing the number of sampling times. It does not require additional storage space and can save calibration parameters at different temperatures, improving the reliability of variable optical attenuator control and thus improving the reliability of output light intensity control in the quantum key distribution system.

[0034] This invention requires no hardware modifications and can be implemented solely through firmware upgrades, thus not increasing hardware costs. Furthermore, the firmware upgrade reuses the previous communication interface, without affecting the original system, making the upgrade simple. Attached Figure Description

[0035] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0036] Figure 1 This is a flowchart illustrating this embodiment. Detailed Implementation

[0037] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0038] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0039] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0040] Example 1

[0041] To facilitate understanding of the technical solution of the present invention by those skilled in the art, this embodiment uses a microelectromechanical system-type variable optical attenuator as an example to illustrate the technical solution, but it does not mean that the present invention is only applicable to this type of variable optical attenuator.

[0042] like Figure 1 As shown, the Taylor formula was used to fit the collected 6 to 10 data points (attenuation value and voltage value) to obtain the polynomial curve formula.

[0043] This example uses a polynomial with a class of 5, i.e., the polynomial is f(x) = a0 + a1x + a2x. 2 +a3x 3 +a4x 4 +a5x 5 .

[0044] In other embodiments, the number of order levels can be adjusted according to calibration requirements or other practical situations, such as becoming fourth or sixth order.

[0045] This embodiment uses the Taylor formula for fitting, which can achieve fast and high-precision calibration.

[0046] Then the parameters (a0, a1, a2, a3, a4, a5) of the curve formula f(x) are stored in the QKD system.

[0047] Of course, in other embodiments, the parameters can be stored in other devices or memory, which the QKD system can then access.

[0048] Because the fitting curve requires fewer data points (taking the fifth-order curve in this embodiment as an example, only 6 to 10 data points are needed per temperature), multiple sets of temperature points can be stored in a smaller amount of storage space. For example, 13 temperature point parameters can be stored, with a temperature range of -10℃ to 50℃, and one set of parameters can be stored every 5℃.

[0049] In other embodiments, the above parameters can all be adjusted, such as the temperature range or the data acquisition interval. Similarly, in some embodiments, data points may be acquired at non-uniform temperature intervals.

[0050] During operation, the QKD system obtains the parameters a0, a1, a2, a3, a4, and a5 of the corresponding MEMSVOA calibration curve based on the current ambient temperature. According to the formula f(x) corresponding to the calibration curve parameters and the attenuation value, the voltage for controlling the MEMSVOA is calculated and sent out, thereby realizing the attenuation control of the output light intensity of the QKD system.

[0051] During use, at least six data points (attenuation value and voltage value) of MEMSVOA are collected at temperature T. Then, the matrix is ​​solved according to the Taylor formula f(x) mentioned above. Taking six points as an example, namely (X1,Y1), (X2,Y2), (X3,Y3), (X4,Y4), (X5,Y5), and (X6,Y6), the following matrix is ​​constructed, and the matrix is ​​solved to obtain (a0, a1, a2, a3, a4, a5). Where X is the attenuation value and Y is the voltage value.

[0052]

[0053] Repeat the above process to store the values ​​a0, a1, a2, a3, a4, and a5 at different temperature points into the QKD system. During operation, the QKD system obtains the corresponding parameters (a0, a1, a2, a3, a4, and a5) based on the current ambient temperature, calculates the voltage value for controlling the MEMSVOA based on the formula f(x) and the attenuation value corresponding to the parameters, and then sends it out.

[0054] If the current ambient temperature is not calibrated during calculation, you can choose the temperature that is closest to the current ambient temperature and has been calibrated for calculation.

[0055] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0056] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0057] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0058] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0059] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0060] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.< / ndb>

Claims

1. A method of variable optical attenuator calibration and attenuation control, characterized by, The method comprises the following steps: acquiring a plurality of data of the variable optical attenuator at different temperatures; fitting the data collected at the corresponding temperatures to obtain a polynomial curve formula, and storing the parameters of each curve formula; in the running process, obtaining the parameters of the corresponding curve according to the current ambient temperature, calculating the voltage for controlling the variable optical attenuator according to the formula corresponding to the calibration curve parameters, and issuing the voltage, so as to realize the attenuation control of the outlet light intensity; the number of acquired data is at least greater than the order number of the fitted curve formula; the temperatures are equidistantly distributed, and data collection is performed every set temperature; the fitting is performed by using Taylor formula.

2. A method of calibrating and controlling attenuation of a variable optical attenuator as claimed in claim 1, characterized by, Each data point in the acquired data includes an attenuation value and a voltage value.

3. The method for calibration and attenuation control of a variable optical attenuator as described in claim 1, characterized in that, The distribution interval of the temperature covers the working temperature interval of the quantum key distribution system / variable optical attenuator.

4. The method for calibration and attenuation control of a variable optical attenuator as described in claim 1, characterized in that, The parameters of each curve formula are stored in the quantum key distribution system.

5. A variable optical attenuator calibration and attenuation control system, performing the steps of the method of any of claims 1-4, characterized by, The method comprises the following steps: a data acquisition module configured to acquire a plurality of data of the variable optical attenuator at different temperatures; a curve fitting module configured to fit the data collected at the corresponding temperatures to obtain a polynomial curve formula, and store the parameters of each curve formula; an attenuation control module configured to, in the running process, obtain the parameters of the corresponding curve according to the current ambient temperature, calculate the voltage for controlling the variable optical attenuator according to the formula corresponding to the calibration curve parameters, and issue the voltage, so as to realize the attenuation control of the outlet light intensity.

6. A computer readable storage medium characterized by, A plurality of instructions are stored therein, and the instructions are adapted to be loaded and executed by the processor of the terminal device to implement the steps in the method of any one of claims 1-4.

7. A terminal device, characterized by comprising: The computer readable storage medium is used to store a plurality of instructions, and the instructions are adapted to be loaded and executed by the processor to implement the steps in the method of any one of claims 1-4.

8. A quantum key distribution system, characterized by, The method of any one of claims 1-4 is used for control, or the system of claim 5, the computer readable storage medium of claim 6, or the terminal device of claim 7 is included. The method of any one of claims 1-4 is used for control, or the system of claim 5, the computer readable storage medium of claim 6, or the terminal device of claim 7 is included.

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