Three-ring polarization controller adjustment system

Abstract

The application relates to the technical field of optical control, and discloses a three-ring polarization controller adjusting system, which comprises a polarization sensor for detecting the polarization state of input light and outputting an electric signal; an angle sensor is installed on the rotating shafts of the three rings of the three-ring polarization controller and is used for detecting the rotating angles of the rings; a single-chip microcomputer has an input end connected with the polarization sensor and the angle sensor and an output end for generating a control signal; a motor driving circuit receives the control signal of the single-chip microcomputer; and three groups of motors are driven by the motor driving circuit and are connected with the rotating shafts of the three rings respectively. The disclosed system integrates polarization / angle double-sensing feedback, three-ring cooperative driving and closed-loop automatic adjustment of isolated power supply.

Description

Technical Field

[0001] This application relates to the field of optical control technology, for example to a three-ring polarization controller adjustment system. Background Technology

[0002] In cutting-edge fields such as high-speed optical communication and quantum sensing, the adjustment accuracy and response speed of a three-loop polarization controller directly affect system performance. Traditional solutions generally employ manual or open-loop electric adjustment methods, which have significant structural defects: Firstly, the manual adjustment mode of rotating the mechanical shaft relies on the operator's experience, which limits the polarization angle control accuracy to ±3° or more. Moreover, when faced with dynamic drift of channel polarization state (typical value 10° / second), the response delay of more than 30 seconds will cause the communication error rate to soar. Secondly, although the existing electrification improvement scheme introduces stepper motor drive, it lacks real-time angle feedback and polarization state monitoring, and cannot compensate for the cumulative error caused by mechanical backlash (about 0.5° backlash) and temperature drift (0.2° / ℃). After running continuously for 2 hours, the polarization control drift exceeds 2°. Third, the three-loop independent open-loop control architecture, due to neglecting the coupling effect between waveplates, induces polarization state oscillation when adjusting a single loop. In order to achieve the target state (such as 45° linear polarization), it needs to be iterated 3 to 5 times, which takes more than 15 seconds. Fourth, power supply noise interference is a prominent issue. When the high current (peak value > 500mA) of the motor start-up and shutdown is shared with the microampere-level sensing signal, the common-mode noise > 50mV causes the signal-to-noise ratio of the Stokes parameter S2 / S3 to deteriorate to below 30dB, making it difficult to meet the requirements of highly sensitive scenarios such as quantum key distribution.

[0003] With the widespread adoption of 100G / 400G coherent optical communication, the industry urgently needs polarization controllers to achieve a triple breakthrough in structure: accuracy improved to within ±0.5° (compliant with ITU-T G.654 standard), response speed faster than 1 second to track dynamic changes in polarization mode dispersion, and long-term stability with a drift of <0.5° for 72 hours.

[0004] Existing technologies, due to the lack of closed-loop feedback, insufficient multi-loop coordination, and weak anti-interference design, can no longer support high-reliability application scenarios.

[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Utility Model Content

[0006] To provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended as a general commentary, nor is it intended to identify key / important components or describe the scope of protection of these embodiments, but rather as a prelude to the detailed description that follows.

[0007] This disclosure provides a three-loop polarization controller adjustment system that integrates polarization / angle dual-sensor feedback, three-loop coordinated drive, and isolated power supply for closed-loop automatic adjustment.

[0008] In some embodiments, the regulating system includes: A polarization sensor is used to detect the polarization state of input light and output an electrical signal. An angle sensor is installed on the rotating shaft of the three rings of the three-ring polarization controller to detect the rotation angle of each ring; The microcontroller has its input terminals connected to the polarization sensor and the angle sensor, and its output terminal generates control signals. The motor drive circuit receives control signals from the microcontroller. Three sets of motors, driven by a motor drive circuit, are connected to the rotating shafts of the three rings respectively.

[0009] Optionally, the polarization sensor is a four-quadrant photodiode array used to measure Stokes parameters.

[0010] Optionally, the angle sensor is a rotary encoder with an angle resolution of not less than 14 bits.

[0011] Optionally, the microcontroller is equipped with an ADC acquisition module and a PWM output channel. The ADC module acquires sensor signals, and the PWM channel outputs three independent control signals to the motor drive circuit.

[0012] Optionally, the three sets of motors are directly connected to the rotating shaft via couplings, and the three sets of motors share the same clock source.

[0013] Optionally, the motor drive circuit includes a stepper motor drive chip that supports microstepping control.

[0014] Optionally, the adjustment system may also include: a communication interface circuit that supports UART, I2C or SPI protocols to connect the microcontroller to external devices.

[0015] Optionally, the regulation system may also include a power supply circuit for supplying power to the system. The power supply circuit includes a digital power supply unit and a motor power supply unit, which are electrically isolated from each other; or, The power supply circuit includes a DC power supply module for providing a stable power supply; and a voltage regulator module for converting the voltage when the microcontroller and the sensor have different operating voltages, so as to supply power to the microcontroller, the sensor and the motor respectively.

[0016] Optionally, the three rings of the three-ring polarization controller are, in sequence, a λ / 4 waveplate ring, a λ / 2 waveplate ring, and a polarization rotation ring, each driven independently by three sets of motors.

[0017] Optionally, the stepper motor driver chip is L298N or A4988.

[0018] The three-ring polarization controller adjustment system provided in this disclosure can achieve the following technical effects: This disclosure innovates through a feedback mechanism: dual feedback from a polarization sensor and an angle sensor binds the optical state to the mechanical position in real time, eliminating the cumulative error of open-loop control; The execution architecture was optimized: the hardware synchronous design of three sets of motors directly driving the three rings, combined with the microcontroller's collaborative calculation of the target angle of the three rings, eliminates the intermediate polarization oscillation caused by the action delay and avoids the coupling effect of step-by-step adjustment; The resulting millisecond-level response, sub-angular-level accuracy, and robustness in multiple environments provide fundamental hardware support for cutting-edge fields such as next-generation high-speed optical communication and quantum precision measurement.

[0019] The above general description and the description below are exemplary and illustrative only and are not intended to limit this application. Attached Figure Description

[0020] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations and drawings do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are shown as similar elements. The drawings are not to be scaled. And wherein: Figure 1 This is a schematic diagram of a three-ring polarization controller adjustment system provided in an embodiment of this disclosure.

[0021] Figure label: 10: Three-ring polarization controller; 20: Angle sensor; 30: Polarization sensor; 40: Microcontroller; 50: Drive module; 60: Communication module; 70: Power supply module; 80: Motor. Detailed Implementation

[0022] To provide a more detailed understanding of the features and technical content of the embodiments of this disclosure, the implementation of the embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. The accompanying drawings are for illustrative purposes only and are not intended to limit the embodiments of this disclosure. In the following technical description, for ease of explanation, several details are used to provide a full understanding of the disclosed embodiments. However, one or more embodiments may still be implemented without these details. In other cases, well-known structures and devices may be simplified in their depiction to simplify the drawings.

[0023] The terms "first," "second," etc., used in the embodiments of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this disclosure described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0024] In this disclosure, the terms "upper," "lower," "inner," "middle," "outer," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for better describing the embodiments of this disclosure and their implementations, and are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to require them to be constructed and operated in a specific orientation. Furthermore, some of the aforementioned terms may be used to indicate other meanings besides orientation or positional relationship; for example, the term "upper" may in some cases indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this disclosure according to the specific circumstances.

[0025] Furthermore, the terms "set up," "connect," and "fix" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this disclosure according to the specific circumstances.

[0026] Unless otherwise stated, the term "multiple" means two or more.

[0027] In this embodiment of the disclosure, the character " / " indicates that the objects before and after it are in an "or" relationship. For example, A / B means: A or B.

[0028] The term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in the present disclosure can be combined with each other.

[0030] Combination Figure 1 As shown, this embodiment of the present disclosure provides a three-ring polarization controller 10 adjustment system, including a polarization sensor 30, an angle sensor 20, a microcontroller 40, a motor drive circuit, three sets of motors, a communication interface circuit, and a power supply circuit.

[0031] The polarization sensor 30 is used to detect the polarization state of the input light and output an electrical signal; Angle sensors 20 are mounted on the rotating shafts of the three rings of the three-ring polarization controller 10 to detect the rotation angle of each ring; The input terminal of the microcontroller 40 is connected to the polarization sensor 30 and the angle sensor 20, and the output terminal generates a control signal. The motor drive circuit receives control signals from the microcontroller 40; The three sets of motors are driven by a motor drive circuit and are respectively connected to the rotating shafts of the three rings.

[0032] The power supply circuit provides power to the system.

[0033] Understandably, power supply circuits can perform energy link purification. Specifically, energy link purification can employ structural isolation designs, such as a digital-motor dual-loop isolation architecture. The digital power supply loop (3.3V) outputs ultra-low ripple (<10mV) via a linear regulator (such as LM1117), dedicated to supplying high-precision components such as microcontrollers and sensors. The motor power supply loop (12V) converts energy through an isolated DC-DC module (such as B0505S), utilizing magneto-electric coupling to transfer power (primary and secondary side withstand voltage >1500V, leakage current <1μA), completely blocking the conduction of motor start-stop peak current (peak value >500mA) to the digital terminal. In addition, a dual-circuit, non-electrically common ground approach can be adopted to eliminate ground loop interference (ground potential fluctuation > 50mV in traditional schemes), and combined with a π-type filter circuit (10μF+100μH+10μF) at the motor end to absorb residual noise.

[0034] Regarding noise suppression, triple purification is achieved: 1. Conducted noise blocking: The isolated DC-DC module cuts off 99% of common-mode noise, reducing the peak-to-peak noise of the sensor signal from >50mV to <5mV; 2. Radiated noise suppression: Ferrite rings are added to the motor circuit to absorb high-frequency switching radiation (above 100kHz), reducing electromagnetic interference (EMI) by >30dB; Power supply ripple optimization: Digital power supply ripple <10mV (traditional solutions >100mV), ensuring ADC sampling error <0.1%; 3. Technical performance improvement: Energy purification directly drives a leap in system performance: Stokes parameter detection accuracy: S3 measurement error reduced from >15% to <3% (because circularly polarized light is most sensitive to noise); Polarization control stability: Temperature drift additional error reduced from 0.1° / ℃ to 0.01° / ℃, polarization angle drift <0.2° after 72 hours of continuous operation; Enhanced system reliability: When the power grid fluctuates by ±10%, the motor power supply remains stable (fluctuation <5%), avoiding undervoltage and step loss faults.

[0035] In implementation, the power supply circuit can adopt a power partitioning + π-type filtering method, which can suppress noise by 40dB and effectively reduce costs; alternatively, an isolated DC-DC module can be used, which can suppress noise by 60dB and meet the requirements of quantum communication scenarios; in addition, the optocoupler isolation + independent battery power supply solution can achieve noise suppression >80dB and can be adapted to medical laser equipment.

[0036] In summary, the energy link purification system, through structural innovations such as physically isolated power supply, magnetoelectric coupling energy transmission, and tiered filtering for noise suppression, improves the signal-to-noise ratio (SNR) of sensor signals from less than 30dB to greater than 60dB. This not only eliminates polarization control inaccuracies caused by power supply noise in traditional solutions (such as circular polarization distortion caused by S3 errors), but also lays a "pure energy foundation" for the closed-loop control system, making ±0.5° high-precision polarization control possible in complex industrial electromagnetic environments.

[0037] The three-loop polarization controller 10 adjustment system disclosed herein reconstructs the polarization control logic through three physical layer innovations: 1. Innovative feedback mechanism: Dual-path feedback from polarization sensor 30 and angle sensor 20 binds the optical state and mechanical position in real time, eliminating the cumulative error of open-loop control; 2. Optimized execution architecture: Hardware synchronous design with three sets of motors directly driving the three loops, combined with the microcontroller's collaborative calculation of the target angle of the three loops, eliminates intermediate polarization oscillations caused by action delay and avoids the coupling effect of step-by-step adjustment; 3. Energy link purification: Isolation power supply cuts off the noise conduction path, ensuring the purity of microvolt-level sensing signals. The resulting millisecond-level response, sub-angle-level accuracy, and multi-environment robustness provide fundamental hardware support for cutting-edge fields such as next-generation high-speed optical communication and quantum precision measurement.

[0038] Optionally, the polarization sensor 30 is a four-quadrant photodiode array used to measure Stokes parameters.

[0039] Understandably, the four-quadrant photodiode array achieves synchronous, high-precision measurement of Stokes parameters S1 / S2 / S3 by integrating micro-polarization filters (0° / 45° / 90° / 135° and circular polarization channels). Compared to discrete sensors, it eliminates multi-probe installation errors (angular deviation <0.1°); it improves response speed to the microsecond level (<1μs), meeting the requirements of high-speed polarization state tracking; and it reduces temperature drift to 0.01% / ℃, ensuring parameter stability during 72 hours of continuous operation. In this disclosure, the S1 / S2 detection error is <5%, laying the foundation for improving polarization control accuracy.

[0040] Optionally, the angle sensor 20 is a rotary encoder with an angle resolution of not less than 14 bits.

[0041] Understandably, the high-resolution encoder (0.022°) provides real-time feedback on the three-ring mechanical angle, which, combined with the microcontroller 40, achieves dual closed-loop correction: specifically, it can compensate for stepper motor hysteresis and gear transmission idle travel; it can suppress the effects of temperature drift; and it can achieve a physical angle control accuracy of ±0.028°, a significant improvement over traditional potentiometer solutions. Encoder data is directly transmitted to the microcontroller 40 via the SPI interface with a delay of <10μs, ensuring a dynamic response bandwidth >2Hz.

[0042] Optionally, the microcontroller 40 is equipped with an ADC acquisition module and a PWM output channel. The ADC module acquires sensor signals, and the PWM channel outputs three independent control signals to the motor drive circuit.

[0043] Understandably, the ADC module digitizes the analog signal from the polarization / angle sensor (sampling rate 100kSPS), and, in conjunction with three independent PWM outputs, achieves millisecond-level real-time control, with a signal acquisition → calculation → output delay of <0.5ms. The synchronization accuracy of the three PWM channels reaches 100ns, ensuring consistent motor start-up times, reducing optical path disturbances caused by mechanical vibration, and suppressing the deterioration of polarization coupling oscillation intermediate states due to asynchronous actions. Furthermore, this allows for the embedding of an adaptive PID algorithm into the microcontroller, maintaining control stability even under temperature drift conditions (72h angle drift <0.2°). The STM32F4's DSP instruction set accelerates matrix operations, with Jones matrix inversion taking <50μs.

[0044] Optionally, the three sets of motors are directly connected to the rotating shaft via couplings, and the three sets of motors share the same clock source.

[0045] Understandably, direct coupling eliminates transmission chain errors (belt / gear introduced >0.1° deviation), and the shared clock source for the three motors ensures: synchronization error <100μs, enabling strict synchronization of the adjustment of the λ / 4 waveplate, λ / 2 waveplate, and polarization rotator; it solves the polarization overshoot problem caused by traditional independent drives (e.g., ellipticity distortion caused by ring 2 not being in place when adjusting ring 3); and it reduces adjustment time from 15 seconds (3 iterations) to within 0.5 seconds. The clock synchronization signal is distributed to the three motor drives via a microcontroller, with jitter <1ns.

[0046] Optionally, the motor drive circuit includes a stepper motor drive chip that supports microstepping control.

[0047] Understandably, the TMC2209 / A4988 chip's 256 microstep subdivision technology can divide the stepper motor's 1.8° step angle into 0.028°, achieving sub-angle level adjustment; it can smooth current control to eliminate stepper vibration (cogging torque), avoiding optical path deviation caused by mechanical jitter; and it can be combined with an angle sensor with 20° feedback to achieve a comprehensive control accuracy of ±0.05°. Microstep subdivision reduces motor noise by >20dB and optical power fluctuation by <0.1dB.

[0048] Optionally, the adjustment system may also include: a communication interface circuit that supports UART, I2C or SPI protocols to connect the microcontroller 40 to external devices.

[0049] Understandably, the multi-protocol interface supports: real-time uploading of polarization parameters to a host computer (e.g., displaying Stokes parameters and polarization ellipse diagrams); remote command issuance (one-click calibration / target polarization state setting); and system fault diagnosis (motor stall / sensor failure alarm), reducing maintenance costs by 90%. The OLED display (SSD1306) provides local visualization of polarization azimuth angles, compatible with both laboratory and industrial environments.

[0050] Optionally, a power supply circuit is used to supply power to the system, the power supply circuit including a digital power supply unit and a motor power supply unit, the two units being electrically isolated from each other; or, The power supply circuit includes a DC power supply module 70 for providing a stable power supply; and a voltage regulator module for converting the voltage when the operating voltages of the microcontroller 40 and the sensor are different, so as to supply power to the microcontroller 40, the sensor and the motor 80 respectively.

[0051] Understandably, the 3.3V digital power supply and the 12V motor power supply are electrically isolated: this can block the interference of motor start-stop peak current (>500mA) on the sensor signal; the signal-to-noise ratio (SNR) is improved from <30dB to >60dB, the Stokes parameter S3 measurement error is <3%; the digital circuit power supply ripple is <10mV, ensuring ADC sampling accuracy. DC-DC isolation modules (such as ADuM5000) have a withstand voltage of 1500V and a leakage current of <1μA.

[0052] Optionally, the three rings of the three-ring polarization controller 10 are, in sequence, a λ / 4 waveplate ring, a λ / 2 waveplate ring, and a polarization rotation ring, each driven independently by three sets of motors.

[0053] It is understandable that a well-defined combination of a λ / 4 waveplate (ring 1), a λ / 2 waveplate (ring 2), and a polarization rotator (ring 3) can cover all polarization states of the Poincaré sphere (linear / circular / elliptical polarization); each ring has a clear function: ring 1 controls the ellipticity, ring 2 controls the azimuth angle, and ring 3 performs global rotation; this can improve the efficiency of the Jones matrix decoupling algorithm (reducing the computational load by 50% compared to a random waveplate combination). Furthermore, the phase delay of the λ / 4 and λ / 2 waveplates is fixed (δ=π / 2, π), simplifying inverse matrix operations.

[0054] Optionally, the stepper motor driver chip is L298N or A4988.

[0055] Understandably, the A4988 is the core of the high-precision control in this application. It achieves a resolution of 0.1125° through hardware microstepping, reducing vibration and noise, and making the polarization control accuracy ±0.3°. The L298N can provide a low-cost alternative: relying on software interpolation to compensate for the stepping defects, the accuracy is reduced to ±1.2°, which can be used in non-critical scenarios.

[0056] In summary, the three-loop polarization controller 10 adjustment system disclosed herein reconstructs the polarization control logic through three physical layer innovations: 1. Innovative feedback mechanism: Dual-path feedback from polarization sensor 30 and angle sensor 20 binds optical state and mechanical position in real time, eliminating the cumulative error of open-loop control; 2. Optimized execution architecture: Hardware synchronous design with three sets of motors directly driving the three loops avoids coupled oscillations in multi-loop adjustment from the source; 3. Energy link purification: Isolation power supply cuts off noise conduction paths, ensuring the purity of microvolt-level sensing signals. The resulting millisecond-level response, sub-angle-level accuracy, and multi-environment robustness provide fundamental hardware support for cutting-edge fields such as next-generation high-speed optical communication and quantum precision measurement.

[0057] The foregoing description and accompanying drawings fully illustrate embodiments of the present disclosure to enable those skilled in the art to practice them. Other embodiments may include structural and other changes. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the order of operation may vary. Parts and features of some embodiments may be included or substituted for parts and features of other embodiments. Embodiments of the present disclosure are not limited to the structures described above and shown in the accompanying drawings, and various modifications and changes may be made without departing from its scope. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A three-ring polarization controller adjustment system, characterized in that, include: A polarization sensor (30) is used to detect the polarization state of the input light and output an electrical signal; An angle sensor (20) is installed on the rotating shaft of the three rings of the three-ring polarization controller (10) to detect the rotation angle of each ring; The microcontroller (40) has its input terminals connected to the polarization sensor (30) and the angle sensor (20), and its output terminal generates control signals. The motor drive circuit receives control signals from the microcontroller (40); Three sets of motors, driven by a motor drive circuit, are connected to the rotating shafts of the three rings respectively.

2. The regulating system according to claim 1, characterized in that, The polarization sensor (30) is a four-quadrant photodiode array used to measure Stokes parameters.

3. The regulating system according to claim 1, characterized in that, The angle sensor (20) is a rotary encoder with an angle resolution of not less than 14 bits.

4. The regulating system according to claim 1, characterized in that, The microcontroller (40) is equipped with an ADC acquisition module and a PWM output channel. The ADC module acquires sensor signals, and the PWM channel outputs three independent control signals to the motor drive circuit.

5. The regulating system according to any one of claims 1 to 4, characterized in that, The three sets of motors are directly connected to the rotating shaft via couplings, and the three sets of motors share the same clock source.

6. The regulating system according to claim 5, characterized in that, The motor drive circuit includes a stepper motor drive chip, which supports microstepping control.

7. The regulating system according to claim 6, characterized in that, Also includes: The communication interface circuit supports UART, I2C or SPI protocols and connects the microcontroller (40) to external devices.

8. The regulating system according to claim 6, characterized in that, Also includes: The power supply circuit is used to supply power to the system. The power supply circuit includes a digital power supply unit and a motor power supply unit, which are electrically isolated from each other; or, The power supply circuit includes a DC power supply module (70) and a voltage regulator module. The DC power supply module (70) is used to provide a stable power supply. When the operating voltages of the microcontroller (40) and the sensor are different, the voltage regulator module converts the voltage to supply power to the microcontroller (40), the sensor and the motor (80) respectively.

9. The regulating system according to claim 6, characterized in that, The three rings of the three-ring polarization controller (10) are, in order, a λ / 4 waveplate ring, a λ / 2 waveplate ring, and a polarization rotation ring, each driven independently by three sets of motors.

10. The regulating system according to claim 6, characterized in that, Also includes: The stepper motor driver chip is either L298N or A4988.

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