Power calibration device based on laser stable regulation and control, quantum sensor and method

Abstract

The application provides a power calibration device based on laser stable regulation and control, a quantum sensor and a method, wherein the calibration device comprises a laser chip, a driving circuit, a TEC module, a first photodetector, a first PID control module, a second PID control module, an optical power meter and a calibration module; the first PID control module regulates the operating temperature of the laser chip to a temperature within the tolerance noise, locks the temperature PID parameter and maintains the target temperature; the second PID control module adjusts the PID parameter suitable for all target laser electrical signals to maintain the subsequent multiple required target laser electrical signals respectively; and the calibration module is used for establishing the corresponding relationship between the multiple required target laser electrical signals and the corresponding optical power values. Parameter adjustment is not required for each switching, and the switching efficiency is improved. When applied to the quantum sensor, the stable low-noise light output power can improve the fluorescence excitation efficiency, can adapt to different switching requirements and significantly improve the overall efficiency.

Description

Technical Field

[0001] This invention relates to the field of quantum sensing, and in particular to a power calibration device, quantum sensor and method based on laser-stabilized control. Background Technology

[0002] Solid-state spin centers are quantum systems with relatively long spin coherence times. Among them, diamond nitrogen-vacancy (NV) centers have attracted widespread attention because they can achieve high-sensitivity magnetic field detection at room temperature. In quantum sensing applications based on NV centers, lasers are typically used to excite the centers to generate fluorescence, and then a detector is used to collect and analyze the fluorescence signal, thereby enabling precise measurement of physical quantities such as magnetic fields, temperature, and pressure.

[0003] As an excitation source, the characteristics of laser directly affect the intensity and stability of fluorescence signals, thus impacting the performance of the entire measurement system. To suppress laser power fluctuations, existing technologies typically employ active feedback control, using spectral sampling combined with a photodetector to monitor the actual output power. The monitored value is compared to a set value, and the drive current is adjusted via feedback to achieve stable power output. The monitored laser electrical signal is directly proportional to the output power; using the laser electrical signal as the target for regulation allows for corresponding power control. However, in practical applications, obtaining the true power value requires calibration of both the power and the electrical signal before use. Existing technologies only regulate a single laser power; each power switch necessitates parameter readjustment. For calibration scenarios involving rapid and frequent laser power switching, this results in low switching efficiency and insufficient reliability. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a power calibration device, quantum sensor and method based on laser stabilization control, which solves the problem that the laser power control in the prior art is only for a single power point. In calibration scenarios where the laser power needs to be switched quickly and frequently, the PID parameters need to be readjusted for each switch, resulting in low switching efficiency and insufficient reliability.

[0005] To achieve the above and other related objectives, a first aspect of the present invention provides a power calibration device based on laser stabilization control, comprising: Laser chip, used to emit laser light; The driving circuit is used to provide driving current to the laser chip and adjust the driving current according to the power control signal. The TEC module, thermally coupled to the laser chip, is used to detect the operating temperature of the laser chip and output a feedback temperature signal, as well as to adjust the heating or cooling of the laser chip according to the temperature control signal. The first photodetector is used to detect the laser output power and output a laser electrical signal corresponding to the output power. The first PID control module is used to acquire the real-time operating temperature based on the feedback temperature signal, and execute a PID algorithm according to the deviation between the real-time operating temperature and the target temperature. It outputs a temperature control signal to the TEC module until the real-time operating temperature is stably maintained within the allowable fluctuation range of the target temperature. Then, it locks the PID parameter of this temperature and continues to control the target temperature using this parameter, and outputs a start signal to the second PID control module. The target temperature is selected from the temperature range corresponding to the tolerance noise range. This tolerance noise range is obtained by selecting the tolerance noise spectral density based on the noise spectral density of the laser chip at different operating temperatures tested under a preset output power. The second PID control module, upon activation, executes a PID algorithm on multiple target laser signals based on their deviations from the actual laser signal output by the first photodetector. It then outputs a power control signal to the drive circuit until each actual laser signal stably remains within the allowable fluctuation range of its corresponding target value under the same PID parameters. This power PID parameter is then locked, and the module continues to control the multiple target laser signals individually using this parameter. The target laser signals are all selected from the laser chip's output power range and the corresponding laser signal range detected by the photodetector. An optical power meter is used to receive emitted laser light and output optical power values. The calibration module is used to receive optical power values ​​and establish the correspondence between multiple desired target laser electrical signals and their corresponding optical power values.

[0006] Furthermore, it also includes a noise testing module, which is used to receive the laser electrical signal detected by the first photodetector, and under the stable control of the set output power by the second PID control module, test the noise spectral density at different temperatures controlled by the first PID control module, and select the temperature range corresponding to the tolerance noise range.

[0007] Furthermore, the tolerance noise interval is selected as follows: the noise spectral density values ​​are arranged in order of magnitude of the corresponding operating temperature, and all non-adjacent and non-overlapping candidate continuous intervals are selected. Each candidate continuous interval must meet the following requirements: the number of data points is not less than the preset number, and the fluctuation of the maximum noise spectral density value relative to the minimum noise spectral density value does not exceed the preset first threshold. Then, the interval with the lowest mean among all candidate continuous intervals is selected as the tolerance noise interval.

[0008] Furthermore, the second PID control module is also used to, when controlling the desired target laser signal with the locked power PID parameter, if the actual laser signal cannot be stably maintained within the allowable fluctuation range of the corresponding target value, select the current target laser signal and several other target laser signals, readjust the PID parameter until each actual laser signal is stably maintained within the allowable fluctuation range of the corresponding target value under the same PID parameter, lock this power PID parameter, and continue to control the desired target laser signal with this parameter.

[0009] Furthermore, the second PID control module is also used to output an abnormal signal to the first PID control module when the same PID parameter that makes each actual laser electrical signal stably maintain within the allowable fluctuation range of the corresponding target value cannot be found within a preset time. The first PID control module is also used to reset a target temperature that falls within the temperature range according to the abnormal signal and perform temperature control. After the temperature is controlled to the target temperature, it outputs a start signal to the second PID control module to control multiple target laser electrical signals until both PID control modules lock to the PID parameter.

[0010] To achieve the above and other related objectives, a second aspect of the present invention provides a quantum sensor based on a solid-state spin color center, comprising: The probe includes a solid-state spin color center; The power calibration device based on laser stabilization control as described in any one of the first aspects; a probe or an optical power meter is selectively disposed in the output optical path of the laser chip. When a probe is disposed, the output laser irradiates the probe to excite the solid spin center to generate fluorescence; the second PID control module is also used to receive the target output power to be regulated and the corresponding relationship output by the calibration module, and convert the target output power to be regulated into the target laser electrical signal according to the corresponding relationship. The microwave module is used to radiate microwaves to the probe; A detection device is used to collect and detect the fluorescence and output a fluorescence electrical signal.

[0011] To achieve the above and other related objectives, a third aspect of the present invention provides a power calibration method based on laser stabilization modulation, comprising: S1, the operating temperature of the laser chip is controlled by a PID closed-loop control algorithm until it is stably maintained within the allowable fluctuation range of the target temperature. The temperature PID parameter is locked, and the target temperature is controlled by this parameter. The target temperature is selected from the temperature range corresponding to the tolerance noise range. The tolerance noise range is obtained by selecting the tolerance noise spectral density based on the noise spectral density of the laser chip at different operating temperatures tested under a preset output power. S2, the output power of the laser chip is photoelectrically detected to obtain the laser electrical signal. The output power of multiple target laser electrical signals is controlled in a closed loop using the same PID parameter until each detected laser electrical signal can be stably maintained within the allowable fluctuation range of the corresponding target value. This power PID parameter is locked, and multiple desired target laser electrical signals are further controlled separately using this parameter. The target laser electrical signals are all selected from the laser electrical signal range corresponding to the laser chip's output power range after photoelectric detection. S3, when the laser electrical signal of each desired target is adjusted to a stable state, measures the optical power value of the laser emitted by the laser chip and establishes the correspondence between multiple desired target laser electrical signals and their corresponding optical power values.

[0012] Furthermore, step S2 also includes: when regulating the desired target laser signal with the locked power PID parameter, if the actual laser signal cannot be stably maintained within the allowable fluctuation range of the corresponding target value, the current target laser signal and several other target laser signals are selected, and the PID parameter is readjusted until each actual laser signal is stably maintained within the allowable fluctuation range of the corresponding target value under the same PID parameter. The power PID parameter is then locked, and the regulation of the desired target laser signal is continued using this parameter.

[0013] Furthermore, step S2 also includes: if it is not possible to find the same PID parameter that allows the detected laser electrical signal to be modulated to the selected multiple target laser electrical signals within a preset time, then a target temperature that falls within the temperature range is reset, step S1 is executed, and step S2 is executed again after the temperature is modulated to the target temperature, until the temperature PID parameter and the power PID parameter are locked.

[0014] To achieve the above and other related objectives, a fourth aspect of the present invention provides a quantum measurement method for solid-state spin centers, comprising: Using the power calibration method based on laser stabilization control as described in any of the third aspects, the correspondence between the emitted optical power of the laser chip and the laser electrical signal is calibrated. The laser emitted from the laser chip is irradiated onto a solid-state spin center to excite it to produce fluorescence. The target laser electrical signal corresponding to the required output power is set according to the calibrated correspondence, and the locked temperature PID parameter and power PID parameter are continuously controlled. Radiating microwaves toward the solid-state spin color center; The fluorescence generated by solid-state spin centers is detected to form a fluorescent electrical signal.

[0015] As described above, the power calibration device, quantum sensor, and method based on laser stabilization control of the present invention have the following beneficial effects: A first PID control module is set up to regulate the operating temperature of the laser chip to within the noise tolerance range, locking the temperature PID parameter to stabilize the target temperature; then, a second PID control module regulates the PID parameter to adapt to all target laser electrical signals, stabilizing the subsequent required target laser electrical signals, and performing calibration under each stabilized target laser electrical signal. This overcomes the limitations of traditional single-power-point PID parameter adaptation, eliminating the need to configure parameters separately for each power point, and achieving stable adaptation of PID parameters over a wide power range. On the one hand, accurate calibration of the corresponding relationship is achieved through stabilization; on the other hand, the same PID parameter can achieve efficient and reliable switching between multiple power levels by stabilizing the entire output power range. When applied to quantum sensors, it is suitable for both power calibration and the excitation of solid-state spin centers to achieve high-precision measurement; the seamless power switching characteristic can adapt to the switching requirements of different application scenarios, significantly improving overall efficiency. Attached Figure Description

[0016] Figure 1 The diagram shows the structure of the power calibration device. Figure 2 The diagram shows the noise spectral density at different temperatures under a set output power. Figure 3 The diagram shows the noise spectral density at different output powers at the target temperature. Figure 4 The diagram shows a dynamic representation of the stabilization of the target temperature and the switching and stabilization of the target laser electrical signal. Figure 5 The diagram shows the calibration relationship. Figure 6 The diagram shows an example structure of a quantum sensor. Figure 7 The graph shows a comparison of ODMR curves for laser power in stable and unstable states. Figure 8 The diagram shows a flowchart of the power calibration method.

[0017] Component labeling: 1—Laser chip; 2—Driver circuit; 3—TEC module; 4—First photodetector; 5—First PID control module; 6—Second PID control module; 7—Optical power meter; 8—Calibration module; 9—Noise test module; 10—Beam splitter; 100—Power calibration device; 200—Probe; 300—Microwave module; 301—Microwave source; 302—Microwave antenna; 400—Detection device; 401—Filter; 402—Second photodetector; 500—Data processing module; 600—Magnet. Detailed Implementation

[0018] 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.

[0019] 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 illustrations 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.

[0020] Example 1: As Figure 1 As shown, this embodiment provides a power calibration device based on laser stabilization and control, comprising: Laser chip 1, used for emitting laser; The driving circuit 2 is used to provide driving current to the laser chip 1 and adjust the driving current according to the power control signal; TEC module 3, thermally coupled to laser chip 1, is used to detect and output the operating temperature of laser chip 1, and to adjust the heating or cooling of laser chip 1 according to the temperature control signal. The first photodetector 4 is used to detect the laser output power and output a laser electrical signal corresponding to the output power; The first PID control module 5 is used to acquire the real-time operating temperature based on the feedback temperature signal, and execute the PID algorithm according to the deviation between the real-time operating temperature and the target temperature, outputting a temperature control signal to the TEC module 3 until the operating temperature of the laser chip 1 is stably maintained within the allowable fluctuation range of the target temperature, locking this temperature PID parameter, and continuing to control the target temperature with this parameter, outputting a start signal to the second PID control module; the target temperature is selected from the temperature range corresponding to the tolerance noise range, which is obtained by selecting the tolerance noise spectral density based on the noise spectral density of the laser chip at different operating temperatures tested under a preset output power; The second PID control module 6, upon activation, executes a PID algorithm based on the deviation between the set multiple target laser signals and the actual laser signal output by the first photodetector 4, outputting a power control signal to the drive circuit. By adjusting the PID parameters, the actual laser signals are stably maintained within the allowable fluctuation range of their respective target values ​​under the same PID parameters. This power PID parameter is then locked, and the control of multiple desired target laser signals continues using this parameter. The target laser signals are all selected from the laser chip's output power range and the corresponding laser signal range detected by the photodetector. Optical power meter 7 is used to receive the emitted laser and output the optical power value; The calibration module 8 is used to receive optical power values ​​and establish the correspondence between multiple desired target laser electrical signals and their corresponding optical power values.

[0021] In this embodiment, the first PID control module 5 regulates the operating temperature of the laser chip 1 to within the noise tolerance range, locking the temperature PID parameter. This reduces the cross-perturbation between temperature and power at its source, lowers the sensitivity of the output power to temperature disturbances, and improves the long-term stability of the output power, providing a stable boundary free from thermal disturbance for subsequent power control. Then, at the target temperature, the second PID control module 6 iteratively optimizes the power PID parameter, achieving full adaptation and stability of the same PID parameter across multiple laser electrical signal sampling points within a wide power range. This overcomes the limitations of traditional single-power-point PID parameter adaptation, eliminating the need for separate parameter configuration for each power point and ensuring stable adaptation of the PID parameter across a wide power range, thus guaranteeing consistent stability across the entire power range. Therefore, during calibration, on the one hand, accurate calibration of the corresponding relationship is achieved through stabilization; on the other hand, the stabilization of the same PID parameter across the entire output power range enables efficient and reliable switching between multiple power levels.

[0022] like Figure 4 As shown in (a), under the target temperature stability shown in (b), no parameter adjustment is required for each power switch. The locked parameters can be automatically and quickly stabilized to the switching power, which significantly reduces the time spent on re-adjusting parameters during the switching process, improves the switching efficiency, avoids the risk of parameter drift caused by repeated adjustments, and greatly improves the reliability of power switching.

[0023] For example Figure 6As shown, a noise testing module 9 is also provided to receive the laser electrical signal detected by the first photodetector 4. Under a set output power, the noise spectral density is tested at different temperatures, and the temperature range corresponding to the tolerance noise range is selected. The test frequency band is determined according to application requirements. When selecting the test operating temperature, the operating temperature range within the low noise range can be found according to the product specifications provided by the laser chip manufacturer. Testing the noise spectral density within this range can improve testing efficiency.

[0024] The output power and different temperature conditions set for the test are all stably controlled by the second PID control module 6 and the first PID control module 5, respectively. Specifically, the noise test module 9 also transmits a test temperature signal to the first PID control module 5 and a test laser electrical signal to the second PID control module 6. This test electrical signal corresponds to the corresponding output power. The first PID control module 5 is also used to receive the test temperature signal and execute a PID algorithm based on the deviation between the temperature detected by the TEC module 3 and the test temperature, outputting a temperature control signal to the TEC module 3 until the operating temperature of the laser chip 1 is stably maintained within the allowable fluctuation range of the test temperature. The second PID control module 6 is also used to receive the test laser electrical signal and execute a PID algorithm based on the deviation between the actual laser electrical signal output by the first photodetector 4 and the test laser electrical signal, outputting a power control signal to the drive circuit 2 until the actual laser electrical signal is stably maintained within the allowable fluctuation range of the corresponding target value. The noise testing module 9 also tests the noise spectral density when the two modules stabilize and adjust the test power and test temperature respectively. After completing the noise spectral density at all test temperatures, it determines the temperature range corresponding to the tolerance noise range and the target temperature, and transmits it to the first PID control module 5.

[0025] The noise testing module 9 may include, for example, a lock-in amplifier and a noise analysis module. The lock-in amplifier is used to receive laser electrical signals and test the noise spectral density. The noise analysis module analyzes the measured noise spectral density and filters out the tolerance noise range and its corresponding temperature range.

[0026] The preset output power can be selected from any set laser electrical signal, preferably a commonly used power value. A rough calibration is performed to obtain the corresponding laser electrical signal value, which is then used as the target laser electrical signal for control. The noise spectral density can be expressed in amplitude or power form. The tolerance noise interval is determined based on the measured noise. The specific setting method is as follows: arrange the noise spectral density values ​​in order of their corresponding operating temperature, and filter out all non-adjacent, non-overlapping candidate continuous intervals. Each candidate continuous interval must meet the following requirements: the number of data points is not less than a preset number, and the fluctuation of the maximum noise spectral density value relative to the minimum noise spectral density value does not exceed a preset first threshold. Then, select the interval with the lowest mean among all candidate continuous intervals as the tolerance noise interval. The preset first threshold and preset number are empirical values ​​determined through multiple statistical experiments. The preferred preset first threshold is ±10% to ±40%, and the preset number is 3 to 5.

[0027] For example Figure 2 The example shows a laser chip tested at 80mW power in the 1k-110k frequency band, using a first threshold of ±40% and a preset quantity of 3. Following the order of the corresponding temperatures from smallest to largest, starting with the first noise data point, data from the right are sequentially added to the current interval. If the interval after addition meets the requirement that the fluctuation of the maximum noise spectral density value relative to the minimum noise spectral density value does not exceed the preset first threshold, then the expansion continues to the right until the first data point appears that does not meet the first threshold requirement. At this point, the expansion of that interval stops. If the number of data points in the interval before adding this data point is not less than 3, then that interval is used as a candidate interval, and the above interval expansion operation is repeated with that data point as the starting data point until all data points are traversed. Finally, the candidate interval that meets the requirements is 18.5-23℃, which is also the choice with the lowest mean. Therefore, the temperature range is 18.5-23℃. If there are multiple consecutive candidate intervals that meet the threshold requirements, their mean values ​​need to be calculated separately, and the interval with the lowest mean value is selected. When selecting the target temperature, the temperature corresponding to the middle position of the temperature range with the lowest noise value is preferred. Figure 2 The temperature was 21.5℃.

[0028] By setting the noise tolerance in this way, the operation of the laser chip at the corresponding temperature can be limited to a range with low noise and good stability, which can ensure the stable operation of the laser chip. It can effectively suppress classical temperature-related noises such as gain fluctuations, thermally induced mechanical vibrations, carrier recombination, and thermally induced modes. Among the remaining quantum noises, shot noise increases with the square root of power, but its absolute amplitude does not change significantly within the normal power range. The power fluctuation amplitude of other quantum noises such as vacuum fluctuation noise is basically constant, and the relative proportion of all noises decreases with increasing power, thereby ensuring stable control at different output powers. Figure 3The noise spectral density was measured at different output powers after selecting 21.5℃ as the target temperature. The results showed that the noise level did not differ much, and the noise tended to decrease as the output power increased.

[0029] In this embodiment, the allowable fluctuation range of the target temperature and the allowable fluctuation range of the target laser signal can be determined based on empirical values ​​from experiments, and are generally close to zero. In this embodiment, for example... Figure 4 As shown, after using 23.5℃ as the target temperature, the allowable fluctuation range of the target temperature is ±0.0025℃, and the allowable fluctuation range of the target laser electrical signal is ±1mV. Here, the electrical signal is a voltage signal. Figure 4 (a) shows the temperature change of the target temperature controlled by the locked temperature PID parameter, and (b) shows the voltage change of the target laser signal controlled by the locked power PID parameter. In (b), when switching the voltage V1-V5, both the temperature and voltage signals will fluctuate, but under the control of the locked temperature PID parameter and the power PID parameter, they will quickly return to a stable state without the need for parameter readjustment, thus achieving efficient and seamless switching.

[0030] The number of target laser electrical signals set in the second PID control module 6 is determined based on application requirements, the required stability, and other factors. Generally, it covers the two extremes and the middle value of the power range. For power points that are frequently switched, the number of nearby set points can be increased. The values ​​can be fixed or random. In this embodiment, for a voltage signal range of 300mV-2000mV, 20-30 target points are provided as an example.

[0031] This embodiment selects multiple electrical signal values ​​within the laser electrical signal range as feedback targets for the second PID control module 6 to regulate the output power. By adjusting the PID parameters, multiple electrical signals remain stable under the same PID. These PID parameters are the parameters that satisfy the stable regulation of the entire output power range. By locking these parameters, subsequent regulation can be continuously performed. When switching the output power, i.e., when switching the regulation feedback target, the stable output of the target power can still be maintained without further PID parameter adjustment. This achieves seamless switching with zero additional parameter adjustment time, greatly improving efficiency.

[0032] In this embodiment, the TEC module 3 integrates a thermoelectric cooler 31 (i.e., TEC) and a temperature sensor 32. The thermoelectric cooler 31 is used to adjust the heating or cooling of the laser chip 1 according to the received temperature control signal. The temperature sensor 32 is used to detect the operating temperature of the laser chip 1 and output a feedback temperature signal. For example, a thermistor can be used to output a resistance signal. This signal is read by the first PID control module 5, converted into a real-time operating temperature, and then the deviation from the target temperature is calculated. The PID algorithm is executed, and a temperature control signal is output to the thermoelectric cooler 31. Here, the temperature control signal is a bidirectional adjustable current signal. The thermoelectric cooler 31 cools or heats the laser chip 1 according to the magnitude and direction of the current signal through the Peltier effect. The thermal coupling method between the TEC module 3 and the laser chip 1 is a conventional technology, which can be designed according to existing technology or a finished integrated structure can be purchased. The conventional design is that the laser chip 1 and the temperature control surface of the thermoelectric cooler 31 are directly thermally coupled, or the TEC module 3 also includes, for example, Figure 6 The heat sink 33 shown is used to thermally couple the temperature control surface of the laser chip 1 and the thermoelectric cooler 31. The temperature sensor 32 is integrated on the same temperature control surface or the heat sink 33 and is located near the laser chip 1 to detect the operating temperature of the laser chip 1.

[0033] The first photodetector 4 can be built-in, such as Figure 1 As shown, it is positioned in the backward optical path of laser chip 1 and integrated into the laser chip 1 package. It is used to receive the backward emitted light from laser chip 1 and output a laser electrical signal corresponding to the emitted light power; it can also be as follows... Figure 6 As shown, it is set separately from laser chip 1 and located in the laser emission path to detect the emitted light and convert it into an electrical signal. The electrical signal output by the first photodetector 4 is a current signal, which can be converted into a voltage signal by a transimpedance amplifier in the second PID control module 6 as needed before acquisition.

[0034] The second PID control module 6 is also used to, when controlling the desired target laser signal with locked power PID parameters, if the actual laser signal cannot be stably maintained within the allowable fluctuation range of the corresponding target value, select the current target laser signal and several other target laser signals, readjust the PID parameters until, under the same PID parameters, each actual laser signal is stably maintained within the allowable fluctuation range of the corresponding target value, lock the power PID parameters, and continue to control the desired target laser signal with these parameters. This provides a further solution for power instability during the stabilization period, ensuring the operational stability and output consistency of the laser under complex operating conditions, and significantly improving its adaptability and robustness to various disturbances.

[0035] The second PID control module 6 is also used to output an abnormal signal to the first PID control module 5 when the same PID parameter that keeps each actual laser electrical signal stably within the allowable fluctuation range of the corresponding target value cannot be found within a preset time. The first PID control module 5 is also used to reset a target temperature that falls within the temperature range based on the abnormal signal and perform temperature control. After the temperature is adjusted to the target temperature, it outputs a start signal to the second PID control module 6 to control multiple target laser electrical signals until both PID control modules lock onto the PID parameter. This supplementary information on abnormal situations further ensures stable adaptation between temperature and power, and guarantees the reliable realization of seamless power switching.

[0036] This anomaly occurs for two main reasons. First, the initial target temperature doesn't match the optimal performance state of the laser chip, preventing it from maintaining stability at different power levels. This is less common because the initial target temperature is typically chosen for low noise; as discussed earlier, the temperature selection already suppresses some noise, allowing for relatively smooth power adjustment to a stable state. Second, the drive circuit's output conditions drift over time (e.g., output current fluctuations, increased ripple, or changes in response rate), causing the laser chip's photoelectric performance to deviate from its initial state (e.g., decreased power efficiency, shift in spectral center wavelength). The originally set target temperature can no longer maintain the chip in its optimal operating state, and the chip's suitable operating temperature (the temperature point with the lowest noise, highest efficiency, or most stable wavelength) shifts. This is more frequent. In this embodiment, by changing the temperature within the aforementioned temperature range and adjusting multiple power levels within the power range until a temperature is found that allows both PID modules to lock onto the PID parameters, the laser chip regains its optimal performance state, and the output power stabilizes again, thus ensuring efficient power switching.

[0037] The preset time is at least the time required to adjust the laser electrical signals of all targets one by one.

[0038] The temperature search method is reselected, using the original target temperature as a reference point. The temperature is incremented in one direction with a preset step size until the temperature boundary value in that direction is reached. If the boundary value is not found, the temperature is incremented in another direction with a preset step size until the temperature boundary value in that direction is reached. Since the temperature deviation is generally near the original temperature value, it is preferable to first increment the temperature in the neighborhood on both sides of the reference point with a preset step size, and then increment the temperature in each of the two directions with preset step sizes until the temperature boundary value in the corresponding direction is reached. The temperature search stops once a target temperature that meets the aforementioned requirements is found. Each neighborhood is generally selected to be ±1℃ to ±2℃, with a preset step size of 0.05℃ to 0.1℃.

[0039] Multiple target laser electrical signals are used for calibration; the number depends on the calibration accuracy. Calibration module 8 receives the optical power value output by optical power meter 7. Based on multiple optical power values ​​received under steady-state conditions for the same target laser electrical signal, it determines the power calibration value. This value can be the average of the multiple optical power values ​​or the nearest integer value. After determining all power calibration values, a system is established as follows: Figure 5 The diagram shows the correspondence between multiple target laser electrical signals and their corresponding calibrated power values.

[0040] During the calibration process, both PID control modules remain in a stable control state. The second PID control module also includes transmitting stable or unstable signals to the calibration module 8 based on whether locked power PID parameter control is used. The calibration module 8 determines the power calibration value based on the stable signal and pauses the calibration value determination process based on the unstable signal. This adaptively matches the calibration response with laser stabilization control, improving the signal-to-noise ratio and accuracy of the calibration.

[0041] Example 2: Figure 6 As shown, this embodiment provides a quantum sensor based on a solid-state spin color center, comprising: Probe 200, including solid-state spin color centers; As described in Embodiment 1, the power calibration device 100 based on laser stabilization control is configured such that either a probe 200 or an optical power meter 7 is selectively disposed in the output optical path of the laser chip. When the probe 200 is disposed, the output laser irradiates the probe 200 to excite the solid-state spin center to generate fluorescence. The second PID control module 6 is also used to receive the target output power to be controlled and the corresponding relationship output by the calibration module 8, and convert the target output power into the required target laser electrical signal according to the corresponding relationship. Microwave module 300 is used to radiate microwaves to probe 200; The detection device 400 is used to collect and detect the fluorescence and output a fluorescence electrical signal.

[0042] In this embodiment, the power calibration device from Embodiment 1 is applied to quantum sensing technology. While applicable to power calibration, it is also suitable for exciting solid-state spin centers to achieve high-precision measurement. Stable, low-noise output power improves fluorescence excitation efficiency, effectively enhancing the fluorescence signal-to-noise ratio and spin state readout fidelity, ultimately improving measurement sensitivity in quantum magnetic and temperature measurement scenarios. Seamless power switching adapts to the switching requirements of different application scenarios, significantly improving overall efficiency. Adaptive power fluctuation control and target temperature adaptation matching under changing driving conditions ensure the continuity of the measurement process in complex environments. Stable operation can be maintained without manual calibration, greatly improving the system's automation and environmental adaptability.

[0043] In this embodiment, the solid-state spin color center used is one of the following: diamond nitrogen-vacancy (NV) color center, silicon carbide silicon-carbon double vacancy color center, silicon carbide silicon vacancy color center, and hexagonal boron nitride boron vacancy color center, all of which are based on the photoluminescence effect of the color center. Figure 6 For example, diamond containing NV centers is used. The diamond has a nano / micron-sized granular structure or a bulk structure of tens to hundreds of microns. The laser wavelength may vary for different solid-state spin centers. For example, a 532nm green laser is generally used for diamond nitrogen-vacancy centers and hexagonal boron nitride boron-vacancy centers; a 900-940nm laser is used for silicon carbide double-vacancy centers; and other centers can be excited using corresponding lasers.

[0044] For example Figure 6 As shown, the microwave module 300 includes a microwave source 301 and a microwave antenna 302. In this embodiment, the microwave source 301 is not only used to generate microwaves and modulate microwaves, but also has microwave amplification, isolation and protection functions to meet usage requirements. The microwave antenna 302 can be a microstrip antenna, such as a coplanar waveguide antenna, and is placed close to the probe 200, for example, on one side of the probe 200, to radiate microwaves to it.

[0045] The fluorescence detection device 400 includes a filter 401 and a second photodetector 402, which convert the received fluorescence into an electrical signal.

[0046] In this embodiment, since a first photodetector 4, separate from the laser chip 1, is used and located in the laser's output light path, a beam splitter 10 is also provided in the calibration device to split the laser into two beams. One beam enters the first photodetector 4 and is collected and detected, while the other beam illuminates the optical power meter 7 or the probe 200. However, when using... Figure 1 When the first photodetector 4 and the laser chip 1 are integrated into a package, there is no need for a beam splitter; the emitted light can be directly irradiated onto the optical power meter 7 or the probe 200.

[0047] When probe 200 needs to be replaced, the concentration of solid spin centers differs in the new probe. To improve the excitation efficiency of the centers, probes with different concentrations require different excitation light powers. Therefore, it is necessary to switch the output power to match the concentration. This embodiment allows for seamless switching of power without additional parameter adjustments, improving overall measurement efficiency. Of course, this effect can also be achieved for other switching needs, such as studying the characteristics of output power on fluorescence excitation.

[0048] like Figure 6As shown, it also includes a data processing module 500, which is connected to the fluorescence detection device 400, receives fluorescence electrical signals, processes the fluorescence electrical signals, and calculates the magnetic field or temperature as needed.

[0049] Depending on the application requirements, the data processing module 500 may include, but is not limited to, functions such as microwave modulation, demodulation of fluorescent electrical signals, frequency tracking, magnetic field or temperature calculation.

[0050] A bias magnetic field module can also be configured to apply a bias magnetic field to the probe 200. The bias magnetic field can be used to adjust the resonance peak generated by the solid-state spin color center, or to ensure that the color center's detection of weak magnetic fields operates in the linear region, or to adjust the detection frequency band to improve the sensitivity of weak magnetic field detection. For example... Figure 6 As shown, the bias magnetic field module includes a magnet 600, which can be a permanent magnet or an electromagnet.

[0051] In the process of applying quantum sensors to measure physical quantities such as magnetic fields and temperature, both the first PID control module 5 and the second PID control module 6 are in a stable control state. As described in Embodiment 1, when the second PID control module 6 controls the target laser signal with locked power PID parameters, if the actual laser signal cannot be stably maintained within the allowable fluctuation range of the corresponding target value, adaptive control will be initiated. Furthermore, if the same PID parameter that makes each actual laser signal stably maintained within the allowable fluctuation range of the corresponding target value cannot be found within a preset time, this abnormal situation will be handled, and a suitable temperature matching the performance of the laser chip will be re-found. During the handling of these situations, the data responded by the quantum measurement must be processed to a normal state before it can be used. The data processing module 500 of this embodiment also monitors the fluctuation of the fluorescence signal. When the average fluctuation of the fluorescence signal deviates from the reference beyond a preset second threshold range, further processing of the fluorescence signal is paused until the fluctuation falls back to the second threshold range, at which point processing resumes. The reference is the average fluctuation of the fluorescence signal in the non-resonant state when the power is stable. The preset second threshold range is an empirical value, selected here as within ±10%. Therefore, by adaptively matching the quantum response with laser stabilization, the signal-to-noise ratio and accuracy of the measurement can be improved.

[0052] Figure 7 The figure shows the ODMR curves when the laser output power is tuned to a steady state and when abnormal fluctuations occur. In the non-resonant state, the output of the fluorescence signal is theoretically a straight line. In the steady state, due to minute fluctuations in the laser and other noise interference, it will exhibit minute fluctuations (such as...). Figure 7 In (a) of the diagram, when the laser power is unstable, the fluctuation will increase (e.g., Figure 7In (b) of this embodiment, based on the stability of laser power, the stability of fluorescence can be controlled, and abnormal handling during stabilization can be performed to interrupt subsequent data processing in a timely manner, reduce error interference, and maximize the accuracy of measurement.

[0053] Example 3: Figure 8 As shown, this embodiment provides a power calibration method based on laser stabilization control, including: S1, the operating temperature of the laser chip is controlled by a PID closed-loop control algorithm until it is stably maintained within the allowable fluctuation range of the target temperature. The temperature PID parameter is locked, and the target temperature is controlled by this parameter. The target temperature is selected from the temperature range corresponding to the tolerance noise range. The tolerance noise range is obtained by selecting the tolerance noise spectral density based on the noise spectral density of the laser chip at different operating temperatures tested under a preset output power. S2, the output power of the laser chip is photoelectrically detected to obtain the laser electrical signal. The output power of multiple target laser electrical signals is controlled in a closed loop using the same PID parameter until each detected laser electrical signal can be stably maintained within the allowable fluctuation range of the corresponding target value. This power PID parameter is locked, and multiple desired target laser electrical signals are further controlled separately using this parameter. The target laser electrical signals are all selected from the laser electrical signal range corresponding to the laser chip's output power range after photoelectric detection. S3, when the laser electrical signal of each desired target is adjusted to a stable state, measures the optical power value of the laser emitted by the laser chip and establishes the correspondence between multiple desired target laser electrical signals and their corresponding optical power values.

[0054] This embodiment, based on regulating the operating temperature of the laser chip to the target temperature within the noise tolerance range, further regulates multiple target laser electrical signals corresponding to the power until they stabilize under the same PID parameters. The coordinated regulation of temperature and power enables stable adaptation of the same PID parameters over a wide power range. Switching within this power range and calibrating the correspondence between the target laser electrical signals and the output power can reduce the time spent on parameter readjustment during power switching and improve switching efficiency.

[0055] When determining the temperature range, the noise spectral density of the laser chip at different operating temperatures is tested under a preset power. The noise spectral density can be expressed in amplitude or power form, and the preset output power can be a commonly used value. The tolerance noise range is determined based on the measured noise. The specific setting method is as follows: arrange the noise spectral density values ​​in order of magnitude corresponding to the operating temperature, and filter out all non-adjacent and non-overlapping candidate continuous intervals. Each candidate continuous interval must meet the following conditions: the number of data points is not less than a preset number, and the fluctuation of the maximum noise spectral density value relative to the minimum noise spectral density value does not exceed a preset first threshold; then select the interval with the lowest mean among all candidate continuous intervals as the tolerance noise range. In this way, temperature-related noise can be suppressed to the maximum extent, ensuring stable control of subsequent output power.

[0056] The allowable fluctuation range of the target temperature and the allowable fluctuation range of the target laser electrical signal can be determined based on empirical values ​​from experiments, and are generally close to zero.

[0057] Step S2 further includes: when regulating the desired target laser signal using the locked power PID parameter, if the actual laser signal cannot be stably maintained within the allowable fluctuation range of the corresponding target value, then the current target laser signal and several other target laser signals are selected, and the PID parameter is readjusted until, under the same PID parameter, each actual laser signal is stably maintained within the allowable fluctuation range of the corresponding target value. This power PID parameter is then locked, and the regulation of the desired target laser signal continues using this parameter. Thus, adaptive regulation is performed for unstable abnormal factors, enhancing the reliability of stability maintenance.

[0058] Step S2 further includes: if it is not possible to find the same PID parameter within a preset time to modulate the detected laser signal to the same of the selected multiple target laser signals, then a target temperature falling within the temperature range is reset, step S1 is executed, and step S2 is executed again after the target temperature is reached, until the temperature PID parameter and power PID parameter are locked. Therefore, for situations where the initial target temperature is mismatched with the laser chip performance, or where the output conditions of the drive circuit drift, resulting in the laser chip not being able to maintain a stable state at different powers under the selected target temperature, a suitable operating temperature is sought again to re-match the performance of the laser chip, thereby enabling the output power to be controlled to a stable state.

[0059] For finding the temperature, it is preferable to first change the temperature in the neighborhood on both sides of the reference point with a preset step size, and then change the temperature in two directions with a preset step size until the temperature boundary value in the corresponding direction is reached.

[0060] The method of this embodiment can be implemented by the power calibration device 100 based on laser stabilization control in Embodiment 1. For specific details, please refer to the description in Embodiment 1. Of course, other devices that can realize the stabilization control method of this embodiment can also be used.

[0061] Example 4: This example provides a quantum measurement method for solid-state spin centers, including: Using the power calibration method based on laser stabilization control as described in Example 3, the correspondence between the emitted optical power of the laser chip and the laser electrical signal was calibrated. The laser emitted from the laser chip is irradiated onto a solid-state spin center to excite it to produce fluorescence. The target laser electrical signal corresponding to the required output power is set according to the calibrated correspondence, and the locked temperature PID parameter and power PID parameter are continuously controlled. Radiating microwaves toward the solid-state spin color center; The fluorescence generated by solid-state spin centers is detected to form a fluorescent electrical signal.

[0062] In this embodiment, the relationship between optical power and laser electrical signal is first calibrated using the power calibration method described in Embodiment 3. Then, under continuous control with locked PID parameters, fluorescence excitation is performed on the solid-state spin center to achieve quantum measurement. On the one hand, laser stabilization can improve fluorescence excitation efficiency and enhance the sensitivity of quantum precision measurement. On the other hand, the stabilized PID parameters are adapted to the optical power range, which can meet the power switching scenarios in quantum measurement according to the calibrated correspondence. Moreover, no time-consuming PID parameter adjustment is required during switching, which can significantly improve measurement efficiency.

[0063] It may also include applying a bias magnetic field to the solid spin color center.

[0064] The quantum measurement method in this embodiment can be implemented using the quantum sensor in Embodiment 2. For details, please refer to the description in Embodiment 2. Of course, other quantum sensors that can implement the measurement method in this embodiment can also be used.

[0065] 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 power calibration device based on laser stabilization and control, characterized in that, The power calibration device includes: Laser chip, used to emit laser light; The driving circuit is used to provide driving current to the laser chip and adjust the driving current according to the power control signal. The TEC module, thermally coupled to the laser chip, is used to detect the operating temperature of the laser chip and output a feedback temperature signal, as well as to adjust the heating or cooling of the laser chip according to the temperature control signal. The first photodetector is used to detect the laser output power and output a laser electrical signal corresponding to the output power. The first PID control module is used to acquire the real-time operating temperature based on the feedback temperature signal, and execute a PID algorithm according to the deviation between the real-time operating temperature and the target temperature. It outputs a temperature control signal to the TEC module until the real-time operating temperature is stably maintained within the allowable fluctuation range of the target temperature. Then, it locks the PID parameter of this temperature and continues to control the target temperature using this parameter, and outputs a start signal to the second PID control module. The target temperature is selected from the temperature range corresponding to the tolerance noise range. This tolerance noise range is obtained by selecting the tolerance noise spectral density based on the noise spectral density of the laser chip at different operating temperatures tested under a preset output power. The second PID control module, upon activation, executes a PID algorithm on multiple target laser signals based on their deviations from the actual laser signal output by the first photodetector. It then outputs a power control signal to the drive circuit until each actual laser signal stably remains within the allowable fluctuation range of its corresponding target value under the same PID parameters. This power PID parameter is then locked, and the module continues to control the multiple target laser signals individually using this parameter. The target laser signals are all selected from the laser chip's output power range and the corresponding laser signal range detected by the photodetector. An optical power meter is used to receive emitted laser light and output optical power values. The calibration module is used to receive optical power values ​​and establish the correspondence between multiple desired target laser electrical signals and their corresponding optical power values.

2. The power calibration device based on laser stabilization control according to claim 1, characterized in that: It also includes a noise testing module, which receives the laser electrical signal detected by the first photodetector, and tests the noise spectral density at different temperatures controlled by the first PID control module under the stable control of the set output power by the second PID control module, and selects the temperature range corresponding to the tolerance noise range.

3. The power calibration device based on laser stabilization control according to claim 1 or 2, characterized in that: The tolerance noise interval is selected as follows: the noise spectral density values ​​are arranged in order of magnitude of the corresponding operating temperature, and all non-adjacent and non-overlapping candidate continuous intervals are selected. Each candidate continuous interval must meet the following requirements: the number of data points is not less than the preset number, and the fluctuation of the maximum noise spectral density value relative to the minimum noise spectral density value does not exceed the preset first threshold. Then, the interval with the lowest mean among all candidate continuous intervals is selected as the tolerance noise interval.

4. The power calibration device based on laser stabilization control according to claim 1, characterized in that: The second PID control module is also used to, when controlling the desired target laser signal with the locked power PID parameter, if the actual laser signal cannot be stably maintained within the allowable fluctuation range of the corresponding target value, select the current target laser signal and several other target laser signals, readjust the PID parameter until each actual laser signal is stably maintained within the allowable fluctuation range of the corresponding target value under the same PID parameter, lock this power PID parameter, and continue to control the desired target laser signal with this parameter.

5. The power calibration device based on laser stabilization control according to claim 1 or 4, characterized in that: The second PID control module is also used to output an abnormal signal to the first PID control module when the same PID parameter that makes each actual laser electrical signal stably maintain within the allowable fluctuation range of the corresponding target value cannot be found within a preset time. The first PID control module is also used to reset a target temperature that falls within the temperature range according to the abnormal signal and perform temperature control. After the temperature is controlled to the target temperature, it outputs a start signal to the second PID control module to control multiple target laser electrical signals until both PID control modules lock to the PID parameter.

6. A quantum sensor based on a solid-state spin color center, characterized in that, The quantum sensor includes: The probe includes a solid-state spin color center; The power calibration device based on laser stabilization control as described in any one of claims 1 to 5; a probe or an optical power meter is selectively disposed in the output optical path of the laser chip; when a probe is disposed, the output laser irradiates the probe to excite the solid-state spin center to generate fluorescence; the second PID control module is further used to receive the target output power to be controlled and the corresponding relationship output by the calibration module, and convert the target output power to be controlled into the target laser electrical signal according to the corresponding relationship; The microwave module is used to radiate microwaves to the probe; A detection device is used to collect and detect the fluorescence and output a fluorescence electrical signal.

7. A power calibration method based on laser stabilization control, characterized in that, The calibration method includes: S1, the operating temperature of the laser chip is controlled by a PID closed-loop control algorithm until it is stably maintained within the allowable fluctuation range of the target temperature. The temperature PID parameter is locked, and the target temperature is controlled by this parameter. The target temperature is selected from the temperature range corresponding to the tolerance noise range. The tolerance noise range is obtained by selecting the tolerance noise spectral density based on the noise spectral density of the laser chip at different operating temperatures tested under a preset output power. S2, the output power of the laser chip is photoelectrically detected to obtain the laser electrical signal. The output power of multiple target laser electrical signals is controlled in a closed loop using the same PID parameter until each detected laser electrical signal can be stably maintained within the allowable fluctuation range of the corresponding target value. This power PID parameter is locked, and multiple desired target laser electrical signals are further controlled separately using this parameter. The target laser electrical signals are all selected from the laser electrical signal range corresponding to the laser chip's output power range after photoelectric detection. S3, when the laser electrical signal of each desired target is adjusted to a stable state, measures the optical power value of the laser emitted by the laser chip and establishes the correspondence between multiple desired target laser electrical signals and their corresponding optical power values.

8. The power calibration method based on laser stabilization control according to claim 7, characterized in that: Step S2 further includes: when regulating the desired target laser signal with the locked power PID parameter, if the actual laser signal cannot be stably maintained within the allowable fluctuation range of the corresponding target value, the current target laser signal and several other target laser signals are selected, and the PID parameter is readjusted until each actual laser signal is stably maintained within the allowable fluctuation range of the corresponding target value under the same PID parameter. The power PID parameter is then locked, and the regulation of the desired target laser signal is continued using this parameter.

9. The power calibration method based on laser stabilization control according to claim 7 or 8, characterized in that: Step S2 further includes: if it is not possible to find the same PID parameter that allows the detected laser signal to be modulated to the selected multiple target laser signals within a preset time, then a target temperature that falls within the temperature range is reset, step S1 is executed, and step S2 is executed again after the temperature is modulated to the target temperature, until the temperature PID parameter and power PID parameter are locked.

10. A quantum measurement method for solid-state spin centers, characterized in that, The method includes: Using the power calibration method based on laser stabilization control as described in any one of claims 7-9, the correspondence between the emitted optical power of the laser chip and the laser electrical signal is calibrated. The laser emitted from the laser chip is irradiated onto a solid-state spin center to excite it to produce fluorescence. The target laser electrical signal corresponding to the required output power is set according to the calibrated correspondence, and the locked temperature PID parameter and power PID parameter are continuously controlled. Radiating microwaves toward the solid-state spin color center; The fluorescence generated by solid-state spin centers is detected to form a fluorescent electrical signal.

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