Laser source control method and system for miniaturized atomic magnetometer

Abstract

One technical solution of this invention provides a method for controlling the laser source of a miniaturized atomic magnetometer, characterized by the following steps: a pump laser emitted from a VCSEL diode strikes a photodiode to generate a current; the voltage converted from the current output by the photodiode is used as a temperature adjustment reference for the VCSEL diode; the temperature of the VCSEL diode and the magnitude of the converted voltage are collected in real time, and the temperature of the VCSEL diode is PID-regulated using a heating system. Another technical solution of this invention provides a control system for the laser source of a miniaturized atomic magnetometer. This invention proposes a method for determining whether the wavelength is stable at a target value using the converted voltage of the photodiode, utilizing the physical phenomenon of optical pumping to control laser frequency stabilization.

Description

Technical Field

[0001] This invention relates to a miniaturized atomic magnetometer, belonging to the field of high-sensitivity magnetic sensors. Background Technology

[0002] With the development of brain science, the demand for precise brain signal detection is increasing day by day. Applications such as disease diagnosis and brain-computer interface urgently need a way to reflect brain signals in real time and accurately. With its advantages of non-invasiveness, high degree of reconstruction and restoration and high-precision source localization, magnetoencephalography (MEG) signal detection is becoming one of the important ways to develop brain science[1],[2]. At present, the main instruments for MEG signal detection are superconducting quantum interference device (SQUID)[3],[4] and optically pumped quantum magnetometer (OPM)[5],[6]. Compared with SQUID, which requires ultra-low temperature, large volume and high maintenance cost, OPM MEG measurement system has gradually become the main method in the field of MEG measurement due to its advantages of low cost, high performance and high applicability. OPM has extremely high requirements for the frequency of pump laser beam when working. Frequency control can usually be stably achieved on a desktop laser. However, there are two problems with the application of desktop lasers. On the one hand, the size is limited by the size of the laser and its collimator, which prevents the sensor size from being further reduced, thus making it impossible to increase the number of sensor arrays to provide more accurate brain signal reconstruction[7],[8]; on the other hand, the weight is difficult to control, and its sensor array will put pressure on the subject[9].

[0003] Vertical-cavity surface-emitting laser (VCSEL) diodes have advantages such as small size and low power consumption, making them an excellent choice for built-in light sources in miniaturized, highly integrated OPM sensors

[10] ,

[11] . The size of a VCSEL is usually around several hundred micrometers, and compared to other components in an OPM, it is not the main factor determining the size. Generally speaking, the wavelength of a VCSEL is difficult to output according to the set parameters and is affected by thermal equilibrium and laser aging, thus maintaining a stable value. For simplified single-path OPM designs, considering that the wavelength of a VCSEL is a function of the excitation current and the diode's operating temperature, adjusting the current and temperature are the two main means of controlling the stability of the laser wavelength.

[0004] Adjusting the current to control the laser wavelength offers higher precision because the circuit system can provide a stable current source with precise control up to 10nA. Furthermore, current control has a fast response time, enabling frequency stabilization in a short period. However, the limitations of current control are also obvious: the control range is small and it is temperature-dependent. The current through the VCSEL diode cannot change significantly with variations in ambient temperature; otherwise, mode hopping, center wavelength shift, and changes in optical power will occur.

[0005] Adjusting the laser wavelength for temperature control offers a wider adjustment range. Typically, a temperature sensor is placed near the VCSEL diode, and proportional-integral-derivative (PID) control is used to achieve a stable closed-loop laser temperature control. However, temperature is a slow-response process, and simple temperature control is limited by the thermal equilibrium time, failing to control the wavelength in a timely manner.

[0006] Existing active laser frequency stabilization technologies are already mature, such as molecular absorption harmonic frequency stabilization

[12] , Pound-Drever-Hall frequency stabilization

[13] , and curve reduction stabilization

[14] . These methods using complex systems can achieve laser frequency stabilization from multiple aspects, including frequency stability, long-term working stability, cost control, and sensitivity. Currently, a short-term variance of 2*10-7 for laser frequency has been achieved on OPMs

[15] . However, for sensors with miniaturized designs, any added structure is a challenge to the overall size. Using active laser frequency stabilization requires the addition of an external reference frequency to provide feedback for laser frequency stabilization, and also requires beam splitting to achieve real-time detection of laser frequency, which greatly increases the complexity of miniaturized OPM laser frequency stabilization systems.

[0007] [1] F.Lotte et al., "A review of classification algorithms for EEG-based brain-computer interfaces: a 10 year update," J.Neural Eng., vol.15, no.3, p.031005, Jun.2018, doi: 10.1088 / 1741-2552 / aab2f2.

[0008] [2]M. R. Hari, R. J. Ilmoniemi, J. Knuutila, and OV Lounasmaa, “Magnetoencephalography—theory, instrumentation, and applications to noninvasive studies of the working human being brain," Rev.Mod.Phys., vol.65, no.2, pp.413-497, Apr.1993, doi: 10.1103 / RevModPhys.65.413.

[0009] [3] J.Clarke, M.Hatridge, and M. “SQUID-Detected Magnetic ResonanceImaging in Microtesla Fields,”Annu.Rev.Biomed.Eng.,vol.9,no.1,pp.389-413,Aug.2007,doi:10.1146 / annurev.bioeng.9.060906.152010.

[0010] [4]K.Sternickel and A.I.Braginski,“Biomagnetism using SQUIDs:statusand perspectives,”Supercond.Sci.Technol.,vol.19,no.3,pp.S160-S171,Mar.2006,doi:10.1088 / 0953-2048 / 19 / 3 / 024.

[0011] [5]R.Mhaskar,S.Knappe,andJ.Kitching,“A low-power,high-sensitivitymicromachined optical magnetometer,”Appl.Phys.Lett.,vol.101,no.24,p.241105,Dec.2012,doi:10.1063 / 1.4770361.

[0012] [6]J.Iivanainen,M.Stenroos,and L.Parkkonen,“Measuring MEG closer tothe brain:Performance of on-scalp sensor arrays,”NeuroImage,vol.147,pp.542-553,Feb.2017,doi:10.1016 / j.neuroimage.2016.12.048.

[0013] [7]Y.J.Kim,I.Savukov,and S.Newman,“Magnetocardiography with a 16-channel fiber-coupled single-cell Rb optically pumped magnetometer,”Appl.Phys.Lett.,vol.114,no.14,p.143702,Apr.2019,doi:10.1063 / 1.5094339.

[0014] [8]J.-J.Li,P.-C.Du,J.-Q.Fu,X.-T.Wang,Q.Zhou,and R.-Q.Wang,“Miniaturequad-channel spin-exchange relaxation-free magnetometer formagnetoencephalography,”Chin.Phys.B,vol.28,no.4,p.040703,Apr.2019,doi:10.1088 / 1674-1056 / 28 / 4 / 040703.

[0015] [9]O.Alem et al.,“Fetal magnetocardiography measurements with anarray of microfabricated optically pumped magnetometers,”Phys.Med.Biol.,vol.60,no.12,pp.4797-4811,Jun.2015,doi:10.1088 / 0031-9155 / 60 / 12 / 4797.

[0016]

[10] F.Wang,Z.Hu,and X.Liu,“Low Noise VCSEL Driver for SERF AtomicMagnetometer,”IOP Conf.Ser.Mater.Sci.Eng.,vol.711,no.1,p.012093,Jan.2020,doi:10.1088 / 1757-899X / 711 / 1 / 012093.

[0017]

[11] H.Zhang et al.,“ULPAC:A Miniaturized Ultralow-Power AtomicClock,”IEEE J.Solid-State Circuits,vol.54,no.11,pp.3135-3148,Nov.2019,doi:10.1109 / JSSC.2019.2941004.

[0018]

[12] K.Nyholm,M.Merimaa,T.Ahola,and A.Lassila,“Frequency stabilizationof a diode-pumped nd:yag laser at 532nm to iodine by using third-harmonictechnique,”IEEE Trans.Instrum.Meas.,vol.52,no.2,pp.284-287,Apr.2003,doi:10.1109 / TIM.2003.811679.

[0019]

[13] H.Shen,L.Li,J.Bi,J.Wang,and L.Chen,“Systematic and quantitativeanalysis of residual amplitude modulation in Pound-Drever-Hall frequencystabilization,”Phys.Rev.A,vol.92,no.6,p.063809,Dec.2015,doi:10.1103 / PhysRevA.92.063809.

[0020]

[14] D.J.McCarron,I.G.Hughes,P.Tierney,and S.L.Cornish,“A heated vaporcell unit for dichroic atomic vapor laser lock in atomic rubidium,”Rev.Sci.Instrum.,vol.78,no.9,p.093106,Sep.2007,doi:10.1063 / 1.2785157.

[0021]

[15] Y. Yan, G. Liu, H. Lin, K. Yin, K. Wang, and J. Lu, "VCSEL frequencystabilization for optically pumped magnetometers," Chin.Opt.Lett., vol.19, no.12, p.121407, 2021, doi:10.3788 / COL202119.121407. Summary of the Invention

[0022] The purpose of this invention is to provide an effective means to achieve stable wavelength control with a simple single-optical-path setup.

[0023] To achieve the above objectives, one technical solution of the present invention provides a method for controlling a laser source in a miniaturized atomic magnetometer, characterized by comprising the following steps:

[0024] The pump laser emitted from the VCSEL diode strikes the photodiode to generate current. The voltage converted from the current output by the photodiode is used as a reference for temperature regulation of the VCSEL diode. The temperature of the VCSEL diode and the voltage converted by the photodiode are collected in real time, and the temperature of the VCSEL diode is PID regulated by the heating system.

[0025] Preferably, after the VCSEL diode control system starts working, the rated current is applied and the heating system is turned on with temperature as PID control feedback. At this time, the temperature of the VCSEL diode rises rapidly to near the target temperature. The VCSEL diode continues to be heated. During the process of the VCSEL diode temperature exceeding the target temperature, the laser frequency is briefly at the resonant frequency. At this time, the pump beam is absorbed by the alkali metal atoms because it reaches the resonant frequency. Subsequently, due to the deviation from the resonant frequency, the absorption amount decreases and finally passes completely through the alkali metal atom gas cell and hits the photodiode.

[0026] Meanwhile, the voltage change trend of the photodiode is that it first decreases from the saturation voltage until it reaches the minimum value, and then gradually rises back to the saturation state. The minimum value of the photodiode conversion voltage obtained in the process is taken as the lower limit of the photodiode conversion voltage control PID. The most suitable point of the photodiode conversion voltage is selected as the conversion voltage target value. The difference between the conversion voltage target value and the minimum value of the photodiode conversion voltage is taken as the positive and negative operating range of the photodiode conversion voltage control PID. The temperature of the VCSEL diode corresponding to the lower limit and upper limit of the positive and negative operating range is recorded. Finally, the photodiode conversion voltage stabilizes near the conversion voltage target value and remains stable for a long time.

[0027] Preferably, the temperature of the VCSEL diode corresponding to the target value of the photodiode conversion voltage is recorded in real time and used as the target value of the temperature sensor for detecting the temperature of the VCSEL diode. When the pump laser wavelength deviates from the target value and falls out of the range of the photodiode conversion voltage control PID, the temperature control PID will once again take the lead based on the temperature sensor digital controller, and the heating system will be controlled to heat the VCSEL diode based on the target value until the pump laser wavelength returns to the accurate working range.

[0028] Preferably, the temperature of the VCSEL diode is acquired in real time using a temperature acquisition circuit, and a low-pass filter is connected in series in the temperature acquisition circuit. Then, the heating voltage V of the heating system is... h The governing equations are shown below:

[0029]

[0030] In the formula: and It is a constant control coefficient;

[0031] and These are the errors in temperature and the conversion voltage of the photodiode, respectively. T m T represents the temperature of the VCSEL diode. o Indicates the optimal operating temperature. H represents the transfer function of the low-pass filter, V m This represents the voltage value converted from the current output by the photodiode, in V. o This indicates the voltage value converted from the current output by the photodiode when it is in optimal operating condition;

[0032] χ α and χ β It is the diode temperature T m The function, denoted as χ α (T m ) and χ β (T m Then we have:

[0033]

[0034]

[0035] In the formula, ξ is a constant coefficient, and ΔT represents the temperature range in which the dual feedback operates simultaneously.

[0036] Another technical solution of the present invention is to provide a miniaturized atomic magnetometer laser source control system, characterized in that it includes:

[0037] A photodiode is generated by a pump laser emitted from a VCSEL diode striking the photodiode.

[0038] Temperature acquisition circuit, used to acquire the temperature of VCSEL diode in real time;

[0039] The temperature PID control module uses the voltage converted from the current output by the photodiode as the temperature control reference for the VCSEL diode. After obtaining the real-time collected VCSEL diode temperature and the voltage converted by the photodiode, the temperature PID control module uses the heating system to perform PID control on the temperature of the VCSEL diode.

[0040] The heating system is used to heat the VCSEL diode under the control of the temperature PID regulation module.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) A method is proposed to determine whether the wavelength is stable at the target value by using the conversion voltage of the photodiode, and to control the laser frequency stabilization by using the physical phenomenon of optical pumping; (2) The VCSEL diode can be heated quickly so that the laser frequency is stable near the target value without considering the thermal equilibrium process; (3) The magnitude of the PD conversion voltage can be monitored for a long time, thereby ensuring that the VCSEL diode works at the target wavelength for a long time without large fluctuations.

[0043] Experimental results show that the variances of the output signal using the traditional temperature feedback control method at 1s and 1000s are 2.37*10. -4 and 4.97*10 -3 In comparison, the method provided by this invention can reduce the signal variance to 4.89*10^6 at 1s and 1000s, respectively. -6 and 7.69*10 -7 Furthermore, the sensitivity of the miniaturized OPM using the method provided by this invention was experimentally tested, and the sensitivity at 10 Hz reached 14 fT / Hz1 / 2. Attached Figure Description

[0044] Figure 1 The OPM sensor system is illustrated.

[0045] Figure 2 The diagram illustrates the VCSEL diode temperature acquisition circuit in a specific implementation.

[0046] Figure 3 The diagram illustrates the VCSEL diode heating circuit in a specific implementation.

[0047] Figure 4 The diagram illustrates the frequency stabilization effect of the VCSEL diode.

[0048] Figure 5 A comparison chart of the output signal stability between traditional temperature control methods and this method.

[0049] Figure 6 The graph shows the sensitivity test results of a miniaturized atomic magnetometer. Detailed Implementation

[0050] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0051] This invention addresses the wavelength stabilization requirements of optically pumped atomic magnetometers, and the technical problems it aims to solve include:

[0052] (1) Frequency Stabilization of Single-Beam OPM without Splitting Based on VCSEL Diode. The current of the OPM sensor during operation can be provided by a precision current source to achieve accurate current control. However, using only the temperature sensor's detection value for temperature control feedback is not accurate enough for the following reasons: First, there will always be a distance deviation between the temperature sensor and the VCSEL diode, which cannot reflect the temperature status of the VCSEL diode in real time; second, the actual temperature of the VCSEL will change with the thermal equilibrium process, thus deviating from the accurate wavelength temperature; third, without wavelength detection, it cannot be guaranteed that the VCSEL diode operates at the accurate frequency. Based on the above reasons, a method for frequency stabilization under these conditions is needed.

[0053] (2) Fast frequency stabilization mechanism of VCSEL diode. In practical applications of OPM, it is necessary to stabilize the current and temperature of the sensor at a fixed value as quickly as possible to ensure wavelength accuracy. Due to the slow response of temperature control, the process of stabilizing the temperature to the target value will be prolonged. This requires us to find a way to quickly determine the target heating temperature and adjust it in a timely manner according to the state of thermal equilibrium.

[0054] (3) Frequency stabilization effect of OPM under long-term operation. OPM needs to maintain a stable frequency for extended periods during weak magnetic field detection, which places demands on the long-term stability of the VCSEL diode. Due to factors such as diode aging and changes in the operating environment, even the same VCSEL diode cannot guarantee maintaining the same output wavelength under the same current and temperature conditions. Therefore, this requires the wavelength of the VCSEL diode to be monitored and adjusted in real time, responding promptly to environmental changes, and quickly restoring an accurate wavelength value in the face of occasional situations.

[0055] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0056] To achieve frequency stability of the pump light emitted by the VCSEL diode in an OPM without introducing additional noise, this invention utilizes the physical nature of optical pumping and proposes using the voltage converted from the current output by the photodiode (PD) as a temperature adjustment reference for the VCSEL diode. An STM32 microcontroller is used to collect real-time data on the VCSEL diode temperature and the PD conversion voltage for PID control. Since the amount of light absorbed by alkali metal atoms remains constant when the wavelength is stable near the resonant frequency, and consequently the PD conversion voltage remains constant, this invention uses the PD conversion voltage to determine whether the VCSEL diode is stable at the target frequency. The OPM sensor system is as follows: Figure 1 As shown, the pump laser is emitted from a VCSEL diode, passes through a collimating lens and a quarter-wave plate, then through an alkali metal atom gas cell, and finally strikes the PD to generate a current. When the wavelength of the pump light emitted by the VCSEL diode is at the resonant frequency of the alkali metal atoms, the pump light is absorbed, and the light intensity received on the PD decreases.

[0057] After the VCSEL diode control system starts working, the rated current is applied, and the heating system is activated, using temperature as the PID control feedback. The temperature rapidly rises to near the target temperature. Heating continues, and as the VCSEL diode temperature exceeds the target temperature, the laser frequency briefly reaches its resonant frequency. At this point, the pump beam is absorbed by alkali metal atoms because it has reached the resonant frequency. Subsequently, the absorption decreases due to the deviation from the resonant frequency, and eventually, it completely passes through the alkali metal atom gas chamber. During this process, the voltage conversion on the PD initially decreases from the saturation voltage until it reaches its minimum value, and then gradually rises back to saturation. We use the minimum PD conversion voltage obtained during this process as the lower limit of the PD control PID. The most suitable point for the PD conversion voltage is selected as the target value, and the difference between the target value and the minimum value is taken as the positive and negative operating ranges of the PD conversion voltage control PID. The temperatures corresponding to the lower and upper limits of the operating range are recorded. Eventually, the PD voltage stabilizes near the target value and remains stable over a long period. Considering drastic changes in ambient temperature and the continuous thermal equilibrium process, the optimal operating temperature will change accordingly; therefore, the temperature corresponding to the target PD conversion voltage value is also recorded in real time. When the laser wavelength deviates from the target value and falls outside the range of the PD conversion voltage control PID, the temperature control PID will take over again and control the heating back to the accurate operating range.

[0058] Heating voltage V of the heating system h The governing equations are shown below:

[0059]

[0060] In the formula: and It is a constant control coefficient;

[0061] and These are the errors in temperature and PD voltage, respectively. T m T represents the temperature of the VCSEL diode. o Indicates the optimal operating temperature. H represents the transfer function of the low-pass filter, V m This represents the voltage value converted from the current output by the photodiode, in V. o This represents the voltage value converted from the current output by the photodiode when it is in optimal working condition. It should be noted that during the measurement process, the magnetic signal is modulated to a relatively high frequency. Therefore, a low-pass filter is used to ensure that the modulated high-frequency signal is not affected by the proposed feedback control method.

[0062] χ α and χ β It is the diode temperature T m The function can also be represented as χ. α (T m ) and χ β (T m Then we have:

[0063]

[0064]

[0065] In the formula, ξ is a constant coefficient, and ΔT represents the temperature range in which the dual feedback operates simultaneously.

[0066] When T m -T o +ΔT << -1 / ξ or T m -T o When -ΔT>>1 / ξ, χ α ≈1 and χ β ≈0, at this time the heating voltage V h Mainly controlled by the VCSEL diode temperature T m When the VCSEL diode temperature T m Approaching the optimal operating temperature T o When, χ α ≈0 and χ β ≈1, at this time V h It is mainly controlled by the signal of PD.

[0067] This invention designs an OPM device for use in a rubidium atom gas chamber in the laboratory, such as... Figure 1 As shown. Figure 1 The VCSEL diode portion of the sensor, packaged on the left, provides the pump laser from the 795nm rubidium atom D1 line. This beam, after passing through a beam expander and collimator lens and a quarter-wave plate, passes through a sealed, transparent rubidium atom gas cell and is ultimately received by the photodiode on the far right. To optimize OPM operation, the rubidium atom gas cell is heated to achieve the optimal number of atoms resonating with the pump beam. Based on this, the heating effect of the VCSEL diode is tested, demonstrating the feasibility of the method proposed in this invention.

[0068] Temperature acquisition circuit for VCSEL diodes, such as Figure 2 As shown in the diagram, we use a Pt1000 platinum resistance thermometer to monitor the diode temperature in real time. A follower circuit and a Wheatstone bridge are used to accurately acquire the resistance value, and the temperature value is determined based on the Pt1000 platinum resistance thermometer versus temperature table. The current acquired on the PD is converted into a voltage signal by a transimpedance amplifier, and then further filtered and amplified before acquisition.

[0069] Based on the collected temperature and PD conversion voltage results, PID calculations are performed to obtain a heating feedback signal, which is then output through a microcontroller unit. For example... Figure 3 As shown, the heating signal passes through a digital-to-analog converter (DAC) and a gain amplifier (VGA), and then enters the heating device after voltage and power amplification.

[0070] Based on this experimental setup, the present invention tested the actual heating process, such as... Figure 4 As shown, as heating begins, the temperature gradually stabilizes near the target temperature. After minor adjustments, the voltage converted by the PD stabilizes at the target value. This demonstrates the sensor's frequency stabilization effect and proves the feasibility of the invention.

Claims

1. A miniaturized atomic magnetometer laser source control method, characterized by, Includes the following steps: The pump laser emitted from the VCSEL diode strikes the photodiode to generate current. The voltage converted from the current output by the photodiode is used as a reference for the temperature regulation of the VCSEL diode. The temperature of the VCSEL diode and the voltage converted by the photodiode are collected in real time, and the temperature of the VCSEL diode is PID regulated by the heating system. After the VCSEL diode control system starts working, the rated current is applied and the heating system is turned on with temperature as the PID control feedback. At this time, the temperature of the VCSEL diode rises rapidly to near the target temperature. The VCSEL diode continues to be heated. During the process of the VCSEL diode temperature exceeding the target temperature, the laser frequency is briefly at the resonant frequency. At this time, the pump beam is absorbed by the alkali metal atoms because it reaches the resonant frequency. Subsequently, due to the deviation from the resonant frequency, the absorption amount decreases and finally passes completely through the alkali metal atom gas cell and hits the photodiode. Meanwhile, the voltage change trend of the photodiode is that it first decreases from the saturation voltage until it reaches the minimum value, and then gradually rises back to the saturation state. The minimum value of the photodiode conversion voltage obtained in the process is taken as the lower limit of the photodiode conversion voltage control PID. The most suitable point of the photodiode conversion voltage is selected as the conversion voltage target value. The difference between the conversion voltage target value and the minimum value of the photodiode conversion voltage is taken as the positive and negative operating range of the photodiode conversion voltage control PID. The temperature of the VCSEL diode corresponding to the lower limit and upper limit of the positive and negative operating range is recorded. Finally, the photodiode conversion voltage stabilizes near the conversion voltage target value and remains stable for a long time.

2. The method of claim 1, wherein the laser source is a laser diode. The temperature of the VCSEL diode corresponding to the target value of the photodiode conversion voltage is recorded in real time and used as the target value for the temperature sensor used to detect the temperature of the VCSEL diode. When the pump laser wavelength deviates from the target value and falls out of the range of the photodiode conversion voltage control PID, the temperature control PID will once again take the lead based on the temperature sensor digital controller, and the heating system will be controlled to heat the VCSEL diode based on the target value until the pump laser wavelength returns to the accurate working range.

3. The laser source control method for a miniaturized atomic magnetometer as described in claim 1, characterized in that, The temperature acquisition circuit is used for collecting the temperature of the VCSEL diode in real time, and a low-pass filter is connected in series in the temperature acquisition circuit, so that the heating voltage of the heating system is controlled The control equation of the heating system is as follows: In the formula: , , and It is a constant control coefficient; and These are the errors in temperature and the conversion voltage of the photodiode, respectively. , Indicates the temperature of the VCSEL diode. Indicates the optimal operating temperature. , This represents the transfer function of a low-pass filter. This represents the voltage value converted from the current output by the photodiode. This indicates the voltage value converted from the current output by the photodiode when it is in optimal operating condition; and Diode temperature The function is represented as and Then we have: In the formula, .

4. A laser source control system for a miniaturized atomic magnetometer, characterized in that, The laser source control method for the miniaturized atomic magnetometer as described in claim 1 includes: A photodiode is generated by a pump laser emitted from a VCSEL diode striking the photodiode. Temperature acquisition circuit, used to acquire the temperature of VCSEL diode in real time; The temperature PID control module uses the voltage converted from the current output by the photodiode as the temperature control reference for the VCSEL diode. After obtaining the real-time collected VCSEL diode temperature and the voltage converted by the photodiode, the temperature PID control module uses the heating system to perform PID control on the temperature of the VCSEL diode. The heating system is used to heat the VCSEL diode under the control of the temperature PID regulation module.

Images