Phvsical Research And Probe Development Of Miniaturized Mx Atomic Magnetometer

In recent years,high-sensitivity atomic magnetometers operating in the earth’s field and much weaker magnetic fields have been extensively and increasingly utilized in a diverse range of fields,including electromagnetic wave communication,geophysics,space science,military anti-submarine warfare,biomedicine,and fundamental physics research.Especially with the development of application scenarios such as deep sea,deep space,and aeromagnetic detection,the demand for microminiature and chip-scale atomic magnetometers is more urgent.Based on this,this thesis is committed to the development of a high-sensitivity,miniaturized atomic magnetometer prototype,and verifies the application of the magnetometer as a magnetic sensor for low-frequency electromagnetic wave communication(LFEWC)receiver.The main research contents of the thesis are as follows:(1)The related theory and technical basis of atomic magnetometer are analyzed systematically.The atomic magnetometer uses the interaction between light and atoms to measure the magnetic field precisely,so the theories of atomic energy level structure,Zeeman effect,atomic polarization,atomic relaxation and Larmor precession are introduced in this thesis.Starting from the Bloch equation,the evolution process of the combined magnetic moment with time is derived and the form of the steady-state solution of the Bloch equation is solved.According to the steady-state solution of the Bloch equation,the inaccuracy and response rate of the Mx and Mz atomic magnetometers are analyzed and compared.And according to the actual communication application requirements,put forward the main research object of this thesis.(2)The open-loop Mx atomic magnetometer experimental system was designed and built.According to the development purpose of the miniaturized and chip-based atomic magnetometer prototype,this thesis chooses the single-beam Mx atomic magnetometer scheme with simple optical path and easy integration to carry out experimental research.In this scheme,the light component parallel to the magnetic field is used as the pump light to polarize atoms,and the light component perpendicular to the magnetic field is used as probe light to obtain magnetic resonance signals.In order to deal with the problems existing in the traditional optically pumped atomic magnetometer,this scheme selects a diode laser with well directional monochromaticity,stable wavelength and low volume power consumption as the experimental light source compared with the spectral lamp,and suppresses the wall collision relaxation by plating a paraffin coating on the wall of the atomic vapor cell,thereby improving the signal quality.Then,DAVLL laser frequency stabilization system was built,and the laser frequency was stabilized at the frequency required for the resonance transition by using the DAVLL frequency stabilization technology with a wide frequency stabilization range,little influence by laser power jitter,and no external modulation,so as to reduce the frequency of the magnetometer noise level(especially FM-AM noise).Then,after optical path adjustment and system debugging,the magnetic resonance spectrum signal of the open-loop Mx magnetometer is obtained by optical adjusting,and the experimental parameters of the magnetometer are studied,and finally a high-sensitivity open-loop Mx atomic magnetometer is obtained under the optimal experimental conditions.(3)A self-oscillating Mx atomic magnetometer and communication receiver are designed and implemented.Based on the parameter research of the above-mentioned magnetometer,the closed-loop mode of the Mx magnetometer is realized through the loop design under the optimal parameter condition.The difference between the sensitivity of the closed-loop and the open-loop mode was compared,and the sensitivity and response rate of the magnetometer were evaluated and tested.In addition,the magnetic field noise introduced by the sampling rate of the counter is analyzed,and the mathematical relationship between the sampling rate and the noise is obtained.Compared with the LFEWC receiver using traditional receiving coils,the atomic magnetometer has the advantage of smaller volume as a magnetic sensor,which is conducive to the development of micro-miniature communication receivers.Finally,a communication receiver is implemented based on the magnetometer as a magnetic sensor,and the ability of the communication receiver to receive LFEWC signals is verified.This exploration offers a feasible opportunity for receiving LFEWC signals.(4)A miniaturized atomic magnetometer probe was designed and developed.Firstly,the overall scheme of the magnetometer probe is designed.According to the actual needs,the probe material is selected andthe components required for the probe are obtained by using machining and 3D printing technology.And the processed components,laser,optical fibers,optical lenses and radio frequency coils of atomic gas chambers are installed and debugged.DC modulation laser frequency stabilization and atomic gas chamber temperature PID closed-loop feedback control were performed on the installed probe.The performance of the magnetometer probe was evaluated and tested by noise analysis and sensitivity test.Finally,a miniaturized and high-sensitivity atomic magnetometer probe was developed,which also laid an important foundation for the subsequent development of low-power,micro-miniature atomic magnetometer prototypes.