Research On All-optical Sub-Vector Cesium Atomic Magnetometer

Magnetic phenomenon is one of the earliest physical phenomena realized by human.The technology of high sensitivity magnetic field measurement has been used in many applications such as geophysical prospection,aerospace engineering,earth-magnetism navigation,biomedicine,fundamental physics,and so on.With the development of laser technology and signal processing technology,the study of atomic magnetometer makes great progresses for the past few decades.In this thesis,we propose a scheme of all-optical sub-vector Cesium atomic magnetometer based on Bell-Bloom configuration and circular dichroism detection with double probe beams.The main topics of the thesis are listed as follows.（1）Based on level structure of Cesium,the spin polarization and magnetic moment caused by optically resonant pumping,the precession of the moment in the magnetic field and the process of circular dichroism detection are analyzed theoretically.In view of Heisenberg uncertainty relation,the thesis obtains the limit sensitivity of atomic magnetometer with circular dichroism detection at the experimental condition.（2）Analyzing of magnetic field distribution produced by a set of circular coils theoretically,we design and realize a set of Helmholtz coils to provide a high stability magnetic field for atomic magnetometer system.To keep the stability of the measured magnetic field,a very steady constant current source to drive the coils has been developed.The constant current source provides a near ideal current of 1 mA,the short-term stability of current is 5.8×10^-7 mA and the stability of magnetic field is about 60 fT when magnetic strength is 100 nT.（3）We design the overall scheme of all-optical sub-vector Cesium atomic magnetometer with double probe beams.We discuss the theoretical response model of scalar atomic magnetometer with the Bloch equations and propose a new model of measuring magnetic vector field with two freedom degrees which might be called a sub-vector field.The composition of the magnetometer system is studied in detailed.After completing the development and testing work of each part of the system,we have finally built the system of all-optical sub-vector Cesium atomic magnetometer.（4）While test of all-optical sub-vector Cesium atomic magnetometer was performed,we analyze the experimental data of the time-domain signal,the frequency response signal and the phase frequency signal respectively.Discussing the limit sensitivity of this magnetometer and the noise in the experiment system,the experiment demonstrates the optimum magnitude sensitivity of 63 fT/Hz^1/2 at magnetic intensity of 100 nT.Proving feasibility of the sub-vector magnetometer and analyzing the dependence of resonance amplitude and linewidth on field direction,we research the dependence of relative sensitivity on the field direction experimentally.The experiment achieves the orientation sensitivity of 0.1°/Hz^1/2 and can keep the magnitude sensitivity better than 120 fT/Hz^1/2 in the angle range from 0°to 90°.（5）We study some key technologies about atomic magnetometer also.A new fiber integrated saturated absorption spectrum device,laser heating device and temperature controller are designed.Manufacturing the heating device where energy derives form a semiconductor laser with fiber output,we test the device of laser heating and temperature controller.