Optimization of electric heater for magnetic field reduction in SERF atomic magnetometer

One of the essential requirements for achieving ultra-high sensitivity magnetic field measurement in Spin-Exchange Relaxation-Free (SERF) atomic magnetometers (AM) is heating the core sensitive element, the vapor cell, to a high temperature. However, the static magnetic interference and magnetic noise introduced by the electric heater during the heating process directly affect the magnetic measurement sensitivity. This paper proposes a micro-heater structure optimization method based on the firefly algorithm. First, a square coil magnetic field model is established by integrating the vapor cell and the electric heater structure. With the objective of minimizing the magnetic flux density at multiple target points inside the vapor cell, and subject to the constraint of the minimum spacing between adjacent coils, the firefly algorithm is employed to optimize the half-side length and current direction of the electric heater. Subsequently, the magnetic flux density generated by the electric heater inside the vapor cell and the corresponding temperature distribution are simulated, and the optimized electric heater is fabricated and assembled on the wall of a vapor cell with a side length of 4 mm. Finally, experimental results demonstrate that the magnetoelectric coefficient of the optimized electric heater is reduced by 79.6%, and the influence of the introduced magnetic noise on the AM sensitivity is reduced by 0.8 (Formula presented). Furthermore, the results of the heating uniformity verification indicate that the maximum temperature deviation within the vapor cell is reduced by 35.6%.