Date Thesis Awarded
Honors Thesis -- Open Access
Bachelors of Science (BS)
David S. Armstrong
Magnetometers with high precision and accuracy have wide applications across various areas. We are developing an atomic magnetometer based on nonlinear magneto-optical rotation (NMOR). The magnetometer measures the polarization rotation of a light field, which is proportional to the magnetic field strength. However, such a magnetometer usually has a limited operation range and stops working for fields stronger than the Earth's magnetic field. To overcome this shortage, we implement frequency and amplitude modulation that induces side frequencies in the Fourier space which allows us to measure strong magnetic fields, up to 200 mG. We have achieved 60 pT sensitivity for the zero resonance using a quarter-waveplate and compensation coils. We further optimize the sensitivity of the side resonance to the nT level by separating the probe and pump beam. We finally generate a squeezed pump beam using polarization self-rotation and observe a noise reduction below the shot-noise-limit, which leads to a factor of two improvement on the SNR.
Li, Jiahui, "An Atomic Magnetometer based on Nonlinear Magneto-Optical Polarization Rotation" (2022). Undergraduate Honors Theses. William & Mary. Paper 1773.