Yb atomic magnetometer with unique capabilities*

We report on a fast, sensitive atomic vector magnetometer, which relies on atomic spectroscopy and Zeeman splitting in the ³P₁ state of Yb atoms. In the presence of a magnetic field gradient, we observed prominent dark stripes in the fluorescence when thermal Yb atoms are driven by square wave amplitude-modulated light. The ¹S₀-³P₁ transition forms a "V" configuration where two laser sidebands interact with two ³P₁ Zeeman sublevels simultaneously. The dark resonance occurs when the Zeeman splitting matches the frequency difference between the sidebands. We estimate the magnetic field sensitivity to be ≈1 mG with a large dynamic range from mG to kG. The contrast of the lines is readily observable by eye or camera, allowing direct imaging of the local magnetic field in 2D with a short response time of ≈10 μs. The magnetic vector orientation can be inferred from measurements with different laser polarizations. We are developing a numerical model to compute the spectra and the dark-line contrast by solving Optical Bloch Equations for a 4-level atom and multiple optical fields. The model includes the effects of Doppler broadening from the atoms’ velocity distribution, which will allow direct comparison to the experimental results and computation of a magnetic field map from the data.