Saturated absorption technique used in potassium microcells for magnetic field sensing

It is demonstrated that the use of a micrometric thin K-39 vapor cell (MTC) and saturated absorption (SA) spectroscopy allows the formation of narrow atomic lines in the transmission spectrum without unwanted cross-over resonances. Another important feature is the small characteristic magnetic field value B-0 = A(hf)/mu(B) of K-39, significantly smaller than for Rb and Cs. As a consequence, decoupling of J and I can be observed at relatively low magnetic fields similar to 300 G, which results in the formation of two groups of four spectrally-resolved and equidistantly-positioned atomic transitions having the same amplitude (each group corresponds to a given circular polarization a sigma(+/-)) which we record using a simple experimental setup with a linearly polarized tunable diode-laser and a longitudinal magnetic field obtained with two permanent magnets. Fabrication of a MTC is much easier than the fabrication of the K-39 nanocells used in our previous works. A simple method to determine the magnitude of a wide range of B-fields with a spatial resolution of 30 mu m is presented, which is intrinsically calibrated and does not require a frequency reference.

Automated summary

This study demonstrates the formation of narrow atomic lines in the transmission spectrum using a micrometric thin K-39 vapor cell and saturated absorption spectroscopy. The small characteristic magnetic field value of K-39 allows for decoupling of J and I at relatively low magnetic fields, resulting in the formation of two groups of spectrally-resolved atomic transitions.