Derivation of bandwidth and filter characteristics of various types of optically pumped magnetometers

We present a unified and easy-to-follow analytical framework based on the Bloch equations for deriving the small-signal frequency response of several common types of optically pumped magnetometers (OPMs). These include the Mx, light-shift dispersed Mz, Bell–Bloom, and RF (radio-frequency) types, as well as the class of unmodulated zero-field OPMs. It is shown that, depending on the operating regime, the frequency response of some of these magnetometers deviates significantly from the commonly assumed first-order filter behavior.