Nonlinear magneto-optical rotation with frequency-modulated light

We demonstrate a magnetometric technique suitable for precision measurements of fields ranging from the sub-microgauss level to above the Earth field. It is based on resonant nonlinear magneto-optical rotation (NMOR) caused by alkali atoms contained in a vapor cell with anti-relaxation (paraffin) wall coating. The physical mechanisms causing NMOR are discussed in detail, with particular attention paid to the role of optically induced atomic polarization---responsible for the ultra-narrow (∼1 Hz) NMOR resonances we employ for magnetometric measurements.; Linearly polarized, frequency-modulated laser light is used for optical pumping and probing. If the time-dependent optical rotation is measured at the first harmonic of the modulation frequency Om, ultra-narrow resonances are observed at near-zero magnetic fields, and at fields where the Larmor frequency OL is an integer multiple of the light modulation frequency. We demonstrate a sensitivity of 5 x 10-10G/ Hz and show that the projected magnetometric sensitivity of the technique can exceed 10-11G/ Hz .; The technique of nonlinear magneto-optical rotation with frequency-modulated light (FM NMOR) allows selective generation and study of atomic polarization moments of up to the highest rank kappa = 2F possible for a quantum state with total angular momentum F. Various polarization moments are distinguished by the periodicity of light-polarization rotation induced by the atoms during Larmor precession and exhibit distinct light-intensity and frequency dependences. We study the FM NMOR signals from various optically induced polarization moments of Rb atoms.; We also report on the use of an atomic magnetometer based on FM NMOR to detect nuclear magnetization of xenon gas. The magnetization of a spin-exchange-polarized xenon sample, prepared remotely to the detection apparatus, is measured with an atomic sensor. An average magnetic field of ∼10 nG induced by the xenon sample on the atomic sensor is detected with signal-to-noise ratio ∼10, limited by residual noise in the magnetic environment. The possibility of using modern atomic magnetometers as detectors of nuclear magnetic resonance and in magnetic resonance imaging is discussed.