Chopped nonlinear magneto-optic rotation: A technique for precision measurements
Department of Physics, Indian Institute of Science - Bangalore 560 012, India
Accepted: 19 April 2011
We have developed a technique for precise measurement of small magnetic fields using nonlinear magneto-optic rotation (NMOR). The technique relies on the resonant laser beam being chopped. During the on time, the atoms are optically pumped into an aligned ground state (Δm=2 coherence). During the off time, they freely precess around the magnetic field at the Larmor frequency. If the on-off modulation frequency matches (twice) the Larmor precession frequency, the rotation is resonantly enhanced in every cycle, thereby making the process like a repeated Ramsey measurement of the Larmor frequency. We study chopped-NMOR in a paraffin-coated Cs vapor cell. The out-of-phase demodulated rotation shows a Lorentzian peak of linewidth 85 μG, corresponding to a sensitivity of . We discuss the potential of this technique for the measurement of an atomic electric-dipole moment.
PACS: 33.57.+c – Magneto-optical and electro-optical spectra and effects / 32.80.Xx – Level crossing and optical pumping / 42.50.Gy – Effects of atomic coherence on propagation, absorption, and amplification of light; electromagnetically induced transparency and absorption
© EPLA, 2011