Breaking the Stokes-anti-Stokes symmetry in Raman heterodyne detection of magnetic-resonance transitions

Coherent Raman scattering can generate Stokes and anti-Stokes fields of com parable intensities. When the Raman shift is due to a magnetic resonance tr ansition (usually in the MHz to GHz range), the Raman fields are generally detected by optical heterodyne detection, using the excitation laser as the local oscillator. In this case, the two sidebands generate beat signals at the same frequency and are therefore indistinguishable. Separation of the two contributions becomes possible, however, by superheterodyne detection w ith a frequency-shifted optical local oscillator. We compare the two scatte ring processes, and show how the symmetry between them can be broken in Pr3 +:YAlO3. [S1050-2947(98)08412-1].