Physical Review Letters
Optical Difference-Frequency Generation in Atomic Thallium Vapor
Allen M. Flusberg, THOMAS W. MOSSBERG, Sven R. Hartmann
Abstract
Coherent radiation at the 1.28-\ensuremath{\mu}m electric-dipole-forbidden $6^{2}P_{\frac{3}{2}}\ensuremath{-}6^{2}P_{\frac{1}{2}}$ transition in thallium vapor has been produced by the simultaneous application of a magnetic field and two collinear, overlapping laser beams nearly resonant with the $6^{2}P_{\frac{1}{2}}\ensuremath{-}7^{2}S_{\frac{1}{2}}$ and $6^{2}P_{\frac{3}{2}}\ensuremath{-}7^{2}S_{\frac{1}{2}}$ transitions, respectively. The effect of the magnetic field is to mix hyperfine levels---atomic polarization effects are negligible. The optical difference-frequency power generated at low magnetic field varies as the square of the magnetic-field component normal to the laser-beam propagation direction.