Optical coherent transients by laser frequency switching: subnanosecond studies

By extending the laser-frequency-switching technique to a 100-psec time scale, we have observed for the Na D1 line the first-order free-induction decay, its inhomogeneous dephasing time T2*, its interference with the nonlinear free-induction decay, and a 1.8-GHz interference beat of the ground-state hfs. Detailed theoretical predictions of these new coherence effects are faithfully observed. © 1978 The American Physical Society.