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 (FID), its inhomogeneous dephasing time T*2, its interference with the nonlinear FID, and a 1.8 GHz interference beat of the ground state hfs. Detailed theoretical predictions of these new coherence effects are faithfully observed.