Optical Free-Induction Decay Effect in a Λ-Type Quantum-Beat Three-Level System

With Bloch form, a coherent transient effect-optical free-induction decay is studied semiclassi-cally in the Λ-type three-level system driven by a coherent microwave field. The decay behavior has three contributions: a homogeneous part with transverse relaxation time and two inhomo-geneous parts with different time constants that reflect the velocity bandwidth excited and the action of the driving microwave field.