Semiclassical theory of amplification and lasing

In this article we present a systematic derivation of the Maxwell‐Bloch equations describing amplification and laser action in a ring cavity. We derive the Maxwell‐Bloch equations for a two‐level medium and discuss their applicability to standard three‐ and four‐level systems. After discusing amplification, we consider lasing and pay special attention to obtaining the laser equations in the uniform field approximation. Finally, the connection of the laser equations with the Lorenz model is considered.