Gain saturation

This lecture covers the concept of gain saturation in laser systems, where the stimulated emission cannot be neglected above the threshold, illustrated with examples like the Ruby laser and the 3-level system. It also discusses the rate equations for photo and photon interactions, emphasizing the importance of maintaining a balance between pumping and emission processes. The lecture delves into the dynamics of atoms in different energy levels and the factors influencing laser output power, such as diode pumping and output coupling efficiency.