Gas lasers: theory and modern applications

This lecture covers the theory and applications of gas lasers, including gain saturation, laser power output dependence, and examples like the He-Ne laser, Ruby laser, CO2 laser, Ar-ion laser, and Excimer laser. It explains the rate equations for atoms and photons, intracavity intensity, photon rate equation, and single mode operation. The lecture also delves into the working principles and characteristics of different gas lasers such as He-Ne, CO2, Ar-ion, and Excimer lasers, highlighting their energy levels, transitions, output powers, and applications in various fields like cutting, welding, lithography, and corneal surgery.