Lecture
This lecture covers the basic building blocks of a laser, including the medium with radiative transitions, energy sources for population inversion, and the importance of a cavity for multiple passes. The instructor explains the concept of a laser resonator, also known as an etalon, consisting of two mirrors to create a feedback loop for laser amplification. The lecture delves into the design and function of the etalon, emphasizing the significance of multiple passes within the resonator. Various configurations and characteristics of laser resonators are discussed, highlighting the role of mirrors in controlling the laser beam. The lecture concludes with an overview of optical transmission through the etalon, introducing the concepts of finesse and free spectral range (FSR).