Semiconductor Lasers: Fundamentals and Theory

This chapter will introduce the fundamentals and theory of semiconductor lasers. To this end, it is important to understand that a semiconductor laser is a non-equilibrium system that undergoes a second-order phase transition at the oscillation threshold. It consists of many electrically- or optically-pumped emitters, ranging from a few to over trillions ( \(10^{12}\) ), which interact with different optical modes within a cavity. Consequently, this presents a highly complex problem that necessitates a diverse range of physical concepts, including semiconductor physics, quantum optics, nonlinear dynamics, and others. In the following sections, I will briefly introduce the principles of quantum-confined lasers, followed by an overview of different theoretical models that address specific aspects of laser behaviour.