2 - Interaction of Electrons and Photons

This chapter provides the basis for the discussion in the following chapters by summarizing the fundamental concepts and the quantum theory concerning the interaction between electrons and photons in a form that is convenient for theoretical analysis of semiconductor lasers [1–9]. First, quantization of electromagnetic fields of optical waves is outlined, and the concept of a photon is clarified. Quantum theory expressions for coherent states are also given. Then the quantum theory of electron–photon interactions and the general characteristics of optical transitions are explained. ...