Basics of Optical Emission and Absorption

Abstract

Optical emission and absorption are fundamental processes which are exploited when electrical energy is converted into optical energy and vice versa. Optoelectronics is based on these energy conversion processes. Light emitters such as light-emitting diodes (LEDs) and diode lasers convert electrical energy into optical energy. Photodetectors convert optical energy into electrical energy. In this chapter, the most important factors needed for the comprehension of light emitters and photodetectors will be summarized in a compact form. For a detailed description of the basics of optical emission and absorption, the book [1] can be recommended. Here, emphasis will, of course, be placed on silicon devices. First we will introduce photons and the properties of light. Then, the consequences of the band structure for optical emission and absorption will be dealt with. Photogeneration will be defined. Furthermore, optical reflection and its consequences on the efficiency of photodetectors will be described.