ABSTRACT
Optical sources and detectors are at the heart of all optoelectronic systems, and most of the sources and detectors employed in practical systems are semiconductor based. This chapter outlines the basics of semiconductor light sources and detectors, including the device structure and characteristics. It discusses the semiconductor materials for optoelectronics. The chapter presents the basic structure and device characteristics of semiconductor lasers. Photodetectors are based on the generation of photocarriers due to the incident light, which results in a current in the external circuit. Photodetectors are broadly classified into two types: photoemissive type and photoconductive type. Three types of semiconductor photo-detectors are widely used: photoconductors, PIN photodiodes and APDs. The chapter also discusses the device structure, the working principle and the characteristics of these photodetectors. APDs are photodiodes with a built-in gain mechanism for the number of carriers contributing to the photocurrent in the circuit.
