Semiconductor lasers

Abstract

In this short-course, we described simply the physics of semiconductor lasers. After a few reminders of basic solid state physics on electronic states in semiconductors, how a semiconductor can emit light has been considered. The p-n junction is the basic mechanism for obtaining the population inversion required for stimulated emission gain. We presented the principies and fundamental equations governing the optical gain in these structures. The threshold conditions is then determined and the various improvements over the basic p-n junction (double heterostructure laser, quantum well laser) are set in historical perspective. Then, the variety of semiconductor lasers is illustrated by sorne examples: distributed feedback (DFB) lasers, distributed Bragg reflector (DBR) lasers, mode-locked lasers (MLL). Finally, an attempt to put into perspective sorne advanced semiconductor lasers, in particular the quantum dot lasers, has been made.