HIGH-SPEED DIRECT MODULATION OF SEMICONDUCTOR LASERS

The high speed direct modulation of semiconductor lasers has made tremendous progress since the early works of Suemune et al. that proposed for the first time the potential for semiconductor lasers to be directly modulated to frequencies approaching 60–90 GHz. Technical achievements as well as an improved understanding of the role of carrier dynamics in the modulation response have made much of these advances possible. This paper discusses the various methods that have been used to improve the direct modulation bandwidth over the last decade. An understanding of the theoretical and technical concepts that have led to the development of millimeter-wave directly modulated lasers is critical in understanding how these lasers can be further optimized for efficient operation in a number of optical communication links.