Abstract

Direct modulation of laser diodes can reach frequencies as high as 33 GHz¹ sacrificing, however, other performance aspects such as operating power, optical loss, linewidth, and chirp. A better approach is to use external interferometric modulators, which can provide lower insertion losses than electroabsorption modulators,² and also allow the chirp level to be engineered to suit the associated optical link. Although integration is feasible using etch and regrowth techniques to realise the material composition variation required between the laser and the modulator, such techniques have major limitations.³ An alternative, more elegant, solution has become feasible due to recent advances in the process of quantum well intermixing (QWI).

© 1998 IEEE