Abstract

There has been recently a widespread interest in the theoretical and experimental studies of the excess quantum noise which appears in lasers with unstable cavities [1]. One striking feature of such systems is that the laser linewidth can be much larger than the usual Schawlow-Townes linewidth, by a factor which is known as the Petermann excess noise factor K [1]. In recent experiments with suitably designed unstable laser cavities, K can be as large as several hundreds; it is therefore a very large unambiguous effect, which deserves thorough attention.

© 1998 IEEE