FREQUENCY CONTROL OF SEMICONDUCTOR LASERS.

Abstract

The requirement of a stable single-wavelength coherent source for high-speed, long-distance optical-fiber communication systems has imposed severe conditions on the frequency control of semiconductor lasers. The two main candidates for a dynamic single-wavelength source are: (1) the distributed-feedback (DFB) and distributed Bragg reflector (DBR) lasers; and (2) the interference lasers. The performances of interference lasers of the internal-reflection type are first reviewed. Then, the outstanding features and problems of the Bragg lasers and the interference lasers of both internal and external reflection types are compared. Finally, a new laser structure is proposed, called the interference-DFB laser, to take advantage of the interference and DFB lasers. An analysis of this laser also provides valuable insights in understanding the behavior of the DFB laser.