9308126 Griffel The tunable semiconductor laser (SCL) is a key component in the most advanced lightwave communication systems, which are based on frequency tuning and wavelength division multiplexing (WDM) techniques. In these systems, the tunable SCL is used as the light source for optical fiber links. Due to its unique properties it is capable of efficiently delivering the high data rate of information required in telecommunication and computer networks, CATV, LAN, etc. Other important applications for the tunable SCL include frequency domain optical memory (FDOM), optical pumping of Erbium doped fiber amplifiers and solid state lasers, laser spectroscopy, as well as direct source for space communication. In this project, we propose to carry out both theoretical and experimental studies of a new class of composite-cavity semiconductor lasers that consist of multi-active-section structures. Such semiconductor lasers have been the subject of extensive research and development effort in the recent years 1-5,9,10 , which was driven by their improved operation and finer characteristic. As a result, single longitudinal mode, higher side-mode suppression ratio, improved modulation efficiency, wider tuning range, and, in the case of coupled cavities, high output power were obtained. However understanding of many of these structures is incomplete, and comprehensive design criteria have not yet been established. In a recent study we have outlined the basis for modelling these devices, and used it for the specific case of two-section gain-levered distributed-feedback SCL. The preliminary results obtained so far, as well as other studies are extremely encouraging 3,5,8 and stress the necessity to acquire a better understanding to optimize their operation. The study program is projected to include the theoretical and experimental investigation of parameters such as modulation efficiency, optical linewidth, tuning range, field patterns, as well as other pertinent characteristics. ***
