Abstract

Monolithic and external cavity mode-locked semiconductor lasers with multiple contacts have produced excellent results [1–3]. The goal of this paper is to show how to optimize the design of these structures as a function of the free parameters in the design: (1) Active region composition and waveguiding, (2) segment lengths, and (3) electrical parasitics. The paper also explains how the effects of self-phase modulation in the saturable absorber and gain section interact with gain dispersion to limit the achievable pulse width. Figure 1 shows the types of structures that were fabricated and analyzed in this work. Both quantum well and bulk active region devices were tested at 0.85 μm and 1.55 μm. The functions of the various segments are: segment A provides the overall gain, segment B is reverse biased to form an intra-waveguide saturable absorber/photodetector, and segment C is used for active gain modulation or for repetition rate tuning.

© 1992 Optical Society of America