Abstract

All-optical switching devices will play an important role in future optical time-division multiplexing (OTDM) networks. Interferometer arrangements consisting of semiconductor laser amplifiers (SLA) are very attractive for this purpose. Here, the cross-phase modulation due to the gain-saturation nonlinearity of SLAs provides the differential phase shift required for interferometric switching. Recently, we developed monolithically integrated Mach-Zehnder interferometers (MZI) and demonstrated their use in 40 to 5 Gbit/s demultiplexing and 20 to 5 Gbit/s add/drop multiplexing experiments [1-2]. In these devices the SLA lengths, inter-SLA spacing, and pulse widths are all in the range of ≈ 2-5 ps. In order to investigate the capabilities of such MZI devices for several tens of Gbit/s, it is essential to obtain a deeper understanding of ultrafast intraband effects and the associated gain and phase dynamics. In this paper we investigate, for the first time, gain and phase dynamics in SLA based monolithically integrated asymmetric MZIs by pump-probe experiments and develop a model to explain the interdependencies of various design relevant parameters. In addition, implications of fast intraband effects for all-optical demultiplexing and add-drop multiplexing using the MZI devices are discussed.

© 1996 Optical Society of America