Laser diodes integrated with electroabsorption modulators for 40 Gb/s data transmission

Abstract

Due to the ongoing expansion in the data communication market, the demand for high bandwidth applications is ever increasing. Today, this market is about to overtake the classical telecommunication industry. Multimedia applications like music and video on demand or video telephony require data rates in the range of tens of megabits per second (Mbps) at the consumer end. Numerous electrical and optical transceiver systems are struggling to dominate the communication market. For a breakthrough, inexpensive and reliable optical single-mode products are a must. This thesis will evaluate the potential of electroabsorption modulators integrated with distributed feedback (DFB) lasers (EMLs), featuring the most simple integration concept of a shared active area. Comparable to standard DFB lasers in terms of epitaxy, chip technology and packaging, they have the potential to replace both, directly modulated lasers and Mach-Zehnder modulators, due to a better 10 Gbps performance and lower costs, respectively. Until now, fast EMLs with shared active area were only realized in the GaInAsP on InP material system. For the first time, the integration concept was transferred to the aluminum containing material system AlGaInAs on InP yielding devices capable of 40 Gbps operation. In addition, the very first single growth EMLs including metal grating DFB lasers were manufactured. They have high potential in further reducing chip costs, considerably lowering the production effort by rendering the overgrowth process unnecessary, and boosting the single-mode yield from 20 % to 100 %. This advancement was achieved by the implementation of multiple design tools within this thesis. They cover absorption, gain and waveguiding as well as temperature and dynamic modulation behavior. During the development process of the simulation tools, emphasis was put on the incorporation of fast and simple models that are suitable for reproducing measured effects with a high degree of accuracy. For that purpose, every simulation result was carefully compared to experimental findings. In contrast to many commercial all-in-one solutions, this tailored approach enables the identification of predominant mechanisms and target-oriented device design.