Electro-absorption Modulators Integrated With V-coupled Tunable Lasers

Breakthroughs in optical communication technology has greatly promoted the development of the information age along with the expansion of the optical transmission capacity. WDM (wavelength-division multiplexing) is one of the most widely used technology in the optical communication system and is the key to the future construction of the intelligent optical networks. In order to maximize the advantages of WDM, we need wavelength tunable semiconductor lasers which are able to switch their operating wavelength upon particular demand. Such tunable lasers can serve as the backup light source in dense WDM (DWDM) systems and increase the optical transmission capacity dramatically. With their compactness and high stability, wavelength tunable lasers are now attracting widespread attention in the optical device market.In the high speed optical communication system, external modulation of the laser light is necessary to avoid the unacceptably high chirping of directly modulated lasers and to overcome the dispersion of standard single mode fiber. Electro-absorption modulators (EAM) for example, are promising candidates because of their low cost and process compatibility with the corresponding semiconductor laser light sources. As the WDM technology extends towards access networks, the cost reduction and fabrication simplicity of the key devices becomes more and more important.This thesis proposes the simulation and optimization of a novel electro-absorption modulated laser (EML) design which contains a lumped electrode type EAM integrated with a V-cavity laser. The integration is realized by quantum well intermixing (QWI) scheme to simplify the fabrication process. A simplified circuit model of the EML is adopted to analyze the high frequency characteristics. By optimizing its layer structure and geometry dimension, we obtain a -3dB bandwidth over 16 GHz and modulator capacitance below 0.17 pF. Fabrication of the device structure shall be carried out in future work to verify the simulation results with the experimental data. We believe this module is very promising for the next generation WDM applications.