Semiconductor quantum dot (QD) lasers and optical amplifiers have drawn much attention due to expected performance improvement over quantum well (QW) lasers and amplifiers.GaAs-based 1.3-1.55 um vertical-cavity surface-emitting lasers (VCSELs) and semiconductor optical amplifiers (SOAs) are very promising to be used as low-cost and high-performance optical devices for fibre-optic metropolitan and local area networks, which current InP-based QW optoelectronic technology cannot provide.Many characteristics of current 1.3-1.55 um QD VCSELs and SOAs fulfil system requirements, but there are still many physical and technical issues to be further investigated before the deployment of mass production.In this project, the applicant will develop the advanced numerical modelling tools for QD VCSELs and SOAs based on the realistic QD wave functions and carrier distribution with its experimental verification. The realistic wave functions of QDs will be calculated in various three-dimensional QD potential and strain distributions. The carrier scattering time constants in QDs will be quantum-mechanically calculated.The material optical gain and carrier distribution will be obtained by solving the coupled rate equations. The static and dynamic output performance of QD V CSELs and SOAs will be calculated by incorporating the calculated QD parameters into simulation software tools. Finally, the calculated results will be compared with the measured data for verification.This project will contribute to understanding how the unique QD characteristics affect output performance of QD VCSELs and SOAs, and providing with a practical guideline to design high speed, high power QD VCSELs and polarization-insensitive QD SOAs.Realization of the low-cost and high-efficiency 1.3-1.55 um QD VCSELs and SOAs will facilitate the deployment of the cost-effective fibre-optic metropolitan and local area networks, which provide European community with a lot of convenience in network accessibility.