High-speed AlGaInAs multiple-quantum-well (MQW) electroabsorption modulated lasers (EMLs) based on an identical epitaxial layer (IEL) integration scheme are developed for 40-Gb/s optical fiber communication systems. A self-aligned planarization technique has been adopted to reduce the capacitance of the electroabsorption modulator (EAM). The IEL structure EML chips exhibit a small signal modulation bandwidth around 40 GHz. The influence of residual reflection at the modulator facet on the small signal modulation response is investigated. Submount containing a grounded coplanar waveguide (GCPW) transmission line is used for packaging the EML chips into transmitter modules. The optimization of the GCPW structure to suppress resonances in frequency response due to parallel-plate modes is presented. Clear eye opening under 40-Gb/s nonreturn-to-zero (NRZ) modulation has been demonstrated for the packaged EML module.