US Patent 7656922 Multi-level integrated photonic devices

A laser and electroabsorption modulator (EAM) are monolithically integrated through an etched facet process. Epitaxial layers on a wafer include a first layer for a laser structure and a second layer for an EAM structure. Strong optical coupling between the laser and the EAM is realized by using two 45-degree turning mirrors to route light vertically from the laser waveguide to the EAM waveguide. A directional angled etch process is used to form the two angled facets.