Microwave CAD circuit modeling of a traveling-wave electroabsorption modulator

Conformal-mapping techniques are used to derive an effective and advanced calculation model for the microwave properties of a light-intensity traveling-wave electroabsorption modulator, resulting in a quasi-TEM computer-aided-design circuit model. For a given device geometry, the model provides the transmission-line (TML) parameters´ characteristic impedance and waveguide (WG) propagation constant. Closed-form expressions are derived for the reactive circuit elements. The calculation model includes both the effect of metal conduction loss, as well as losses due to induced currents in the semiconductor substrate. We treat both the buried heterostructure, as well as the ridge-mesa optical WG implementations. The model is validated with full-wave simulations and compared to measured TML parameters.