Larger width of P-cladding layer in p-i-n waveguide of traveling wave electroabsorption modulator (TWEAM) results in lower resistance and microwave propagation loss which provides an enhanced high speed electro-optical response. In this paper, a full-vectorial finite-difference-based optical mode solver is presented to analyze mushroom-type TWEAM. The important parameters in the high-frequency TWEAM design such as optical effective index and transverse mode confinement factor are calculated. The modulation response of mushroom-type TWEAM is calculated by considering interaction between microwave and optical fields in waveguide and compared with conventional ridge-type TWEAM. The calculated 3dB bandwidths for ridge-type and mushroom-type TWEAM are about 139 GHz and 166 GHz for 200 mum and 114 GHz and 126 GHz for 300 mum waveguide length, respectively.
