Novel structures of traveling-wave MQW electro-absorption modulators for 1.55 /spl mu/m operation

We analyze microwave transmission characteristics of the travelling wave electroabsorption modulator (TW EAM) using the 3D finite difference time domain (FDTD) method, and achieve structural optimization overcoming bandwidth limitation factors such as phase velocity mismatch and microwave loss. Phase velocity mismatch between lightwave and microwave results in continuous phase shift in the modulated lightwave transmitting through waveguide, and microwave loss increases with the increase of frequency and transmission length. Here, we focus on structural optimization of the 1.55 μm TW co-planar waveguide MQW as well as the N-I-N parallel plate EAM structure. The optimization is accomplished with optical waveguide analysis considering the thickness and conductivity of the N-doped layer, characteristic impedance matching, and microwave attenuation.