Design and optimization of evanescently coupled waveguide photodiodes

We present the design and optimization of evanescently coupled waveguide photodiodes(EC-WPDs) based on the coupling modes theory and the beam propagation method. Efficient focalization of the optical power in the absorber is achieved by an appropriate choice of index matching layers of EC-WPDs. Numerical simulation shows that high-speed(40 GHz), high quantum efficiency(81%) and high linearity photodiodes can be achieved, and EC-WPDs are promising devices for future optical communication systems.?2011 Chinese Institute of Electronics