An optimization method for depletion-based silicon optical modulators

摘要

A new optimization method is described and performed on high-speed silicon optical modulators based on carrier depletion in a p-i-n junction. Quantitative results on the geometry of the waveguide and doping concentrations of the p-and n-doped regions are presented at the end of the optimization. General rules can thus be applied to design high performances optical modulators in term of modulation efficiency and insertion loss. Complete electro-optical simulations have been performed on optimal designs to evaluate the corresponding Figures of Merit and theoretical limits on performances have been exhibited. V_πL_π as low as 1.25 V.cm has been obtained at best for the p-n configuration, for a bias of 5 V and for a rib height of 400 nm. A strong dependence of the total optical loss with the geometry of the waveguide has also been demonstrated with an optimal value of 3 dB.