A Si ridge waveguide integrated with a lateral p-i-n diode forms a basic optical amplitude
and phase modulator. An efficient Si modulator is expected to establish a carrier concentration in
the waveguide with a minimum amount of electrical drive power.
We show that P+ and N+ doping sections that are recessed below the slab lead to lower power
consumption. This configuration is compared with alternative doping section arrangements. The
optimum arrangement results in less Si active area and reduced carrier recombination.