Second-harmonic generation in periodically poled silicon waveguides with lateral p-i-n junctions

Electric-field-induced second-harmonic generation is demonstrated in silicon waveguides with reverse biased lateral p-i-n junctions. Phase matching is achieved by periodically poling the applied electric field. Two different poling configurations are compared: in the first, the p- and n-type doped regions of the junctions are on different sides of the waveguide (simple configuration), while in the second, they are alternated periodically across the waveguide sides (interdigitated configuration). Both simulations and experiments show that the generation efficiency is increased by 10 times comparing the interdigitated and simple configurations. The effective second-order susceptibility modulation obtained at a reverse bias voltage of 3.5 V is Δχeff,S(2)≃0.14pm/V for the simple configuration and Δχeff,I(2)≃0.64pm/V for the interdigitated one.