Electric Field Induced Second Harmonic Generation in Silicon Waveguides: The role of the disorder

One way to achieve a second-order susceptibility χ (2) in Si is by exploiting a third-order nonlinear effect, the Electric Field Induced Second Harmonic Generation (EFISHG) [1] . This phenomenon, through the use of a constant electric field ( E DC ) within the waveguide generated by lateral p-i-n junctions, gives rise to a χ (2) proportional to the electric field, χ(2)_{EFISH}=3χ(3)E_{DC} . In [2] , [3] we have shown that using an interdigitated poling structure to satisfy the quasi phase matching condition required for SHG results in an increase in the generation efficiency ( η ) compared to a simple configuration, see Fig. 1 . The presence of disorder in the waveguide and poling geometry was also shown to cause a widening of the η spectrum.