Normal-incidence second-harmonic generation in ordered Ga/sub 0.5/In/sub 0.5/P

Summary form only given. Usual III-V semiconductors have the strong zinc-blende 43m symmetry that leads to the existence of only one non-linear coefficient (d/sub 14/) for the second-order susceptibility tensor. Though this coefficient is extremely large one important consequence of the symmetry rules is that second-order processes are forbidden along the three common substrate orientations crystal axes [100], [010] and [001]. This vanishing susceptibility prevents any second-order nonlinear opto-electronic device grown on usual crystal direction GaAs from working in a normal incidence configuration (i.e. with fields propagating along the [001] direction). We demonstrate experimentally that ordered semiconductors, changing the crystal symmetry from the usual zinc-blende for III-V semiconductors to CuPt-type can overcome this limitation.