Linear and quadratic electro-optic coefficients of self-organized In0.4Ga0.6As/GaAs quantum dots

The electro-optic properties of self-organized ${\mathrm{In}}_{\mathrm{0.4}}{\mathrm{Ga}}_{\mathrm{0.6}}\mathrm{As/GaAs}$ quantum dots have been studied experimentally. Single-mode ridge waveguide structures were grown by molecular beam epitaxy with self-organized ${\mathrm{In}}_{\mathrm{0.4}}{\mathrm{Ga}}_{\mathrm{0.6}}\mathrm{As/GaAs}$ quantum dots in the guiding region. The measured linear and quadratic electro-optic coefficients are ${\text{2.58×10}}^{\text{−11}}$ m/V and ${\text{6.25×10}}^{\text{−17}}\hspace{0.17em}{\mathrm{m}}^{\mathrm{2}}{\mathrm{/V}}^{\mathrm{2}},$ respectively, which are much higher than those obtained for bulk GaAs or quantum well structures. The measured transmission characteristics indicate that low-voltage amplitude modulators can be realized with quantum dot active regions.