Ultrashort mach-zehnder space switch based on quantum dots

Abstract

We investigate whether the discrete energy levels and the high peak absorption in quantum dots (QDs) provide an opportunity for increasing the electro-optic and nonlinear optical properties. For this purpose we calculate the electrorefraction spectra of QDs starting from the Luttinger-Kohn Hamiltonian and using a plane-wave expansion for solving the eigenstates of the QD. For a pyramidal InAs/GaAs quantum dot, we find a high peak electrorefraction of 0.35 for TE-polarization, which is 35x larger than in a quantum well. In the tail of the quantum dot absorption spectrum, we find an electrorefraction of 1.3.10-2 at an absorption loss of 0.15 dB/cm. Finally we investigate the refractive index variation due to state filling in InAs/InP cylindrical quantum dots