| abstract |
A non-linear optical device for carrying out optical signal processing using a non-linear optical material having a biasing electric field perpendicularly applied to a semiconductor that is laminated to form a quantum well structure. A well layer of the quantum well structure has substantially the same thickness as the Bohr radius of an exciton, and the magnitude of the biasing electric field is selected so that the distance between centers of gravity of an electron and a hole, which constitute the exciton, is from a fraction of to substantially equal to the effective Bohr radius. The thickness and potential of a barrier layer of the quantum well structure is selected such that the increase in the width of the absorption peak of the exciton caused by ionization due to tunneling in the biasing electric field is smaller than the width of the absorption peak with no electric field, and the wavelength of light used to activate the device is selected such that the photon energy nω is substantially equal to or slightly smaller than Eex/2, where Eex is the energy generated by the exciton of the quantum well structure. That light is polarized, and its electric field vector has a component normal to the layer of the quantum well structure. |