Coupled quantum-well electro-optical modulator

Claim 1

A reverse-biased coupled quantum well electro-optical modulator consisting of a structure composed of a plurality of semiconductor layers, comprising: a first metal layer allowing the structure to be connected to a lead for the application of a control electrical potential, a p-type layer in the form of an AlGaAs layer with a thickness of about 1 micrometer below said first metal layer, an intrinsic layer in the form of an AlGaAs layer having a thickness of about 1 micrometer below said p-type layer, at least one layer sandwich below said intrinsic layer and comprising: a first GaAs quantum well layer, and an intrinsic AlGaAs barrier layer, a second GaAs quantum well layer, and a further intrinsic layer of the layer sandwich, a first n-type layer in the form of an AlGaAs layer of a thickness of about 3 micrometers below said further intrinsic layer, an n-type cover layer below said fist n-type layer, a substrate below said cover layer, and a second metal layer allowing the structure to be connected to a second lead of the application of the control electrical potential, said metal layers, said substrate and said cover layer having holes to allow the passage of a light radiation perpendicular to the layers and entirely through all said layers and the modulator, said first and second quantum well layers and said barrier layer, having thicknesses in a range of 33ű10% so that said layer sandwich presents a light radiation absorption threshold which shifts toward shorter wavelengths in a blue shift when an electrical field of the order of 10 4 V/cm is applied, said modulator absorbing little light radiation in an absence of said electrical field.