Electroabsorption in GaAs quantum-well waveguides

The measurement of electroabsorption in GaAs quantum-well waveguide modulators is reported. The absorption of the waveguide modes is ¿20cm1 at ¿10 V applied bias for photon energies ¿90meV below bandgap. The electro-absorption is polarisation-dependent. The absorption for light polarised along the field (TM mode) is smaller (by a factor of four) than for light polarised normal to the field (TE mode). The principal advantage of quantum-well modulators over regular double-heterostructure modulators is in the strong polarisation-dependent absorption. The electro-absorption effect can be used to produce light amplitude modulators, polarisers and photodetectors.