Light propagation in a coupled waveguide‐triple quantum well structure

Abstract

AbstractThe light propagation in a waveguide which was weakly coupled to a quantum well (QW) structure was studied to demonstrate the detectability of the electronic states in the small area of QW. The small area of QW was made with a GaAs/AlGaAs asymmetric triple QW. Since the electronic states in the triple QW were easily controlled by an electric field which was induced by an optical injection, we observed the optical spectra obtained from the waveguide under the various intensities of optical injection. The spectral change was observed around the characteristic wavelengths of the QW. In order to verify the observed spectral change, we measured the optical spectra of the traveling wave in a sample whose QW surface has been etched off. By comparing the results, we interpreted that the spectral change is due to the reconstruction of the electronic states in the small area of QW due to the optically excited carriers. This proves the detection of small electronic state changes in the small area of QW with the traveling light in the waveguide. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)