Phase control of an exciton-polariton in a quantum well waveguide and its application to optical devices

Electric-field-induced phase change of an exciton-polariton transmitted along the GaAs quantum well waveguide was measured as a function of temperature. Large phase changes up to 120 K were obtained. These phase changes explain the highly-efficient operation of Mach-Zehnder-type modulators and directional-coupler-type switches up to 77 K. These results are not explainable simply in terms of polariton stability, which indicates that the temperature-dependent phase change under the electric field is affected by more complex factors related to the polariton effect. (C) 2002 Elsevier Science B.V. All rights reserved.