Photoelastic waveguides formed on bulk GaAs or Si

In this work, we proposed a new waveguide structure that can be formed on bulk semiconductor substrates without requiring any epitaxial or separate cladding layers for vertical confinement of light. In the proposed structure, vertical confinement of light is achieved via a photoelastic effect induced by thin-film stress, and lateral confinement is obtained by a semiconductor mesa or a photoelastic effect itself. We have carried out numerical analyses on the stress distribution, dielectric constant changes, and mode profiles at 1.3 micrometer or 1.55 micrometer wavelength in GaAs or Si. The results show that the proposed structure can support guided modes with the amount of stress that can be obtained from typical thin-film/semiconductor interfaces. To demonstrate the proposed waveguide concept, we fabricated the photoelastic waveguides on bulk GaAs substrate. The fabricated structures were characterized in terms of their guided mode profiles, using ga 1.3 micrometer wavelength semiconductor laser as a light source. Both the vertical and the horizontal profiles were obtained, and the results show a good agreement with the simulation results, thus confirming the proposed concept.