Abstract
We report stress-induced channel waveguides formed in epitaxial BaTiO 3 films. BaTiO 3 epitaxial films (doped with and without erbium) were grown on MgO (001) single- crystal substrates using rf magnetron sputtering. In the channel waveguides developed, the lateral confinement of light is achieved via the photoelastic effect in BaTiO 3 induced by thin-film stress. As a stress-inducing film, a 0.5- micrometer-thick SiO 2 film was sputter-deposited on top of a 3.0-micrometer-thick BaTiO 3 film with a 7 to 10- micrometer-wide window opening. The fabricated structures were characterized in terms of their guided mode profiles at 1.3 and 1.55 micrometer wavelength. The measurement result clearly shows both the lateral and vertical confinement of light in the channel region. The stress distribution in the channel structure was calculated by solving the coupled equations that describe the elastomechanical and piezoelectric effects in the ferroelectric material. The refractive index changes were than calculated taking into account both the photoelastic and electro-optic effects of BaTiO 3 . The simulation results show a good agreement with the measurement results. The waveguide structure developed in this work does not require etching of BaTiO 3 , and is expected to be useful as a simple and economical method for forming channel waveguides with other ferroelectric films as well.
Published Version
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