Optical waveguiding in BaTiO3∕MgO∕AlxOy∕GaAs heterostructures

Abstract

Thin films of BaTiO3 with MgO buffer layers were deposited on patterned GaAs substrates incorporating AlxOy for optical confinement. The inclusion of AlxOy layers are used to provide a means for obtaining thick optical confinement layers as a substitute for MgO cladding layers which have large thermal expansion mismatch with respect to GaAs and BaTiO3 that typically result in thin film cracking. Deposition on patterned features was found to reduce thin film cracking and is attributed to a reduction in thin film stress resulting from thermal expansion mismatch. A maximum ridge width of 10–20 μm is estimated for 1-μm-thick BaTiO3 thin films. Optical waveguiding was observed in BaTiO3∕MgO∕GaAs∕AlxOy∕GaAs ridges suggesting the potential application of these structures for integrated optoelectronics.