Progress Toward Viable Epitaxial Oxide Ferroelectric Waveguide Heterostructures on Gaas
AbstractDiscoveries within the last two years have created possibilities for the fabrication of epitaxial oxide heterostructures on GaAs substrates. In particular, magnesium oxide, MgO, may have broad applications, including its use as a cladding layer in optical waveguides. This report expands upon earlier work by revealing additional epitaxial structures involving lithium niobate which have been grown. There are now five known variants of Z-lithium niobate on GaAs: direct Z-cut growth on GaAs (111)A or B, Z-cut growth on MgO (111)/GaAs (111)A or B, and Z-cut growth on MgO (111)/GaAs (001). Broad in-plane misalignment (about 15°) characterizes the latter structure, whereas the former posses a textural width of 3° to 5° in the plane. All structures contain internal boundaries resulting from 180° rotations about the Zaxis. A critical issue for any ferroelectric heterostructure is its integrity in the presence of thermally induced tensile strain. Approaches to the mitigation of thin fim fracture are discussed and a novel approach to strain relief via ridge waveguide fabrication is reported.
Practical example for use of the supervised vicarious calibration (SVC) method on multisource hyperspectral imagery data – ValCalHyp airborne hyperspectral campaign under the EUFAR framework