Design and fabrication of photonic devices using phase change materials

This dissertation is on the design and fabrication of novel devices using phase change materials, specifically Vanadium Dioxide and germanium antimony-tellurium (GST). First, the principles of subwavelength gratings are developed using the Rigorous Coupled Wave Analysis (RCWA) Model for studying the diffraction efficiency of different orders for both TM and TE waves. This work also includes fabrication and process development as well as addressing the challenges of subwavelength gratings using deep-UV interference lithography. The next part is on material characterization of the two most important phase change materials, Vanadium Dioxide and germanium-antimony tellurium (GST), followed by the design of polarizing and birefringent devices. Modeling results for switchable polarizers using vanadium dioxide and GST are developed, as well as a comprehensive study of the doping effects of GST to reduce its resistivity, especially in its amorphous state. It is shown that nickel-doping is able to reduce the resistivity without compromising the contrast in optical properties, thereby allowing GST-based devices to be electrically switched without a large impedance discrepancies between the amorphous and crystalline states