Developing novel nonlinear materials for metaphotonics device applications

Recent advancements in flat-optics, metamaterials research, and integrated optical devices have established the need for more efficient, spectrally tunable, and Si-compatible optical media and nanostructures with designed linear/nonlinear responses that can enable high-density integration of ultrafast photonic-plasmonic functionalities on the chip. Traditional methodologies for nanoscale photon manipulation utilize lossy materials, such as noble metals, which lack significant optical tunablility and compatibility with complementary metal-oxide-semiconductor technologies. In this dissertation, we propose, develop, and characterize alternative plasmonic materials that overcome these limitations while providing novel opportunities for significant optical nonlinear enhancement. Specifically, we investigate the plasmonic resonant regime and the nonlinear optical responses of Si- and O2- doped titanium nitride, SiO2- doped indium oxide, and Sn-doped indium oxide with engineered structural and optical dispersion behavior. We study a number of novel passive metaphotonic devices that leverage refractive index control in low-loss materials for near-field engineering and nanoscale nonlinear optical enhancement. Moreover, we integrate the developed alternative plasmonic materials into active metaphotonic surfaces for electro-optical modulation, enhanced light absorption, and ultrafast photon detection. Furthermore, utilizing the double-beam accurate Z-scan technique, we characterize the intrinsic nonlinear susceptibility χ(3) of optical nanolayers with epsilon-near-zero behavior as a function of their microstructural properties that we largely control by post-deposition annealing. A main objective of this work is to establish robust structure-property relationships for the control of optical dispersion, Kerr nonlinearity, and near-field resonances that extend from the visible to the infrared. This work substantially expands and diversifies the reach of plasmonics, flat-optics, and nonlinear optics across multiple spectral regions within scalable and Si-compatible novel material platforms