FABRICATION OF PHOTONIC DEVICES ON LITHIUM NIOBATE ON INSULATOR (LNOI) CHIPS

Abstract

The high electro-optic and nonlinear coefficients of lithium niobate make it a highly promising material for optical modulator design, cavity quantum electrodynamics experiments, and microwave photonics. This thesis describes the fabrication techniques developed and optimized to produce low-loss waveguides and resonators in lithium-niobate-on-insulator (LNOI) chips. LNOI chips comprise a thin film of lithium niobate adhering on an insulating substrate like silicon dioxide. Devices fabricated on LNOI through etch-based techniques provide good vertical and mode confinement because of the high index contrast between the waveguiding and cladding regions. Also, because of the smaller waveguide widths attainable, a greater control of the critical dimensions of devices is possible. Optical waveguides, power splitters, and microring resonators are fabricated on lithium-niobate-on-insulator chips, with robust fabrication techniques, namely electron beam lithography (EBL) and ion-beam etching, which have the potential to be used in the mass manufacture of compact lithium niobate based optical devices.