Accurate characterization of nanophotonic grating structures

Abstract

Augmented reality waveguides are designed to have grating regions to in-couple, out-couple, and propagate light from a light engine to the user. This thesis develops two reliable systems to qualify manufactured waveguides. The first system determines grating quality by measuring grating pitch and orientation uniformity across grating regions. The system uses scatterometry in Littrow configuration and captures both the reflected zeroth and first order diffracted light. The second system determines the overall quality of a waveguide by measuring the resolution of the device using a Modulation Transfer Function, MTF, technique. MTF is commonly measured using either the line pair method or the slant edge method. This thesis proposes a new method to measure MTF using single pixel illumination and point spread function. Results from the two systems are presented, and the capabilities and limitations of each system are explored.