These guys were definitely going to be using diffractive waveguides (photonic crystal waveguides). Look at the LinkedIn profiles of some of the folks on their

These guys were definitely going to be using diffractive waveguides (photonic crystal waveguides). Look at the LinkedIn profiles of some of the folks on their optical design team (especially the ones with titles that include "Diffractive Optics Engineer"). One had a PhD adviser at Berkeley (Eli Yablanovitch) who originally coined the term "photonic crystal", another wrote a widely used open source implementation of RCWA (S4) while working with a top group in photonic crystal design at Stanford (Shanhui Fan), and some of their engineering leadership came to the company from what was Digital Optics Corporation.