Experimental validation of SiN photonic integrated waveguide arrays at λ=532 nm for Augmented Reality display applications

Our team is currently developing an innovative and compact retinal projection display concept for augmented reality applications. This concept intends to break with conventional optics using a device based on an integrated photonics architecture. Designs and simulations of test structures have been presented in previous works. Here, we present experimental results obtained on stoichiometric Si3N4 integrated photonic circuits designed for lambda = 532nm. The samples combine several building blocks such as grating couplers, Multi-Mode Interferometers (MMI) and dense waveguide arrays with several emissive areas. We used a goniometric characterization bench to perform far field measurements. For near field characterization, an imaging setup using a 4.5mm-focal lens system and a high-resolution CMOS camera was mounted on the goniometer. The power profiles of emissive points were measured in the near and far field. Regarding the dense waveguide arrays, their angular characterization confirms our simulations and allows us to emphasize the impact of trapezoidal-shaped waveguides on the emission angle. We measured a homogeneously distributed power profile accross the waveguide distribution on the emissive areas. The power ratio of each emissive area remains relatively uniform. This is a promising result for our future work where light must be equally and uniformly distributed over the surface of the display.