LPCVD Silicon Nitride Photonic Integrated Components Designed at 532 Nm Wavelength for a Novel Retinal Projection Concept and Visible Domain Applications

This paper describes the design, fabrication, and experimental characterization of several photonic integrated components specifically made for a novel retinal projection concept for augmented reality applications. The retinal projection concept is based on the combination of integrated optics and holography to generate a self-focusing image on the retina. The photonic integrated circuit used for the retinal projector is made of several passive photonic components fabricated with stoichiometric Si ₃ N ₄ : single-mode strip waveguides, variable radius bent waveguides, MMI couplers (Multi-Mode Interference), diffraction grating couplers and waveguide crossings. The photonic components are designed to work in the visible spectrum at λ = 532 nm. They are compact and generally show low losses, which are the two main requirements to easily insert the photonic integrated circuit on wearable glasses and enhance the image quality of the retinal projector. Our photonic components can also find applications in a variety of other fields related to the visible spectrum, such as biophotonics, optical phased arrays, visible light communication and more.