3D waveguides with fiber couplers and 90 degree bends in holographic photopolymer

Abstract

Two active areas of research in the field of integrated optics are the coupling of on-chip waveguides to off-chip optical fibers and the reduction of circuit size which is dominated by the minimum bend radius of waveguides. Traditional approaches using mask-based lithography involve the complex etching of micro-mechanical on-chip mounts for the fiber or total-internal-reflection facets for sharp waveguide bends. Holographic photopolymers have several unique properties that enable a significantly simpler approach to both problems. Chief among these are the ability to be cast with low stress around embedded components and the ability to create localized 3D index structures. This is demonstrated by the fabrication of optical waveguides which couple directly to encapsulated fibers after making 90 degree bends off of encapsulated front-surface mirrors. The results are low loss and significantly simpler than existing approaches.