Self-aligned fabrication process for coupling of photonic waveguides

Abstract

A self-aligned fabrication process for aligning photonic waveguide layers of a 3D photonic structure such that light may be efficiently transferred between the two layers is described. The self-aligned fabrication process comprises using a mask to pattern both photonic waveguide layers, such that they are aligned three-dimensionally via a single lithographic processing step, and thus fabricating a photonically coupled region of the 3D photonic structure. Selective etching may also be used to taper a given photonic waveguide layer for adiabatic coupling, and/or to produce other non-trivial geometric shapes in the photonic waveguide layers. Such 3D photonic structures may be fabricated for use in quantum memory devices, in which one of the photonic waveguide layers may host quantum memories and another photonic waveguide layer may interface with an optical fiber, such that light may be transferred between an optical fiber and respective ones of the quantum memories.