Modeling, Design, Fabrication, and Characterization of Ultra-High Bandwidth 3-D Glass Photonic Substrates

This article presents the modeling, design, fabrication, and characterization of ultra-low loss 3-D optical waveguides integrated on a glass photonic substrate. A novel, single-step process was developed using moving-mask lithography to fabricate a single-mode optical waveguide with a built-in turning mirror capable of achieving 40° or 45° turns for vertical grating couplers or photodetectors, respectively. Planar alignment of the waveguide to fiber interfaces enable passive alignment of the fibers, contributing to system cost reduction. An optical path with 0.81 dB loss from fiber to die was obtained from optical modeling, while the fabrication of single-mode waveguides with built-in total internal reflecting mirrors at <0.2 μm uniformity and <1° angular control was demonstrated.