The Unique Problem of Fabricating Tapered Transitions

While propagation loss in electro-optically active waveguides remains a great concern, typically the greatest contribution to device insertion loss comes from mode mismatch between silica fibers and electro-optic waveguides. At 

Another approach to low loss coupling makes use of the production of vertical waveguide transitions (to be discussed later with respect to packaging [65, 272-278]). Essentially, a section of high index electro-optic waveguide is fabricated on top of a very low loss passive polymer waveguide [65,273,275]. The op- 

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