Strip-loaded slot waveguide: a step beyond integrated photonics limits (Conference Presentation)

Abstract

We propose a novel waveguide type based on the concept of strip-loaded waveguide. A strip-loaded waveguide is composed of a thin-film slab waveguide allowing a vertical confinement of the electromagnetic field. A lower refractive index strip provides the lateral confinement by inducing a slight modification of the effective index in the slab. By using such a generic device we will demonstrate how the limits of integrated photonics can be extended, especially, in terms of propagation losses while adding complex structure on the waveguide. Since light sees only a slight variation of effective index, and not an abrupt change of material, propagation losses of the device are fully determined by the film rather than by the structuration. Different micro- and nano-structures will be presented through simulation and experimental results. We will focus especially on the study of Y-junctions, ring resonators, interferometers, and Bragg gratings. Another advantage of strip-loaded waveguides is the simplicity of fabrication. In order to fabricate the devices we employed nano-imprinting of polymer, a fabrication technique suitable for mass production. The low refractive index of the polymer allows a large panel of materials for the slab waveguide, e.g., silicon, titanium dioxide, and lithium niobate. This diversity in the choice of the materials gives to the platform the potential to operate on a wide wavelength range from UV to IR, for multiple applications in telecommunications, sensing and bio-sensing, and medical devices.