Micromachined multimode interference device in flat-fiber

Abstract

A novel flat-fiber platform is presented for fabricating integrated optical multimode interference (MMI) devices. Fabrication is achieved by modifying a standard optical fiber drawing process and applying a micromachining technique. The fabricated structure consists of an MMI region within the flat-fiber that is defined by micromachined trenches, illustrated in Figure 1(a). A 1×3 splitter has been demonstrated, with a spatial output mode that be tuned by placing refractive index oils within the micromachined trenches.
MMI devices have been demonstrated in different planar platforms such as silicon-on-insulator and silica-on-silicon. However, many of these materials are potentially expensive, high loss or have a complex fabrication process. The desire to have a fiber-like platform, capable of supporting multiple waveguides in a planar format, led us to develop a novel silica optical flat-fiber technology. This allows us to overcome the limitations of existing planar technologies by offering a low cost, low loss substrate with fiber-like flexibility, long lengths and the ability to make integrated devices. The flat-fiber substrate is fabricated using standard silica fiber fabrication but differs by collapsing the preform during the fiber drawing stage by using a vacuum. The trenches of the device were diced using an ultra-precision micromachining technique.

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Identifiers

ORCID for C. Holmes: orcid.org/0000-0001-9021-3760

ORCID for J.C. Gates: orcid.org/0000-0001-8671-5987

ORCID for P.G.R. Smith: orcid.org/0000-0003-0319-718X

ORCID for J.K. Sahu: orcid.org/0000-0003-3560-6152

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