AuthenX: Widening FAU Alignment Tolerance to ±18µm, With Everything Riding on a Single Metalens
In this series we have broken down FOCI, Largan, SENKO, Teramount and TSMC. With AuthenX (7928), a new kind of player enters: a startup that only listed on Taiwan's emerging stock board in 2026, betting everything on one critical interface in CPO optical coupling. It uses a metalens to widen FAU-to-PIC alignment tolerance all the way to ±18µm.
Let us be upfront: I could not find any public FAU or metalens patents filed under AuthenX. The company was founded only in 2019, its metalens-FAU was first presented at OFC 2026, and Taiwan patents have a publication delay of about 18 months, so they may simply not be public yet. This piece is therefore a "technology positioning analysis", not a patent-by-patent breakdown.
A Flat Lens Built from Arranged Nanostructures
A conventional lens refracts light through a curved surface; a metalens instead arranges a large field of nanopillars on a flat surface. The size of each pillar sets how much phase it imparts to light, and with the overall phase profile designed correctly, a flat surface can collimate or focus. AuthenX uses two metalenses: one attached to the PIC collimates the diverging light from the grating into a beam about 70µm wide, and one attached to the FAU focuses it into single-mode fiber.
Because it is a planar nanostructure, it can be made on wafers with semiconductor lithography, which is what gives AuthenX the confidence to promise "12-inch volume production".
±18µm: Widen the Tolerance and the Whole Path Opens Up
This is the most important number in the piece. Coupling fiber directly to a silicon waveguide traditionally means a sub-micron mode field, where a lateral offset of a few tenths of a micron loses a lot of light. By expanding the beam with metalenses, AuthenX widens the 1-dB alignment tolerance to ±18µm, one to two orders of magnitude larger; attaching the metalens to the PIC itself needs only ±2µm, well within existing die-bonder capability.
Wide tolerance is not just about easier alignment. It simultaneously unlocks pluggability (replace a failed FAU without scrapping the ASIC) and manufacturability (auto-generated GDS, lithography, 12-inch wafers). Behind all this, however, lie two questions that must be answered before investing.
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That concludes the key takeaways of this piece.
STT's full assessment, covering a section-by-section breakdown of the dual-metalens architecture; key figures such as ±18µm, M² 1.2 and 89.7°±0.17°; the technical basis for pluggability and 12-inch volume production; and the two most important watch points: whether the "patented metalens" is owned by AuthenX or licensed (metalens is one of the world's most patent-dense fields, with Metalenz, universities and TSMC COUPE all filing), and whether it can clear US certification and yield, is available in the premium section, including all 5 original schematic diagrams and a positioning assessment table (in Chinese).
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