The assignee ranking in this dataset spans 100 companies, with the leader holding 439 records against 189 for the fifth-place assignee — a meaningful gap that signals a sustained, deliberate filing program rather than incidental activity. The leaders include large semiconductor foundries and networking equipment makers alongside academic and research-centre filers. No single company controls the field: the top 5 combined hold only 22.2% of all 6,368 records, leaving substantial room for other filers.

Filing activity peaked in 2021 at 549 records and had fallen to 350 by 2024, a 36% decline over that three-year span. That is a real pullback from an unusually active year rather than an abandonment of the technology. The 2025 and 2026 figures in the trend line should be read cautiously, since patent publication typically lags filing by around 18 months and those years are still filling in.

Both are structural approaches to getting light between a fiber and a photonic chip, and both appear heavily in this dataset’s search terms alongside coupling efficiency and alignment tolerance claims. Grating couplers use periodic structures etched into the waveguide layer to diffract light vertically, while edge couplers taper the waveguide to match the fiber’s mode at the chip’s facet. The representative filing in this dataset, US12591095B2, combines both coupler types on a single semiconductor layer, which is itself a sign that integration of the two approaches is an active area of claim activity.