This search identifies 379 patent families published between 2015 and mid-2026 that combine PIC or silicon-photonics terminology with waveguide-specific claim language in the relevant optical-elements IPC subclasses. That figure counts families, not raw document counts, which avoids double-counting continuations and multi-jurisdiction filings of the same invention. The true total for later years will grow as publication catches up, since filing-to-publication lag runs about 18 months.

The assignee ranking in this dataset is led by a small group of repeat filers, including imec, Ghent University, Intel, GlobalFoundries US and others tracked in the momentum data, but the broader pattern is a long tail of single- or few-filing entrants beneath them. Only 10 co-assignee pairs exist across all 379 families, and one pairing — imec with Ghent University, at 20 shared filings — is far stronger than any other. That concentration of joint work in one partnership is itself a useful signal for anyone mapping who collaborates with whom in this space.

Filings rose from 13 in 2017 to a peak of 44 in 2022, then decline through the rest of the window, which reads as flat-to-declining rather than accelerating. However, the most recent one to two years are understated in any patent trend chart because publication lags filing by roughly 18 months, so the 2025-2026 dip should not be read as an actual stop in R&D activity. A clearer picture of 2024-2025 filing levels will only emerge once those applications publish.

WO2024231800A1, filed by École Polytechnique Fédérale de Lausanne (EPFL) and published 2024-11-14, covers a silicon nitride waveguide fabrication method built around a stress-release trench structure formed in a silicon oxide layer, with a silicon nitride layer deposited on top and a silicon oxide hard mask used to define and dry-etch an elongated waveguide core. The stress-release step is the distinguishing feature: it addresses a known fabrication challenge in depositing thick nitride films without cracking. Anyone fabricating nitride waveguides with a comparable stress-management step should review this filing's claim scope closely.

The core waveguide claim space (G02B) is dense and usually filed alongside laser (H01S) and modulation (G02F) claims, but adjacent applications such as gyroscope-grade waveguide designs (G01C overlap, 16 records) and material-analysis-integrated waveguide sensing (G01N overlap, 13 records) show much thinner filing density. That gap suggests these branches are less claimed rather than technically unworkable, since the same core waveguide fabrication methods used elsewhere in the dataset could plausibly extend into them. A first claim written specifically for one of these adjacent use cases would face less crowded prior art than a claim filed directly against the core G02B waveguide class.