Silicon photonics testing: CPO patent landscape | Patsnap Insights

Silicon photonics testing: the CPO bottleneck and who owns the patents

In under two months in early 2026, a wafer-level burn-in specialist most of the market had never heard of booked four separate silicon-photonics orders, landed its first major hyperscale networking customer, and raised $60M to expand capacity. It is tempting to read that as a stock story. It is not. It is a signal about a wall the entire optical-interconnect industry just hit.

As co-packaged optics (CPO) and 1.6T optical interconnects move from demo to volume in 2025–2026, the hardest unsolved problem is not fabricating the silicon photonic chip. It is proving the chip is good before it is permanently bonded to a switch ASIC it can never be separated from again. Get it wrong, and a single latent defect scraps a package worth thousands of dollars. That one constraint, known-good die before co-packaging, is quietly redrawing the competitive map.

And the action is not where most market maps look. It is not the big logic vendors everyone watches; it is OSATs in Taiwan, networking incumbents, and a handful of test-equipment specialists racing to file the test, burn-in, and reliability patents that will gate who can manufacture CPO at scale. This analysis breaks down the five technical bottlenecks strangling silicon photonic test today, maps the ~467-patent IP landscape around them, and names the players positioning to own the chokepoint. The patent corpus, filing trends, and assignee clusters throughout were surfaced and structured using Patsnap Eureka.

Reviewed by the Patsnap Insights editorial team · 26 June 2026

Why testing became the silicon photonics bottleneck

As CPO and 1.6T interconnects enter volume production in 2025–2026, silicon photonic (SiPh) ICs face a fundamentally different and harder test problem than either conventional CMOS or pluggable optics. The core difficulty is that SiPh chips are simultaneously optical and electronic devices, yet most production-line automated test equipment was built for one or the other. The patent corpus reflects how fast the field has responded: filings climbed from roughly 47 in 2021 to 103 in 2022, 89 in 2023, and 77 in 2024 (with 2024–2025 still publishing), for ~467 relevant patents in scope. That IP concentrates around five distinct technical clusters.

The five core bottlenecks

1. Wafer-level optical probing: the throughput wall

Unlike electronic ICs, where a probe card simply touches metal pads, SiPh wafers require simultaneous electrical probing and optical signal coupling into sub-micron waveguide facets or grating couplers. Misalignment of even 100–200 nm causes coupling loss above 3 dB, making automated wafer-level test far slower and less reliable than for CMOS. At 1.6T line rates (eight lanes of 200G), every lane must be tested at speed: a single wafer with hundreds of dies can demand hours of optical alignment.

Teradyne has flagged this among the top emerging test challenges for SiPh in CPO form factors, noting that solutions are needed at the wafer, package and system levels at once. The 2026 SWTest conference featured a session on a first probe card for measurements at 120 GHz to support 1.6 Tbps, a sign the probe-card ecosystem is still catching up. Key filings here include Mellanox/NVIDIA’s shared on-wafer test coupler (US12174238B2), Huawei’s angled-fiber edge-coupler approach (WO2020132968A1), Xilinx/AMD’s probe-access chip architecture (EP3607370B1), and King Yuan Electronics’ floating auto-alignment handler module (US20260169061A1).

2. Pre-packaging burn-in: the known-good-die crisis

CPO irreversibly bonds the SiPh photonic IC and the switch ASIC or XPU on the same substrate. If a latent defect surfaces after co-packaging, the entire expensive assembly is scrapped. Burn-in for optical components needs elevated-temperature, elevated-bias stress, but SiPh dies combine stable silicon waveguide passives with thermally sensitive III-V-bonded lasers and modulators, and traditional high-temperature operating-life conditions can degrade those optical elements irreversibly. A new burn-in regime is required.

Aehr Test Systems has become the dominant commercial player, with its FOX-XP wafer-level burn-in platform adopted for CPO applications and TSMC CPO samples referenced as ready for its systems. On the IP side, Chunghwa Precision Test’s pre-co-packaging fixture (US20250216450A1) forms independent optical and electrical signal loops to qualify the photonic and electronic stack before bonding, aimed squarely at the known-good-die problem. The foundational Arrhenius accelerated-life framework for laser burn-in (II-VI/Finisar, US6977517B2) has since expired, but remains the basis of most photonic burn-in protocols.

3. Built-in self-test (BIST) and loopback architecture

Once co-packaged, external optical access to the SiPh die is limited or impossible, so system-level test and field diagnostics depend on on-chip loopback and self-test. This is acute for CPO on switch ASICs, where hundreds of optical lanes must be validated at power-on, and for field RMA diagnosis when the module cannot be opened. Cisco’s three-patent optoelectronic BIST family (US9960888B2, US10348459B2, US10721035B2) covers PRBS-based self-test with a replica loopback photodetector and is among the most cited in the space. Arista’s on-PIC optical loopback (US11411643B1) switches between communications and test modes specifically for CPO devices, and Marvell’s monolithic SiPh SoC self-test (US11630799B2, US12174781B2) folds loopback calibration into the chip itself.

4. Thermal management and reliability under co-packaging stress

In a CPO package the photonic die sits beside a 500–1000W switch ASIC. Thermal gradients drive differential expansion, waveguide phase drift, and ring-resonator wavelength shift (silicon’s thermo-optic coefficient is roughly 1.86×10⁻⁴/K). Qualification must span thermal cycling, high-temperature storage and thermal shock, adapted to photonic performance metrics, and datacenter-grade SiPh is increasingly being held to telecom-grade reliability expectations. Innolight Technology’s waveguide structure (SG11202601415PA) is engineered to survive high-temperature and high-humidity testing while remaining reflow- and TSV-compatible, and Applied Materials’ PIC-to-glass evanescent bonding (WO2025165612A1) targets the mechanical reliability of the optical coupling interface under thermal cycling.

5. Optical coupling interface reliability and connector alignment

The fiber-to-chip or chip-to-chip optical interface is the single highest-failure-risk mechanical element in a SiPh module. At 1.6T densities this means MT-ferrule or lensed-fiber arrays with sub-micron tolerances, where insertion cycles, vibration and thermal expansion all degrade coupling loss over time. Test fixtures must hold alignment repeatability across thousands of device insertions, the focus of King Yuan Electronics’ pressure-sensing floating-connector design and Chunghwa Precision Test’s reflective-wall jig coupling.

The IP landscape: who holds what

The ~467-patent corpus (scoped to SiPh by test, burn-in and reliability, by CPO and optical interconnect, and by qualification methods) has a revealing assignee structure. Intel holds the largest position by raw count, but that lead is broad silicon photonics integration IP rather than CPO-specific test IP. The patents that actually gate CPO manufacturing concentrate elsewhere.

The technology-cluster view tells the same story from the other side. Top terms across the corpus (integrated circuit, electrically conductive structures, silicon substrate, photonic integrated circuit, die, waveguide and semiconductor) show the filings clustering where the optical and electronic domains physically meet, which is exactly where test and qualification get hard.

Strategic implications for IP and R&D teams

Known-good die before co-packaging is the dominant forcing function. Because CPO cannot be reworked, the industry is converging on pre-package photonic-die qualification, opening IP opportunity around fixture design, optical-electrical co-test, and burn-in protocols. Chunghwa Precision Test and King Yuan Electronics are staking early OSAT-side claims here.

Intel’s count is broad, not CPO-specific. Its ~214 in-scope patents span SiPh integration generally; the CPO-specific test IP is concentrated in Cisco, Arista, Marvell and Mellanox/NVIDIA. Anyone building CPO products should run freedom-to-operate analysis against the active, highly cited Cisco BIST family (US9960888B2 / US10348459B2 / US10721035B2) and the Arista loopback patent (US11411643B1).

Burn-in methodology is largely open; the equipment IP is not. The foundational Arrhenius accelerated-life family has expired, freeing the underlying method, but the equipment and fixture IP around wafer-level burn-in for SiPh specifically is still being actively filed.

1.6T is pushing test infrastructure now, not later. The SWTest 2026 session on a 120 GHz probe card for 1.6 Tbps signals that probe-card and test-signal generation are a near-term constraint. And thermal qualification standards are still unsettled: the gap between telecom-grade reliability and datacenter product cycles is unresolved, so whoever helps define the standard through OIF, IEEE 802.3 or JEDEC working groups will shape the IP landscape for the next decade.

Frequently asked questions

References

All data and statistics in this article are derived from Patsnap’s innovation intelligence platform and the references above. This landscape reflects a targeted query scope (SiPh by test, burn-in and reliability, by CPO and optical interconnect, by qualification methods) and represents a snapshot of innovation signals within that dataset only. Assignee counts reflect the query scope and may not represent each company’s total portfolio; an ~18-month publication lag applies to 2024–2025 filings. It should not be read as a comprehensive view of the full industry, nor as legal or investment advice.