800G and 1.6T optics raise testing requirements across physical and system layers, says Viavi

Higher data rates narrow margin for error. Signal integrity becomes harder to maintain as links grow more susceptible to noise, insertion loss and crosstalk. That increases the need for high-bandwidth oscilloscopes, bit-error-rate testers, and measurement techniques that reveal subtle impairments. Tests that were adequate at lower speeds no longer expose issues that will matter at 800G and 1.6T.

System-level validation expands scope

Validating a single link is necessary but not sufficient. AI fabrics require synchronized throughput, consistent low latency and reliability across the entire interconnect. Multi-vendor interoperability testing is essential as deployments mix optics, switch silicon and host interfaces. Demonstrations at industry events such as OFC 2026 highlighted how interoperability testing surfaces problems that link-level checks miss.

Power, heat and density are test parameters

Higher-speed optics and denser module counts increase power draw and heat generation. Test programs must measure power consumption, thermal behavior and system stability under real operating conditions. That includes airflow and cooling-efficiency validation in high-density racks. Maintaining performance while staying within power and thermal limits is now as important as meeting bandwidth and latency targets.

Design trends driving test requirements

Vendors are responding with new optical designs meant to lower power per bit and fit tighter spaces. Changes include alternative form factors and increased use of silicon photonics, along with architectures optimized for cooling and space constraints. These design shifts create new measurement points and test scenarios, especially around module thermal response and platform-level interactions.

The industry is already preparing for still higher rates such as 3.2T. That will amplify existing challenges: even tighter signal margins, greater demands on interoperability, and more acute power/thermal trade-offs. Test and measurement strategies should evolve now to be scalable for future speeds.

• Physical metrics: signal integrity, noise, loss, crosstalk, BER under stress.
• System metrics: synchronized performance across the fabric, latency tails, and reliability under real workloads.
• Operational metrics: power per bit, module and system thermal behavior, airflow and cooling efficiency.
• Interoperability: multi-vendor conformance and end-to-end validation across devices and optics.

Moving to 800G and 1.6T changes how networks are validated. Test programs need broader scope and higher-fidelity instruments. They must combine deep physical-layer measurements with system-level and operational tests that reflect AI workload demands and the realities of dense, high-power deployments.