Silicon Photonics

Overview

Silicon photonics uses silicon as a photonic material platform for optical interconnects, switches, and computing elements — leveraging existing CMOS fabrication infrastructure for cost-effective, high-density photonic integrated circuits. The fundamental appeal is monolithic co-integration: photonic waveguides, modulators, detectors, and CMOS control electronics can be built on the same wafer using 193 nm immersion lithography at 300 mm scale, enabling the cost amortization of semiconductor manufacturing investment over optical components.

In the AI infrastructure context, silicon photonics is emerging as the primary candidate technology for co-packaged optics (CPO), where optical transceivers are integrated directly onto switch packages rather than in pluggable modules. NVIDIA Spectrum-6 uses silicon photonics with Micro Ring Modulators co-developed with TSMC via the COUPE process, claiming the industry-first 1.6T silicon photonics CPO chip. The technology is simultaneously advancing as a platform for optical circuit switching and — in research settings — for photonic AI accelerators.