CPO ramp pushes silicon photonics testing upstream to catch defects early

The shift of silicon photonics testing upstream due to CPO ramp reflects a deep transformation in the semiconductor supply chain driven by AI compute demands. Upstream wafer fabrication faces tighter yield pressures, as testing moves from post-process to early-stage defect screening, intensifying requirements for EUV, photoresist, and thin-film processes. Midstream test equipment vendors must rapidly evolve to meet early-stage detection needs, while downstream server makers adjust supply chains to cope with shortened delivery cycles. Policy-wise, U.S. export controls on advanced tech continue tightening, accelerating domestic substitution but leaving reliance on high-end tools. In global competition, TSMC and Samsung are poised to gain early advantages, while local players must balance R&D investment and technical strategy. Over the next 12-24 months, upstream testing will become industry standard, forcing the entire ecosystem toward greater precision and intelligence.