SOI substrate monopoly for silicon photonics engines
AI supply-chain thesis — mapping bottlenecks, focus companies, and supply-chain exposure for investors.
**Bottleneck theme:** InP & Substrates
**Focus:** $SOI — Soitec
Soitec is the global monopoly in SOI (silicon-on-insulator) substrates and is positioned as a critical supplier to the silicon-photonics build-out. Every silicon-photonics engine — pluggable transceiver, CPO, Lightmatter/Ayar-style reticle-scale interposer — needs a high-quality SOI wafer with a precisely engineered buried-oxide layer. Soitec's Smart Cut process and decades of substrate engineering experience give it ~80%+ market share in SOI for advanced applications, with no credible alternative supplier outside Asia.
The thesis is two-pronged: (1) silicon-photonics SOI demand is growing fast as 800G→1.6T→3.2T optics shift to silicon; (2) Soitec's traditional RF-SOI franchise (smartphones) provides a stable cash-cow base. Risks include consumer-electronics RF-SOI cyclicality, China substrate competition (NSIG, Simgui working to qualify SOI domestically), and customer concentration with a few large foundries (TSMC, GlobalFoundries) and integrated photonics players. EU-listed, lower trading liquidity than US peers — treat as a structural pure-play on SOI substrate scarcity.
Silicon Photonics — Photonic integrated circuits fabricated on silicon and silicon-on-insulator substrates — modulators, photodetectors, waveguides, grating couplers — used mainly in optical transceivers for data-center and telecom interconnects, with growing roles in co-packaged optics, LiDAR, and biosensing.
Optical Transceivers — Optical modules for data center and telecom interconnects
