Electrical I/O hits the wall at 400G+. Co-Packaged Optics moves lasers inside the chip package. 1.6T optical interconnects begin mass production. The hidden bottleneck mainstream investors miss.
As AI clusters scale to 100,000+ GPUs, copper cannot move data fast enough — electrical I/O becomes the new constraint. Co-Packaged Optics (CPO) is the architectural shift: lasers integrated directly onto the chip package, eliminating the electrical bottleneck. A new supply chain of laser makers, substrate specialists, and optical engine builders emerges. Most are still valued like sleepy industrial companies. Source: @aleabitoreddit (Serenity) photonics research.
| Ticker | Company | Thesis |
|---|---|---|
| SIVE | Sivers Semiconductors (Nasdaq Stockholm) | CW laser chokepoint for CPO; sole/primary supplier to Ayar Labs, Celestial AI, Lightmatter, Lightelligence; CHIPS Act funded; Blackrock/Vanguard passive inflow on NASDAQ index inclusion; volume ramp 2027 |
| AXTI | AXT Inc | InP (Indium Phosphide) substrate monopoly — every optical transceiver chip starts here; 10x'd from $14 → $140; supply chain cannot be easily substituted |
| AAOI | Applied Optoelectronics | 800G/1.6T optical transceiver maker; major hyperscaler qualifications; volume ramp H1 2027; from $65 → $170 |
| SLOIF | Soitec (OTC: SLOIF) | SOI substrate monopoly for silicon photonics; licenses to Shin-Etsu; TSMC COUPE dependency; from $45 → $170 |
| COHR | Coherent Corp | Vertically integrating lasers + transceivers + substrates through acquisitions; largest optical components maker |
| IQE | IQE PLC (London / OTC) | Western epiwafer monopoly; critical for AI + defense photonics supply chain diversification away from Asia |
| LITE | Lumentum Holdings | Leading laser & photonics component maker; EML lasers for 400G/800G transceivers; diversified across datacom, telecom, 3D sensing |
| POET | POET Technologies | Optical Interposer platform integrates lasers + electronics on single chip without wire bonds — solves the CPO integration problem; design wins with hyperscaler supply chain |
| AEHR | Aehr Test Systems | Only company that wafer-level tests compound semiconductors (GaAs, InP, SiC, GaN) at volume; every photonics wafer must pass through here; ~$3.5B market cap |
★ Taiwan CPO plays (small caps): Win Semi (3105), Shunsin (6451), FOCI (3363), MSScorp (6830). Private leaders: Ayar Labs, Celestial AI, Lightmatter.
Educational framework, not financial advice. Tickers and theses are illustrative of each phase's investment thesis, not recommendations.