Plain-English Explanation
The big picture
In an AI data center, GPUs (like NVIDIA's) need to talk to each other at insane speeds — way too fast for copper wires. So they send data as pulses of light through fiber-optic cables. An "optical module" is the little plug-in device that converts electrical signals ↔ light. The diagram breaks down the three parallel "rivers" of parts that flow into every optical module, and how they all converge at NVIDIA.
The three sub-chains
Chain A — Semiconductor substrate → Active optical chip (left)
This is the light-generating branch — it makes the tiny lasers.
- InP (indium phosphide) wafer — the raw "pancake" the laser is grown on. AXT is one of the world's top 3 suppliers.
- Active optical chips — the actual lasers (EML, VCSEL, silicon photonics, DFB).
- Lumentum = #1 in EML lasers
- Coherent = #1 in VCSEL
- Broadcom = leader in silicon photonics ("Sian")
- MACOM = InP DFB lasers
Chain B — CMOS → Electronic chips (middle)
This is the brains branch — the chips that drive the lasers and decode the signals.
- CMOS/SiGe wafer — standard semiconductor wafer.
- Electronic chips: DSP / Driver / TIA (digital signal processor, laser driver, receiver amplifier).
- Broadcom & Marvell = the DSP duopoly
- Credo = the #3 DSP player
- MACOM = drivers/TIA
Chain C — Optical fiber & cable (right, runs straight down)
This is the plumbing branch — the glass fibers light travels through.
- Corning dominates the entire fiber + cable supply chain.
- Notice: this chain skips the chip + module layer and goes straight to the data center room.
Where they converge (middle of diagram)
The lasers (Chain A) and electronic chips (Chain B) get packaged together step by step:
- TOSA / ROSA — the laser/receiver "sub-assemblies." (Coherent, Lumentum's EDFA amplifiers)
- PIC + DSP optical engine — the photonic integrated circuit fused with the DSP. (Broadcom, Lumentum CW Lasers, Fabrinet as the contract manufacturer)
- Finished optical module — the plug-in transceiver. (AAOI modules, Ciena for coherent long-haul gear)
Market size: global optical modules $51B (2024) → $89B (2029), 12.5% CAGR.
Final convergence — at the data center
All three rivers meet at the network system + end application:
- Arista = the AI fabric switch leader (the big network boxes).
- NVIDIA = the king of compute, and now the CPO (co-packaged optics) definer.
- A single NVIDIA GB200 GPU system is paired with 18× 800G optical modules. That's the explosive demand driver.
A useful number on the right: the DSP alone is 30–40% of an 800G module's bill of materials — explaining why Broadcom/Marvell/Credo are so valuable.
Why it matters now (timeline)
- Mar 2025: NVIDIA GTC announces Quantum-X CPO (co-packaged optics — fusing optics directly onto the switch chip).
- 2026: 1.6T modules deploy at scale.
In short: AI factories need light. Light needs lasers (A) + driver chips (B) + fiber (C). Those three streams merge into optical modules, which plug into Arista switches and NVIDIA GPUs. The 13 tickers shown are the pure-play ways to invest in each link of that chain.
