Why Is Money Suddenly Chasing AXTI? InP Could Be Heading Into a Supply Crunch — But What Exactly Is InP?

AXT Inc. doesn’t make GPUs. It doesn’t make switching ASICs. It doesn’t build 800G or 1.6T optical modules. Optical communications chips aren’t even its core business.

And yet, as the AI optical networking trade keeps broadening, AXTI is showing up more and more frequently on investors’ screens.

There is really one reason:

InP — indium phosphide.

More specifically, AXT sells InP wafer substrates.

It sounds obscure. That is exactly why the setup is interesting.

While investors are busy chasing optical transceivers, silicon photonics, and co-packaged optics, one of the least glamorous components sitting at the very top of the supply chain may be turning into one of the hardest bottlenecks to solve.

The real AXTI trade is not simply “AI.”

The real question is:

If 1.6T optics, silicon photonics, and CPO all ramp at the same time, will there be enough InP supply?

That is the core of the thesis.

As AI Scales, GPUs May Not Be the Only Scarce Resource

For the past two years, the central bottleneck in AI infrastructure was compute. Everyone needed more GPUs.

But once GPU clusters scale from thousands of accelerators to tens of thousands, and eventually hundreds of thousands, the bottleneck changes.

It doesn’t matter how many GPUs you own if those GPUs cannot move data between each other fast enough. Cluster efficiency starts becoming a networking problem.

That is why AI infrastructure is gradually shifting from a compute race to a connectivity race.

Network speeds are moving rapidly:

100G → 400G → 800G → 1.6T → eventually 3.2T

The faster the network gets, the more traditional copper interconnects run into problems with distance, power consumption, and signal integrity.

The natural consequence is that more data transmission has to move from electrons to photons.

That is why 800G, 1.6T, silicon photonics, and CPO have become major new branches of the AI infrastructure trade.

But investors tend to focus on the optical module.

They often forget to ask the more fundamental upstream question:

Where does the light actually come from?

One major answer is the InP-based laser.

And before you can manufacture an InP laser, you first need a high-quality InP wafer.

That is where AXT sits.

AXTI Is Not an Optical Module Company

The supply chain can be simplified like this:

Raw materials
→ InP single crystal
→ InP wafer substrate
→ epitaxy
→ DFB / EML lasers / photodetectors
→ optical engines / silicon photonics PICs
→ 800G / 1.6T optical modules
→ AI data centers