Lightwave Logic on Powering Co-Packaged Optics for AI

Co-packaged optics change manufacturing and integration requirements for electro-optic polymers, said Robert Blum, senior vice president of sales and marketing at Lightwave Logic, which develops EO polymers. That means much closer integration with the switch ASIC, CPU or GPU, he said, along with hybrid bonding processes that run at higher temperatures than optical assemblies for pluggable transceivers.

This summer, TechArena has been asking the companies that build AI infrastructure how their requirements are changing as deployments scale. We sat down with Robert, who discussed where interconnect materials science needs to go next, what separates EO polymers from competing approaches, and what's standing in the way of faster industry-wide adoption of optical solutions over copper. Here's what we learned.

Q1: Copper, pluggables and now co-packaged optics have each marked a step change in how data moves inside the data center. Where does interconnect materials science need to go next to keep pace with AI bandwidth demand?

A: There has been tremendous progress in both the materials used for lasers and modulators. III-V materials have improved, enabling higher-power lasers and electro-absorption modulators up to 200 Gb/s per lane. Silicon photonics has improved, achieving 200 Gb/s with micro-ring modulators and highly doped p-n junctions.

But new materials are required for the next modulator generation where 400 Gb/s speeds are needed. That's where thin-film lithium niobate and electro-optic polymers come into play. We see strong momentum behind EO polymers, because they can be easily integrated into standard silicon photonics foundry processes.

Q2: Electro-optic polymers are one of several competing approaches to improving modulator performance, alongside indium phosphide and lithium niobate. What does the industry still get wrong about how these materials compare?

A: EO polymers have really improved in performance and reliability, thanks in part to the lessons learned from the OLED industry, and are now ready for deployment. They integrate much more easily with silicon photonics than lithium niobate, so the foundries love these materials. And customers like them because they can enable much more compact modulators with lower drive voltages than lithium niobate. The real race is about ramping production capacity and getting the 400G ecosystem in place.

Q3: Given copper's physical limitations in the interconnect layer as data rates climb, what is the bottleneck to faster adoption of optical solutions industry-wide?

A: Optics tends to be more complicated than copper. High-fiber-count detachable optical connectors are one of the bottlenecks. Form factors for optical engines are not standardized, so many solutions are proprietary or require custom designs and packages.

Silicon photonics foundries have ramped capacity at astonishing rates, but lead times can still be quite long. On the other hand, there is a large payback for going to optical at these higher data rates, so many suppliers are eager to make the transition.

Q4: Lightwave Logic is developing electro-optic polymers that can be used for co-packaged optics (CPO) in AI and hyperscale data centers. What does co-packaging change about the requirements for your polymer, versus a pluggable transceiver?

A: Optical assemblies that go into pluggable transceivers tend to have more forgiving process requirements. Going through standard solder reflow or wire bonding is one of the main requirements.

For CPO, you need to integrate much more tightly with the switch ASIC, CPU or GPU. So you potentially start to look at hybrid bonding, which has higher processing temperatures and also much more complex assemblies in general. All this requires much closer collaboration with system integrators.

Q5: With five Fortune Global 500 customers actively engaged in prototype testing, what's the biggest technical gate left between prototype and the high-volume production you're targeting for 2027?

A: There are several items that are required for true high-volume production: Silicon photonics foundries need to mature their slot waveguide processes, which means that the doping profiles and slot dimensions, for example, are within their required tolerances.

The back end of line process transfer needs to be completed and qualified. And customers need to complete the design and qualification of their own module.