Hermetic Packaging for Silicon Photonic Modules — When Optical Chips Move Into Ceramic Homes

I. Why Do Optical Chips Need to "Live" in Ceramic Houses?

In September we introduced the high-temperature co-fired ceramic (HTCC) process — burying circuits "inside" ceramics and firing them in a single pass. In this first article of the month, we continue with one of its most promising application directions: silicon photonic modules.

Simply put, silicon photonics integrates optical devices that were once separate — lasers, optical waveguides, photodetectors and more — onto a single silicon chip, much like building blocks. The benefits are straightforward: a dramatic reduction in size and cost, and the ability to leverage mature chip production lines for volume manufacturing. It is widely regarded in the industry as the inevitable path forward for future ultra-high-speed optical modules.

But optical chips have an Achilles' heel — they are extremely sensitive to moisture. Once the optical waveguide layer on the chip surface is affected by humidity, transmission loss rises noticeably; at best performance degrades, and at worst the entire module fails to "light up". Silicon photonic chips therefore also need a moisture-proof "house", and ceramic packaging — with its excellent hermeticity and support for multi-layer wiring — is the ideal choice for that "house".

Xuri's HTCC ceramic headers can simultaneously carry optical chips, driver circuits and thermal management structures in a variety of silicon photonic modules, providing silicon photonics customers with an integrated packaging foundation.

II. Going a Step Further: Co-Packaged Optics — Light and Electricity Living Under the Same Roof

One step beyond silicon photonics lies the industry's hottest topic: co-packaged optics (CPO). In the traditional approach, optical modules are standalone components plugged into switches, and electrical signals must travel a long detour before reaching the optical devices. Co-packaging, by contrast, integrates the optical engine and the switch chip directly on the same substrate, drastically shortening signal paths and significantly reducing overall power consumption.

This places new demands on packaging: denser wiring, lower signal loss, and the ability to accommodate multiple materials — silicon, glass, gallium arsenide and more — on the same substrate. And "multiple materials coexisting harmoniously, fired in one pass" is precisely the home turf of ceramic packaging — giving the HTCC process a new stage to shine.

Xuri has positioned itself early in this direction, carrying out joint development with multiple customers so that ceramic packaging continues to play a key role in next-generation optical modules.

[Next Article] Next up: hermetic packaging for LiDAR — the packaging story behind two wavelength routes.

[Glossary]

1. Silicon Photonics: a technology that integrates optical devices such as lasers, waveguides and photodetectors onto a silicon chip — small, low-cost, and mass-producible.

2. Co-Packaged Optics (CPO): a next-generation packaging form that integrates the optical engine and the switch chip on the same substrate, shortening signal paths and reducing power consumption.