Intel demonstrated an eight-wavelength laser array on a silicon wafer. The research paves the way for the next generation of integrated silicon photonics products in the data center, such as switches with packaged optics and optical connection chipsets.
From discrete transceivers to integrated photonics
Intel has been selling 100G transceivers based on silicon photonics for about half a decade, and has also begun commercializing up to 400G transceivers, with 800G also on the roadmap. Gartner predicts that by 2025, more than 20% of all data center communications will be based on silicon photonics, up from 5% in 2020, representing a $ 2.6 billion market.
However, to further reduce force, the next step for silicone photonics is to be more closely integrated with other silicone. The first instance of this is packaged optics, which is expected in the next two years. The ultimate goal is fully integrated photonics, where the photonic integrated circuit is directly connected to the rest of the computer using advanced packaging.
Integrated DWDM laser series
The latest research from Intel Labs delivers what it calls “industry-leading” advances in multi-wavelength integrated optics, Intel claims. It’s about demonstrating an eight-wavelength scattered feedback (DFB) laser array that is fully integrated on a 300mm silicone wafer using Intel’s hybrid silicon photonics platform, paving the way for cost-effective high-volume manufacturing for broad deployment. The laser has achieved power uniformity and wavelength spacing uniformity that exceeds industry specifications.
One of the distinctive features of Intel’s 300mm wafer silicon photonics platform is its integrated hybrid silicon laser. The new multi-wavelength advancement enables the production of the optical source for future high-volume applications such as packaged optics or optical connections, which facilitates the growing bandwidth requirements of data-intensive applications such as artificial intelligence (AI) and machine learning (ML). .
More specifically, the laser uses a technology called dense wavelength division multiplexing (DWDM) to send different, narrowly spaced wavelengths over the same optical link. This technique therefore increases the bandwidth while also reducing the physical size of the photonic chips. The key challenges overcome were the uniformity of the power and wavelength spacing.
Intel’s current silicon photonics transmitter receivers use coarse wavelength division multiplexing (CWDM) where the wavelengths are further apart. These products use 100G lines that use four wavelengths, each delivering 25G bandwidth.
To achieve the eighth-wavelength DFB array, Intel used advanced lithography (the same technique used to define features on slides) to define the silicon wavelength gratings before the III-V wafer bonding process where the III-V laser attached to the silicone wafer. Intel said this has resulted in better wavelength uniformity compared to conventional semiconductor lasers manufactured in 3-inch or 4-inch III-V waferfabs. Due to the close integration, this uniformity remained even in different ambient temperatures.
“This new research demonstrates that it is possible to achieve well-fitted output power with uniform and densely spaced wavelengths,” said Haisheng Rong, senior chief engineer at Intel Labs. The most important thing is that this can be done through existing manufacturing and process controls in Intel’s fabs, thus ensuring a clear path to volume production of the next generation of packaged optics and optical computer interconnection to scale.
Optical chipsets
Intel said the integrated laser array of this research is being implemented by its Silicon Photonics Products division. Intel is aiming for a future optical computer interconnection chiplet product that will provide “multi-terabits per second” bandwidth between computer resources such as CPU, GPU and memory. This is in line with Intel’s long-standing vision that optical I / O will eventually complement or even replace existing copper-based connections such as PCIe, providing higher bandwidth and lower power.