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20 Feb 2025
Chip giant's first PIC products to provide customers with independent volume supply of two key components for optical modules.
Chip maker STMicroelectronics (ST) has revealed details of a new generation of proprietary technologies enabling faster optical interconnects in data centers and artificial intelligence (AI) clusters, with a ramp in production slated for the second half of this year.
The Geneva, Switzerland, company, which owns several semiconductor manufacturing facilities in Europe and east Asia, has developed new silicon photonics and BiCMOS silicon-germanium processes in collaboration with key customer and data center giant Amazon Web Services (AWS).
Those new processes are intended to improve the performance of optical interconnects offering 800 Gb/s and 1.6 Tb/s data speeds, including more power-efficient operation.
“With the exponential growth of AI computing needs, challenges arise in performance and energy efficiency across computing, memory, power supply, and the interconnections linking them,” explained ST.
“At the heart of interconnections in a data center are thousands, or even hundreds of thousands, of optical transceivers. These devices convert optical into electrical signals and vice versa to allow data flow between graphics processing unit (GPU) computing resources, switches and storage.
“Inside these transceivers, ST’s new, proprietary silicon photonics technology will bring customers the ability to integrate multiple complex components into one single chip, while ST’s next-generation, proprietary BiCMOS technology brings ultra high-speed and low power optical connectivity, which are key to sustain the AI growth.”
First PIC products
Remi El-Ouazzane, the president of ST’s microcontrollers, digital ICs and RF products group, noted: “Both technologies will be manufactured on 300 mm processes in Europe, bringing customers an independent high-volume supply for two key components of their optical module development strategy.
“Today’s announcement represents the first step for our photonic integrated circuit (PIC) product family and, thanks to close collaboration with key partners across the entire value chain, our ambition is to become a key supplier of silicon photonics and BiCMOS wafers for the data center and AI cluster market, be it pluggable optics today or optical I/O tomorrow.”
Nafea Bshara, a VP at AWS, added in ST’s announcement: "AWS is pleased to collaborate with STMicroelectronics to develop a new silicon photonics technology, PIC100, that will enable interconnection between any workload including AI.
“AWS is working with STMicroelectronics based on their demonstrated capability to make PIC100 a leading silicon photonics technology for the optical and AI market. We are enthusiastic about the potential innovations this will unlock for silicon photonics.”
ST also quotes Vladimir Kozlov, the chief analyst at optical communications market consultancy LightCounting, who pointed out that the market for pluggable optics - already worth $7 billion in 2024 - is poised for more rapid growth.
Kozlov suggests that total will grow at an average rate of 23 per cent over the next five years, meaning that the market would exceed $24 billion by 2030. “[The] market share of transceivers based on silicon photonics modulators will increase from 30 per cent in 2024 to 60 per cent by 2030,” he added.
French fab
ST’s new PICs are set to be manufactured at the firm’s Crolles facility near Grenoble in France, along with the BiCMOS technology.
In an accompanying blog post describing the silicon photonics launch as “highly symbolic”, the company stated: “The PIC100 is ST’s first silicon photonics technology and one of the most efficient PICs on a 300 mm wafer, thus enabling 200 Gbps/lane and even greater bandwidth in the future.”
The post points out that as bandwidth rises it becomes harder to keep modules cool. “The problem is that while servers need greater data throughput for AI and other data-intensive applications, high heat can cause serious challenges, such as performance degradation and reliability issues,” wrote ST.
“Moreover, data centers strive to be more sustainable and efficient, but hotter and more demanding optical transceivers run counter to these objectives.”
Edge couplers
To improve efficiency, the PIC100 process incorporates a number of optical innovations, including what ST calls a “best-in-class” silicon waveguide to reduce loss to just 0.4 dB/cm, and a silicon nitride (SiN) waveguide loss as low as 0.5 dB/cm.
PIC100 also offers a Mach-Zehnder modulator with a bandwidth of 50 GHz and a high-speed photodetector up to 80 GHz.
“Put simply, the PIC100 is unique because of the integration of all these state-of-the-art devices in the same 300 mm stack,” claims the firm. “Efficiency is also the reason why we adopted an edge coupler.”
While grating couplers allow wafer-level tests and offer a more flexible placement, ST says that they suffer from greater losses due to scattering effects and a more significant mismatch between the coupler and the fiber.
“By adopting an edge coupler, we can better match the fiber mode to the on-chip SiN waveguide, which results in a far more efficient coupling, with losses below 1.5 dB."
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