Computing with light quanta Photonic ICs as a blockade breaker for China?

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China is increasingly focusing on integrated photonic chips. These are supposed to compute quickly without relying on the latest manufacturing processes. However, although research has been conducted worldwide for many years, integrated photonics is still in its infancy.

Photonic chips could help China partially circumvent US technology boycotts. "This future technology could potentially change the contours of US-Chinese competition in semiconductors and AI," says an analysis by the Center for Strategic and International Studies (CSIS) in Washington.

While the application possibilities are limited and many technical hurdles remain to be overcome, replacing electrons with photons (light quanta) shows great potential in certain areas, writes Matthew Reynolds from the Asia Program of the CSIS in his study. This could eventually enable China to train and apply the most advanced AI algorithms without the need for powerful semiconductors from the USA.

"Recent advances in silicon photonics suggest that China could manufacture computer systems in domestic production without the most advanced semiconductor equipment, which are capable of performing certain key AI tasks better than their fully-electronic equivalents," writes Reynolds.

One of the advances Matthew is referring to is the construction of a "production line for photonic chips" by Sintone Microelectronics in Beijing. Company CEO Sui Jun explained that China has the capability to produce photonic chips itself because the processes do not require EUV lithography machines, reported Trendforce.

Light transmission for more power

For years, Washington has been trying to deny China access to the most advanced lithography machines, which are used to manufacture logic chips with process nodes of less than 14 or 16 nanometers. Additionally, the US has significantly restricted the export to China of the latest generation of chips – which, among other things, are needed for the best AI algorithms.

Photonic chips are considered a promising future technology not only in China. Especially now, as the miniaturization of chips becomes increasingly difficult and Moore's Law gradually reaches its limits, while demands on computing power rapidly increase due to AI and LLM, using light to transmit information promises new possibilities.

The "US Defense Advanced Research Projects Agency" (DARPA) already began researching integrated photonic chips in 2019. The European Union followed in 2020 with its "PHOOUSING" project.

The USA and Europe are also researching photonic chips

Research into this new technology is also not new in China. As early as 2017, the Ministry of Industry and Information Technology (MIIT) in Beijing had released a "Roadmap" for the development of opto-electronic devices. Moreover, in the 14th Five-Year Plan running from 2021 to 2025, the development of the photonics route in semiconductors is already described as particularly worthy of support by the communist central planners.

Which country will ultimately emerge as a leader in this field is still undecided. However, it is already certain that "silicon photonics technology has the potential to enable China to break through to the forefront of semiconductor manufacturing," comments Trendforce.

Photonics: Two main research focuses

Currently, research and development in China are mainly focused on two areas of photonics. First, there are the electro-optical connections where copper cables in circuits are replaced by photonics. The result is particularly fast, particularly energy-efficient "hybrid chips".

Secondly, there is significant research in the field of “optical computing” at Chinese universities, where wholly newly developed processors work solely with light instead of electrical currents.

Currently, their application possibilities are extremely limited compared to the all-purpose silicon chip. However, particularly in performing computational operations with matrix multiplications, which are used in ChatGPT and other "Large-Language-Models," optical computing shows "significant potential," writes Trendforce.

Symbiosis of silicon and photonics likely

Chinese scientists see this as an opportunity to break through the US technological "blockade" in the medium term. The first production line for photonic chips in China will soon be completed, wrote economist Chen Wenling from the "China Center for International Economic Exchanges" (CCIEE) in an article. "This means that China will take the lead globally in terms of photonic chips and will even completely change the technology development route of the semiconductor industry," said the patriotic Chinese.

Independent experts caution that much application-oriented research and software development is still needed before photonic chips can replace good old silicon—and that in the future, a symbiosis of both technologies is more likely.

However, researchers everywhere agree that photonic chips, due to their lower latency, higher efficiency, and low energy consumption, are currently one of the most promising paths in semiconductor research.

Increased speed through photonics

Already in 2021, the Chinese company Lightelligence developed prototypes of combined circuits with photonic and silicon chips, which, according to their statements, were "25 to 100 times" faster than the fastest GPU chips from Nvidia at the time.

"We can use 28-nm chips to achieve the effect of 7-nm chips faster," quotes the CSIS study from Washington, Shen Yichen, the CEO of Lightelligence. Together with the Chinese Academy of Sciences, his company is working on "key projects."

The chip boycotts from Washington have further reinforced Beijing's determination to play a globally leading role in photonic technology in the future. The new route is evidence that the US is "shooting itself in the foot" with its chip war, as Yao Yang, the director of the National Development Institute at Peking University, puts it.

The recent advances in China should not be overestimated, on the other hand, the analysis from CSIS in Washington cautions. Yet, they do question the effectiveness of US boycotts against China, writes Reynolds. Silicon photonics is "a reminder that the US should not assume that the manufacturing capabilities of the Chinese semiconductor industry could be permanently limited just because China is denied access to the most advanced semiconductor equipment," says the author of the US study. (me)

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