From electricity to light, China's chip industry is moving towards light | Koshi light-years

China's core opportunity in the post-Moore era

Author | Xiao Xian

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Traditional electrical chips are gradually approaching the performance limit after the failure of Moore's Law, and more and more practitioners are turning their attention to light.

Compared with electronic chips, optical chips are characterized by high speed and low power consumption. In the field of communications, optical fiber communications support the coverage of 5G in data transmission, while the fields of computing and storage have also left a huge stage for optical chips.

Optical chips far exceed the performance potential of electric chips, making them a definitive track for the development of hard technology. In recent years, Intel, Nvidia, GF and other overseas chip manufacturers have invested in mergers and acquisitions of optical chip projects, and grasped the layout in the new track. In China, Huawei and other manufacturers have also invested in more than a dozen optical chip companies, covering the upstream and downstream of the industrial chain.

From the perspective of technological competition, optical chips are considered to be the chip technology with the smallest gap with foreign research progress, and are pinned on China's hope of "lane change overtaking".

He Jin, a professor at the School of Information Science and Technology of Peking University and the director of the Shenzhen Key Laboratory of System Chip Design of Peking University, told "Jiazi Lightyear" that from electrical chips to optical chips is the focus of the development of the chip industry. Relying on its huge application terminals, China may be on a par with foreign countries in optical chip applications in the future.

From electricity to light, China's chip industry is moving towards light.

1. The dawn of the post-Moorish era

Transistor density is doubling every 18 to 20 months, pushing the performance of electric chips roughly double every two years while prices fall by half of what they were before. Over the past 50 years, the computing power of chips has been following Moore's Law and has continued to grow.

But today, computing chips have begun to develop from 5 nanometers to 3 nanometer processes, and the diameter of atoms is about 0.3 nanometers, and after the 3-nanometer process, the physical, technical and cost limits will be infinitely closer.

Although the growth of hash rate slows as the limit approaches. However, with the continuous popularization of digitalization and intelligence, the demand for computing power in human society is still expanding sharply.

According to openAI, an American artificial intelligence research company, since 2012, the demand for computing power of artificial intelligence has increased at an average rate of doubling every 3 to 4 months. Today, the largest neural network model is 150,000 to 300,000 times what it was 10 years ago.

The power of the electrical chip touching the ceiling is caused by a variety of reasons. For example, when the chip size is less than 5nm, it may bring about a "quantum tunneling effect". Moreover, even if the transistor is smaller, the power consumption of a single transistor operation is difficult to reduce, and the heat generated cannot be effectively dissipated. This physical property directly determines the computing density that can be done on the unit area electrical chip, and it is difficult to have room for improvement.

In addition to making transistors smaller, expanding the area of electric chips is also a way to increase computing power in the industry in the past. However, this practice will also face the problem of power consumption ratio. The increase in chip area means that longer wires are needed, and the chip power consumption is proportional to the length of the trace, and the wire power consumption is too high, which is undoubtedly a bottleneck that cannot be bypassed in the entire system. The end result is that if the chip is larger, the power consumption will increase significantly with the increase of the area.

The size of the electrical chip is about to shrink to the limit, and the expansion of the area will not be able to effectively increase the computing power. The two paths of the electric chip in seeking a breakthrough to a higher computing power are difficult to pass.

At this time, the optical chip was given the high hope of breaking through the computing power.

In fact, for decades, scientists have been working to find a way to use light for information transmission processing. This exploration of light even came earlier than the electric chip.

In 1960, the American scientist Theodore M. Meyman invented the world's first visible light output laser, which led to a major breakthrough in the development of optics. This means that human understanding, mastery and use of light have entered a new stage.

During the same period, Chinese scientist Gao Kun proposed a method of replacing copper wires with glass fibers and replacing electric currents with light. After this breakthrough technology was applied, it developed into optical fiber communication in today's long-distance communication.

Looking back at the development process of optical chips, as early as 1969, Bell Labs in the United States has proposed the concept of integrated optics. However, due to technical and commercial reasons, it was not until the beginning of the 21st century that enterprises and academia represented by Intel and IBM began to cooperate intensively, focusing on the development of optical signal transmission technology for silicon chips.

Since the development of optical communication, optical has fully proved its advantages in data transmission. All current long-distance communication, including servers and data between servers in data centers, is conducted through optical fibers instead of copper wires.

In recent years, people have begun to shift their attention from the "transmission" of light data to "processing". Relative to microelectronic chips, which use electrical signals as information carriers, optical chips use light waves with higher frequencies as information carriers.

Compared with integrated circuits, optical chips technically avoid heating problems, lower transmission losses, higher bandwidth, less latency, and stronger immunity to electromagnetic interference. These are all huge advantages of optical chips.

"Today, we have discovered the great power of photons for information carriers in optical fiber transmission. What an exciting time it would be if photons were used inside a future chip system to transmit and process information. At present, it seems that light is the best and fastest medium. Professor of the School of Information Science and Technology of Peking University and master of the Shenzhen Key Laboratory of System Chip Design of Peking University said.

At present, silicon light technology has been widely used in the field of transmission, carrying the task of information transmission in large data centers and telecommunications. In the field of light sensing represented by lidar, it is also gradually maturing. Optical computing based on silicon optical chips is expected to gradually appear in some computing scenarios in the next 5-10 years.

In the context of the neck of China's chip industry being stuck, the power light chip has another layer of "lane change overtaking" significance.

The development of electric chips is a process of accumulation and thin development, which means that it is difficult to "make up for the work" in a short period of time due to backward technology. He Jin said: "There is a gap of 4-5 generations between China's electronic chip technology and foreign countries, but optical chips are still in the research and development stage on a global scale, have not yet been applied on a large scale, and have not formed intergenerational differences. Therefore, relying on China's own huge application terminal and unique unified market, we may realize synchronization with foreign countries in the industrial application of optical chips in the future. ”

2. The birth of an optical computing chip

Although the development of optical chips has been highly expected, for a long time in the past, optical computing is a technology that has been trapped in laboratories and universities for a long time. In 2017, Shen Yichen, Ph.D., of the Massachusetts Institute of Technology physics, opened a breakthrough with a blockbuster paper on AI computing light chips.

At that time, Shen Yichen, as the first author, published an important academic achievement in integrated photon computing in the journal Nature – Photons as a cover paper, the concept of which is to convert traditional electronic signals into optical signals, let optical signals pass through photonic chips, and control the interference between these lights. When these lights interfere with each other, and when these numbers are calculated, the entire calculation time is the time it takes for the light to pass through the chip: 0.1 -0.5 nanoseconds. The same large matrix multiplication takes about a hundred times longer on the electrical chip.

This paper has become a major node in the development of photonic computing chips, and has set off a huge response in the academic community and the industry, and investors and entrepreneurs have come to the door. This has also become a major driving force for Shen Yichen to go out of the laboratory and create a company. In the same year, Shen Yichen founded Xizhi Technology, a photonic AI chip company. Nicholas Harris, the paper's second author, founded Lightmatter in the same technical field.

Recalling the scene at that time, Shen Yichen said: "Xizhi Technology is one of the earliest companies to start. At the time of its inception, even AI chips were a new concept, not to mention photonic AI chips. Therefore, the industry often classifies us and cutting-edge technologies such as quantum computing. ”

With the gradual release of the achievements of Intel, Nvidia and other industry giants in the field of photonic computing chips, throughout the scientific research to the industry, photonic AI chips began to take a process from being questioned to widely recognized. The confidence of entrepreneurs and the market is becoming more and more obvious. In 5 years, the number of photonic AI chip companies around the world has increased from one or two sporadic to more than 20 at present.

According to reports, since the establishment of Xizhi Technology, the company's total financing has exceeded 220 million US dollars. With more than 10 MIT doctors as the core, the global team has more than 200 people, and the offices and laboratories are distributed in Boston, Shanghai, Hangzhou, Nanjing and other places.

Lightmatter, which was established at the same time, has also attracted considerable attention in the United States, and public information shows that after its establishment, it has successively received investment from Matrix Partners, GV (formerly Google Capital), HP, Lockheed Martin, and the US Department of Defense, with a total financing of about 110 million US dollars.

"Photonic chips are undoubtedly one of the hottest directions in the industry." Shen Yichen said.

At the end of 2021, Xizhi Technology launched PACE, a computing processor based on photonic chips, which is also the world's first computing system that can show the advantages of photons. It is understood that the structure of PACE is composed of two parts: an optical chip and an electrical chip. The electric chip mainly carries out the storage of data and the scheduling of digital-analog hybrid, while the optical chip performs the calculation of data. Finally, the optical and electrical chips are stacked upside down by 3D packaging technology.

Pace photonic chip integrates more than 10,000 photonic devices, the chip runs at a speed of 1GHz, compared with the current market can buy a single NVIDIA GPU3080 with the highest computing power, running a specific recurrent neural network algorithm, PACE takes less than 1% of the time required by the GPU.

Shen Yichen said that this comparison is not to prove in terms of versatility that PACE can run all neural networks and increase the speed by a hundred times. But PACE's performance illustrates the upper limit of the optical computing advantage and its potential.

In addition, the advantages of optical chips are not only reflected in the technology itself, but also in terms of performance improvement, optical chips are less dependent on advanced process processes.

Shen Yichen said that silicon optical chips do not need to have particularly high requirements for the process, such as 65 or 45 nanometer COMS process lines can meet all the requirements of the current optical chips and optical computing. The improvement of optical chip performance is more from other aspects of technical iteration, including main frequency, wavelength number and different modes.

Strictly speaking, PACE represents the operation of photoelectric hybridization of the deep combination of electronic chips, rather than pure light computing. "In the foreseeable future, it will be a deeply integrated photoelectric hybrid operation with electronic chips." Shen Yichen said.

In this way, PACE can interact with the outside world through the electric chip, carry all instruction set compilers and SDKs on the electric chip, and are compatible with the ecology of existing chips in terms of software. The optical chip part, on the other hand, undertakes processor work for the main tasks, including linear computing and data networking.

Shen Yichen said that Xizhi is about to launch more generalized computing products, if the interconnection of light and the calculation of light are added together, for the first generation of products, as long as it can show 3-5 times the computing power advantage, it is enough to find a huge market space in a wide range of applications.

3. Silicon light era, China's opportunities

Although photonic integrated circuits are still in the initial stage of development, there is no doubt that this development trend has become inevitable. In December 2021, Alibaba Damo Academy released the top ten technology trends in 2022, and optoelectronic chips were also among them.

However, it should be pointed out that the emergence of optical chips is not to completely subvert and replace electrical chips. In fact, photonic chips need to be integrated with mature electronic chip technology, the use of electronic chips advanced manufacturing technology and modular technology, combined with photonics and electronic advantages of silicon optical technology will be the mainstream form in the future.

At present, the reasons why the development of silicon light is not yet mature are manifold. The commercialization of chips relies on a very long industrial chain, from design and manufacturing to later sample feeding and commercialization, with a time period of several years. At present, the silicon light integration process is not yet mature, bringing low chip yield, cost advantage is not obvious, as well as no automation design, design and process disconnection and other issues, the need for upstream and downstream of the industrial chain to participate together to form a more perfect silicon light ecology.

"Commercialization itself is an ongoing and lengthy process, just as it took 10 years for the first smartphone to become widespread, and a hybrid computing chip can be delivered to customers in the next year or two." But large-scale commercial, general-purpose computing products will take time. Shen Yichen said.

Overall, the current silicon optical chip industry chain is far less mature than the electric chip, and the industrial chain is growing rapidly under the resources of chip giants. The rapid development of lidar based on optical communication, including optical computing and optical sensing routes, is driving the silicon optical supply chain to become more and more mature.

"Especially in the past two or three years, many large fabs, EDA design companies, and packaging and testing plants in the world have begun to formally layout the direction of silicon light." Shen Yichen said. Xizhi Technology is also establishing strategic cooperation with first-line fabs and packaging plants to promote the development of silicon light ecology.

Mi Lei, founding partner of Zhongke Chuangxing, told Jiazi Lightyear, "When the fund was first established in 2013, photoelectric chips belonged to a very unpopular track in China, and looking around, only scientific research institutes and a small number of returnee chip talents engaged in related research work, and few investment institutions asked for it." ”

Coincidentally, for the first time that year, China's chip imports surpassed oil. After capturing this phenomenon, Mi Lei judged that China's chip industry is very likely to be "stuck in the neck" in the future. So Mi Lei, who came from an optical background, began to look for photoelectric chip projects in China.

In order to create a photonic industry ecology, in 2015, Zhongke Chuangxing launched the first photoelectric chip industry incubation platform - Shaanxi Optoelectronic Pilot Institute, and invested hundreds of millions of yuan to purchase professional equipment, build clean plants, recruit professional talents, provide complete supporting services, and help early chip companies tape-out.

The following year, Zhongke Chuangxing set up an early fund of 1 billion yuan, which was specially invested in the field of optoelectronics. In this year, the market environment turned a corner, the integrated circuits that have been popular for nearly 60 years encountered a bottleneck in development, and the giant Intel announced that it would no longer launch chips in accordance with "Moore's Law". Mi Lei put forward the "Mi 70" law and called on everyone to pay attention to the integrated optical path.

He believes that in the future, optical costs will account for at least 70% of the total cost of products. At that time, optical devices, mechanical devices, and electronic devices may be gradually chipted, and may even be integrated into a chip.

Today, among the more than 370 hard technology enterprises incubated by Zhongke Chuangxing Investment, there are more than 150 optical + semiconductor projects, which promotes the formation of an investment layout with "optoelectronic chips" as the core.

At the recent EmTech China Global Emerging Technology Summit, Mi Lei said in his sharing that the scientific and technological revolution of the past six decades has been an information revolution promoted by integrated circuits and optical communications, and the future will be a new round of scientific and technological revolution represented by photonics, artificial intelligence, new energy and life sciences.

With the maturity of one subdivision of technology fields in recent years and the realization of landing applications, the development of the optoelectronic industry has been accelerating.

In 2017, the iPhone X is equipped with a 3D camera, and the face recognition technology hidden behind the liu hai screen is widely accepted in the field of mobile phones, and the VCSEL laser chip, which is the core component of 3D sensing technology, ushered in a spurt of growth. In the field of automatic driving, lidar as an important part of the perception link, lidar companies represented by Quanergy have quickly become unicorns in the autopilot boom, and have also brought more attention to optical chips.

Huaxi Securities said in a silicon light industry report that in 2019, the global silicon light market size was 480 million US dollars, and it is expected to grow to 3.9 billion US dollars by 2025, a compound growth of 40%.

"In general, the era of electric chips is to use original technology to find the market, optical chips are the market demand, in turn to develop original technology to meet the demand, from this point of view, the era of intelligence, we have new formats, new needs, China than any country in the world has more people willing to embrace new technologies." He Jin said.

He believes that at the level of information infrastructure construction and new IT technology construction, China has greater market demand and more enthusiasm for embracing the new technology ecology, and the application ecology is better than that of foreign countries, so China's optical chip industry may use the application ecological advantages to form certain advantages in the field of optical chips.

"In the future, China's biggest opportunity must be in the photonic era." Mi Lei said in an interview that light is the infrastructure of the era of artificial intelligence, whether it is a 5G network or a sensor that obtains data, in short, in most fields such as communications, industry, and consumption, optical chips are needed to support it.

"Today's development stage of optoelectronic chips is equivalent to the stage of microelectronic chips in the 1960s and 1970s, and the vast market space is still waiting for us." Milei said.