In 1965, Gordon Moore, co-founder of Intel, proposed Moore's Law, predicting that the density of transistors on chips would double every 18 to 24 months. However, after decades of development, silicon-based electronic chips are nearing the physical theoretical limits of their capabilities.
The emergence of photonic chips is seen as a key way to break through the limitations of Moore's Law.
Recently, a team led by Associate Professor Wang Cheng of the City University of Hong Kong, in collaboration with researchers from the Chinese University of Hong Kong, developed a microwave photonic chip using lithium niobate as a platform. This chip processes signals faster and consumes less energy, using optics for ultra-fast analog electronic signal processing and computation.
The research was published in "Nature" on February 29th. It is reported that integrated lithium niobate microwave photonic chips are not only 1000 times faster than traditional electronic processors but also have a super wide processing bandwidth and extremely high computational accuracy, with lower energy consumption.
The concept of photonic chips is no longer unfamiliar, and new technologies in the field of photonic chips are emerging frequently. For example, in December 2022, a team led by Professor Zou Weiwen from the Department of Electronic Engineering at the School of Electronic Information and Electrical Engineering of Shanghai Jiao Tong University proposed an innovative idea that intersects photonics with computational science. They developed a new type of photonic tensor processing chip capable of high-speed tensor convolution operations. The results were published in "Nature" under the title "High-order Tensor Stream Processing Based on Integrated Photonic Chips."
Furthermore, Chinese researchers have made significant breakthroughs in photonic integrated circuits, photonic transistors, and optical computing. These achievements not only demonstrate China's strength in photonic chip technology but also make a significant contribution to the development of the global photonic chip industry.
In the past decade, photonic technology has become a focal point for the next generation of information technology, artificial intelligence, smart vehicles, and healthcare. It is also considered one of the key technologies for maintaining a leading position in the international market by related countries.
Simply put, a photonic chip is a chip that uses optical signals for data acquisition, transmission, computation, storage, and display. Photonic chips are highly sought after in the current era mainly due to two advantages: performance and manufacturing.
Advantage 1: High computing speed, low power consumption, and low latency
Compared to traditional electronic chips, photonic chips have many advantages, mainly in terms of high speed and low power consumption. Optical signals transmit at the speed of light, greatly increasing speed; ideally, photonic chips compute approximately 1000 times faster than electronic chips. Photonic computing consumes less energy, with the power consumption of optical computing expected to be as low as 10^-18 joules per bit (10^-18 J/bit). With the same power consumption, photonic devices are hundreds of times faster than electronic devices.
Additionally, light has a natural ability for parallel processing and mature wavelength division multiplexing technology, greatly enhancing the data processing capacity, storage, and bandwidth of photonic chips. The frequency, wavelength, polarization state, and phase of light waves can represent different data, and light paths do not interfere with each other when crossing. These characteristics make photons adept at parallel computing, fitting well with artificial neural networks, where most of the computing process involves "matrix multiplication."
Overall, photonic chips feature high computing speed, low power consumption, and low latency, and are less susceptible to changes in temperature, electromagnetic fields, and noise.
Advantage 2: Lower manufacturing requirements
Unlike integrated circuit chips, photonic chips have relatively lower manufacturing requirements. The highest technical barriers lie in epitaxial design and manufacturing. The technological route of light has advantages like high speed, low energy consumption, and anti-crosstalk, allowing it to replace many functions of electronics.
Sui Jun, president of China's Xintong Microelectronics Technology (Beijing) Co., Ltd., once stated, "Photonic chips do not need to use extremely high-end lithography machines like extreme ultraviolet (EUV) lithography machines required for electronic chips. We can produce them using relatively mature domestic materials and equipment."
Regarding whether photonic chips will replace electronic chips, it's important to understand the current bottlenecks facing electronic chips.
The first challenge for electronic chips is the limitation of Moore's Law. In the past nearly 50 years, the density of transistors could double every 18-20 months, but from a physical standpoint, the size of an atom is close to 0.3 nanometers. When the semiconductor process reaches 3 nanometers, it is very close to the physical limit, making it nearly impossible to continue doubling every 18-20 months.