Can you imagine that through clever arrangements, many football teams are training on the same pitch without interfering with each other? A Chinese research team has found such a compact solution for light waves on photoelectronics chips. Optical electronic spratings are cutting-edge devices in the field of optical communication, and the high-capacity optical signaltransmitted by optical fiber translates into a server and the processor can “read” the electrical signal.
(Original title: China’s Top Ten Optical Progress, Add lanes to the chip photons, break through the bottleneck of large-scale integration)
Journalist Yu Hanqi
In the face of rolling data streams, small- and low-power optoelectronic smaller optical chips are under pressure in terms of bandwidth.
Xu Ke, associate professor of Harbin University of Technology (Shenzhen), and Song Qinghai, a researcher at Shanghai Jiaotong University, and He Zuyuan, a professor, have successfully designed new structures and optimization algorithms to add “lanes” to optoelectronic chips, while solving the problemofs of crosstalk and loss, paving the way for large-scale integration.
The China Laser Magazine, sponsored by the Shanghai Institute of Optical Precision Machinery of the Chinese Academy of Sciences and the China Optical Society, recently released the top ten advances in Chinese optics for 2019, with the above-mentioned “advanced and arbitrary lym-multiplexphoto chips” selected as the result of applied research.
In an exclusive interview with Thepaper.cn on March 26, Mr Xu said the work was based on a cutting-edge concept of “module reuse” and broke through key bottlenecks.
“We made it possible to multi-use photonic chips on a large scale, ” he says. “We’ve demonstrated three data channels so far, the latest results are four, and in the future we’re going to make further breakthroughs in the number of multiplexed channels while reducing the power consumption of the chip.” “
The gateway to photoelectric conversion
The semiconductor optoelectronic smsets studied by the team are among the kinds of communication chips that have emerged in recent years.
The basic principle of optical communication system is this: the transmitter modulates the electrical signal of the high-speed data stream to the optical signal output of the laser, transmits it through optical fiber, receives the optical signal at the receiving end and then converts it into an electrical signal, which is converted into information after modulation.
Photoelectronic smies take on the task of photoelectric conversion. According to Xu Ke, large-capacity, high-data stream photovoltaic chips, in 5G forward transmission, data center, supercomputing interconnect system have important applications. They may also be seen in other areas such as quantum computing, artificial intelligence, and biosensing in the future.
As you can imagine, the bandwidth of optical chips is critical to the speed of the entire system. Even if the fiber transmission speed is faster, like the flight time of the plane is very short, but only a queue at the exit security check, will slow down the entire journey.
Increase the “lane” of communication
The concept of module duplexing was born to significantly improve the parallel processing power of a chip without increasing the number of lasers.
“Before we mention the concept of multiplexing, let’s first introduce wave duplex. Xu ke said. Wave division reuse was proposed as early as 1978, and has been widely used in trunk fiber optic transmission systems.
Each data channel (waveguide) transmits several to dozens of wavelengths, each loading different data. Since the wavelengths do not interfere with each other, the communication capacity can be increased by increasing the number of wavelength channels, which is wave division reuse.
“The module multiplexing is similar to wave duplexing, but it replaces the wavelength with another physical quantity of light wave (wave guide mode), adding a dimension to the multiplexing technology, and is a new method to increase communication capacity.” Xu Ke said.
He believes that as bandwidth demand continues to grow rapidly, module multiplexing technology can further increase the bandwidth of photonic chips when wavelength resources are saturated.
Moving towards large-scale integration
In recent years, people have done a lot of research to improve the bandwidth of optoelectronic chips through the multiplexing technology. However, a key problem that cannot be solved is the loss of multimoded photoguided and crosstalk.
“This makes it impossible for module multiplexing chips to be routed on a large scale as integrated circuits. Xu ke said.
In view of this difficult problem, the team designed a discrete waveguide superstructure, which is a new photon structure that looks a bit like two-dimensional code, and can realize the fine regulation of the light field with the optimization algorithm.
The researchers designed and prepared key devices such as a pattern (solution) multiplexer, multimode curved waveguide, and waveguide crossover, measuring only a few microns in size, an order of magnitude smaller than conventional devices, and fully compatible with the standard silicon photoflow process.
The transmission waveguide maintains high efficiency and low crosstalk signal transmission at any bending and crossover.
(a) A microscope photograph of a three-mode multiplex and curved structure; (b) A microscope photograph of the mode reuse and the consition of the device; (c) A photo of a curved waveguide SEM with a sub-wavelength superstructure; (d) Three-mode reuse and cross-structure of microscope photographs; (e) Cascade waveguide cross-device microscope photos; (f) SEM photo of a waveguide crossover device with a sub-wavelength superstructure.
This new multimode device of the micron scale makes it possible for the module multiplexing signal to perform low loss, low crosstalk (solution) multiplexing and arbitrary large-scale interconnection on the chip, and also provides a new technology option for cutting-edge optical communication devices.
The global optical communications device market has grown steadily in recent years and is expected to generate $16.6 billion in revenue by 2020. China has a market share of about 30%, but the core infrastructure is weak in research and development and manufacturing capabilities.
The Ministry of Industry and Information Technology issued the “China Optoelectronics Devices Industry Technology Development Roadmap (2018-2022)” proposed to ensure that the 2022 low-end optoelectronic chip localization rate of more than 60%, high-end optoelectronic chip localization rate of more than 20%.
“High-end optoelectronic chips have been the upstream technology of developed countries to compete for the first layout, and China’s current degree of localization is still very low. Xu Ke said. “We must be acutely aware of the need to break through key core chip technology and get rid of the ‘lack of core and lack of soul’ dilemma. “