The Hong Kong Polytechnic University (PolyU) has reportedly achieved the world’s fastest optical communications speed for data centers by reaching 240 G bit/s over 2 km, which is 24 times the existing speed available. Compared to existing alternatives in the market, the technology developed by PolyU has reduced the cost of data transmission per unit to just one-fourth, and therefore is practical for commercialization purposes.

Speedy transmission at a significantly low cost for data centers enables end users to use new forms of communications such as immersive videos, augmented reality, and virtual reality. On a societal level, the increased transmission speed will open up a new era for Big Data and Internet of Things (IoT) applications, driving innovation and technology advancement.

With this development, around 10,000 people can stream 4K video at the same time, compared to only 400 under the current available speed. The research was jointly undertaken by Prof. Alex Wai, PolyU vice president (Research Development) and chair professor of Optical Communications; Prof. Chao Lu, professor, Department of Electronic and Information Engineering (EIE); Alan Lau, Ph.D., associate professor, Department of Electrical Engineering (EE); and Kangping Zhong, Ph.D., post-doctoral fellow, Department of Electronic and Information Engineering. The group collaborated with Huawei Technologies Co. Ltd., a global information and communications technology (ICT) solution provider.

Processing Data

Data centers refer to collections of interconnected computer servers and associated components that process a vast amount of Internet traffic and computations. Google, Facebook and YouTube are some widely known examples of data centers on a global scale. Whenever we conduct a search in search engines, read a newsfeed on a social media platform, stream a video online, or upload a file to the cloud, the traffic goes through data centers.

Due to the ever-increasing demand for data transmission, data center systems are the fastest-growing and most important part of today’s global telecommunications networks; they serve as the backbone of Big Data and IoT applications. However, data centers are also where the bottleneck of data transmission speed lies. Low-cost and high-speed upgrades for data center connections are needed, but the lack of a practical solution in the market has been a major technological challenge.

Overcoming Distortion

In optical communications, all types of information (e.g., text, sound, music, image and video) are digitized and transmitted as light signals over optical fiber. As light interacts (through reflection and refraction) with the molecules of the fiber during transmission, the light signal changes when it arrives at the receiver, causing a distorted signal. The higher the transmission speed and the longer the distance, the more severe the distortion becomes, rendering the light signal unrecognizable at the receiver. This leads to failed transmission and limits the maximum transmission speed. By overcoming the challenge of distortion, speed can be increased.

The existing approach to undo distortion is through the use of specialized hardware. Using high-cost components such as specialized optical fiber, for example, is a possible way to reduce distortion. However, the high cost and bulky size rendered such a solution impractical for the data center industry. Instead of using costly components, PolyU’s research team has developed a software approach to solve the distortion problem.

According to theories in optics, interactions between light and a single molecule of fiber are well-known. However, in an optical fiber consisting of billions of molecules randomly placed and oriented with each other, the overall effect of interactions between the light signal and the fiber become unknown, and therefore the signal distortion is also random. Nevertheless, there is “an order in chaos.” Through performing Big Data statistical analyses of massive amounts of transmitted and received light signals, the researchers can identify the distortion pattern—and a considerable reversion of distortion can be made. In doing so, a significant increase in transmission speed can be achieved with inexpensive and mature components. By combining optics and statistics, the algorithm software developed by PolyU enables simpler, cheaper, and commercially favorable optical communications solutions with world-record breaking speeds for next-generation data center applications.