Breaking the Wall of Full-Spectrum Communication

Breaking the Wall of Full-Spectrum Communication

Global Call 2026 Finalist Interview: Engineering & Technology

Xingjun Wang is Boya Distinguished Professor at Peking University. He is also a Fellow of the Optical Society of America, the China Institute of Communications, and the Chinese Society for Optical Engineering. His research focuses on integrated photonics for next-generation communication, sensing, and computing systems. He has authored two books, published more than 200 papers in leading journals, including Nature and Nature Photonics, and holds over 50 patents.

Which wall does your research or project break?  

Our research breaks the frequency wall that limits the evolution of future communication networks.
The rapid growth of digital technologies, artificial intelligence, and intelligent systems is driving an unprecedented demand for communication capacity. While optical fibers can already support enormous data rates, wireless networks remain constrained by fragmented frequency bands and limited hardware capability. The transition from 5G to 6G requires a fundamental shift toward full-spectrum communications, where different frequency bands, from low-frequency microwaves for wide coverage to millimeter-wave and sub-terahertz waves for ultra-high-speed connections, can be flexibly utilized according to different applications and environments.
However, current wireless systems face a fundamental frequency wall. Conventional electronic components are typically optimized for specific frequency ranges and struggle to operate across a broad spectrum. As a result, different frequency bands require separate hardware platforms, increasing system complexity, power consumption, and deployment cost. Moreover, existing technologies lack the ability to dynamically reconfigure operating frequencies in real time, preventing wireless networks from efficiently adapting to changing environments, interference, and diverse application requirements.
This limitation is becoming increasingly critical as future networks expand beyond traditional mobile communication toward applications such as immersive reality, autonomous systems, intelligent manufacturing, satellite communication, and integrated sensing and communication. Different scenarios require different frequency characteristics: low frequencies provide wide-area coverage, while higher frequencies offer the bandwidth needed for data-intensive services. Without a unified approach to managing the full electromagnetic spectrum, future communication systems will remain fragmented and unable to fully exploit available bandwidth resources.
Breaking this frequency wall is therefore essential for moving from today’s band-specific communication systems toward truly intelligent, adaptive, and full-spectrum networks that can support the next generation of information technologies.

What is the main goal of your research or project?

The main goal of our project is to establish an integrated photonic platform that enables seamless, ultrabroadband, and high-capacity communication across optical-fiber and wireless networks.
Current communication systems are divided into separate technological domains: optical technologies carry large volumes of data through fiber, while different electronic platforms generate, process, and receive wireless signals in individual frequency bands. Our goal is to replace this fragmented architecture with a unified photonic approach capable of operating from conventional microwave frequencies to millimeter-wave and sub-terahertz bands. To achieve this, we aim to develop integrated modulators, photodetectors, optical frequency combs, and programmable photonic circuits with operating bandwidths extending beyond 250 GHz. These devices are intended to provide efficient and nearly frequency-independent conversion between optical and electrical signals, allowing a single compact platform to generate, modulate, process, distribute, and detect signals over an exceptionally broad spectral range.
At the system level, our objective is to create frequency-agile wireless links that can access different communication bands without requiring separate hardware for each frequency range. By combining ultrabroadband photonic devices with flexible on-chip optical control, we seek to support continuous operation from sub-6-GHz frequencies to millimeter-wave and ultimately sub-terahertz regimes, while maintaining data rates comparable to those of modern optical-fiber systems.
The broader goal is to transform fiber and wireless communications from two separately optimized networks into a unified full-spectrum infrastructure. Such a network would dynamically allocate frequency, bandwidth, and transmission capacity according to application requirements, providing both the high capacity of optical fiber and the flexibility and mobility of wireless access. Ultimately, this project aims to establish the technological foundation for scalable 6G networks, AI-driven connectivity, integrated sensing and communication, and future data-intensive information systems.


What impact does your research or project have on society?

Our research can contribute to society by providing the ultrabroadband integrated photonics technologies required for the continued evolution of 6G networks, artificial intelligence infrastructure, and next-generation optical interconnects. For future 6G networks, communication systems will need to flexibly operate across an increasingly wide electromagnetic spectrum, from conventional microwave frequencies to millimeter-wave and potentially sub-terahertz bands. Our integrated photonic technologies provide a unified platform for generating, processing, and receiving signals across these diverse frequency ranges. This capability could support emerging applications including immersive communication, autonomous vehicles, intelligent factories, integrated sensing and communication, and high-capacity wireless access, while reducing the need for separate hardware solutions for different frequency bands. The rapid development of artificial intelligence is creating an even more urgent demand for high-capacity interconnects. As computing systems scale from individual processors to thousands or millions of interconnected chips, the challenge is no longer only computational capability, but also the ability to efficiently move massive amounts of data. The computing capacity of a chip is largely determined by its area, while the communication throughput between chips is fundamentally constrained by the available interconnection perimeter. This creates a widening mismatch between computing power and data-transfer capability. Ultrawideband integrated photonics can help bridge this gap by dramatically increasing communication density and reducing energy consumption. A single-channel analog bandwidth exceeding 200 GHz can enable optical transmission rates approaching the practical engineering limits of today’s systems, such as 400G and 800G per wavelength, providing a scalable solution for future AI computing infrastructure. Beyond communication and computing, our work can accelerate the development of the integrated photonics ecosystem by enabling compact, high-performance photonic systems for data centers, wireless networks, sensing, and microwave photonic applications. By connecting advances in integrated photonic devices with real-world communication and computing needs, this research can help build a faster, more energy-efficient, and more sustainable digital infrastructure that supports healthcare, transportation, scientific discovery, and everyday connectivity.

What advice would you give to young scientists or students interested in pursuing a career in research, or to your younger self starting in science?

My advice to young scientists is: first, build a strong foundation in your own field, but do not let disciplinary boundaries limit your vision.
A solid foundation determines whether you can truly understand a problem, evaluate whether a result is reliable, and identify meaningful scientific questions. Regardless of the field, it is essential to patiently develop a deep understanding of fundamental theories, experimental methods, and research tools. Only with systematic and profound knowledge of your own discipline can you move beyond superficial understanding and develop independent judgment when facing complex challenges.
At the same time, many of today’s most important scientific and technological challenges cannot be solved by a single discipline alone. Integrated photonics, for example, is not only rooted in optics and physics, but also closely connected with materials science, micro/nanofabrication, electronics, communications, computing, packaging, and system engineering. Young researchers do not need to master every field from the beginning, but they should remain open and curious, actively learning the languages, methods, and ways of thinking of other disciplines. Truly valuable innovations often emerge at the intersection of different areas of knowledge.
I would also like to emphasize that science is a collective endeavor. Few significant achievements are accomplished by one person alone. A great idea requires researchers with different expertise to jointly develop, validate, and refine it. Therefore, it is important to listen to others, respect different perspectives, communicate ideas clearly, and sincerely recognize the contributions of collaborators, students, and technical staff.
Scientific collaboration is not merely a division of tasks; it is a process of mutual learning and collective growth. Sharing knowledge, supporting young researchers, and building an open and trusting research environment often create more lasting value than pursuing individual achievements alone. A meaningful scientific career is defined not only by the problems we solve, but also by the people we work with, the communities we build, and the individuals we help grow.


 What inspired you to be in the profession you are today?

What drew me to this field was the question of how far optoelectronic technologies can push the limits of information transmission, processing, and sensing. I still do not have a final answer, and the pursuit of that answer continues to drive my research.
 

What is one surprising fact about your research or project that people might not know?

One surprising fact is that shrinking an optical system onto a chip does not simply make it smaller—it can give light entirely new capabilities. On a photonic chip, light can be generated, routed, modulated, processed, and detected within structures smaller than a fingernail, enabling functions that would otherwise require an entire laboratory.

What’s the most exciting moment you've experienced over the course of your research or project?

The most exciting moment was when the integrated modulator we designed and developed achieved a bandwidth exceeding 200 GHz for the first time. This nearly doubled the previously common level of around 110 GHz and marked a critical step towards photonic systems with greater bandwidth and higher data rates, capable of supporting state-of-the-art fiber-optic and wireless channels simultaneously.