Photonic Continuity: Sustainable Wired and Wireless Photonics from kilobits per second (kbps) to Petabits per second (Pbps)
Introduction
In 1889, Nikola Tesla created a high-frequency radio generator. A few years later, he tested the world’s first wireless communication. Then, in 1897, Guglielmo Marconi accomplished the first radio communication, using Morse code signals, over 14 km in Great Britain. This marked the beginning of the remarkable progression of radio communication through a wide range of applications, from radar and television to smartphones and Wi-Fi.
Concerning the optical transmission technologies, Alexander Graham Bell invented the Photophone in 1881 where he transmitted a sound with an optical ray over 200 m in the free space. More recently, in the 1960s, benefitting from the joint discoveries of the laser and light detectors, researchers came up with the idea of using silica fiber to carry a light signal that could transport information potentially at very high bit rates according to the Shannon transmission limits creating then a breakthrough for telecommunication networks. And a decade later, given the evolution of communication services and their ever-increasing bandwidth requirements, fiber optics have progressively replaced copper cables and opened the patch to high-capacity transmission system. In addition, capabilities offered by fiber optics in terms of speed and low linear attenuation enabled long-distance connections to support the sub-marine transmission needs. Indeed, fiber optic transmission systems have a capacity offered in the range of Petabit (Pbps), making them the preferred medium for carrying large amounts of data in communication networks [1]. Fiber optics were first used to establish long-distance connections, by linking intercontinental and transcontinental communication nodes, for instance or to build backbones requiring high-capacity transmission systems. Today, ever-growing bandwidth requirements have resulted in the large-scale deployment of fiber optics, including the access part, making this technology increasingly accessible to the end users. For example, the rapid development of Passive Optical Networks (PONs) provided increasingly high speeds for homes, businesses (as PON+WiFi) or 5G antennas access [2].
Alongside progress in photonics for telecommunications, the world of lighting and display also underwent a technological revolution using Light Emitting Diode (LED). This solution was also applied to telecommunications because LED light intensity can be modulated and can therefore transmit binary messages. Lasers, like Vertical Surface Emitting Lasers (VSCELs) or classical lasers also played a part to build optical wireless systems operating in the Infrared spectrum (IR). The first solutions, mainly for military purposes, were outdoor point-to-point devices (FSO — Free Space Optics) or spatial (OSC – Optical Satellite Communications) and, more recently, point-to-multipoint commercial devices have become available for general deployment within a room (Li-Fi — Light Fidelity) [3]. Today’s very high-broadband wireless communications, via radio frequency in the terahertz spectral band or in the optical band, use narrow communication beams that must point at each other to connect the terminals. The established connections must be within Line Of Sight (LOS).
There is a new field of research called Fiber Wireless (Fi-Wi) or fiberless, whose operating principle is extremely simple. Inside a room, it involves taking the light beam of an optical fiber (Data Plane) from the Access Point (AP) and automatically pointing it at the User Equipment (UE) with Acquisition Pointing Tracking (APT) functions, and of course vice versa, in order to achieve very high-speed two-way communication (Figure 1).
This new idea enables a direct connection between two optical fibers, thereby reducing the optical-to-electrical-to-radio conversion to a simple optical-to-electrical conversion, while also eliminating all algorithmic processing related to radio communications. Fi-Wi connections are therefore inherently bidirectional and transparent to the modulation format or protocol (GPON, XG-PON, XGS-PON, NG-PON…) and to the wavelength. The proposed connection offers a throughput of between 1 Gbps and 1 Pbps [4] without changing the AP or UE. Furthermore, data transmission is extremely secure as the optical light beam is highly directional, energy consumption is low thanks to reduced media conversion, positioning achieves high accuracy (3 degrees of freedom, 3-DoF accuracy) thanks to the APT principle, and throughput is guaranteed for each user using point-to-point communication. The indoor network management and handover are ensured by low speed (few kbps) information exchange, between AP and UE, using LED/Camera couple (Control Plane). This control plan could also be used to collect information from devices that monitor parameters such as temperature, humidity, brightness, torque and pressure. In addition, these devices could manage their own energy production to become zero-energy devices connected to the Internet of Things (ZED IoT). Furthermore, integrating them into a FiWi system provides access to their location within a factory or greenhouse, for example. Figure 1 illustrates the proposed concept.
Figure 1: Photonic continuity concept
It should be initially used for immersive services based on virtual reality or augmented reality call Cross Reality (XR) techniques, which require high data transmission speeds. There are several possible applications of Fi-Wi, such as remote surgical operations without electrical or radio conversion, or in Virtual Reality Arcades. In the medium-term, one possible use could be holographic video call communication, which requires speeds of several Tbps and a latency of less than one microsecond.
Next stage
Associated with PON, the Fi-Wi solution provides an opportunity for an end-to-end, wireless and all-optical network test, and research in this area has generated growing interest [5–8]. This new approach is a real technological breakthrough, directly connecting the fiber-optic network and the terminals. In addition to full duplex data rate performance and positioning, this approach also offers no Electro-Magnetic Frequencies (EMF), an economic on-demand evolution with more 80 % material reuse, as well as less complexity.
The Proof of Concept defined inside the SUSTAIN 6G project will use standard components that will be integrated into a simple and compact housing for pre-industrial production to reduce size, latency and costs.
REFERENCES
[1] Prof Philip M. Parker Ph.D., “The 2025-2030 World Outlook for Optical Fiber Cables”, ICON Group International, ASIN: B0CYDYDMP2, March 3, 2024.
[2] Data Insights Market, “Passive Optical Network 2025 Trends and Forecasts 2033: Analyzing Growth Opportunities”, July 7th, 2025, https://www.datainsightsmarket.com/reports/passive-optical-network-471888#
[3] Huy Nguyen, Al-Imran, Yeong Min Jang, “Survey of next-generation optical wireless communication technologies for 6G and Beyond 6G”, ICT Express Volume 11, Issue 3, June 2025, Pages 576-589, https://www.sciencedirect.com/science/article/pii/S2405959525000529
[4] National Institute of Information and Communications Technology Japan, “World Record Achieved in Transmission Capacity and Distance: With 19-core Optical Fiber with Standard Cladding Diameter 1,808 km Transmission of 1.02 Petabits per Second”, May 29, 2025 (Japanese version released on April 24, 2025), https://www.nict.go.jp/en/press/2025/05/29-1.html
[5] Y. Hong, F. Feng, K. R. H. Bottrill, N. Taengnoi, R. Singh, G. Faulkner, D. O’Brien, and P. P., “Beyond terabit/s wdm optical wireless transmission using wavelength-transparent beam tracking and steering,” in OSA Conference on Optical Fiber Communication (OFC), OSA, 2020.
[6] Feng Shree Prakash Singh, Shreesh Kumar Shrivastava, “Fiberless optical communication: issues and challenges”, Journal of Optical Communications, February 3rd, 2023, https://doi.org/10.1515/joc-2022-0280 .
[7] Weijie Liu; Shuaiqi Chen; Nuo Huang; Chen Gong; Yuwei Chen; Zhengyuan Xu, “A Real-Time MEMS Mirror Based Beam Steering and Tracking System for Optical Wireless Communication”, Journal of Lightwave Technology – Volume: 43 Issue: 6, March 15th 2025, https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10772633
[8] Xu C, Khan UA, Ghafoor S, Mirza J, Aljohani AJ and Aziz I, “A ground-to-GEO-to-LEO satellite optical wireless communication link based on a spectrally efficient and secure modulation scheme”, Front. Phys., Sec. Optics and Photonics – Volume 13, March 15th 2025, DOI: 10.3389/fphy.2025.1562799.
