Advancements in the Internet of Things (IoT) and next-generation wireless networks like 5G and 6G have escalated the demand for higher bandwidth and faster data transmission rates.1 Optics offers innovative solutions, such as optical fibers and optical wireless communication (OWC) technologies, to address these network challenges.
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Optical fiber communication uses lasers for information transmission, while OWC uses light beams to modulate information. High-speed and secure wireless communication using these optical solutions can strengthen the foundation of emerging fields, such as cloud computing, virtual reality, big data, and artificial intelligence.1,2
Role of Optical Fiber in Enhanced Network Capacity
Optical fibers use electromagnetic waves (light pulses) for data transmission along a glass or plastic fiber as thin as a human hair. They do not use electricity and are favored for long-distance and efficient communication because of their high bandwidth and transmission speeds.
Transmitting high-quality audio, visual, and digital data over long distances using a single low-loss fiber optic cable eliminates the need for amplifiers and repeaters.2
Technological enhancements in optical fibers have allowed optical fiber networks to gradually replace copper wires and become the prominent mode of communication.2
Today, optical fibers connect all continents and form the backbone of modern communication structures in metropoles, cities, towns, and even homes.3 This shift can be attributed to the advantages of optical fiber communication, such as immunity from external noise, electromagnetic interference, fire, and explosions.2
Further advancements in fiber materials and room-temperature semiconductor lasers have increased data capacity and reduced latency in optical fiber communication.2 Thus, the optical fiber medium is now being extended to the free-space medium for flexible last-mile connectivity.3
These technologies are being deployed in wireless infrastructure to support the massive increase in data traffic and connectivity requirements.2
OWC Technologies
Wireless communication provides IoT devices and users complete flexibility and necessary mobility. Most wireless networks currently use radio-frequency (RF) technologies.1 However, the RF network is too congested to future-proof wireless communication.3
The expansion of the 5G cellular network has further pushed the limits of RF technologies. Thus, researchers are now focusing on OWC technologies, which operate across a broad, license-free spectrum covering infrared, visible, and ultraviolet bands. OWC technologies such as free space optics (FSO) and visible light communication (VLC) are great alternatives to RF communications in congested areas.1
FSO communication systems, long used by the military, have recently gained commercial attention. They use light propagation across free space (atmosphere, space, or vacuum) to communicate between transceivers in the line of sight (LOS).2
FSO uses a point-to-point mechanism and the infrared spectrum to transfer information at speeds up to hundreds of gigabytes per second, far surpassing those of optical fibers.2,3 The LOS nature of OWC also provides the network with an additional layer of physical security, making it more secure than optical fiber communication.1
VLC uses the visible wavelength range and is widely employed in indoor, terrestrial, and underwater applications. It is favorable for communication and light-emitting diode (LED)-based illumination of living quarters, workspaces, and businesses. VLC links can be installed to accomplish indoor wireless networks and establish power line communication between buildings.1
Among several potential applications, the concept of smart cities is a major driver of OWC research. OWC can be used to develop indoor systems capable of monitoring and adjusting building lights, ventilation, and temperatures according to ambient conditions.
They also support building management services such as power management, security, surveillance, and communications, utilizing OWC-compatible receivers for each function. In such smart environments, OWC can revolutionize healthcare through active medical implants like ventricular heart assistance devices, biomedical sensors, and wearable devices.1
Integration Challenges and Technological Hurdles
Despite their potential, wireless technologies, including OWC, face several fundamental issues.
A primary challenge is integrating OWC with existing communication networks, as this requires LOS between modules to achieve high data transmission rates. Unfortunately, misalignment can hinder maintaining a reliable LOS link, especially in mobile applications.1
In indoor systems, wireless networking systems must connect to many devices simultaneously. This can create imbalances due to the small sizes of detectors handling diffused optical power.3
The mobile terminals in a wireless network randomly change orientation, obstructing the mobile terminal-fixed access point connection. This is due to the strict LOS requirements of OWC systems.3
The presence of numerous optical link points in a network can lead to overlapping light signals and interference. This results in poor service quality due to signal fading, low mobility, limited range, slow data rates, and high costs.2
Open communication is not entirely secure as it is prone to interference and jamming. Atmospheric twinkling (light intensity fluctuations across time and space) and unstable refractive indices due to changing air temperature can deflect light paths, increasing interference challenges and lowering the signal-to-noise ratio negatively. This negatively impacts the reliability and efficiency of the wireless network.2
In indoor applications, point sources like lasers in wireless communication systems raise concerns over eye safety. Transforming these point sources into extended ones requires additional steps.3
To fully leverage OWC technologies in next-generation wireless networks, issues related to frame rate, safety, synchronization, and ambient conditions must be addressed.1
Future Prospects and Innovations in Communication Technology
The realization of 6G communication hinges on overcoming the continuously changing obstacles in the LOS path between a base station and a user. Researchers are therefore focusing on the terahertz band (microwave and infrared), which provides near-field links for mobile network users.
However, most current FSO systems are designed for far-field operation and are suitable for long-range links. To address the issue of blockages in wireless communications, novel terahertz links that exploit self-accelerating beams are currently under development.4
Optical materials and components form the foundation of wireless optical networks. Their performance and sensitivity determine data rates, link distance, and overall link budget.3
Significant efforts are being invested in advancing optical devices, such as high-gain antennas with directional beams, which can overcome free-space path loss and achieve ultrahigh data rates.4 Arrays of micro-LEDs and novel lasers, like vertical-cavity surface-emitting lasers, are being developed for high-speed OWC applications.3
Hybrid systems that combine novel OWC technologies with existing RF wireless networks and fiber optics can improve the overall communication system with reduced interference and higher capacity.2,3 Thus, dynamic network management algorithms like software-defined networking are being developed to seamlessly integrate optical wireless networks with existing RF wireless networks and realize heterogeneous wireless networks.3
In this regard, integrated photonics and advanced modulation techniques can help achieve efficient and scalable next-gen wireless communication.
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References and Further Reading
1. Hamza, A., Tripp, T. (2020). Optical Wireless Communication for the Internet of Things: Advances, Challenges, and Opportunities. INDIGO (University of Illinois at Chicago). doi.org/10.36227/techrxiv.12659789.v1
2. Kaur, S., Singh, P., Tripathi, V., Kaur, R. (2022). Recent Trends in Wireless and Optical Fiber Communication. Global Transitions Proceedings. doi.org/10.1016/j.gltp.2022.03.022
3. Haas, H., Elmirghani, J., White, I. (2020). Optical wireless communication. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. doi.org/10.1098/rsta.2020.0051
4. Guerboukha, H., Zhao, B., Fang, Z., Knightly, E., Mittleman, D. M. (2024). Curving THz wireless data links around obstacles. Communications Engineering, 3(1). doi.org/10.1038/s44172-024-00206-3
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