The evolution of sixth-generation (6G) mobile communication systems necessitates unprecedented demands for ultra-high data rates, ultra-low latency, and ultra-reliable connectivity across terrestrial, aerial, maritime, and extraterrestrial environments. While traditional radio frequency (RF) communication has served as a foundation, it encounters significant limitations including spectrum scarcity, interference, and high energy consumption. These constraints particularly affect emerging applications such as holographic communication, real-time industrial automation, autonomous vehicles, and massive-scale Internet of Things (IoT), where current technologies struggle to meet stringent performance requirements.

Visible Light Communication (VLC), operating in the 380?700 nm wavelength range of the electromagnetic spectrum, presents a viable solution. The visible spectrum provides an extensive, unlicensed bandwidth of approximately 400 THz, enabling high-capacity communication without increasing spectral congestion. Furthermore, VLC integration with existing lighting infrastructure through LEDs and laser diodes (LDs) facilitates cost-effective deployment while serving dual purposes of illumination and communication. This approach enhances energy efficiency and supports sustainable communication technologies.

VLC demonstrates distinct advantages in specific environments. Its resistance to electromagnetic interference makes it particularly suitable for hospitals, airplanes, and factories, while its line-of-sight characteristics ensure robust physical-layer security—crucial for defense, financial, and industrial applications. Additionally, VLC proves effective for underwater communication where RF signals face severe attenuation, and in dense indoor environments where RF performance deteriorates. The high directionality and limited signal dispersion of visible light enable efficient spatial reuse, improving system capacity in multi-user scenarios.

The academic and industrial communities worldwide have identified VLC as a crucial component of 6G development. Various governmental and research initiatives actively promote VLC standardization and commercialization. As data traffic increases exponentially and ubiquitous connectivity becomes essential, VLC emerges as a vital complement to conventional wireless systems. This technology represents not merely an alternative communication method but a fundamental shift toward secure, high-capacity, low-latency networks. Consequently, advancing VLC research constitutes both a technological necessity and a critical element in developing future digital infrastructure.

Recent years have witnessed significant advancements in VLC technology across light sources, receivers, modulation and coding, signal processing, channel modeling, and MIMO systems. VLC systems utilize either LED or Laser Diode (LD) light sources. While LED systems offer cost advantages and lighting compatibility, their bandwidth remains limited. However, innovations in multi-color LEDs and micro-LED arrays have achieved data rates exceeding 25 Gbit/s over short distances (Table 1, Fig. 1). LD-based systems demonstrate superior bandwidth and coherence, with recent implementations reaching over 600 Gbit/s using 50-wavelength WDM systems (Table 2, Fig. 1).

Receiver technology developments include large field-of-view detectors, wearable perovskite receivers, and GaN-based photodetectors achieving speeds above 15 Gbit/s (Fig. 2). Signal processing advances have adapted and optimized modulation formats such as carrierless amplitude and phase (CPA), orthogonal frequency division multiplexing (OFDM), and discrete multi-tone modulation for VLC, incorporating sophisticated bit-loading algorithms and hybrid modulation schemes (Figs. 4?6). These developments enable flexible spectrum utilization and robust performance in challenging conditions.

Machine learning applications, particularly deep learning, have transformed channel modeling and equalization. Neural networks effectively model nonlinearities and turbulence-induced distortions in VLC channels (Figs. 3 and 9). Implementations of sparse multi-layer perceptrons and hybrid neural networks have optimized computational efficiency while improving post-equalization performance (Figs. 7?9). These approaches demonstrate significant effectiveness in both indoor and underwater VLC applications.

MIMO VLC systems combined with WDM have expanded capacity through spatial multiplexing. Contemporary systems utilizing compact multi-wavelength LDs and advanced precoding techniques have achieved 805 Gbit/s with spectral efficiency exceeding 50 bit/(s/Hz) (Fig. 10). Additionally, beamforming implementations using meta-surfaces, liquid crystal spatial modulators, and intelligent reflective surfaces have improved system adaptability, supporting mobile multi-user environments (Fig. 11).

Integration efforts between VLC and other communication technologies have increased. A hybrid VLC-PON system demonstrates potential for indoor high-capacity access, showing scalability toward 100 Gbit/s requirements [Fig. 12(a)]. In vehicular applications, MIMO VLC systems incorporating car headlights and structured receivers demonstrate promise for reliable high-speed in-vehicle networking [Fig. 12(b)].

VLC continues its evolution from experimental prototypes to practical implementations addressing critical limitations in current communication networks. Its vast unlicensed spectrum, lighting infrastructure compatibility, and RF interference immunity establish VLC as an innovative solution for 6G networks, particularly where RF systems prove inadequate. Nevertheless, technical challenges persist, specifically in developing efficient, cost-effective transceiver components for visible wavelengths. Future VLC systems require externally modulated coherent devices, integrated photonic circuits, and AI-driven design methodologies to overcome bandwidth and integration constraints.

Moreover, VLC demonstrates considerable potential in emerging applications such as optical interconnects in data centers, where short-range high-speed communication is essential. Laser-based VLC systems, enhanced with WDM and advanced equalization, can deliver Tbit/s-class links with reduced power consumption and system complexity. In space and underwater environments, VLC provides superior directionality and immunity to electromagnetic interference. However, the technology must address challenges related to turbulence and scattering, which can be mitigated through predictive modeling and adaptive optics techniques.

The future prospects for VLC technology appear highly promising. Ongoing research should emphasize multi-disciplinary integration, combining advancements in materials science, AI, signal processing, and nano-photonics. The development of chip-scale VLC transceivers, intelligent beam steering, and adaptive modulation strategies will facilitate VLC’s implementation in smart homes, factories, autonomous vehicles, satellite constellations, and underwater exploration systems. In the emerging 6G era, where communication demands pervasive, reliable, and instantaneous connectivity, VLC is positioned to become an integral component of the global communication infrastructure.