Visible light communication (VLC) is an advanced, highly developed optical wireless communication (OWC) technology that can simultaneously provide lighting and high-speed wireless data transmission. A VLC system has several key advantages: ultra-high data rate, secure communication channels, and a lack of interference from electromagnetic (EM) waves, which enable a wide range of applications. Light-emitting diodes (LEDs) have been considered the optimal choice for VLC systems since they can provide excellent illumination performance. However, the quantum confinement Stark effect (QCSE), crystal orientation, carrier lifetime, and recombination factor will influence the modulation bandwidth, and the transmission performance is severely limited. To solve the insufficient modulation bandwidth, micro-LEDs (μ-LEDs) and laser diodes (LDs) are considered as new ideal light sources. Additionally, the development of modulation technology has dramatically increased the transmission capacity of the system. The performance of the VLC system is briefly discussed in this review article, as well as some of its prospective applications in the realms of the industrial Internet of Things (IoT), vehicle communications, and underwater wireless network applications.

Optical modulators are indispensable components in optical communication systems and must be designed to minimize insertion loss, reduce driving voltage, and enhance linearity. State-of-the-art silicon modulator technology has limitations in terms of power, performance, and spatial size. The addition of materials such as thin-film lithium niobate (TFLN), silicon–organic hybrids (SOH), and plasma–organic hybrids (POH) has improved the modulation performance in silicon photonics. An evaluation of the differences among these modulators and their respective performance characteristics is conducted.

We propose a highly polarized vertical-cavity surface-emitting laser (VCSEL) consisting of staggered InGaN multiple quantum wells (MQWs), with the resonance cavity and polarization enabled by a bottom nanoporous (NP) n-GaN distributed Bragg reflectors (DBRs), and top TiO₂ high-index contrast gratings (HCGs). Optoelectronic simulations of the 612 nm VCSEL were systematically and numerically investigated. First, we investigated the influences of the NP DBR and HCG geometries on the optical reflectivity. Our results indicate that when there are more than 17 pairs of NP GaN DBRs with 60% air voids, the reflectance can be higher than 99.7%. Furthermore, the zeroth-order reflectivity decreases rapidly when the HCG’s period exceeds 518 nm. The optimal ratios of width-to-period (52.86 ± 1.5%) and height-to-period (35.35 ± 0.14%) were identified. The staggered MQW design also resulted in a relatively small blue shift of 5.44 nm in the emission wavelength under a high driving current. Lastly, we investigated the cavity mode wavelength and optical threshold gain of the VCSEL with a finite size of HCG. A large threshold gain difference of approximately 67.4–74% between the 0th and 1st order transverse modes can be obtained. The simulation results in this work provide a guideline for designing red VCSELs with high brightness and efficiency.

Compact photonic devices that integrate metasurfaces with light sources have been widely studied. However, experimental demonstrations of a higher efficiency of integration are still lacking. To enhance the efficiency of light sources integrated with metasurfaces, we employed a forward design optimization method and index matching between the light source and metasurface substrate to design metagratings. To optimize the overall diffraction efficiency, we manipulated the degrees of freedom in phase, the lattice constants, and the number of unit cells. The same material was utilized for the nanostructures and substrate (homo-metagrating) for index matching, while Si and GaAs materials were used for working at 1550 and 940 nm, respectively. The experimental homo-metagratings operating at 1550 nm and made of Si exhibited an overall average efficiency of 51.3% at diffraction angles of 60.3°. On the other hand, experimental homo-metagratings operating at 940 nm and made of GaAs exhibited an overall average efficiency of 52.4% at diffraction angles of 49.3°. This suggests that the future integration of metagratings with a polarization-specific laser can further enhance the overall diffraction efficiency.