Path-loss optimized indoor laser-based visible light communication system for variable link length gigabit-class communication

• Published in: IEEE photonics journal Vol. 12; no. 4; p. 1
• Main Authors: Ahmad, Faheem, Ramachandrapura, Sathisha Nagaraju, Manattayil, Jyothsna Konkada, Raghunathan, Varun
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 01.08.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Advanced optics design; Communication; Communications systems; Error correction; Free-space communication; Illuminance; Illumination; Laser applications; Laser beams; Lasers; Lenses; Lighting; Luminaires; Optical communication; Optical fiber communication; Optical receivers; Optical transmitters; Optimization; Phosphors; Photodetectors; Ray tracing; Solid-state lighting; Visible lasers; White light
• ISSN: 1943-0655; 1943-0655; 1943-0647
• DOI: 10.1109/JPHOT.2020.3014216

We discuss an optical ray-tracing approach to minimizing path-loss in a variable link length indoor blue laser down-converted white light visible light communication(VLC) system. For a given link length, minimum path-loss is achieved by finding optimum positions of transmitter and receiver lenses relative to phosphor and detector respectively such that collection efficiency is maximized. The designed VLC system is experimentally implemented for two different optimized link lengths of 25 and 300cm. Down-converted white light for the optimized link is found to exhibits narrow beam spread, spot-lighting type profile. The white light is measured to quantify beam profile, color rendering, illuminance and blue-content. Illumination beam profile and propagation characteristics are found to be in good agreement with optical simulations. Communication experiments with on-off modulated at 1.5Gbps achieved BER of \sim 3 \times 10^{-3} for the two optimized link, which is below the forward-error correction threshold. Above communication performance is achieved at illuminance levels as low as \sim; 45 and 16lx. Comparison with previous laser-based VLC implementations shows that path-loss optimization helps achieve gigabit-class communication at practically relevant link lengths and at lowest illuminance thus far reported. Such low illuminance level, narrow beam spread VLC luminaires can potentially coexist with lighting infrastructure for eye-safe indoor applications.