A novel integrated fully passive optical network for free-space optics and visible light communication for last-mile access network based on composite phosphor film

A simple and low cost, integrated, fully passive optical network of free-space optics (FSO) and indoor visible light communication (VLC) technique, which can be used for both solid-state lighting and last-mile access network, is proposed in this paper. As a proof of a concept, a non-return-to-zero on-off keying (NRZ-OOK) modulation scheme for transmission over an integrated fully passive optical link of 7-m FSO, 2-m plastic optical fiber and 30-cm VLC was demonstrated by achieving 1.4-Gbps data rate with a bit error rate of 2.6 ×10⁻³. The phosphor film diverges the blue laser beam to a white light spot covering a radian angle up to approximately 120° with Commission Internationale de l'Eclairage CIE of (0.3439, 0.3541), which is very close to the perfect white area of CIE 1931 chromaticity coordinates (0.3333, 0.3333). Additionally, the generated white-light exhibits low correlated color temperature (CCT) of 5056 K and a high color rendering index (CRI) of 91. The proposed technique will find a wide range of applications in integrated, fully passive optical networks of free-space optics and indoor visible light communication.