POF-assisted quantum-dot fiber-wireless system for simultaneous high-speed underwater optical communication and white-light illumination

We propose and experimentally demonstrate a novel POF-assisted, QD-based fiber–wireless (Fi–Wi) hybrid system for simultaneous high-speed underwater wireless optical communication (UWOC) and high-quality white-light illumination using a single blue laser diode. A 10 m plastic optical fiber (POF) together with a passive QD-based liquid color conversion module (CCM) at the underwater front end composes the hybrid architecture, with no active electronics required below the waterline. The modulated blue light, delivered via the POF, excites cadmium selenide/zinc sulfide (CdSe/ZnS) \(QD_1\) (526 nm) and \(QD_2\) (626 nm) within a hermetically sealed liquid glass cavity, generating broadband white light with a CRI of 79, a CCT of 4214 K, and CIE chromaticity coordinates of (0.359, 0.3297). A maximum data rate of 1.4 Gbps with a BER of \(2.5 \times 10^{-3}\) is achieved over a combined 10 m POF and 2 m underwater link under NRZ–OOK modulation, satisfying the FEC threshold of \(3.8 \times 10^{-3}\) . Compared with existing RGB laser-diode architectures, the proposed configuration reduces the number of optical sources and eliminates wavelength-combining optics and electrically powered components at the submerged node. A stage-by-stage analytical link budget, a rate–complexity assessment, a water/POF scalability model, and a model-based QD-ratio sensitivity analysis are additionally provided to define the present performance envelope and the assumptions underlying extrapolation beyond the measured configuration. The results establish a compact laboratory proof of concept for subsea inspection, environmental monitoring, and autonomous underwater platform links.