Experimental demonstration of 38 Gbps over 2.5 m OWC systems with eye-safe 850 nm SM-VCSELs

With a directly modulated 850 nm single-mode vertical cavity surface emitting laser (SM-VCSEL), we experimentally achieve a gross data rate of ∼38 Gbps over a 2.5 m optical wireless communication (OWC) link at the 7% Reed-Solomon forward error correction (RS-FEC) limit. The OWC link is demonstrated using an eye-safe transmitted optical power of -1.47 dBm and discrete multi-tone (DMT) modulation with adaptive bit-and-power loading. The SM-VCSEL has a relative intensity noise (RIN) of ∼-137 dB/Hz, which is lower than that of a typical commercial 850 nm multimode VCSEL (∼-129 dB/Hz). Therefore, under almost identical OWC link operating conditions, the SM-VCSEL provides a gross data-rate increase of ∼19 Gbps and an optical signal-to-noise-ratio (SNR) gain of ∼5 dB compared to its multimode counterpart having a similar modulation bandwidth. Furthermore, we demonstrate an error-free net data rate of ∼17 Gbps at a received optical power of -7 dBm, which suggests the feasibility of utilising the SM-VCSEL to realise indoor gigabit OWC applications