VCSEL and LED Based Visible Light Communication System by Applying Decode-and-Forward Relay Transmission

In this investigation, we propose and demonstrate an integrated vertical-cavity surface-emitting laser (VCSEL) and blue light emitting diode (LED) based visible light communication (VLC) system by using the decode-and-forward (DF) relay scheme indoors. The 682 nm visible VCSEL can reach 3 Gbit/s on-off keying (OOK) modulation rate for 4 m free space transmission by applying 1.25 GHz bandwidth PIN photodiode (PD). Then, the VLC VCSEL signal connects to multiple blue LEDs for broadcasting VLC LED traffic in parallel. Therefore, the maximum VLC LED rates of 775, 700, and 600 Mbit/s are obtained at the free space transmission lengths of 2, 3, and 4 m, respectively within the forward error correction (FEC) target under 4 m VLC transmission at the low detected power of 15 μW. In addition, the number of LEDs used in the DF relay VLC system depends on the practical requirement of VLC LED rate and traffic length indoors.