Author Affiliations
1Department of Photonics and Institute of Electro-Optical Engineering, Taiwan Chiao Tung University, Hsinchu 30010, China2Department of Electronic Engineering, The Chinese University of Hong Kong, Sha Tin, Hong Kong, China3Department of Photonics, Feng Chia University, Taichung 40724, Chinashow less
Fig. 1. (a) Experimental setup of tricolor RGB LD-based bidirectional VLC system. (b) OFDM signal encoding and decoding processes. (c) Photography of tricolor RGB LD to produce white light. AWG, arbitrary waveform generator; PBS, polarization beamsplitter; DM, dichroic mirror; PD, photodiode; RTO, real-time oscilloscope; CF, color filter; AOM, acousto-optic modulator; ED, error detector; PPG, pulse-pattern generator; LPF, low pass filter.
Fig. 2. Experimental output optical power and biased current responses of the RGB LDs. Inset: measured optical spectra.
Fig. 3. (a) Measured SNRs and bit-loading of different OFDM subcarriers. (b) Constellation diagrams of 16, 32, 64, 128, 256-QAM of red LD.
Fig. 4. (a) Measured SNRs and bit-loading of different OFDM subcarriers. (b) Constellation diagrams of 8, 16, 32, 64-QAM of green LD.
Fig. 5. (a) Measured SNRs and bit-loading of different OFDM subcarriers. (b) Constellation diagrams of 8, 16, 32, 64-QAM of blue LD.
Fig. 6. Measured log(BER) of red LD at different received powers and influence on red LD with G/B LDs off and G/B LDs on.
Fig. 7. Measured log(BER) of green LD at different received powers and influence on green LD with R/B LDs off and R/B LDs on.
Fig. 8. Measured log(BER) of blue LD at different received powers and influence on blue LD with R/G LDs off and R/G LDs on.
Fig. 9. Measured Q-value of the remodulated upstream OOK signal (red points: 1 Mbit/s, blue points: 2 Mbit/s) against different received optical powers when different LPFs are used.