Fig. 1. Schematic of multistage coupling optical antenna

Fig. 2. Optical scheme of multistage coupling optical antenna

Fig. 3. Model of compound eyes

Fig. 4. Optical path of turning len

Fig. 5. Geometry of CPC

Fig. 6. Diffusing model of indoor VLC

Fig. 7. (a)-(e) Compound eye lens model with different angles of optical axis and (f) single len model

Fig. 8. Energy collection rates at different detector areas. (a) S=9 mm2; (b) S=25 mm2; (c) S=9 mm2

Fig. 9. Relationship between energy collection rate and detection surface area

Fig. 10. Simulated optical gains

Fig. 11. Received power distributions at different models. (a) Unsheltered model without optical antenna; (b) unsheltered model with multilevel coupling optical antenna; (c) full occlusion model without optical antenna; (d) full occlusion model with multilevel coupling optical antenna