In this work, a full-duplex time and wavelength division multiplexing-passive optical network (TWDM-PON) system is analysed. Orthogonal frequency division multiplexing (OFDM) with m-quadrature amplitude modulation (m-QAM) is employed to improve the performance of TWDM-PON for downstream and upstream transmission. Simultaneously, multi-color (390-750 nm) laser diodes (LDs) are employed for visible light communication (VLC) using various VLC links to encourage the information rate of fiber/VLC optical network. A TWDM-PON utilizing 16-, 32-and 64-QAM OFDM with ten LDs based VLC system has been analysed for full-duplex multi-color VLC signals of the system. The impact of the LDs input current and high transmission rate in the proposed PON/VLC link has been investigated for m-QAM OFDM modulation. The results show that the 40/40 Gbps 16-, 32-and 64-QAM signals over ten 8000 m VLC links and a 50 km fiber link are successfully transmitted at the modulation input current of 9 mA under bit error rate (BER) of 3.8×10 -3 .Also, the proposed system employing 16-, 32-and 64-QAM signals over a 10 km fiber and ten 10 m VLC links provide the maximum transmission rate of 120, 100 and 80 Gbps respectively. Moreover, the measured error vector magnitudes (EVMs) and calculated BER values for 16-QAM downstream and upstream signals, are well below the required FEC limit than high-order modulation formats. Further, the numerical analysis of the proposed system reveals the superiority of the proposed fiber/VLC links.