5Gb/s Eye-Safe LED-Based SI-POF Transmission With Equalization of Transmitter Nonlinearities

Laboratory experiments on optical short range transmission with light-emiting diodes (LEDs), different lengths of step-index polymer optical fiber (SI-POF), and p-i-n-diode-based reception are performed. We compare multilevel pulse amplitude modulation with different spectral efficiencies with a particular focus on the impact of LED-based nonlinear signal impairments. A resonant cavity LED is used which emits a fiber-coupled power of -0.8 dBm at 650 nm. The impact of LED nonlinearities on the system power budget is evaluated, showing that compensation of these nonlinear signal distortions may noticeably increase the system power budget, even for 4-PAM. Applying a reduced-length Volterra-series-based post equalization, we report successful transmission of 5 Gb/s over 20 m of SI-POF, 2.25 Gb/s over 50 m, 1.1 Gb/s over 80 m, and 620 Mb/s over 100 m. To the best of our knowledge, the data rates obtained here set new record values using such an LED and SI-POFs, and we further show that gigabit per second transmission is also possible beyond 50m of SI-POF. Moreover, it generally demonstrates that competitive data rates using LEDs and p-i-n diode reception are possible with a well-adapted digital signal processing scheme. The results obtained here may also serve as a valuable information on how to maximize the bitrate of LED-based visible light communication (VLC) systems.