20.231 Gbit/s tricolor red/green/blue laser diode based bidirectional signal remodulation visible-light communication system

We propose and experimentally demonstrate a recorded 1-m bidirectional 20.231-Gbit/s tricolor R/G/B laser diode(LD) based visible-light communication(VLC) system supporting signal remodulation. In the signal remodulation system, an LD source is not needed at the client side. The client reuses the downstream signal sent from the central office(CO) and remodulates it to produce the upstream signal. As the LD sources are located at the CO, the laser wavelength and temperature managements at the cost-sensitive client side are not needed.This is the first demonstration, to our knowledge, of a >20 Gbit∕s data rate tricolor R/G/B VLC signal transmission supporting upstream remodulation.

Remodulation scheme based on a two-section reflective SOA

A simple and cost-effective remodulation scheme using a two-section reflective semiconductor optical amplifier （RSOA） is proposed for a colorless optical network unit （ONU）. Under proper injection currents, the front section functions as a modulator to upload the upstream signal while the rear section serves as a data eraser for efficient suppression of the downstream data. The dependences of the upstream transmission performance on the lengths and driven currents of the RSOA, the injection optical power and extinction ratio of the downstream are investigated. By optimizing these parameters, the downstream data can be more completely suppressed and the upstream transmission performance can be greatly improved.

Centralized light-wave WDM-PON employing DQPSK downstream and OOK remodulated upstream signals

A novel architecture for wavelength-division-multiplexing passive optical network （WDM-PON） with centralized light-wave is proposed and demonstrated. At the optical line terminal （OLT） session of this architecture, optical differential quadrature phase shift keying （DQPSK） modulated signal with constant-intensity at 10 Gbit/s is utilized for downstream transmission. At the optical network unit （ONU）, part of the downstream optical power is remodulated with on-off keying （OOK） intensity modulation at 10 Gbit/s for upstream without additional laser. Simulation results show that the power penalties of the downstream for 20 km single-mode fiber （SMF） transmission and multi-channels are negligible. While for the upstream, the power penalties are obvious. The simulation results and analysis also reflect that by reducing the launch power of DQPSK transmitters, power penalties can be reduced, although the transmission distance is limited.